Journal of Clinical Neuroscience 22 (2015) 951–954
Contents lists available at ScienceDirect
Journal of Clinical Neuroscience journal homepage: www.elsevier.com/locate/jocn
Review
Hirayama disease Emma Foster a,⇑, Benjamin K.-T. Tsang a, Anthony Kam b, Elsdon Storey a, Bruce Day a,c, Aron Hill a a
Department of Neurosciences, The Alfred Hospital, 55 Commercial Road, Melbourne, VIC 3004, Australia Department of Radiology, The Alfred Hospital, Melbourne, VIC, Australia c Monash University, Melbourne, VIC, Australia b
a r t i c l e
i n f o
Article history: Received 26 January 2013 Accepted 25 November 2014
Keywords: Cervical myelopathy Hirayama disease Motor focal amyotrophy Motor neuron disease
a b s t r a c t This article discusses three patients with likely Hirayama disease. They have no other significant past medical history and no personal or family history of other neurological disorders. Hirayama disease is a form of cervical myelopathy attributed to forward displacement of the posterior cervical dural sac on neck flexion with resultant cord compression and/or venous congestion. It is characterized by a pure motor focal amyotrophy in the distribution of C7, C8 and T1 spinal segmental-innervated muscles and differs from other motor neuron diseases by virtue of its ultimately non-progressive course. Ó 2015 Elsevier Ltd. All rights reserved.
1. Hirayama disease Hirayama disease is a form of cervical myelopathy attributed to forward displacement of the posterior cervical dural sac on neck flexion with resultant cord compression and/or venous congestion. It is characterized by a pure motor focal amyotrophy in the distribution of C7, C8 and T1 spinal segmental-innervated muscles [1] and differs from other motor neuron diseases by virtue of its ultimately non-progressive course.
paresis [3] and an irregular tremor (minipolymyoclonus) on finger extension [2]. In our opinion, this probably represents neurogenic recruitment pattern with giant polyphasic motor unit potentials and an incomplete interference pattern. Muscle fasciculations at rest are observed in approximately 40% of patients, especially during the early phase of the disease [2]. The motor deficit and muscular atrophy typically progresses before stabilization with the clinical course plateauing within five years in approximately 90% of patients [2].
1.1. Clinical presentation
1.2. Investigations
This rare disease has mainly been reported in Asian countries especially Japan, China [2] and India [1]. The male to female ratio is approximately 7:1 [2] and the onset of symptoms occurs between adolescence and the early third decade of life [1,2]. The cardinal features include an insidious and initially progressive onset of either symmetric or asymmetric muscular weakness and atrophy in the C7, C8 and T1 myotomal distribution with relative sparing of the brachioradialis muscle [1]. There is usually no sensory loss in the affected upper limbs and no sensory or motor symptoms or signs in lower limbs or any other part of the body [1]. The majority of patients have a history of unilateral onset [1,2]; bilateral symmetrical involvement has recently been reported to occur in approximately 10% of cases [1]. Common clinical manifestations occurring in over 80% of patients include cold
Muscle enzyme levels and cerebrospinal fluid analysis are uniformly normal [2]. Motor nerve conduction studies (NCS) typically show low ulnar compound muscle action potential (CMAP) amplitudes, that are more severely reduced than the median CMAP [4]. Sensory NCS are typically within normal limits [4]. Additionally, some somatosensory evoked potential studies have provided evidence of an amplitude reduction in the cervical (N13) response during neck flexion [5,6] which presumably reflects subclinical damage to sensory fibres occurring as a result of over stretching of the cervical cord. However, a more recent study failed to replicate these findings [7]. Typical findings on dynamic MRI on neck flexion include anterior shifting of the posterior dura mater with flattening of the spinal cord against the C5–C6 vertebral bodies [8], obliteration or marked reduction in the size of the posterior cervical subarachnoid space and contrast-enhancement of the crescent-shaped posterior cervical epidural space [1]. Other reported MRI findings include
⇑ Corresponding author. Tel.: +61 3 9076 2000. E-mail address: [email protected] (E. Foster). http://dx.doi.org/10.1016/j.jocn.2014.11.025 0967-5868/Ó 2015 Elsevier Ltd. All rights reserved.
