Working Diagnosis:
Right-sided Hirayama’s Disease

Treatment:
Physical therapy and home exercise programs resulted in slight improvement in elbow flexion strength. Soft cervical collar was recommended for cueing against cervical flexion which may exacerbate symptoms and lead to progression of disease.

Outcome:
Unfortunately, the athlete began developing progression of symptoms with weakness in the right abductor digits minimi and 4th and 5th flexor digitorum superficialis. Family discussion and shared decision making concluded with retirement from sport due to concern for worsening symptoms. The patient and family were not interested in operative treatment.

Author's Comments:
Hirayama’s disease is a rare cervical myelopathy which usually affects young men in the second or third decade of life. Hirayama’s disease causes weakness and atrophy in the forearm and hand, often distally and unilaterally. Sensation is classically preserved. The progressive nature of the condition typically halts several years after onset. Proximal weakness is even more rare as a subtype. This patient’s proximal weakness and MRI findings are suggestive of this proximal type Hirayama’s disease and adds to the 6 documented cases available in current literature. Repeated neck flexion results in multiple episodes of ischemia and chronic trauma to the spinal cord
Common MRI findings include:
Short and tight dura mater, causing inability to compensate for lengthening during flexion
Cord compression by an expansion of the posterior extradural space, worsened by neck flexion, possibly caused by vascular congestion in the epidural space
Upper cervical kyphosis

Editor's Comments:
Shoulder pain in the throwing arm of an overhead athlete carries a broad differential diagnosis. Typically, glenohumeral pathology is implicated such as SLAP lesions, biceps tendinopathy, subacromial, subcoracoid, and internal impingement. Side to side examination with the nonthrowing arm can help delineate these conditions from other proximal causes. In this case, a rare variant of Amyotrophic Lateral Sclerosis, Hirayama’s Disease, in which cervical flexion worsens cervical myelopathy was the cause of the loss of pitching velocity. This condition is unique in that a single limb is symptomatic with lower motor neuron features in larger distal muscle groups. This separates this disease from another monomelic amyotrophy, O’Sullivan McLeoud Syndrome which is a unilateral lower motor neuron myelopathy in the intrinsic hand musculature.

References:
Aundhakar, S. C., Mahajan, S. K., & Chhapra, D. A. (2017). Hirayama's Disease: A Rare Clinical Variant of Amyotrophic Lateral Sclerosis. Advanced biomedical research, 6, 95. https://doi.org/10.4103/2277-9175.211797
Chen CJ, Chen CM, Wu CL, Ro LS, Chen ST, Lee TH. Hirayama disease: MR diagnosis. AJNR Am J Neuroradiol. 1998 Feb;19(2):365-8. PMID: 9504496
Kikuchi S, Tashiro K, Kitagawa M, Iwasaki Y, Abe H. [A mechanism of juvenile muscular atrophy localized in the hand and forearm (Hirayama's disease)--flexion myelopathy with tight dural canal in flexion]. Rinsho Shinkeigaku. 1987 Apr;27(4):412-9. Japanese. PMID: 3621739
Tayade AT, Kale SK, Pandey A, Kalantri S. Hirayama disease. J Neurosci Rural Pract. 2010;1(1):46-48. doi:10.4103/0976-3147.63105
Yokote A, Fukuhara K, Tsugawa J, Tsuboi Y. Juvenile Muscular Atrophy of the Proximal Upper Extremity as So-Called Proximal-Type Hirayama Disease: Case Report and Review of the Literature. Case Rep Neurol. 2019 Mar 21;11(1):106-111. doi: 10.1159/000495606. PMID: 31011327; PMCID: PMC6465745

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