Hirayama disease: neutral and flexion magnetic resonance imaging and utility of inter-segmental angle of flexion.

Purpose: Hirayama disease (HD) is a rare disease that was commonly mis-diagnosed in the past. The importance of neutral and flexion magnetic resonance imaging (MRI) in its accurate diagnosis has been emphasized along with utility of the inter-segmental angle of flexion. Aim of the study was to observe MRI findings of HD in neutral and flexion position and measure the inter-segmental angle of flexion. Material and methods: Cervical MR images of 17 patients of suspected HD were evaluated retrospectively for loss of attachment (LOA) of posterior dura, lower cervical cord atrophy, T2 hyperintensity, loss of cervical lordosis, enhancement of posterior epidural venous plexus, and inter-segmental angle of flexion on neutral and flexion MRIs. Results: Flexion MRI showed LOA of posterior dura (most commonly and maximum at C6 vertebral level) and intense enhancement in posterior epidural space in almost all patients. The mean inter-segmental angle of flexion at C5-C6 was 9.2°, and at C6-C7 it was 6°. Neutral MRI revealed LOA in 64.7%, lower cervical cord atrophy in all patients, T2 hyperintensity in the lower cervical cord in 35.2% of patients, and loss of cervical lordosis in 58.8% of patients. Conclusions: Flexion MRI is the gold standard for diagnosis of HD; however, certain imaging attributes, i.e. loss of attachment of posterior dura, asymmetrical lower cervical cord atrophy, T2 hyperintensity, and loss of cervical lordosis, can be seen on neutral MRI as well, which subsequently prompts the radiologist to include flexion MRI for confirmation. The inter-segmental angle of flexion is increased in patients with HD, which plays a role in planning timely surgical intervention.

A Case Report and Review of Literature on Hirayama Disease.

Hirayama disease (HD) is a rare, benign, self-limiting condition that typically affects individuals in their 20s. Although the disease is self-limiting, it can result in functional impairment in those affected. The most common presentation is an asymmetrical, unilateral, or bilateral upper limb weakness with wasting. With an interesting pathogenesis and lack of definitive treatment, HD is an interesting neurological conundrum. Mild symptoms in patients often lead to underreporting of the disease, as individuals may not seek medical attention or may not recognize their symptoms. Most case reports in the literature are from Asia and the Middle East. We report a case of HD in a male patient in his 20s with gradual bilateral upper limb weakness and wasting, confirmed by imaging and nerve conduction studies.

Role of Dynamic Magnetic Resonance Imaging in Hirayama Disease, a Rare Motor Neuron Disease.

Introduction Hirayama disease (HD) is a benign self-limiting motor neuron disease, most commonly occurring in young males. The disease has an insidious onset that affects T1, C8, and C7 myotomes. HD is more common in Japan and Asian countries, and rare in the western population. Magnetic resonance imaging (MRI) is the best technique for the diagnosis of this entity. Early diagnosis is important as the patients can be advised to limit neck flexion movements to arrest the progression of the disease. Any clinically suspected case of Hirayama disease should undergo flexion MRI as conventional neutral MRI may miss findings in a few cases. The purpose of the present study is to evaluate the usefulness of flexion MR imaging and laminodural space (LDS) measurement in young patients with clinical and electroneuromyography (ENMG) definite Hirayama disease. Materials and methods This is a retrospective observational study of 15 patients with clinical and ENMG definite Hirayama disease who were referred to the Department of Radiology. These patients underwent MRI of cervical spine in neutral position and with neck flexion of 30°-40°. In neutral MRI, atrophy and T2-weighted hyperintensities in the cord were noted. In flexion MRI, the maximum forward shifting of the posterior dural sac, also known as the LDS, was noted along with other parameters. Observation The mean age of the study population was 21 ± 3.36 years. Out of 15 patients, 14 were males and one was female; 14 patients (93.3%) had an involvement of unilateral upper extremity while one patient (6.6%) had asymmetric bilateral involvement. Straightening of cervical spinal curvature and cord atrophy was seen in 14 (93.3%) and 12 (80%) patients, respectively, on neutral position MRI. Intramedullary cervical cord T2-weighted hyperintensities were noted in eight patients (53.3%). Loss of the dural attachment and forward shifting of the posterior dural sac with prominent posterior epidural space was noted in all patients (100%). At the maximum forward shift of cord, the LDS ranged from 3.1 to 7.0 mm, with a mean of 5.38 ± 1.13 mm. Epidural flow voids were noted in 86.6% of cases. Conclusion Flexion MRI plays a very important role in confirming the diagnosis of Hirayama disease in clinically suspected cases. Anterior displacement of posterior dura matter and widening of LDS is noted in all cases in our study. Even though findings like cord atrophy and T2 hyperintensities are seen in conventional neutral MRI, these findings are not seen in all cases. So flexion MRI increases diagnostic confidence by showing increased LDS, which is a characteristic finding in Hirayama disease.

Hirayama disease: Nosological classification and neuroimaging clues for diagnosis.