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E. Foster et al. / Journal of Clinical Neuroscience 22 (2015) 951–954
lower cervical cord atrophy, abnormal straightening or reversal of the normal cervical lordosis [9] and anterior horn cell hyperintensity on T2-weighted imaging [9]. However, neutral position imaging is often unrevealing. 1.3. Pathogenesis The pathophysiology of Hirayama disease is uncertain but may involve damage to the anterior horn cells. The leading postulate is that the short length of the cervical dural canal cannot compensate for the flexion-related increased length of the vertebral canal [1]. The dural canal becomes tight during neck flexion resulting in an anterior shift of the posterior dural wall which in turn compresses the spinal cord and it becomes flattened against the lower cervical vertebral bodies. The exact pathogenic mechanism of this tight dural sac remains unknown but is assumed to be due to imbalanced growth between the vertebral column and spinal cord and/ or dura, causing disproportion in length between the two structures [10]. Increased segmental and overall flexed motion range of the cervical spine in Hirayama patients has been demonstrated recently and this has been postulated to aggravate the forward displacement of the posterior dura mater [10]. The forward movement of the posterior dura mater obliterates the subarachnoid space and leaves a large posterior epidural space with prominent epidural venous plexus, presumably due to venous stasis during neck flexion which may in turn affect the anterior horn cells in the C7 to T1 segments of the spinal cord. Findings of patent anterior spinal arteries in case reports involving vertebral angiography and epidural venography suggest that neither the posterior venous engorgement nor compressive flattening of the spinal cord result in obstruction of large vessel arterial blood flow despite forward displacement of the anterior spinal artery [11]. The epidural venography findings from this study also confirmed that the posterior epidural masses seen by MRI and CT scan are caused by venous engorgement of the posterior epidural venous plexus during neck flexion. Interestingly, the dural displacement can decrease and disappear with age suggesting that the dynamic compression during early adulthood may be of pathological significance [11]. To our knowledge, Hirayama reported the first and only autopsy case in which the spinal cord showed anteroposterior flattening and necrotic changes of the anterior horns of the cervical spinal cord at C5 to T1, predominantly at C7 and C8 [12].
Fig. 1. Patient 3, neutral T2-weighted MRI, sagittal. Unremarkable image in the neutral position.
1.4. Radiological diagnosis Optimised MRI in suspected Hirayama Disease is important as many of the described characteristic features such as anterior shift of the dura, loss of dural attachment, epidural space enlargement, flow voids and enhancement are often absent in routine supine cervical spine MRI. Whilst commercially available specialized equipment such as multi-positional MRI scanners and integrated auxiliary coil attachments that allow real dynamic spinal imaging are not widely available, an optimized neutral and flexion cervical spine MRI scan protocol can be achieved using standard MRI equipment. Our optimized MRI protocol includes routine cervical spine sequences obtained in the neutral supine position. In addition, images in 20 to 40 degrees of cervical spine flexion are achieved by asking the patient to flex the head as far forward as possible and then to oppose the chin against the chest. The position is then maintained by supporting the neck and shoulders with MRI-compatible positioning foam pads. Post gadolinium sagittal and axial fat suppressed T1-weighted images are then obtained as a minimum. In our experience, the additional flexion sequences add only several minutes to the examination duration, are well tolerated by the patient and provide imaging findings that are otherwise not available (Fig. 1 and 2).
Fig. 2. Patient 3, flexion T2-weighted MRI, sagittal. Imaging in flexion shows loss of dural contact, posterior epidural flow voids, anterior dural displacement and spinal cord contact.
