J Neurol DOI 10.1007/s00415-014-7261-7
ORIGINAL COMMUNICATION
Clinical, neurophysiological, and skin biopsy findings in peripheral neuropathy associated with hepatitis C virus-related cryoglobulinemia A. Biasiotta • M. Casato • S. La Cesa • S. Colantuono G. Di Stefano • C. Leone • M. Carlesimo • S. Piroso • G. Cruccu • A. Truini
•
Received: 23 November 2013 / Revised: 21 January 2014 / Accepted: 22 January 2014 Ó Springer-Verlag Berlin Heidelberg 2014
Abstract Hepatitis C virus (HCV)-related cryoglobulinemia commonly causes disabling complications including peripheral neuropathy and neuropathic pain. In this prospective clinical, neurophysiological, and skin biopsy study we aimed at assessing clinical characteristics and risk factors of peripheral neuropathy and neuropathic pain in patients with HCV-related cryoglobulinemia. We enrolled 69 consecutive patients with HCV-related cryoglobulinemia. We diagnosed neuropathic pain with the DN4 (Neuropathic Pain Diagnostic) questionnaire, and rated the various neuropathic pains with the Neuropathic Pain Symptom Inventory (NPSI). All patients underwent a standard nerve conduction study to assess Ab-fiber function, laser-evoked potentials to assess Ad-fiber function, and skin biopsy to assess C-fiber terminals. Of the 69 patients studied, 47 had a peripheral neuropathy, and 29 had neuropathic pain. Patients with peripheral neuropathy were older than those without (P \ 0.0001). While peripheral neuropathy was significantly associated with the duration of HCV infection (P \ 0.01), it was unrelated to the duration of cryoglobulinemia and cryocrit (P [ 0.5). The severity of peripheral neuropathy significantly correlated with the duration of HCV infection (P \ 0.05). Laser-evoked potential amplitudes were significantly lower in patients with than in those without neuropathic pain (P \ 0.05). Conversely, no difference was found in nerve conduction A. Biasiotta S. La Cesa G. Di Stefano C. Leone S. Piroso G. Cruccu A. Truini (&) Department of Neurology and Psychiatry, Sapienza University, Viale Universita` 30, 00185 Rome, Italy e-mail: [email protected] M. Casato S. Colantuono M. Carlesimo Department of Clinical Immunology, Sapienza University, Rome, Italy
study and skin biopsy findings (P [ 0.05). Our findings show that peripheral neuropathy is related to age and HCV infection, rather than to cryoglobulinemia, and neuropathic pain is associated with damage to nociceptive pathways as assessed with laser-evoked potentials; this might be useful for designing more effective clinical interventions for these common HCV related-cryoglobulinemia complications. Keywords Peripheral neuropathy HCV Cryoglobulinemia Skin biopsy Neuropathic pain
Introduction Patients with hepatitis C virus (HCV)-related cryoglobulinemia commonly suffer from peripheral neuropathy [1, 11]. The reported prevalence ranges from 9 to 77 % [1, 5, 9, 19]. This complication frequently manifests as a distal, predominantly sensory polyneuropathy, with neuropathic pain being a frequently reported symptom [19, 23]. The reference standard test for diagnosing neuropathy is the nerve conduction study [8, 12]. This neurophysiological technique nevertheless has the disadvantage of assessing non-nociceptive, large-myelinated fibers (Ab fibers) alone and provides no information on nociceptive pathways [7]. The widely accepted methods for investigating nociceptive pathways are laser-evoked potentials, responses mediated by small myelinated (Ad) fibers, and skin biopsy to assess C-fiber terminals [18, 20]. In patients with neuropathic pain due to peripheral neuropathy, clinical assessment relies on psychometric measures, such as pain questionnaires including the DN4 questionnaire [3], a clinician-administered diagnostic screening tool. The self-administered Neuropathic Pain Symptom Inventory (NPSI) is a tool designed to measure the intensity of the various neuropathic pains [2].
123
J Neurol
Although patients with HCV related-cryoglobulinemia commonly present with peripheral neuropathy and neuropathic pain, few studies have dealt with clinical characteristics and risk factors of peripheral neuropathy [1, 9, 19] and none have addressed the frequency, clinical characteristics, and mechanisms underlying neuropathic pain in patients with peripheral neuropathy associated with HCVrelated cryoglobulinemia. This information could be useful for developing more effective therapeutic approaches for these clinical conditions that notoriously adversely affect the patient’s quality of life. We designed this prospective clinical, neurophysiological, and skin-biopsy study in patients with HCV-related cryoglobulinemia to investigate how the various clinical features influence the development of peripheral neuropathy and define the role of primary afferent fibers (nonnociceptive Ab, nociceptive Ad, and C afferent fibers) in neuropathic pain development.
from further analysis owing to their high prevalence in the general population. The research was approved by the local Institutional Review Board and patients gave written informed consent to the procedures. HCV and cryoglobulin determination Antibodies to HCV were determined by enzyme-linked immunosorbent assay, and serum HCV-RNA was identified by reverse transcription polymerase chain reaction (RT-PCR). For determining cryoglobulinemia, full blood samples were collected at 37 °C in serum tubes. About 5 ml were obtained after centrifugation for 10 min at 3,000 g in a pre-warmed centrifuge at 37 °C. Then serum was maintained in a cryocrit tube and incubated for 7 days at 4 °C. If the serum remained completely clear after the incubation, a negative result was reported. Thirty-six of the 69 patients included in the study had a cryocrit C5 % [10]. Clinical examination
Methods In the local university hospital immunologic clinic we prospectively screened in a 2-year period (April 2011– April 2013) 74 unselected patients with HCV-related cryoglobulinemia. Exclusion criteria were diagnosis of neurological diseases other than peripheral neuropathy, cognitive impairment, and other conditions potentially affecting peripheral nerves. To exclude the other causes of neuropathy, several laboratory investigations were performed (glycemia and glycated haemoglobin, electrolytes, kidney and liver function tests, full blood count, vitamin B12 and folate levels, thyroid function tests, serum protein electrophoresis, serology testing including HIV and hepatitis B, syphilis, paraneoplastic antibodies, and autoantibodies). We excluded five patients (four with diabetes, one with kidney failure) and therefore enrolled 69 patients with HCV-related cryoglobulinemia. No patients had hematological or oncological diseases. All of the included patients had type II cryoglobulinemia (monoclonal IgM-polyclonal IgG complexes) with clinically evident vasculitis manifesting with purpura or mild internal organ involvement. All recruited patients underwent neurological examination (including DN4 and NPSI), nerve conduction study, laser-evoked potential recordings, and skin biopsy in the Department of Neurology and Psychiatry. Distal symmetric polyneuropathy was diagnosed on clinical, biological, and electrodiagnostic findings, adhering to the criteria proposed by England et al [8]. Mononeuropathy and mononeuropathy multiplex were diagnosed when neuropathy differently affected one nerve or two non-contiguous, asymmetrically distributed nerves. We also checked isolated mononeuropathies involving the median nerve, but excluded them
123
All patients underwent a detailed neurological examination using bedside tools. Touch was investigated with a piece of cotton wool, vibration with a tuning fork (128 Hz), pinprick sensation with a wooden cocktail stick. In all patients, laser stimuli were used for a quantitative evaluation of warm and pinprick sensations. Muscle strength was assessed using the Medical Research Council score. Patients were also asked to report dysautonomic symptoms. Patients were grouped according to the clinically documented presence or absence of neuropathic pain, as assessed by DN4. Patients with neuropathic pain completed the NPSI questionnaire. NPSI subscores were calculated for the various pain types: ongoing pain (superficial burning, and deep pressing and squeezing pain), paroxysmal, provoked pain, and abnormal sensations (paraesthesia and dysaesthesia). Neurophysiological examination and skin biopsy Patients underwent a motor and sensory nerve conduction study using surface recording electrodes with standard placement. A nerve conduction study comprised sensory nerve action potentials (SNAP) and conduction velocities recorded from sural, ulnar, and superficial radial nerves. Other nerve function variables examined were compound motor action potential (CMAP) amplitude and peroneal, tibial, and ulnar nerve condition velocities. The methods used adhered to those recommended by experts of the International Federation of Clinical Neurophysiology [13]. To study laser-evoked potentials, we used a neodymium:yttrium–aluminium–perovskite (Nd:YAP) laser [22]. The dorsum of the right foot and left hand were stimulated with laser pulses (intensity: 150–200 mJ/mm2, pulse
