Treatment of Hirayama Disease
The primary treatment for Hirayama disease is prevention of neck flexion using a rigid cervical collar, with surgical stabilization reserved for patients who fail conservative management or experience rapid clinical deterioration. 1
Understanding the Disease Mechanism
Hirayama disease is a rare cervical myelopathy affecting predominantly male adolescents (typically ages 14-20 years) that causes painless, progressive distal upper extremity weakness and muscle wasting without sensory loss. 1, 2 The pathophysiology involves forward displacement of the posterior cervical dural sac during neck flexion, causing repetitive compression of the cervical cord and resulting in atrophic and ischemic changes in the anterior horn cells. 2, 3 Disease progression occurs through repeated flexion injury and typically continues for 3-5 years from initial diagnosis before spontaneously arresting. 1, 3
First-Line Conservative Management
Conservative management with strict avoidance of neck flexion and use of a rigid cervical orthosis represents the first-line treatment approach. 1, 3 The primary goal is preventive—to minimize flexion injury by inhibiting motion across the involved cervical joints. 1 This approach effectively halts progressive deterioration when implemented early. 2
Among patients managed conservatively with external orthoses, only 1 of 9 patients (11%) experienced further deterioration in one institutional series. 1 The cervical collar remains the cornerstone of treatment because it directly addresses the mechanical pathophysiology of repetitive flexion-induced cord compression. 3
Surgical Intervention
Surgical stabilization should be offered to patients who fail conservative management or experience rapid clinical deterioration. 1 In the same institutional series, no patient who underwent anterior cervical discectomy with fusion experienced disease progression. 1
Optimal Surgical Strategy
Stabilization-alone procedures produce superior outcomes compared to decompression with or without stabilization. 4 A systematic review and meta-analysis of 70 patients demonstrated that 84.3% experienced improvement in neurological symptoms following surgery, with stabilization-alone being the only significant predictor of improvement on univariable analysis. 4
Patient Selection for Surgery
Decision-tree analysis identified three key predictors of neurological improvement:
- Surgical strategy: Stabilization-alone superior to decompression ± stabilization 4
- Age: Patients under 20 years have better outcomes than those ≥20 years 4
- Surgical approach: Anterior-only approach superior to posterior-only or staged anterior-posterior approaches 4
The most common surgical procedure is anterior cervical discectomy with fusion, which prevents the pathologic flexion-induced cord compression. 1
Functional Restoration for Stable Disease
For patients with stable disease who have residual hand dysfunction, tendon transfers and selective joint arthrodeses can restore hand function. 5 These reconstructive procedures are tailored to specific deficits and may include:
- Tendon transfers for thumb opposition, grasp, and anticlaw deformity 5
- Thumb interphalangeal joint arthrodesis 5
- Selected tenodeses 5
All patients in one series who underwent these procedures demonstrated postoperative grip strength improvement with average follow-up of 3.2 years. 5 However, these interventions should only be considered after disease stabilization, as the risk of ongoing progression must be carefully managed. 5
Diagnostic Confirmation Before Treatment
Patients require multidisciplinary evaluation including:
- Electromyography: Demonstrates denervation in C7-T1 myotomes 1, 3
- Flexion/extension MRI: Shows focal cord atrophy, anterior displacement of posterior dura, and epidural enhancement in flexion 1, 3
- Clinical examination: Confirms distal upper extremity weakness and atrophy without sensory loss 1, 3
Critical Pitfalls to Avoid
Delayed recognition: Early diagnosis and management are essential to halt progressive deterioration effectively. 2 The disease mimics high ulnar neuropathy, lower trunk brachial plexopathy, or C8-T1 radiculopathy, which can delay appropriate treatment. 5
Premature functional reconstruction: Hand reconstruction should only be performed after disease stabilization (typically after the 3-5 year progression period), as ongoing disease activity will compromise surgical outcomes. 5, 3
Inappropriate surgical approach: Decompression procedures are less effective than stabilization-alone, likely because the pathophysiology is dynamic (flexion-induced) rather than static compression. 4
Missing the therapeutic window: Younger patients (<20 years) have superior surgical outcomes, suggesting earlier intervention may be beneficial for those failing conservative management. 4