Acute carpal tunnel syndrome caused by pseudogout Acute carpal tunnel syndrome caused by pseudogout occurred in a Chinese patient. The radiological findings mimicked those of synovial chondromatosis. Such radiological findings were very unusual. Diagnosis of such conditions may be difficult, since the clinical features may be confused with those of gout and infection. Surgical release is the treatment
of choice. (J HAND SURG
K. Y. Chiu, MBBS, W. F. Ng, MRCP (UK), W. B. Wong, MBBS. C. H. Choi, MRCPath (UK), and S. P. Chow, MS, FRCSE, FACS, Hong Kong
carpal tunnel syndrome (CTS) is very rare. ’ Only isolated case reports can be found on review of the literature. It may be precipitated by local trauma, i-3 bums, ’ rheumatoid arthritis, ’ pregnancy,’ spontaneous hemorrhage,4 acute pyogenic infection,5 thrombosis of a persistent median artery,6. ’ and gout.R We treated a patient suffering from acute CTS caused by pseudogout. To our knowledge, there are only two such cases reported in the Englishlanguage literature.&. ‘) Case report A 57-year-old, right-handed Chinese woman complained of a IO-day history of unprovoked pain and swelling of the right wrist. She was previously fit and worked in a factory. The pain was so severe that she refused to move her right wrist and fingers. There was also numbness of the radial three fingers. There was no history of local trauma. Other joints were tree ot’ symptoms. Physical examination revealed localized swelling over the anterior aspect of the right wrist. It was exquisitely tender on palpation. The overlying skin was erythematous. Movements of the right wrist and fingers were restricted because of the pain. Assessment of muscle weakness was therefore difficult. There was no obvious muscle wasting. The twopoint discrimination was greater than 15 mm in the distriFrom the Department of Orthopaedic Surgery, and Department of Pathology. University of Hong Kong, Queen Mary Hospital. Hong Kong. Received for publication Nov. 23. 1990.
Aug. 29. 1990; accepted
in revised form
No benetits m any form have been received or will be received from a commercial party related directly or indirectly to the subject of this article. Reprint requests: Dr. K. Y. Chiu, Department Surgery, University of Hong Kong, Queen Hong Kong. 3/l/274%1
of Orthopaedic Mary Hospital.
bution of the median nerve to the right hand. For the left hand and for the ulnar nerve distribution of the right hand. the two-point discrimination was 5 mm at the fingertips. Tinel’s sign and Phalen’s test were both positive. The presumptive diagnosis was infective synovitis causing acute CTS. On admission the leukocyte count was mildly elevated I1 1.2 x lO”/L). The differential counts showed 75% were neutrophils, 18% were lymphocytes, 5% were monocytes. and less than 1% were eosinophils and basophils. The erythrocyte sedimentation rate was 85 mm in the first hour. Uric acid level was within normal range. Calcium. phosphate, and alkaline phosphatase levels were normal. Radiographs of the right wrist revealed opacities on the anterior side of the carpal bones ( Fig. I, A ). The appearance mimicked that of synovial chondromatosis. There was no radial opacity around the triangular fibrocartilage of the wrist (Fig. 1, B). There was no radiological evidence of other joints affected by pseudogout. Carpal tunnel release was done with the patient under axillary block. At operation, there was significant synovitis around the flexor tendons. The tendons appeared normal. The transverse carpal ligament was thickened and the soft tissues were edematous. The transverse carpal ligament was divided. Radical tenosynovectomy was performed. An outpocketing of the anterior capsule of the radiocarpal joint. measuring 1 cm’. encroached into the carpal tunnel and pressed onto the median nerve. Otherwise the median nerve appeared normal. This pocket was excised, and turbid fluid containing whitish. chalky substance was detected. Several pieces of these chalky particles measured 3 to 5 mm in diameter. The tissues were sent for microbiological investigations. NO bacteria could be detected under microscopy or by culture. Radiographs were rechecked and complete removal of the calcifications was confirmed. Histological sections showed a thin layer of fibrous tissue enclosing clumps of crystalline and amorphous substances with foci of calcification (Fig. 2). High-power view showed the irregular noncrystalline deposits of calcified material mixing with the crystals (Fig. 3). The crystals were small and rhomboid. They exhibited a weak pos-
Chiu et al.
The Journal ot HAND SURGERY
Fig. 1. A, Lateral radiograph showing multiple opacities at the palmar aspect of the wrist. The appearance mimicked that of synovial chondromatosis. B, There was no radial opacity in the triangular fibrocartilage complex on the PA radiograph.
Fig. 2. Histological section showed a thin layer of fibrous tissue enclosing and amorphous substances with foci of calcification at low-power view.
ctumps of crystalline
Vol. 17A. No. 2 March 1992
Fig. 3. High-power with the crystals.
view showed the irregular noncrystalline
itive birefringence on polarized light microscopy. With the use of a first-order red compensator polarizer (Nikon) the crystals were shown to be calcium pyrophosphate. Using the energy-dispersive x-ray analysis of the crystal on the paraffin section. it was shown that calcium and phosphate were present. After operation. the wrist was immobilized in a splint in slight extension. The patient received nonsteroidal antiinflammatory drugs. The wound healed uneventfully. Active mobilization was started 2 weeks after the operation. The symptoms caused by median nerve compression at the wrist disappeared after the operation, Six months later there was no evidence of recurrence; two-point discrimination was 5 mm in the distribution of the median nerve. There was no weakness or wasting of the thenar muscles.