J Neurol
duration: 5 ms, beam diameter: 5 mm) eliciting pinprick sensations. The early, lateralized component, N1, and the main complex, N2–P2, were recorded through disc electrodes from the temporal areas (Tc) referenced to the frontal area (Fz) and the vertex (Cz) referenced to the nose. A range of 10–20 artifact-free trials were collected and averaged. Neurophysiological data were compared with normative ranges established in our laboratory, from a sample of 80 healthy subjects (40 F, 40 M; mean age 64.3 ± 8.3 years, range 30–81 years. The age of this group and the age of enrolled patients did not differ, P [ 0.05). Patients underwent skin biopsies from the proximal thigh (20 cm below the anterior iliac spine) and the distal leg (10 cm above the lateral malleolus, within the sural nerve territory). Biopsies were taken after local anesthesia using a 3-mm disposable punch under a sterile technique. Three sections randomly chosen from each biopsy were immunoassayed with polyclonal anti-protein-gene-product 9.5 antibodies using the free-floating protocol for brightfield immunohistochemistry. In the assessment of the intraepidermal nerve fiber density, we used the recommendations and normative ranges of the European Federation of the Neurological Societies [14]. Statistical analysis We used the unpaired t test and the Mann–Whitney test to compare the normally and the non-normally distributed clinical and laboratory variables in patients with and without peripheral neuropathy, and with and without neuropathic pain. Although in the clinical analysis we used several clinical and neurophysiological variables for diagnosing peripheral neuropathies and categorizing patients, we selected only sural-nerve sensory action potential, foot laser-evoked potential amplitude, and the intraepidermal nerve fiber density at the distal leg for the correlation analysis with the clinical variables, because virtually all patients had a distal symmetric, predominantly sensory neuropathy (see ‘‘Results’’). Hence, these three variables reliably represent the peripheral nerve damage characteristics of our patients. We used the Spearman’s rank correlation coefficient for the correlation analysis between clinical and laboratory variables. The chi-squared test was used to assess frequency differences in HCV genotype and a cryocrit level C5 % in patients with and without peripheral neuropathy. P values \0.05 were considered to indicate significance. All data are reported as the mean ± SD.
Results Of the 69 patients included in the study (56 F, 13 M; mean age 66 ± 11.5 years, range 30–82 years), 35 were treated
for HCV infection or HCV-related cryoglobulinemia (with interferon, ribavirin, rituximab) or both. Of these 69 patients, 47 patients (68 %) had a peripheral neuropathy. Most patients (45 of the 47 with peripheral neuropathy) had a predominantly sensory, distal symmetric polyneuropathy. Of these 45 patients, four had a pure small fiber neuropathy (SFN), yielding normal nerve conduction findings, but abnormal laser-evoked potentials and intraepidermal nerve fiber density. Two patients suffered from a mononeuropathy multiplex. No patient had isolated mononeuropathy, or predominantly motor neuropathy. Although most of the 45 patients with distal symmetric polyneuropathy had sensory disturbances involving all sensory modalities, seven patients had a predominantly large fiber neuropathy (all without hypoalgesia, hyperalgesia and/or pain); conversely the four patients with pure SNF had a selective involvement of thermal-pain sensitivity. The two patients with mononeuropathy multiplex presented sensory disturbances mimicking a mixed-fiber, distal symmetric polyneuropathy. While patients with peripheral neuropathy were older than those without (unpaired t test, P \ 0.0001), gender frequency did not differ (chi-squared test, P [ 0.1). Duration of HCV infection (time from diagnosis) was longer in patients with peripheral neuropathy than in those without (unpaired t test, P = 0.0047); conversely, no difference was found in the duration of cryoglobulinemia or the cryocrit (Mann–Whitney test, P [ 0.5) (Table 1). The development of peripheral neuropathy was unrelated to the HCV genotype (P [ 0.1, chi-squared test). The frequency of peripheral neuropathy in patients with a cryocrit C5 % did not differ from that of patients with a cryocrit \5 % (chisquared test, P [ 0.1). Foot-LEP and sural-nerve sensory action potential amplitudes, and the intraepidermal nerve fiber density were inversely correlated with the duration of HCV infection (sural-nerve action potential: Spearman’s r = -0.3268, P = 0.006; laser-evoked potentials: Spearman’s r = -0.2715, P = 0.02 intraepidermal nerve fiber density: Spearman’s r = -0.3630, P = 0.002). Of the 47 patients with peripheral neuropathy, 29 (62 %) had neuropathic pain as assessed with the DN4. In patients with and without pain, age and gender frequency did not differ (age: unpaired t test, P [ 0.1; gender frequency: chisquared test, P [ 0.5). All patients with neuropathic pain also reported non-painful sensory disturbances (pins-andneedles and tingling), rated as 6.9 ± 2.4 in intensity on the 0–10 numerical pain rating scale. The most frequent pain types were superficial burning (21 patients of the 29 with neuropathic pain, intensity 5.2 ± 3.5) and deep pain (both squeezing and pressure; 22 patients of the 29 with neuropathic pain rated as 5.4 ± 3.5 in intensity for squeezing and 5.3 ± 3.5 for pressing pain). In nine patients (all with neuropathic pain as assessed with DN4), clinical
123
J Neurol Table 1 Clinical and laboratory findings in patients with and without peripheral neuropathy F:M
Age (years)
Patients without peripheral neuropathy
16:6
58.1 ± 13.2
Patients with peripheral neuropathy P
40:7
69.3 ± 8.6
\0.0001*
Duration of HCV (years)
Duration of cryoglobulinemia (years)
Cryocrit
Sural SNAP amplitude (lV)
Foot-LEP amplitude (lV)
Distal leg IENF density (mm)
9.7 ± 7.3
4.9 ± 5.6
4.5 ± 4.3
16.6 ± 6.6
19.9 ± 8.5
6.4 ± 2.7
15.6 ± 8.0
5.5 ± 3.9
4.8 ± 5.9
2.6 ± 4.0
6.4 ± 9.5
3.2 ± 2.3
0.6352*
0.7201**
\0.0001**
\0.0001**
0.0047*
0.0001*
HCV hepatitis C virus, SNAP sensory nerve action potential, LEP laser-evoked potential, IENF intraepidermal nerve fiber * Unpaired t test ** Mann–Whitney test
Fig. 1 Laboratory assessment in patients without peripheral neuropathy and with painless and painful neuropathy. First row sural SNAP (sensory nerve action potential). Second row N1, N2-P2 components of laser-evoked potentials, third row intraepidermal nerve fiber density as assessed with skin biopsy (arrows indicate the nerve fibers). Sural SNAP and foot laser-evoked potential amplitude, and intraepidermal nerve fiber density felt within normal ranges in
patients without peripheral neuropathy. In the representative patients with peripheral neuropathy, all laboratory testing variables were abnormal. While sural SNAP amplitude and intraepidermal nerve fiber density did not differ between the patient with and without pain, laser-evoked potential amplitude was lower in the patient with pain than in the patient without pain
examination also showed pinprick hyperalgesia. Whereas laser-evoked potential amplitudes were lower in patients with neuropathic pain than in those without (Mann–Whitney test, P \ 0.05), no difference was found between groups for the sural-nerve sensory action potentials and the intraepidermal nerve fiber density (Mann–Whitney test P = 0.5; unpaired t test, P = 0.08) (Fig. 1; Table 2). In patients with peripheral neuropathy, superficial burning pain inversely correlated in severity with laser-evoked potential amplitudes (Pearson’s r = -0.3881, P = 0.007), but not with the other laboratory variables (P [ 0.1).
