Treatment of Lhermitte's Sign
The treatment of Lhermitte's sign should focus on addressing the underlying cause while providing symptomatic relief, with high-dose vitamin B6 supplementation being avoided as it can actually cause or worsen Lhermitte's sign at doses exceeding 100 mg/day. 1
Understanding Lhermitte's Sign
Lhermitte's sign is characterized by electric shock-like sensations that travel down the spine, arms, legs, or trunk when the neck is flexed. This symptom results from stretching of demyelinated fibers in the posterior columns of the cervical spinal cord 2. Common causes include:
- Multiple sclerosis (most common cause)
- Cervical spondylotic myelopathy
- Vitamin B12 deficiency (subacute combined degeneration)
- Spinal cord tumors
- Radiation injury to the cervical spine
- Trauma to the cervical spine
- Cisplatin neurotoxicity
Diagnostic Approach
Before initiating treatment, proper diagnosis is essential:
- MRI of the cervical spine (with and without contrast) is the primary investigation 3
- MRI of the brain if multiple sclerosis or other demyelinating disorders are suspected 3
- Laboratory tests to evaluate:
- Vitamin B12 levels
- Anti-glutamic acid decarboxylase (GAD) antibodies if autoimmune etiology is suspected 3
Treatment Algorithm
1. Treat the Underlying Cause
- Multiple sclerosis: Disease-modifying therapies as per MS treatment guidelines
- Vitamin B12 deficiency: Vitamin B12 supplementation (symptoms typically resolve after treatment) 2
- Spinal cord tumors: Surgical removal when possible 4
- Cervical spondylotic myelopathy: Surgical decompression for severe cases
- Radiation-induced: Supportive care and time
- Cisplatin toxicity: Dose modification or discontinuation
2. Symptomatic Management
Membrane stabilizers:
- Carbamazepine
- Gabapentin
- Pregabalin
- Lamotrigine
Avoid high-dose vitamin B6: Long-term doses as low as 100 mg/day have been associated with Lhermitte's sign 1
3. Variant Forms Require Different Approaches
- Typical Lhermitte's sign (tingling on neck flexion): Treat intrinsic spinal cord pathology 5
- Reverse Lhermitte's sign (induced by neck extension): Consider extrinsic compression of cervical cord 5
- Inverse Lhermitte's sign (upward moving paresthesia): Evaluate for nitrous oxide-induced myelopathy 5
Important Considerations
- Even mild Lhermitte's sign should not be dismissed as it may indicate serious underlying pathology 3
- If initial imaging is negative but symptoms persist, consider repeat MRI in 3-6 months 3
- For TNF antagonist therapy users who develop Lhermitte's sign, stop treatment immediately and seek specialist advice as this may indicate demyelinating disease 1
- In patients with vitamin B12 deficiency presenting with Lhermitte's sign, oral supplements of 50-100 mg for 1-2 weeks are safe and effective 1
Monitoring and Follow-up
- Regular clinical assessment to monitor symptom progression
- Follow-up imaging based on underlying etiology
- Adjustment of symptomatic medications as needed
By identifying and treating the underlying cause while providing symptomatic relief, most patients with Lhermitte's sign can experience significant improvement in their symptoms and quality of life.