1.5. Treatment There is currently no treatment to reverse limb weakness for the disease. Avoidance of neck flexion, physiotherapy and occupational therapy have been advocated as the mainstay treatment for Hirayama disease [13]. Spinal decompression and fusion by surgical procedures may be beneficial [14]. Experimental treatments include hand rejuvenation therapy [15], a cosmetic surgical procedure involving the placement of adipose tissue from the abdomen
E. Foster et al. / Journal of Clinical Neuroscience 22 (2015) 951–954
or thigh into areas of atrophy in the affected hand/s for improved aesthetics. 2. Case series This case series discusses three patients with likely Hirayama disease. They have no other significant past medical history and no personal or family history of other neurological disorders. 2.1. Patient 1 Patient 1 is a right handed 29-year-old male of Italian descent. He experienced weakness of his hands in his late teens initially rapidly progressing before plateauing over eighteen months. He described worsening limb weakness with cold weather. Examination revealed wasting of hand and distal forearm muscles with well preserved proximal forearm extensors; this is often described in Hirayama-literature as oblique amyotrophy [16]. Finger abductors and extensors were assessed as Medical Research Council (MRC) Grade 1/5 power on the right and 3/5 on the left, and finger flexors were 4+/5 on the right and 5/5 on the left, except for flexor pollicis longus which was weaker bilaterally. Cervical spine MRI revealed short segment spinal cord atrophy between mid C4 and mid C6 levels, the right side more affected than the left, and anterior displacement of the spinal cord in flexion with an enlarged posterior epidural space (Fig. 3). Initially, the diagnoses that were entertained included an atypical central spinal cord cervical myelitis, spinal muscular atrophy and post-viral phenomenon. Finally, a retrospective diagnosis of Hirayama disease was made approximately after a year after onset of symptoms. Despite not receiving any treatment, his disease remained fairly stable ten years after diagnosis. 2.2. Patient 2 Patient 2 is a right handed 22-year-old male of Ashkenazi Jewish descent. Symptoms began at age 18, initially with bilateral hand
953
fasciculations and followed three months later with weakness and wasting in the right hand. A month later he developed the onset of left hand weakness, albeit not as severe as on the right. The weakness was worse in cold weather and interfered with his activities of daily living. Examination revealed oblique amyotrophy and minimyoclonus of the fingers. Power was assessed as MRC Grade 4/5 in the intrinsic muscles of both hands and 5/5 throughout the rest of the upper limbs. Upper limb reflexes were all hypoactive. The rest of the neurological examination was unremarkable. Cervical spine MRI showed spinal atrophy at the level of C6 and flexion views demonstrated anterior cord compression at this level as well as forward displacement of the posterior dural. Electromyography and NCS showed active denervation of the intrinsic muscles of the right hand and forearm with sparing of brachioradialis and biceps and ulnar F-waves were marginally prolonged. He was trialled on high dose intravenous immunoglobulin daily for five days; this induction course did not improve his symptoms. The diagnosis of Hirayama disease was made. He was discharged with a cervical soft collar to prevent long periods of neck flexion. The patient declined cervical vertebral body fusion surgery. Follow-up MRI of the cervical spine found a decreased magnitude of anterior displacement of the thecal sac on neck flexion. The patient has experienced only modest improvement in his function. 2.3. Patient 3 Patient 3 is a right handed 23-year-old male of Spanish descent who presented with an 18 month history of right upper limb wasting and weakness which worsened in cold weather. Initially, the illness progressed rapidly and then stabilized. Examination revealed oblique amyotrophy and mini-myoclonus of the fingers of his right hand. Power was reduced with finger abduction MRC Grade 4/5 on the right and 4+/5 on the left, supination 5/5 bilaterally and weak wrist flexion. Upper limb reflexes were reduced on the right. Cervical spine MRI in flexion showed the posterior dura was displaced anteriorly compressing the cord from C5 to C7 as well as asymmetrical flattening of the right side of the cord at C5/C6 (Fig. 2). Motor NCS showed no definite evidence of conduction block, however, F-waves were absent from the right median and ulnar nerves to abductor pollicis brevis and abductor digiti minimi. Initially the patient was given a five day induction course of intravenous immunoglobulin, however symptoms did not improve and no further infusions were given. Hirayama disease was diagnosed and the patient was managed with a soft cervical collar. A follow-up MRI showed a reduction in the anterior displacement of the dura in flexion. The patient has experienced modest improvement in his overall function. Conflicts of Interest/Disclosures The authors declare that they have no financial or other conflicts of interest in relation to this research and its publication. References
Fig. 3. Patient 1, neutral T2-weighted MRI, sagittal. Neutral position image showing advanced cord atrophy and myelomalacia at the cervicothoracic junction but no obvious cause.