Discussion
123
In this prospective clinical, neurophysiological, and skin biopsy study in an unselected sample of consecutive patients, we show that most patients with HCV-related cryoglobulinemia (68 %) have peripheral neuropathy, virtually all having a predominantly sensory, distal polyneuropathy. The major clinical variables for the development of peripheral neuropathy are age and duration of HCV infection. Neuropathic pain is a frequent complaint (62 % of patients with peripheral neuropathy) and depends on the
J Neurol Table 2 Clinical and laboratory findings in patients with painless and painful neuropathy F:M
Age (years)
Duration of HCV (years)
Duration of cryoglobulinemia (years)
Cryocrit
Sural SNAP amplitude (lV)
Foot-LEP amplitude(lV)
Distal leg IENF density (mm)
Patients with painless neuropathy
15:3
68.0 ± 7.2
15.9 ± 8.6
5.8 ± 2.6
3.5 ± 4.0
3.2 ± 4.6
10.1 ± 10.5
4.0 ± 2.9
Patients with painful neuropathy P
25:4
70.1 ± 9.4
15.4 ± 7.8
5.1 ± 4.6
5.7 ± 6.7
2.3 ± 3.6
4.1 ± 8.2
2.7 ± 1.6
0.4217*
0.8352*
0.5536*
0.3845**
0.4768**
0.0228**
0.08*
HCV hepatitis C virus, SNAP sural sensory nerve action potential, LEP laser-evoked potential, IENF intraepidermal nerve fiber * Unpaired t test ** Mann–Whitney test
nociceptive afferent fibrer damage documented with laserevoked potentials. The frequency of peripheral neuropathy that we found in patients attending our immunologic clinic matches that shown in previous studies reporting that 80 % of patients had neurophysiological signs indicating peripheral neuropathy [1, 9]. Conversely, a previous study by Santoro and colleagues [19] investigating 56 patients with HCV-related cryoglobulinemia showed a peripheral neuropathy frequency of about 21 %. The discrepancy between our study and that conducted by Santoro and colleagues might depend on various factors. For example, we assessed a larger sample of patients. In Santoro et al.’s study, nerve function was assessed only with the standard nerve conduction study, and this approach probably failed to detect peripheral neuropathy in an additional 13 % of patients who had symptoms compatible with small fiber damage. Equally important, our patients had a far longer disease duration, and possibly a more severe HCV infection than patients in Santoro et al.’s study (many of our patients were treated for chronic HCV infection). A previously unreported finding in our study is that some patients with HCV-related cryoglobulinemia have a pure SFN. Of the 69 patients in whom we undertook detailed neurophysiological testing, four patients (6.5 % of our sample) had distally distributed sensory disturbances, but normal nerve conduction study data [15]. In these patients, laser-evoked potentials recordings and skin biopsy allowed us to diagnose a pure SFN. Hence, in the diagnostic workup in patients with pure SFN, laboratory blood investigation should include tests for HCV and cryoglobulinemia [17, 18]. A distinctive finding is the significant association between age and peripheral neuropathy. This finding receives support from emerging evidence that the extrahepatic manifestations complicating HCV increase with age [4]. In HCV, a clinical condition potentially harmful
for the nerves, this association might also reflect the higher susceptibility to nerve damage in the elderly [16]. The development of peripheral neuropathy was significantly associated with the duration of HCV (defined as time from the diagnosis), but unrelated to the duration of cryoglobulin and the blood cryocrit level. These findings argue against a previous study [10] investigating a large sample of subjects with cryoglobulinemia (71) that reported a higher frequency of peripheral neuropathy in patients with high levels of cryoglobulinemia (C5 %). Although a direct comparison between the two studies is difficult (in their study, Gemignani and colleagues did not analyze the role of HCV in the development of peripheral neuropathy), we hypothesize that the possible discrepancy might be due to different reasons. In their study, Gemignani and colleagues also included patients with idiopathic cryglobulinemia, and 17 patients of the 71 participants had a concomitant disease possibly affecting peripheral nerves. Another important neurophysiological-clinical finding of our study was that the amplitude of the sural-nerve sensory action potential, foot laser-evoked potentials, and the intraepidermal nerve fiber density inversely were correlated with the duration of HCV, thus suggesting that the longer the disease duration is, the more severe the peripheral neuropathy will be. Despite this correlation, we found that the development of peripheral neuropathy was unrelated to the HCV genotype. Although this finding might suggest that the peripheral nerve damage might not be directly related to the virus, admittedly, it is hampered by the limited variation in genotypes of our group of patients (only types 1a, 1b, and 2a/2c). Our study provides previously unavailable data on neuropathic pain and nociceptive pathways in patients with HCV-related cryoglobulin. Of the 47 patients with peripheral neuropathy, 29 had neuropathic pain as assessed with the DN4. Most of these patients complained of ongoing superficial burning and deep pain, whereas only a few
123
J Neurol
reported allodynia. Although nociceptive fiber-mediated, laser-evoked potential amplitudes significantly differed between patients with and without pain, we found no difference in non-nociceptive fiber-mediated, sural-nerve action potential amplitude and the intraepidermal nerve fiber density. When we correlated the intensity of superficial burning pain with the laboratory variables, we found that whereas laser-evoked potential amplitudes significantly correlated with pain intensity for this pain type, sural-nerve action potential amplitude and the intraepidermal nerve fiber density did not. These data indicate that neuropathic pain and ongoing burning pain are related to the nociceptive pathway damage, as documented with laser-evoked potential recordings. Conversely, non-nociceptive Ab-fiber damage has no role in the development of neuropathic pain. Nor was intraepidermal fiber density related to pain. This finding agrees with the many studies involving patients with painful neuropathy of different etiologies that failed to find any correlation between pain and intraepidermal nerve fiber density [14]. We therefore conjecture that in peripheral neuropathy, this type of pain, rather than arising from nociceptive fiber loss alone (i.e., a deafferentation mechanism for pain), also reflects dysfunction in damaged, but still preserved, nociceptive fibers [21]. Although deep pressing and squeezing pain were even more frequent than the superficial burning pain, we did not analyze the correlation between these types of pain and the laboratory variables tested because they presumably arise from nerve damage involving nociceptive group III and IV muscular afferents [6], whereas our neurophysiologic laboratory tools assess only cutaneous afferents. Our findings show that peripheral neuropathy and its severity in patients with HCV-related cryoglobulinemia are associated with age and HCV infection, rather than with cryoglobulinemia, and that superficial burning pain, one of the most common neuropathic pain types in this condition, is associated with nociceptive pathway damage. This conclusion might be useful for designing a more effective treatment for these common HCV-related cryoglobulinemia complications. Conflicts of interest of interest.