Discussion The term pseudogout was first coined in 1962 by McCarty. ” Intrasynovial crystal deposition of calcium pyrophosphate dihydrate was discovered in patients believed to have gout. A definite diagnosis can be made if calcium pyrophosphate dihydrate crystals are demonstrated by definitive means, including the characteristic “tingerprint” by x-ray diffraction powder pattern or by chemical analysis.” Alternatively, a definite diagnosis can be made if typical calcifications are present on the x-ray films and monoclinic or triclinic crystals showing none or a weekly positive birefringence are identified by polarized light microscopy. The deposits
deposits of calcified material mixing
usually appear as heavy punctate or linear calcifications in the fibrocartilage. but they may also occur in hyaline cartilage, joint capsule, ligament and synovium of tendons. At the wrist, the calcifications usually occur at the triangular fibrocartilage and the distal radioulnar joint. In our patient. the diagnosis was confirmed by the demonstration of calcium pyrophosphate dihydrate crystals in the surgical specimen using x-ray diffraction and polarized light microscopy. Radiologically the deposits were periarticular but not located in the cartilage. They mimicked synovial chondromatosis. Such x-ray presentation is very rare and has been reported in only one patient with pseudogout of the knee.” Chronic CTS had been reported by Weinstein and associates” m a patient with pseudogout and hyperparathyroidism. There were crystal deposits in the floor of the carpal tunnel. in the synovium of the flexor tendon sheaths. and in the epineurium of the median nerve. Gerster et al.” detected 8 patients with electromyographic evidence of median nerve compression in 22 unselected patients with chondrocalcinosis of the wrist. However. exploration of the carpal tunnel in 5 of their patients could not establish any direct involvement of the median nerve by a process relating to pseudogout. For such patients with chronic CTS. one can try conservative measures such as antiinflammatory drugs and splintage before considering surgery. In acute CTS caused by pseudogout. only two pa-
The Journal of HAND SURGERY
Chiu er al.
tients have been reported in the English-language literature. Typically, it occurs in elderly persons. Although Spiegel et al. ‘Odid not mention whether his patient was left- or right-handed, in the patient of Lewis and Fiddian’ and in our patient involvement was in the dominant hand. One hypothesis is that with increased use of the dominant hand, the wrist is more susceptible to repeated microtrauma that may precipitate the pseudogout attack. The radiological finding in our patient was peculiar in the sense that it mimicked synovial chondromatosis. There was no chondrocalcinosis of the wrist and knee as in the other two patients. The patient in Spiegel’s study suffered from hypercalcemia. Hyperparathyroidism has to be excluded in such patients since it is present in 7% of patients with pseudogout.” Although pseudogout is a metabolic disease, surgical release of the transverse carpal ligament is the treatment of choice for acute CTS caused by pseudogout. There was good symptomatic relief and uncomplicated recovery in all three patients. One important point is that pseudogout, gout, and septic arthritis may occur concomitantly. They may be seen similarly with an inflamed joint, pyrexia, leucocytosis, and elevated erythrocyte sedimentation rate. Hyperuricemia occurs in 20% of patients suffering from pseudogout, and gouty tophi may be present in 5% of such patients. This makes the diagnosis extremely difficult in certain patients. REFERENCES Adamson JE, Srouji JE, Horton CE, Mladick RA. The acute carpal tunnel syndrome. Plast Reconstr Surg 1971;47:332-6. Lynch AC, Lipscomb PR. The carpal tunnel syndrome and Colles’ fracture. JAMA 1963;185:363-6. Lourie GM, Levin LS , Toby B , Urbaniak J. Distal rupture of the palmaris longus tendon and fascia as a cause of
acute carpal tunnel syndrome. J HAND SURC 1990; 15A:367-9. 4.
Hayden JW. Median neuropathy in the carpal tunnel caused by spontaneous intraneural hemorrhage. J Bone
Joint Surg 1964;46A: 1242-4. 5. Bailey D, Bolton CJF. Median nerve palsy associated with acute infection of hand. Lancet 1955;1:530-2. 6. Jackson IT, Campbell JC. An unusual cause of carpal tunnel syndrome, a case of thrombosis of the median artery. J Bone Joint Surg 1970;52A:330-3. 7. Levy EM, Pauke M. Carpal tunnel syndrome due to a thrombosed median artery: a case report. Hand 1978; 10:65-g. 8. Ogilvie C, Kay RM. Fulminating carpal tunnel syndrome due to gout. J HAND SURG 1988;13B:42-43. 9. Lewis SL, Fiddian NJ. Acute carpal tunnel syndrome a rare complication of chondrocalcinosis. Hand 1982; 14:164-7. 10. Spiegel PG, Ginsberg M, Skosey JL, Kwong P. Acute carpal tunnel syndrome secondary to pseudogout-case report. Clin Orthop 1976;120:185-7. 11. McCarty DJ Jr, Kohn NN, Faires JS. The significance of calcium phosphate crystals in the synovial fluid of arthritic patients; the “pseudogout syndrome”. I. Clinical aspects. Ann Intern Med 1962;56:71 l-37. 12. Ryan LM, McCarty DJ Jr. Calcium pyrophosphate crystal deposition disease; pseudogout; articular chondrocalcinosis. In: McCarty DJ Jr, ed. Arthritis and allied conditions. 10th ed. Philadelphia: Lea & Febiger. 1985: 1515-46. 13. Ellman MH, Krieger MI, Brown N. Pseudogout mimicking synovial chondromatosis. J Bone Joint Surg 1975;57A:863-5. 14. Weinstein JD, Dick HM, Grantham SA. Pseudogout, and carpal tunnel syndrome. hyperparathyroidism, J Bone Joint Surg 1968;50A:1669-74. 15. Gerster JC, Lagier R, Boivin G, Schneider C. Carpal tunnel syndrome in chondrocalcinosis of the wrist. Clinical and histologic study. Arthritis Rheum 1980;23:92631.