Hirayama disease (HD) is a rare, benign, and nonprogressive motor neuron disease (MND) affecting the upper limbs. It usually presents with weakness and amyotrophy in a single upper extremity with an insidious onset between adolescence and the third decade of life. Since its description in 1959, HD has been known under several names and eponyms in Europe and in Asian countries probably due to its heterogeneous clinical features. Thus, the unclear nosological classification makes challenging the differential diagnosis between HD and other neuromuscular conditions, such as MNDs. However, apart from the nosological difficulties and the lack of evidence-based guideline for diagnosis, the neuroimaging is the mainstay for the diagnosis of HD. Indeed, the specific findings on cervical flexion MRI usually lead to a prompt diagnosis. Here, we reviewed the nosological classifications of HD and its neuroimaging features. Also, we report a case of a 18-year-old boy who presented to our Clinic complaining of muscle weakness of the left distal upper limb without other neurological signs. The cervical MRI, in the neutral position, revealed a high T2 signal intensity in the C5-C7 cervical myelomeres as well as the loss of cervical lordosis, whereas, during neck flexion, it showed the anterior displacement of the posterior dura ad the post-gadolinium T1-weighted imaging enhancement of the posterior epidural plexus. These findings are typical for HD allowing the diagnosis as well as the differential diagnosis from other neuromuscular diseases.

Flexion MRI in a case of Hirayama disease.

We report the case of an 18-year old male with a history of asymmetric weakness and amyotrophy of distal upper extremities, suggestive of Hirayama disease. Magnetic resonance imaging (MRI) of the cervical spine was obtained both in flexion and neutral position. Flexion MRI showed forward displacement of the dura and subsequent cord compression, with associated marked enlargement and postcontrast enhancement of posterior epidural plexus. These findings are pathognomonic of the disorder. On neutral MRI abnormalities may be subtle: in our case, they included loss of physiological lordosis, asymmetric atrophy and increased T2 signal intensity of the lower anterior cervical cord. The ability to identify abnormalities on neutral MRI however is even more important in that it allows the radiologist to include a flexion sequence in the MRI examination, if not specifically requested by the referring physician, and in cases in which the suspicion of the disorder has not been raised.

Cervical laminectomy and micro resection of the posterior venous plexus in Hirayama disease.

INTRODUCTION: Hirayama disease is a rare cervical myelopathy predominantly affecting young adults and mainly found in Asia. It results in a pure motor distal lesion of the upper limbs with slow progression. Dynamic magnetic resonance imaging (MRI), which allows the diagnosis to be made, shows a typical appearance of anterior compression of the cervical spinal cord associated with enlargement of the posterior epidural spaces due to a dilated venous plexus. Surgery is considered when conservative treatment has failed. However, the type of surgery is not well standardized in this compressive myelopathy. METHODS: We report on three patients with Hirayama disease operated using an original method: cervical decompressive laminectomy and coagulation of the posterior epidural plexus without fixation. The clinical, radiological and surgical data of these three patients were analyzed. Each patient underwent postoperative MR imaging. RESULTS: The mean age at diagnosis was 18.6 years (16-20 years) with a history of progressive symptoms lasting 1 to 4 years before treatment. Follow-up was 21 to 66 months after surgery. Neurological and electrophysiological improvement was noted in two patients; the third had stabilized. Postoperative MRI confirmed normalization of flexion imaging on MRI. None of the three patients complained of disabling neck pain. CONCLUSION: Posterior cervical decompression with coagulation of epidural venous plexus is a technique that seems effective in Hirayama disease in young subjects. It effectively treats patients by avoiding permanent cervical fixation.

Hirayama disease: imaging profile of three cases emphasizing the role of flexion MRI.

We report three cases of Hirayama disease, cervical flexion myelopathy presenting as unilateral or bilateral asymmetric muscular atrophy of forearm and hand involving C7 - T1 myotomes in young males. MRI revealed asymmetric cord atrophy, altered signal intensity of cord, posterior dural detachment and enlarged posterior epidural space with multiple flow voids. This article emphasizes the role of Flexion MRI in diagnosing Hirayama disease.

Hirayama disease in Austria.

OBJECTIVES: Hirayama disease (HD) is a segmental cervical myelopathy which affects the C7-D1 myotomes and presents with unilateral or asymmetric upper limb weakness/wasting. The study aimed at systematically collecting cases of HD in Austria and at describing and discussing their presentation on clinical and instrumental investigations and at comparing them with cases reported from other countries. METHODS: Neurological Departments of secondary and tertiary centers and colleagues in outpatient units involved in the management of neuromuscular disorders in Austria were contacted and asked to provide standardised data about their HD cases. RESULTS: Altogether, nine unrelated cases were included. Mean age at onset was 18.3 years (range: 12.5-27 years). The female-to-male ratio was 0.29. Mean disease duration was 18.8 years. All patients presented with weakness or wasting of the distal upper limb muscles. A single arm (right: n=2, left: n=3) was affected in five cases and both arms in four. Six patients presented with tremor, two with fasciculations. EMG showed chronic neurogenic changes in all patients. Conventional cervical MRI was normal (n=1), showed focal atrophy (n=3), an intramedullary lesion (n=3), or abnormal straightening of the cervical spine (n=1). Dynamic MRI in a single patient showed anterior displacement of the dorsal dura, prominent epidural space, compressed cord over the posterior surface of vertebra C5-6, and a prominent crescent-shaped mass. Two patients received physiotherapy with beneficial effect in one. CONCLUSIONS: HD rarely also occurs in Austria, predominantly males are affected, and clinical presentation, course and outcome are not at variance from cases in other European or non-European countries.