The authors declare that they have no conflicts
Ethical standard This study has been approved by the local ethic committee and have been performed in accordance with the ethical standards laid down in the 1964 Declaration of Helsinki and its later amendments. All patients gave their informed consent prior to their inclusion in the study.
References 1. Ammendola A, Sampaolo S, Migliaresi S, Ambrosone L, Ammendola E, Ciccone G, Di Iorio G (2007) Autonomic neuropathy in mixed cryoglobulinemia. J Neurol 254:215–259
123
2. Bouhassira D, Attal N, Alchaar H, Boureau F, Brochet B, Bruxelle J, Cunin G, Fermanian J, Ginies P, Grun-Overdyking A, JafariSchluep H, Lante´ri-Minet M, Laurent B, Mick G, Serrie A, Valade D, Vicaut E (2005) Comparison of pain syndromes associated with nervous or somatic lesions and development of a new neuropathic pain diagnostic questionnaire (DN4). Pain 114:29–36 3. Bouhassira D, Attal N, Fermanian J, Alchaar H, Gautron M, Masquelier E, Rostaing S, Lanteri-Minet M, Collin E, Grisart J, Boureau F (2004) Development and validation of the Neuropathic Pain Symptom Inventory. Pain 108:248–257 4. Cacoub P, Poynard T, Ghillani P, Charlotte F, Olivi M, Piette JC, Opolon P (1999) Extrahepatic manifestations of chronic hepatitis C. MULTIVIRC Group. Multidepartment virus C. Arthr Rheum 42:2204–2212 5. Cacoub P, Saadoun D, Limal N, Le´ger JM, Maisonobe T (2005) Hepatitis C virus infection and mixed cryoglobulinaemia vasculitis: a review of neurological complications. AIDS 19(Suppl 3):S128–S134 6. Chen X, Green PG, Levine JD (2010) Neuropathic pain-like alterations in muscle nociceptor function associated with vibration-induced muscle pain. Pain 151:460–466 7. Cruccu G, Sommer C, Anand P, Attal N, Baron R, Garcia-Larrea L, Haanpaa M, Jensen TS, Serra J, Treede RD (2010) EFNS guidelines on neuropathic pain assessment: revised 2009. Eur J Neurol 17:1010–1018 8. England JD, Gronseth GS, Franklin G, Miller RG, Asbury AK, Carter GT, Cohen JA, Fisher MA, Howard JF, Kinsella LJ, Latov N, Lewis RA, Low PA, Sumner AJ (2005) Distal symmetrical polyneuropathy: definition for clinical research. Muscle Nerve 31:113–123 9. Ferri C, La Civita L, Cirafisi C, Siciliano G, Longombardo G, Bombardieri S, Rossi B (1992) Peripheral neuropathy in mixed cryoglobulinemia: clinical and electrophysiologic investigations. J Rheumatol 19:889–895 10. Gemignani F, Brindani F, Alfieri S, Giuberti T, Allegri I, Ferrari C, Marbini A (2005) Clinical spectrum of cryoglobulinaemic neuropathy. J Neurol Neurosurg Psychiatry 76:1410–1414 11. Heckmann JG, Kayser C, Heuss D, Manger B, Blum HE, Neundo¨rfer B (1999) Neurological manifestations of chronic hepatitis C. J Neurol 246(6):486–491 12. Kane NM, Oware A (2012) Nerve conduction and electromyography studies. J Neurol 259(7):1502–1508 13. Kimura J (ed) (2006) Peripheral nerve diseases, handbook of clinical neurophysiology. Elsevier, Amsterdam 14. Joint Task Force of the EFNS and the PNS (2010) European Federation of Neurological Societies/Peripheral Nerve Society Guideline on the use of skin biopsy in the diagnosis of small fiber neuropathy. Report of a joint task force of the European Federation of Neurological Societies and the Peripheral Nerve Society. J Peripher Nerv Syst 15(2):79–92 15. Løseth S, Sta˚lberg E, Jorde R, Mellgren SI (2008) Early diabetic neuropathy: thermal thresholds and intraepidermal nerve fibre density in patients with normal nerve conduction studies. J Neurol 255(8):1197–1202 16. Martyn CN, Hughes RA (1997) Epidemiology of peripheral neuropathy. J Neurol Neurosurg Psychiatry 62:310–318 17. McArthur JC (2012) Painful small fibre neuropathies. Continuum (Minneap Minn) 18:106–125 18. Nebuchennykh M, Løseth S, Lindal S, Mellgren SI (2009) The value of skin biopsy with recording of intraepidermal nerve fiber density and quantitative sensory testing in the assessment of small fiber involvement in patients with different causes of polyneuropathy. J Neurol 256(7):1067–1775 19. Santoro L, Manganelli F, Briani C, Giannini F, Benedetti L, Vitelli E, Mazzeo A, Beghi E, HCV Peripheral Nerve Study Group (2006) Prevalence and characteristics of peripheral neuropathy in hepatitis C virus population. J Neurol Neurosurg Psychiatry 77:626–629
J Neurol 20. Treede RD (2003) Neurophysiological studies of pain pathways in peripheral and central nervous system disorders. J Neurol 250(10):1152–1161 21. Truini A, Biasiotta A, La Cesa S, Di Stefano G, Galeotti F, Petrucci MT, Inghilleri M, Cartoni C, Pergolini M, Cruccu G (2010) Mechanisms of pain in distal symmetric polyneuropathy: a combined clinical and neurophysiological study. Pain 150: 516–521
22. Truini A, Biasiotta A, Di Stefano G, La Cesa S, Leone C, Cartoni C, Leonetti F, Casato M, Pergolini M, Petrucci MT, Cruccu G (2013) Peripheral nociceptor sensitization mediates allodynia in patients with distal symmetric polyneuropathy. J Neurol 260(3):761–766 23. Yoon MS, Obermann M, Dockweiler C, Assert R, Canbay A, Haag S, Gerken G, Diener HC, Katsarava Z (2001) Sensory neuropathy in patients with cryoglobulin negative hepatitis-C infection. J Neurol 258(1):80–88
123
ORIGINAL COMMUNICATION
Clinical, neurophysiological, and skin biopsy findings in peripheral neuropathy associated with hepatitis C virus-related cryoglobulinemia A. Biasiotta • M. Casato • S. La Cesa • S. Colantuono G. Di Stefano • C. Leone • M. Carlesimo • S. Piroso • G. Cruccu • A. Truini
•
Received: 23 November 2013 / Revised: 21 January 2014 / Accepted: 22 January 2014 Ó Springer-Verlag Berlin Heidelberg 2014
Abstract Hepatitis C virus (HCV)-related cryoglobulinemia commonly causes disabling complications including peripheral neuropathy and neuropathic pain. In this prospective clinical, neurophysiological, and skin biopsy study we aimed at assessing clinical characteristics and risk factors of peripheral neuropathy and neuropathic pain in patients with HCV-related cryoglobulinemia. We enrolled 69 consecutive patients with HCV-related cryoglobulinemia. We diagnosed neuropathic pain with the DN4 (Neuropathic Pain Diagnostic) questionnaire, and rated the various neuropathic pains with the Neuropathic Pain Symptom Inventory (NPSI). All patients underwent a standard nerve conduction study to assess Ab-fiber function, laser-evoked potentials to assess Ad-fiber function, and skin biopsy to assess C-fiber terminals. Of the 69 patients studied, 47 had a peripheral neuropathy, and 29 had neuropathic pain. Patients with peripheral neuropathy were older than those without (P \ 0.0001). While peripheral neuropathy was significantly associated with the duration of HCV infection (P \ 0.01), it was unrelated to the duration of cryoglobulinemia and cryocrit (P [ 0.5). The severity of peripheral neuropathy significantly correlated with the duration of HCV infection (P \ 0.05). Laser-evoked potential amplitudes were significantly lower in patients with than in those without neuropathic pain (P \ 0.05). Conversely, no difference was found in nerve conduction A. Biasiotta S. La Cesa G. Di Stefano C. Leone S. Piroso G. Cruccu A. Truini (&) Department of Neurology and Psychiatry, Sapienza University, Viale Universita` 30, 00185 Rome, Italy e-mail: [email protected] M. Casato S. Colantuono M. Carlesimo Department of Clinical Immunology, Sapienza University, Rome, Italy
