Is Riluzole (Rilutek) used to treat Hirayama disease?

Riluzole Has No Established Role in Hirayama Disease Treatment

Riluzole is not used to treat Hirayama disease, as the condition is a mechanical cervical myelopathy requiring immobilization or surgical decompression, not neuroprotective pharmacotherapy. While riluzole has demonstrated neuroprotective properties in spinal cord injury models and is being studied in acute traumatic spinal cord injury trials, Hirayama disease has a fundamentally different pathophysiology that does not respond to pharmacological neuroprotection 1.

Understanding Hirayama Disease Pathophysiology

Hirayama disease is a cervical flexion myelopathy caused by:

• Forward displacement of the posterior cervical dural sac during neck flexion, which compresses the lower cervical spinal cord and causes ischemic damage to the anterior horn cells 2, 3
• Mechanical compression rather than primary neurodegeneration, affecting predominantly young Asian males with progressive distal upper extremity weakness and atrophy 2, 4
• Self-limiting progression that typically arrests spontaneously within 3-5 years, distinguishing it from progressive motor neuron diseases like ALS 2, 3

The disease mechanism involves repetitive flexion-induced cord compression leading to chronic ischemia and anterior horn cell damage, not the glutamate excitotoxicity that riluzole targets in ALS 3, 5.

Evidence-Based Treatment Approach

First-Line Treatment: Cervical Immobilization

Cervical collar immobilization is the first-line and definitive conservative treatment for Hirayama disease 2. This approach:

• Prevents neck flexion and eliminates the mechanical compression that drives disease progression 2, 4
• Should be worn continuously for 3-4 years to allow spontaneous disease arrest 6
• Has been shown to effectively halt progressive deterioration when initiated early 3

Surgical Intervention

Surgical decompression and fusion may be considered for patients who:

• Fail to respond to conservative collar therapy after more than 5 years 6
• Cannot tolerate prolonged cervical collar use 6
• Have severe or rapidly progressive symptoms 6

Surgical options include anterior cervical decompression and fusion (ACDF), which provides permanent stable fixation and has achieved satisfactory results with remarkable improvement in muscle strength 6, 4.

Why Riluzole Is Not Indicated

The evidence for riluzole in spinal cord pathology is limited to:

• Acute traumatic spinal cord injury, where the RISCIS trial is evaluating riluzole 100 mg BID for 24 hours then 50 mg BID for 13 days in patients with C4-C8 injuries within 12 hours of trauma 1
• Neuroprotection in ischemic injury models, but Hirayama disease involves chronic repetitive ischemia from mechanical compression, not acute ischemic injury 1

Riluzole's mechanism of blocking glutamate release and reducing excitotoxicity is relevant for acute neuronal injury and progressive neurodegenerative diseases, but Hirayama disease is neither acute nor primarily neurodegenerative—it is a mechanical compression syndrome 1, 2.

Critical Diagnostic Features

Recognition of Hirayama disease requires:

• Clinical triad: Distal upper extremity weakness/atrophy, insidious onset in young males, absence of sensory loss 2
• Flexion MRI findings: Forward displacement of posterior dural sac, asymmetric cord flattening, intramedullary T2 hyperintensity in anterior horns 2, 5
• Electrophysiology: Segmental neurogenic damage to anterior horn cells at C7-T1 without sensory nerve involvement 2

Common Pitfalls to Avoid

• Do not pursue pharmacological neuroprotection when the underlying problem is mechanical compression requiring physical intervention 2, 5
• Do not delay cervical collar treatment while considering experimental therapies, as early immobilization is critical for halting progression 3
• Recognize Hirayama disease as a "nonsurgical entity" in most cases, avoiding unnecessary operations when conservative management is appropriate 5
• Do not confuse with ALS or other motor neuron diseases that might warrant riluzole—Hirayama disease is self-limiting and mechanically mediated 2, 3