[1] Pradhan S. Bilaterally symmetric form of Hirayama disease. Neurology 2009;72:2083–9. [2] Zhou B, Chen L, Fan D, et al. Clinical features of Hirayama disease in mainland China. Amyotroph Lateral Scler 2010;11:133–9. [3] Sawai S, Misawa S, Kanai K, et al. Altered axonal excitability properties in juvenile muscular atrophy of distal upper extremity (Hirayama disease). Clin Neurophysiol 2011;122:205–9. [4] Lyu RK, Huang YC, Wu YR, et al. Electrophysiological features of Hirayama disease. Muscle Nerve 2011;44:185–90. [5] Restuccia D, Rubino M, Valeriani M, et al. Cervical cord dysfunction during neck flexion in Hirayama’s disease. Neurology 2003;60:1980–3. [6] Polo A, Curro’ Dossi M, Fiaschi A, et al. Peripheral and segmental spinal abnormalities of median and ulnar somatosensory evoked potentials in Hirayama’s disease. J Neurol Neurosurg Psychiatry 2003;74:627–32.
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E. Foster et al. / Journal of Clinical Neuroscience 22 (2015) 951–954
[7] Misra UK, Kalita J, Mishra VN, et al. Effect of neck flexion on F wave, somatosensory evoked potentials, and magnetic resonance imaging in Hirayama disease. J Neurol Neurosurg Psychiatry 2006;77:695–8. [8] Lai V, Wong YC, Poon WL, et al. Forward shifting of posterior dural sac during flexion cervical magnetic resonance imaging in Hirayama disease: an initial study on normal subjects compared to patients with Hirayama disease. Eur J Radiol 2011;80:724–8. [9] Desai JA, Melanson M. Teaching neuroimages: anterior horn cell hyperintensity in Hirayama disease. Neurology 2011;77:e73. [10] Xu X, Han H, Gao H, et al. The increased range of cervical flexed motion detected by radiographs in Hirayama disease. Eur J Radiol 2011;78:82–6. [11] Elsheikh B, Kissel JT, Christoforidis G, et al. Spinal angiography and epidural venography in juvenile muscular atrophy of the distal arm ‘‘Hirayama disease’’. Muscle Nerve 2009;40:206–12.
[12] Hirayama K, Tomonaga M, Kitano K, et al. Focal cervical poliopathy causing juvenile muscular atrophy of distal upper extremity: a pathological study. J Neurol Neurosurg Psychiatry 1987;50:285–90. [13] Huang YL, Chen CJ. Hirayama disease. Neuroimaging Clin N Am. 2011 Nov;21(4):939-50, ix-x. [14] Kohno M, Takahashi H, Ide K, et al. Surgical treatment for patients with cervical flexion myelopathy. J Neurosurg 1999;91:33–42. [15] Puwanant A, Evangelisti SM, Griggs RC. Treating the chief complaint: hand rejuvenation for Hirayama disease. Neurology 2011;77:190–1. [16] Hassan KM, Sahni H, Jha A. Clinical and radiological profile of Hirayama disease: a flexion myelopathy due to tight cervical dural canal amenable to collar therapy. Ann Indian Acad Neurol 2012;15:106–12.