study and skin biopsy findings (P [ 0.05). Our findings show that peripheral neuropathy is related to age and HCV infection, rather than to cryoglobulinemia, and neuropathic pain is associated with damage to nociceptive pathways as assessed with laser-evoked potentials; this might be useful for designing more effective clinical interventions for these common HCV related-cryoglobulinemia complications. Keywords Peripheral neuropathy HCV Cryoglobulinemia Skin biopsy Neuropathic pain
Introduction Patients with hepatitis C virus (HCV)-related cryoglobulinemia commonly suffer from peripheral neuropathy [1, 11]. The reported prevalence ranges from 9 to 77 % [1, 5, 9, 19]. This complication frequently manifests as a distal, predominantly sensory polyneuropathy, with neuropathic pain being a frequently reported symptom [19, 23]. The reference standard test for diagnosing neuropathy is the nerve conduction study [8, 12]. This neurophysiological technique nevertheless has the disadvantage of assessing non-nociceptive, large-myelinated fibers (Ab fibers) alone and provides no information on nociceptive pathways [7]. The widely accepted methods for investigating nociceptive pathways are laser-evoked potentials, responses mediated by small myelinated (Ad) fibers, and skin biopsy to assess C-fiber terminals [18, 20]. In patients with neuropathic pain due to peripheral neuropathy, clinical assessment relies on psychometric measures, such as pain questionnaires including the DN4 questionnaire [3], a clinician-administered diagnostic screening tool. The self-administered Neuropathic Pain Symptom Inventory (NPSI) is a tool designed to measure the intensity of the various neuropathic pains [2].
123
J Neurol
Although patients with HCV related-cryoglobulinemia commonly present with peripheral neuropathy and neuropathic pain, few studies have dealt with clinical characteristics and risk factors of peripheral neuropathy [1, 9, 19] and none have addressed the frequency, clinical characteristics, and mechanisms underlying neuropathic pain in patients with peripheral neuropathy associated with HCVrelated cryoglobulinemia. This information could be useful for developing more effective therapeutic approaches for these clinical conditions that notoriously adversely affect the patient’s quality of life. We designed this prospective clinical, neurophysiological, and skin-biopsy study in patients with HCV-related cryoglobulinemia to investigate how the various clinical features influence the development of peripheral neuropathy and define the role of primary afferent fibers (nonnociceptive Ab, nociceptive Ad, and C afferent fibers) in neuropathic pain development.
from further analysis owing to their high prevalence in the general population. The research was approved by the local Institutional Review Board and patients gave written informed consent to the procedures. HCV and cryoglobulin determination Antibodies to HCV were determined by enzyme-linked immunosorbent assay, and serum HCV-RNA was identified by reverse transcription polymerase chain reaction (RT-PCR). For determining cryoglobulinemia, full blood samples were collected at 37 °C in serum tubes. About 5 ml were obtained after centrifugation for 10 min at 3,000 g in a pre-warmed centrifuge at 37 °C. Then serum was maintained in a cryocrit tube and incubated for 7 days at 4 °C. If the serum remained completely clear after the incubation, a negative result was reported. Thirty-six of the 69 patients included in the study had a cryocrit C5 % [10]. Clinical examination
Methods In the local university hospital immunologic clinic we prospectively screened in a 2-year period (April 2011– April 2013) 74 unselected patients with HCV-related cryoglobulinemia. Exclusion criteria were diagnosis of neurological diseases other than peripheral neuropathy, cognitive impairment, and other conditions potentially affecting peripheral nerves. To exclude the other causes of neuropathy, several laboratory investigations were performed (glycemia and glycated haemoglobin, electrolytes, kidney and liver function tests, full blood count, vitamin B12 and folate levels, thyroid function tests, serum protein electrophoresis, serology testing including HIV and hepatitis B, syphilis, paraneoplastic antibodies, and autoantibodies). We excluded five patients (four with diabetes, one with kidney failure) and therefore enrolled 69 patients with HCV-related cryoglobulinemia. No patients had hematological or oncological diseases. All of the included patients had type II cryoglobulinemia (monoclonal IgM-polyclonal IgG complexes) with clinically evident vasculitis manifesting with purpura or mild internal organ involvement. All recruited patients underwent neurological examination (including DN4 and NPSI), nerve conduction study, laser-evoked potential recordings, and skin biopsy in the Department of Neurology and Psychiatry. Distal symmetric polyneuropathy was diagnosed on clinical, biological, and electrodiagnostic findings, adhering to the criteria proposed by England et al [8]. Mononeuropathy and mononeuropathy multiplex were diagnosed when neuropathy differently affected one nerve or two non-contiguous, asymmetrically distributed nerves. We also checked isolated mononeuropathies involving the median nerve, but excluded them
123
All patients underwent a detailed neurological examination using bedside tools. Touch was investigated with a piece of cotton wool, vibration with a tuning fork (128 Hz), pinprick sensation with a wooden cocktail stick. In all patients, laser stimuli were used for a quantitative evaluation of warm and pinprick sensations. Muscle strength was assessed using the Medical Research Council score. Patients were also asked to report dysautonomic symptoms. Patients were grouped according to the clinically documented presence or absence of neuropathic pain, as assessed by DN4. Patients with neuropathic pain completed the NPSI questionnaire. NPSI subscores were calculated for the various pain types: ongoing pain (superficial burning, and deep pressing and squeezing pain), paroxysmal, provoked pain, and abnormal sensations (paraesthesia and dysaesthesia). Neurophysiological examination and skin biopsy Patients underwent a motor and sensory nerve conduction study using surface recording electrodes with standard placement. A nerve conduction study comprised sensory nerve action potentials (SNAP) and conduction velocities recorded from sural, ulnar, and superficial radial nerves. Other nerve function variables examined were compound motor action potential (CMAP) amplitude and peroneal, tibial, and ulnar nerve condition velocities. The methods used adhered to those recommended by experts of the International Federation of Clinical Neurophysiology [13]. To study laser-evoked potentials, we used a neodymium:yttrium–aluminium–perovskite (Nd:YAP) laser [22]. The dorsum of the right foot and left hand were stimulated with laser pulses (intensity: 150–200 mJ/mm2, pulse
J Neurol
