Upper Extremity Surgery in Hirayama Disease: A Modification of the Current Algorithm.

INTRODUCTION

Hirayama disease (HD) is a rare, nonfamilial, monomelic amyotrophy in which patients present with muscle atrophy and weakness of the forearms and hands, either unilateral or bilateral, and without sensory loss. Current treatment guidelines describe the role of conservative treatments including cervical collars and neurotropic medications, as well as spinal surgery in select patients. Upper extremity surgery has not yet been incorporated into the treatment algorithm of HD. The objective of this study is twofold: to present a case series of HD patients treated with the incorporation of nerve and tendon transfers and joint fusions into the existing treatment algorithm and to perform a literature review of interventions.

METHODS

Three cases (4 limbs) of HD treated surgically with nerve and tendon transfers and fusion are retrospectively reviewed. The subjective and objective results from surgery are reported. A literature review is performed on PubMed using "Hirayama disease" and "peripheral nerve surgery," "nerve transfer," "tendon transfer," "hand surgery," or "upper extremity surgery" as search terms to identify studies describing surgical treatment of HD outside of spinal surgery.

RESULTS

Three HD patients (4 limbs) were identified. The average age was 23 years old (range, 16-33 years). Patients presented with intrinsic muscle atrophy, hypothenar, and thenar atrophy. The disease had been present for an average of 6.5 years (range, 1.5-15 years) prior to referral. Two patients had unilateral involvement, whereas one had bilateral involvement. Two patients (3 limbs) were treated with an anterior interosseous (AIN) to ulnar motor nerve transfer, whereas a patient with delayed presentation underwent thumb metacarpophalangeal joint fusion and a Zancolli lasso to the fingers. All patients had subjective and objective improvements postoperation.The literature reveals three independent case reports of HD patients treated with upper extremity surgery. Two papers describe using a tendon transfer, whereas one paper describes an AIN to ulnar motor nerve transfer. All patients demonstrated functional improvements in follow-up.

CONCLUSIONS

HD can be successfully treated with a combination of upper extremity surgery and nerve transfers. To the authors' knowledge, this is the first literature review and the largest case series presenting such interventions in HD.