Contents lists available at ScienceDirect
Journal of Clinical Neuroscience journal homepage: www.elsevier.com/locate/jocn
Review
Hirayama disease Emma Foster a,⇑, Benjamin K.-T. Tsang a, Anthony Kam b, Elsdon Storey a, Bruce Day a,c, Aron Hill a a
Department of Neurosciences, The Alfred Hospital, 55 Commercial Road, Melbourne, VIC 3004, Australia Department of Radiology, The Alfred Hospital, Melbourne, VIC, Australia c Monash University, Melbourne, VIC, Australia b
a r t i c l e
i n f o
Article history: Received 26 January 2013 Accepted 25 November 2014
Keywords: Cervical myelopathy Hirayama disease Motor focal amyotrophy Motor neuron disease
a b s t r a c t This article discusses three patients with likely Hirayama disease. They have no other significant past medical history and no personal or family history of other neurological disorders. Hirayama disease is a form of cervical myelopathy attributed to forward displacement of the posterior cervical dural sac on neck flexion with resultant cord compression and/or venous congestion. It is characterized by a pure motor focal amyotrophy in the distribution of C7, C8 and T1 spinal segmental-innervated muscles and differs from other motor neuron diseases by virtue of its ultimately non-progressive course. Ó 2015 Elsevier Ltd. All rights reserved.
1. Hirayama disease Hirayama disease is a form of cervical myelopathy attributed to forward displacement of the posterior cervical dural sac on neck flexion with resultant cord compression and/or venous congestion. It is characterized by a pure motor focal amyotrophy in the distribution of C7, C8 and T1 spinal segmental-innervated muscles [1] and differs from other motor neuron diseases by virtue of its ultimately non-progressive course.
paresis [3] and an irregular tremor (minipolymyoclonus) on finger extension [2]. In our opinion, this probably represents neurogenic recruitment pattern with giant polyphasic motor unit potentials and an incomplete interference pattern. Muscle fasciculations at rest are observed in approximately 40% of patients, especially during the early phase of the disease [2]. The motor deficit and muscular atrophy typically progresses before stabilization with the clinical course plateauing within five years in approximately 90% of patients [2].
1.1. Clinical presentation
1.2. Investigations
This rare disease has mainly been reported in Asian countries especially Japan, China [2] and India [1]. The male to female ratio is approximately 7:1 [2] and the onset of symptoms occurs between adolescence and the early third decade of life [1,2]. The cardinal features include an insidious and initially progressive onset of either symmetric or asymmetric muscular weakness and atrophy in the C7, C8 and T1 myotomal distribution with relative sparing of the brachioradialis muscle [1]. There is usually no sensory loss in the affected upper limbs and no sensory or motor symptoms or signs in lower limbs or any other part of the body [1]. The majority of patients have a history of unilateral onset [1,2]; bilateral symmetrical involvement has recently been reported to occur in approximately 10% of cases [1]. Common clinical manifestations occurring in over 80% of patients include cold
Muscle enzyme levels and cerebrospinal fluid analysis are uniformly normal [2]. Motor nerve conduction studies (NCS) typically show low ulnar compound muscle action potential (CMAP) amplitudes, that are more severely reduced than the median CMAP [4]. Sensory NCS are typically within normal limits [4]. Additionally, some somatosensory evoked potential studies have provided evidence of an amplitude reduction in the cervical (N13) response during neck flexion [5,6] which presumably reflects subclinical damage to sensory fibres occurring as a result of over stretching of the cervical cord. However, a more recent study failed to replicate these findings [7]. Typical findings on dynamic MRI on neck flexion include anterior shifting of the posterior dura mater with flattening of the spinal cord against the C5–C6 vertebral bodies [8], obliteration or marked reduction in the size of the posterior cervical subarachnoid space and contrast-enhancement of the crescent-shaped posterior cervical epidural space [1]. Other reported MRI findings include
⇑ Corresponding author. Tel.: +61 3 9076 2000. E-mail address: [email protected] (E. Foster). http://dx.doi.org/10.1016/j.jocn.2014.11.025 0967-5868/Ó 2015 Elsevier Ltd. All rights reserved.