duration: 5 ms, beam diameter: 5 mm) eliciting pinprick sensations. The early, lateralized component, N1, and the main complex, N2–P2, were recorded through disc electrodes from the temporal areas (Tc) referenced to the frontal area (Fz) and the vertex (Cz) referenced to the nose. A range of 10–20 artifact-free trials were collected and averaged. Neurophysiological data were compared with normative ranges established in our laboratory, from a sample of 80 healthy subjects (40 F, 40 M; mean age 64.3 ± 8.3 years, range 30–81 years. The age of this group and the age of enrolled patients did not differ, P [ 0.05). Patients underwent skin biopsies from the proximal thigh (20 cm below the anterior iliac spine) and the distal leg (10 cm above the lateral malleolus, within the sural nerve territory). Biopsies were taken after local anesthesia using a 3-mm disposable punch under a sterile technique. Three sections randomly chosen from each biopsy were immunoassayed with polyclonal anti-protein-gene-product 9.5 antibodies using the free-floating protocol for brightfield immunohistochemistry. In the assessment of the intraepidermal nerve fiber density, we used the recommendations and normative ranges of the European Federation of the Neurological Societies [14]. Statistical analysis We used the unpaired t test and the Mann–Whitney test to compare the normally and the non-normally distributed clinical and laboratory variables in patients with and without peripheral neuropathy, and with and without neuropathic pain. Although in the clinical analysis we used several clinical and neurophysiological variables for diagnosing peripheral neuropathies and categorizing patients, we selected only sural-nerve sensory action potential, foot laser-evoked potential amplitude, and the intraepidermal nerve fiber density at the distal leg for the correlation analysis with the clinical variables, because virtually all patients had a distal symmetric, predominantly sensory neuropathy (see ‘‘Results’’). Hence, these three variables reliably represent the peripheral nerve damage characteristics of our patients. We used the Spearman’s rank correlation coefficient for the correlation analysis between clinical and laboratory variables. The chi-squared test was used to assess frequency differences in HCV genotype and a cryocrit level C5 % in patients with and without peripheral neuropathy. P values \0.05 were considered to indicate significance. All data are reported as the mean ± SD.
Results Of the 69 patients included in the study (56 F, 13 M; mean age 66 ± 11.5 years, range 30–82 years), 35 were treated
for HCV infection or HCV-related cryoglobulinemia (with interferon, ribavirin, rituximab) or both. Of these 69 patients, 47 patients (68 %) had a peripheral neuropathy. Most patients (45 of the 47 with peripheral neuropathy) had a predominantly sensory, distal symmetric polyneuropathy. Of these 45 patients, four had a pure small fiber neuropathy (SFN), yielding normal nerve conduction findings, but abnormal laser-evoked potentials and intraepidermal nerve fiber density. Two patients suffered from a mononeuropathy multiplex. No patient had isolated mononeuropathy, or predominantly motor neuropathy. Although most of the 45 patients with distal symmetric polyneuropathy had sensory disturbances involving all sensory modalities, seven patients had a predominantly large fiber neuropathy (all without hypoalgesia, hyperalgesia and/or pain); conversely the four patients with pure SNF had a selective involvement of thermal-pain sensitivity. The two patients with mononeuropathy multiplex presented sensory disturbances mimicking a mixed-fiber, distal symmetric polyneuropathy. While patients with peripheral neuropathy were older than those without (unpaired t test, P \ 0.0001), gender frequency did not differ (chi-squared test, P [ 0.1). Duration of HCV infection (time from diagnosis) was longer in patients with peripheral neuropathy than in those without (unpaired t test, P = 0.0047); conversely, no difference was found in the duration of cryoglobulinemia or the cryocrit (Mann–Whitney test, P [ 0.5) (Table 1). The development of peripheral neuropathy was unrelated to the HCV genotype (P [ 0.1, chi-squared test). The frequency of peripheral neuropathy in patients with a cryocrit C5 % did not differ from that of patients with a cryocrit \5 % (chisquared test, P [ 0.1). Foot-LEP and sural-nerve sensory action potential amplitudes, and the intraepidermal nerve fiber density were inversely correlated with the duration of HCV infection (sural-nerve action potential: Spearman’s r = -0.3268, P = 0.006; laser-evoked potentials: Spearman’s r = -0.2715, P = 0.02 intraepidermal nerve fiber density: Spearman’s r = -0.3630, P = 0.002). Of the 47 patients with peripheral neuropathy, 29 (62 %) had neuropathic pain as assessed with the DN4. In patients with and without pain, age and gender frequency did not differ (age: unpaired t test, P [ 0.1; gender frequency: chisquared test, P [ 0.5). All patients with neuropathic pain also reported non-painful sensory disturbances (pins-andneedles and tingling), rated as 6.9 ± 2.4 in intensity on the 0–10 numerical pain rating scale. The most frequent pain types were superficial burning (21 patients of the 29 with neuropathic pain, intensity 5.2 ± 3.5) and deep pain (both squeezing and pressure; 22 patients of the 29 with neuropathic pain rated as 5.4 ± 3.5 in intensity for squeezing and 5.3 ± 3.5 for pressing pain). In nine patients (all with neuropathic pain as assessed with DN4), clinical
123
J Neurol Table 1 Clinical and laboratory findings in patients with and without peripheral neuropathy F:M
Age (years)
Patients without peripheral neuropathy
16:6
58.1 ± 13.2
Patients with peripheral neuropathy P
40:7
69.3 ± 8.6
\0.0001*
Duration of HCV (years)
Duration of cryoglobulinemia (years)
Cryocrit
Sural SNAP amplitude (lV)
Foot-LEP amplitude (lV)
Distal leg IENF density (mm)
9.7 ± 7.3
4.9 ± 5.6
4.5 ± 4.3
16.6 ± 6.6
19.9 ± 8.5
6.4 ± 2.7
15.6 ± 8.0
5.5 ± 3.9
4.8 ± 5.9
2.6 ± 4.0
6.4 ± 9.5
3.2 ± 2.3
0.6352*
0.7201**
\0.0001**
\0.0001**
0.0047*
0.0001*
HCV hepatitis C virus, SNAP sensory nerve action potential, LEP laser-evoked potential, IENF intraepidermal nerve fiber * Unpaired t test ** Mann–Whitney test
Fig. 1 Laboratory assessment in patients without peripheral neuropathy and with painless and painful neuropathy. First row sural SNAP (sensory nerve action potential). Second row N1, N2-P2 components of laser-evoked potentials, third row intraepidermal nerve fiber density as assessed with skin biopsy (arrows indicate the nerve fibers). Sural SNAP and foot laser-evoked potential amplitude, and intraepidermal nerve fiber density felt within normal ranges in
patients without peripheral neuropathy. In the representative patients with peripheral neuropathy, all laboratory testing variables were abnormal. While sural SNAP amplitude and intraepidermal nerve fiber density did not differ between the patient with and without pain, laser-evoked potential amplitude was lower in the patient with pain than in the patient without pain
examination also showed pinprick hyperalgesia. Whereas laser-evoked potential amplitudes were lower in patients with neuropathic pain than in those without (Mann–Whitney test, P \ 0.05), no difference was found between groups for the sural-nerve sensory action potentials and the intraepidermal nerve fiber density (Mann–Whitney test P = 0.5; unpaired t test, P = 0.08) (Fig. 1; Table 2). In patients with peripheral neuropathy, superficial burning pain inversely correlated in severity with laser-evoked potential amplitudes (Pearson’s r = -0.3881, P = 0.007), but not with the other laboratory variables (P [ 0.1).
Discussion
123
In this prospective clinical, neurophysiological, and skin biopsy study in an unselected sample of consecutive patients, we show that most patients with HCV-related cryoglobulinemia (68 %) have peripheral neuropathy, virtually all having a predominantly sensory, distal polyneuropathy. The major clinical variables for the development of peripheral neuropathy are age and duration of HCV infection. Neuropathic pain is a frequent complaint (62 % of patients with peripheral neuropathy) and depends on the
J Neurol Table 2 Clinical and laboratory findings in patients with painless and painful neuropathy F:M
Age (years)
Duration of HCV (years)
Duration of cryoglobulinemia (years)
Cryocrit
Sural SNAP amplitude (lV)
Foot-LEP amplitude(lV)
Distal leg IENF density (mm)
Patients with painless neuropathy
15:3
68.0 ± 7.2
15.9 ± 8.6
5.8 ± 2.6
3.5 ± 4.0
3.2 ± 4.6
10.1 ± 10.5
4.0 ± 2.9
Patients with painful neuropathy P
25:4
70.1 ± 9.4
15.4 ± 7.8
5.1 ± 4.6
5.7 ± 6.7
2.3 ± 3.6
4.1 ± 8.2
2.7 ± 1.6
0.4217*
0.8352*
0.5536*
0.3845**
0.4768**
0.0228**
0.08*
HCV hepatitis C virus, SNAP sural sensory nerve action potential, LEP laser-evoked potential, IENF intraepidermal nerve fiber * Unpaired t test ** Mann–Whitney test
nociceptive afferent fibrer damage documented with laserevoked potentials. The frequency of peripheral neuropathy that we found in patients attending our immunologic clinic matches that shown in previous studies reporting that 80 % of patients had neurophysiological signs indicating peripheral neuropathy [1, 9]. Conversely, a previous study by Santoro and colleagues [19] investigating 56 patients with HCV-related cryoglobulinemia showed a peripheral neuropathy frequency of about 21 %. The discrepancy between our study and that conducted by Santoro and colleagues might depend on various factors. For example, we assessed a larger sample of patients. In Santoro et al.’s study, nerve function was assessed only with the standard nerve conduction study, and this approach probably failed to detect peripheral neuropathy in an additional 13 % of patients who had symptoms compatible with small fiber damage. Equally important, our patients had a far longer disease duration, and possibly a more severe HCV infection than patients in Santoro et al.’s study (many of our patients were treated for chronic HCV infection). A previously unreported finding in our study is that some patients with HCV-related cryoglobulinemia have a pure SFN. Of the 69 patients in whom we undertook detailed neurophysiological testing, four patients (6.5 % of our sample) had distally distributed sensory disturbances, but normal nerve conduction study data [15]. In these patients, laser-evoked potentials recordings and skin biopsy allowed us to diagnose a pure SFN. Hence, in the diagnostic workup in patients with pure SFN, laboratory blood investigation should include tests for HCV and cryoglobulinemia [17, 18]. A distinctive finding is the significant association between age and peripheral neuropathy. This finding receives support from emerging evidence that the extrahepatic manifestations complicating HCV increase with age [4]. In HCV, a clinical condition potentially harmful
for the nerves, this association might also reflect the higher susceptibility to nerve damage in the elderly [16]. The development of peripheral neuropathy was significantly associated with the duration of HCV (defined as time from the diagnosis), but unrelated to the duration of cryoglobulin and the blood cryocrit level. These findings argue against a previous study [10] investigating a large sample of subjects with cryoglobulinemia (71) that reported a higher frequency of peripheral neuropathy in patients with high levels of cryoglobulinemia (C5 %). Although a direct comparison between the two studies is difficult (in their study, Gemignani and colleagues did not analyze the role of HCV in the development of peripheral neuropathy), we hypothesize that the possible discrepancy might be due to different reasons. In their study, Gemignani and colleagues also included patients with idiopathic cryglobulinemia, and 17 patients of the 71 participants had a concomitant disease possibly affecting peripheral nerves. Another important neurophysiological-clinical finding of our study was that the amplitude of the sural-nerve sensory action potential, foot laser-evoked potentials, and the intraepidermal nerve fiber density inversely were correlated with the duration of HCV, thus suggesting that the longer the disease duration is, the more severe the peripheral neuropathy will be. Despite this correlation, we found that the development of peripheral neuropathy was unrelated to the HCV genotype. Although this finding might suggest that the peripheral nerve damage might not be directly related to the virus, admittedly, it is hampered by the limited variation in genotypes of our group of patients (only types 1a, 1b, and 2a/2c). Our study provides previously unavailable data on neuropathic pain and nociceptive pathways in patients with HCV-related cryoglobulin. Of the 47 patients with peripheral neuropathy, 29 had neuropathic pain as assessed with the DN4. Most of these patients complained of ongoing superficial burning and deep pain, whereas only a few
123
J Neurol
reported allodynia. Although nociceptive fiber-mediated, laser-evoked potential amplitudes significantly differed between patients with and without pain, we found no difference in non-nociceptive fiber-mediated, sural-nerve action potential amplitude and the intraepidermal nerve fiber density. When we correlated the intensity of superficial burning pain with the laboratory variables, we found that whereas laser-evoked potential amplitudes significantly correlated with pain intensity for this pain type, sural-nerve action potential amplitude and the intraepidermal nerve fiber density did not. These data indicate that neuropathic pain and ongoing burning pain are related to the nociceptive pathway damage, as documented with laser-evoked potential recordings. Conversely, non-nociceptive Ab-fiber damage has no role in the development of neuropathic pain. Nor was intraepidermal fiber density related to pain. This finding agrees with the many studies involving patients with painful neuropathy of different etiologies that failed to find any correlation between pain and intraepidermal nerve fiber density [14]. We therefore conjecture that in peripheral neuropathy, this type of pain, rather than arising from nociceptive fiber loss alone (i.e., a deafferentation mechanism for pain), also reflects dysfunction in damaged, but still preserved, nociceptive fibers [21]. Although deep pressing and squeezing pain were even more frequent than the superficial burning pain, we did not analyze the correlation between these types of pain and the laboratory variables tested because they presumably arise from nerve damage involving nociceptive group III and IV muscular afferents [6], whereas our neurophysiologic laboratory tools assess only cutaneous afferents. Our findings show that peripheral neuropathy and its severity in patients with HCV-related cryoglobulinemia are associated with age and HCV infection, rather than with cryoglobulinemia, and that superficial burning pain, one of the most common neuropathic pain types in this condition, is associated with nociceptive pathway damage. This conclusion might be useful for designing a more effective treatment for these common HCV-related cryoglobulinemia complications. Conflicts of interest of interest.