952
E. Foster et al. / Journal of Clinical Neuroscience 22 (2015) 951–954
lower cervical cord atrophy, abnormal straightening or reversal of the normal cervical lordosis [9] and anterior horn cell hyperintensity on T2-weighted imaging [9]. However, neutral position imaging is often unrevealing. 1.3. Pathogenesis The pathophysiology of Hirayama disease is uncertain but may involve damage to the anterior horn cells. The leading postulate is that the short length of the cervical dural canal cannot compensate for the flexion-related increased length of the vertebral canal [1]. The dural canal becomes tight during neck flexion resulting in an anterior shift of the posterior dural wall which in turn compresses the spinal cord and it becomes flattened against the lower cervical vertebral bodies. The exact pathogenic mechanism of this tight dural sac remains unknown but is assumed to be due to imbalanced growth between the vertebral column and spinal cord and/ or dura, causing disproportion in length between the two structures [10]. Increased segmental and overall flexed motion range of the cervical spine in Hirayama patients has been demonstrated recently and this has been postulated to aggravate the forward displacement of the posterior dura mater [10]. The forward movement of the posterior dura mater obliterates the subarachnoid space and leaves a large posterior epidural space with prominent epidural venous plexus, presumably due to venous stasis during neck flexion which may in turn affect the anterior horn cells in the C7 to T1 segments of the spinal cord. Findings of patent anterior spinal arteries in case reports involving vertebral angiography and epidural venography suggest that neither the posterior venous engorgement nor compressive flattening of the spinal cord result in obstruction of large vessel arterial blood flow despite forward displacement of the anterior spinal artery [11]. The epidural venography findings from this study also confirmed that the posterior epidural masses seen by MRI and CT scan are caused by venous engorgement of the posterior epidural venous plexus during neck flexion. Interestingly, the dural displacement can decrease and disappear with age suggesting that the dynamic compression during early adulthood may be of pathological significance [11]. To our knowledge, Hirayama reported the first and only autopsy case in which the spinal cord showed anteroposterior flattening and necrotic changes of the anterior horns of the cervical spinal cord at C5 to T1, predominantly at C7 and C8 [12].
Fig. 1. Patient 3, neutral T2-weighted MRI, sagittal. Unremarkable image in the neutral position.
1.4. Radiological diagnosis Optimised MRI in suspected Hirayama Disease is important as many of the described characteristic features such as anterior shift of the dura, loss of dural attachment, epidural space enlargement, flow voids and enhancement are often absent in routine supine cervical spine MRI. Whilst commercially available specialized equipment such as multi-positional MRI scanners and integrated auxiliary coil attachments that allow real dynamic spinal imaging are not widely available, an optimized neutral and flexion cervical spine MRI scan protocol can be achieved using standard MRI equipment. Our optimized MRI protocol includes routine cervical spine sequences obtained in the neutral supine position. In addition, images in 20 to 40 degrees of cervical spine flexion are achieved by asking the patient to flex the head as far forward as possible and then to oppose the chin against the chest. The position is then maintained by supporting the neck and shoulders with MRI-compatible positioning foam pads. Post gadolinium sagittal and axial fat suppressed T1-weighted images are then obtained as a minimum. In our experience, the additional flexion sequences add only several minutes to the examination duration, are well tolerated by the patient and provide imaging findings that are otherwise not available (Fig. 1 and 2).
Fig. 2. Patient 3, flexion T2-weighted MRI, sagittal. Imaging in flexion shows loss of dural contact, posterior epidural flow voids, anterior dural displacement and spinal cord contact.