The authors declare that they have no conflicts
Ethical standard This study has been approved by the local ethic committee and have been performed in accordance with the ethical standards laid down in the 1964 Declaration of Helsinki and its later amendments. All patients gave their informed consent prior to their inclusion in the study.
References 1. Ammendola A, Sampaolo S, Migliaresi S, Ambrosone L, Ammendola E, Ciccone G, Di Iorio G (2007) Autonomic neuropathy in mixed cryoglobulinemia. J Neurol 254:215–259
123
2. Bouhassira D, Attal N, Alchaar H, Boureau F, Brochet B, Bruxelle J, Cunin G, Fermanian J, Ginies P, Grun-Overdyking A, JafariSchluep H, Lante´ri-Minet M, Laurent B, Mick G, Serrie A, Valade D, Vicaut E (2005) Comparison of pain syndromes associated with nervous or somatic lesions and development of a new neuropathic pain diagnostic questionnaire (DN4). Pain 114:29–36 3. Bouhassira D, Attal N, Fermanian J, Alchaar H, Gautron M, Masquelier E, Rostaing S, Lanteri-Minet M, Collin E, Grisart J, Boureau F (2004) Development and validation of the Neuropathic Pain Symptom Inventory. Pain 108:248–257 4. Cacoub P, Poynard T, Ghillani P, Charlotte F, Olivi M, Piette JC, Opolon P (1999) Extrahepatic manifestations of chronic hepatitis C. MULTIVIRC Group. Multidepartment virus C. Arthr Rheum 42:2204–2212 5. Cacoub P, Saadoun D, Limal N, Le´ger JM, Maisonobe T (2005) Hepatitis C virus infection and mixed cryoglobulinaemia vasculitis: a review of neurological complications. AIDS 19(Suppl 3):S128–S134 6. Chen X, Green PG, Levine JD (2010) Neuropathic pain-like alterations in muscle nociceptor function associated with vibration-induced muscle pain. Pain 151:460–466 7. Cruccu G, Sommer C, Anand P, Attal N, Baron R, Garcia-Larrea L, Haanpaa M, Jensen TS, Serra J, Treede RD (2010) EFNS guidelines on neuropathic pain assessment: revised 2009. Eur J Neurol 17:1010–1018 8. England JD, Gronseth GS, Franklin G, Miller RG, Asbury AK, Carter GT, Cohen JA, Fisher MA, Howard JF, Kinsella LJ, Latov N, Lewis RA, Low PA, Sumner AJ (2005) Distal symmetrical polyneuropathy: definition for clinical research. Muscle Nerve 31:113–123 9. Ferri C, La Civita L, Cirafisi C, Siciliano G, Longombardo G, Bombardieri S, Rossi B (1992) Peripheral neuropathy in mixed cryoglobulinemia: clinical and electrophysiologic investigations. J Rheumatol 19:889–895 10. Gemignani F, Brindani F, Alfieri S, Giuberti T, Allegri I, Ferrari C, Marbini A (2005) Clinical spectrum of cryoglobulinaemic neuropathy. J Neurol Neurosurg Psychiatry 76:1410–1414 11. Heckmann JG, Kayser C, Heuss D, Manger B, Blum HE, Neundo¨rfer B (1999) Neurological manifestations of chronic hepatitis C. J Neurol 246(6):486–491 12. Kane NM, Oware A (2012) Nerve conduction and electromyography studies. J Neurol 259(7):1502–1508 13. Kimura J (ed) (2006) Peripheral nerve diseases, handbook of clinical neurophysiology. Elsevier, Amsterdam 14. Joint Task Force of the EFNS and the PNS (2010) European Federation of Neurological Societies/Peripheral Nerve Society Guideline on the use of skin biopsy in the diagnosis of small fiber neuropathy. Report of a joint task force of the European Federation of Neurological Societies and the Peripheral Nerve Society. J Peripher Nerv Syst 15(2):79–92 15. Løseth S, Sta˚lberg E, Jorde R, Mellgren SI (2008) Early diabetic neuropathy: thermal thresholds and intraepidermal nerve fibre density in patients with normal nerve conduction studies. J Neurol 255(8):1197–1202 16. Martyn CN, Hughes RA (1997) Epidemiology of peripheral neuropathy. J Neurol Neurosurg Psychiatry 62:310–318 17. McArthur JC (2012) Painful small fibre neuropathies. Continuum (Minneap Minn) 18:106–125 18. Nebuchennykh M, Løseth S, Lindal S, Mellgren SI (2009) The value of skin biopsy with recording of intraepidermal nerve fiber density and quantitative sensory testing in the assessment of small fiber involvement in patients with different causes of polyneuropathy. J Neurol 256(7):1067–1775 19. Santoro L, Manganelli F, Briani C, Giannini F, Benedetti L, Vitelli E, Mazzeo A, Beghi E, HCV Peripheral Nerve Study Group (2006) Prevalence and characteristics of peripheral neuropathy in hepatitis C virus population. J Neurol Neurosurg Psychiatry 77:626–629
J Neurol 20. Treede RD (2003) Neurophysiological studies of pain pathways in peripheral and central nervous system disorders. J Neurol 250(10):1152–1161 21. Truini A, Biasiotta A, La Cesa S, Di Stefano G, Galeotti F, Petrucci MT, Inghilleri M, Cartoni C, Pergolini M, Cruccu G (2010) Mechanisms of pain in distal symmetric polyneuropathy: a combined clinical and neurophysiological study. Pain 150: 516–521
22. Truini A, Biasiotta A, Di Stefano G, La Cesa S, Leone C, Cartoni C, Leonetti F, Casato M, Pergolini M, Petrucci MT, Cruccu G (2013) Peripheral nociceptor sensitization mediates allodynia in patients with distal symmetric polyneuropathy. J Neurol 260(3):761–766 23. Yoon MS, Obermann M, Dockweiler C, Assert R, Canbay A, Haag S, Gerken G, Diener HC, Katsarava Z (2001) Sensory neuropathy in patients with cryoglobulin negative hepatitis-C infection. J Neurol 258(1):80–88
123