1.5. Treatment There is currently no treatment to reverse limb weakness for the disease. Avoidance of neck flexion, physiotherapy and occupational therapy have been advocated as the mainstay treatment for Hirayama disease [13]. Spinal decompression and fusion by surgical procedures may be beneficial [14]. Experimental treatments include hand rejuvenation therapy [15], a cosmetic surgical procedure involving the placement of adipose tissue from the abdomen
E. Foster et al. / Journal of Clinical Neuroscience 22 (2015) 951–954
or thigh into areas of atrophy in the affected hand/s for improved aesthetics. 2. Case series This case series discusses three patients with likely Hirayama disease. They have no other significant past medical history and no personal or family history of other neurological disorders. 2.1. Patient 1 Patient 1 is a right handed 29-year-old male of Italian descent. He experienced weakness of his hands in his late teens initially rapidly progressing before plateauing over eighteen months. He described worsening limb weakness with cold weather. Examination revealed wasting of hand and distal forearm muscles with well preserved proximal forearm extensors; this is often described in Hirayama-literature as oblique amyotrophy [16]. Finger abductors and extensors were assessed as Medical Research Council (MRC) Grade 1/5 power on the right and 3/5 on the left, and finger flexors were 4+/5 on the right and 5/5 on the left, except for flexor pollicis longus which was weaker bilaterally. Cervical spine MRI revealed short segment spinal cord atrophy between mid C4 and mid C6 levels, the right side more affected than the left, and anterior displacement of the spinal cord in flexion with an enlarged posterior epidural space (Fig. 3). Initially, the diagnoses that were entertained included an atypical central spinal cord cervical myelitis, spinal muscular atrophy and post-viral phenomenon. Finally, a retrospective diagnosis of Hirayama disease was made approximately after a year after onset of symptoms. Despite not receiving any treatment, his disease remained fairly stable ten years after diagnosis. 2.2. Patient 2 Patient 2 is a right handed 22-year-old male of Ashkenazi Jewish descent. Symptoms began at age 18, initially with bilateral hand
953
fasciculations and followed three months later with weakness and wasting in the right hand. A month later he developed the onset of left hand weakness, albeit not as severe as on the right. The weakness was worse in cold weather and interfered with his activities of daily living. Examination revealed oblique amyotrophy and minimyoclonus of the fingers. Power was assessed as MRC Grade 4/5 in the intrinsic muscles of both hands and 5/5 throughout the rest of the upper limbs. Upper limb reflexes were all hypoactive. The rest of the neurological examination was unremarkable. Cervical spine MRI showed spinal atrophy at the level of C6 and flexion views demonstrated anterior cord compression at this level as well as forward displacement of the posterior dural. Electromyography and NCS showed active denervation of the intrinsic muscles of the right hand and forearm with sparing of brachioradialis and biceps and ulnar F-waves were marginally prolonged. He was trialled on high dose intravenous immunoglobulin daily for five days; this induction course did not improve his symptoms. The diagnosis of Hirayama disease was made. He was discharged with a cervical soft collar to prevent long periods of neck flexion. The patient declined cervical vertebral body fusion surgery. Follow-up MRI of the cervical spine found a decreased magnitude of anterior displacement of the thecal sac on neck flexion. The patient has experienced only modest improvement in his function. 2.3. Patient 3 Patient 3 is a right handed 23-year-old male of Spanish descent who presented with an 18 month history of right upper limb wasting and weakness which worsened in cold weather. Initially, the illness progressed rapidly and then stabilized. Examination revealed oblique amyotrophy and mini-myoclonus of the fingers of his right hand. Power was reduced with finger abduction MRC Grade 4/5 on the right and 4+/5 on the left, supination 5/5 bilaterally and weak wrist flexion. Upper limb reflexes were reduced on the right. Cervical spine MRI in flexion showed the posterior dura was displaced anteriorly compressing the cord from C5 to C7 as well as asymmetrical flattening of the right side of the cord at C5/C6 (Fig. 2). Motor NCS showed no definite evidence of conduction block, however, F-waves were absent from the right median and ulnar nerves to abductor pollicis brevis and abductor digiti minimi. Initially the patient was given a five day induction course of intravenous immunoglobulin, however symptoms did not improve and no further infusions were given. Hirayama disease was diagnosed and the patient was managed with a soft cervical collar. A follow-up MRI showed a reduction in the anterior displacement of the dura in flexion. The patient has experienced modest improvement in his overall function. Conflicts of Interest/Disclosures The authors declare that they have no financial or other conflicts of interest in relation to this research and its publication. References
Fig. 3. Patient 1, neutral T2-weighted MRI, sagittal. Neutral position image showing advanced cord atrophy and myelomalacia at the cervicothoracic junction but no obvious cause.
[1] Pradhan S. Bilaterally symmetric form of Hirayama disease. Neurology 2009;72:2083–9. [2] Zhou B, Chen L, Fan D, et al. Clinical features of Hirayama disease in mainland China. Amyotroph Lateral Scler 2010;11:133–9. [3] Sawai S, Misawa S, Kanai K, et al. Altered axonal excitability properties in juvenile muscular atrophy of distal upper extremity (Hirayama disease). Clin Neurophysiol 2011;122:205–9. [4] Lyu RK, Huang YC, Wu YR, et al. Electrophysiological features of Hirayama disease. Muscle Nerve 2011;44:185–90. [5] Restuccia D, Rubino M, Valeriani M, et al. Cervical cord dysfunction during neck flexion in Hirayama’s disease. Neurology 2003;60:1980–3. [6] Polo A, Curro’ Dossi M, Fiaschi A, et al. Peripheral and segmental spinal abnormalities of median and ulnar somatosensory evoked potentials in Hirayama’s disease. J Neurol Neurosurg Psychiatry 2003;74:627–32.
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E. Foster et al. / Journal of Clinical Neuroscience 22 (2015) 951–954
[7] Misra UK, Kalita J, Mishra VN, et al. Effect of neck flexion on F wave, somatosensory evoked potentials, and magnetic resonance imaging in Hirayama disease. J Neurol Neurosurg Psychiatry 2006;77:695–8. [8] Lai V, Wong YC, Poon WL, et al. Forward shifting of posterior dural sac during flexion cervical magnetic resonance imaging in Hirayama disease: an initial study on normal subjects compared to patients with Hirayama disease. Eur J Radiol 2011;80:724–8. [9] Desai JA, Melanson M. Teaching neuroimages: anterior horn cell hyperintensity in Hirayama disease. Neurology 2011;77:e73. [10] Xu X, Han H, Gao H, et al. The increased range of cervical flexed motion detected by radiographs in Hirayama disease. Eur J Radiol 2011;78:82–6. [11] Elsheikh B, Kissel JT, Christoforidis G, et al. Spinal angiography and epidural venography in juvenile muscular atrophy of the distal arm ‘‘Hirayama disease’’. Muscle Nerve 2009;40:206–12.
[12] Hirayama K, Tomonaga M, Kitano K, et al. Focal cervical poliopathy causing juvenile muscular atrophy of distal upper extremity: a pathological study. J Neurol Neurosurg Psychiatry 1987;50:285–90. [13] Huang YL, Chen CJ. Hirayama disease. Neuroimaging Clin N Am. 2011 Nov;21(4):939-50, ix-x. [14] Kohno M, Takahashi H, Ide K, et al. Surgical treatment for patients with cervical flexion myelopathy. J Neurosurg 1999;91:33–42. [15] Puwanant A, Evangelisti SM, Griggs RC. Treating the chief complaint: hand rejuvenation for Hirayama disease. Neurology 2011;77:190–1. [16] Hassan KM, Sahni H, Jha A. Clinical and radiological profile of Hirayama disease: a flexion myelopathy due to tight cervical dural canal amenable to collar therapy. Ann Indian Acad Neurol 2012;15:106–12.
