What is the diagnosis and management of Lhermitte's (Lhermitte's sign)?

Lhermitte's Sign: Diagnosis and Management

Lhermitte's sign is a brief, electric-like sensation that runs down the spine and into the limbs upon neck flexion, indicating pathology affecting the posterior columns of the cervical spinal cord, most commonly associated with multiple sclerosis but requiring thorough evaluation to determine the underlying cause.

Diagnosis

Clinical Presentation

• Characterized by shock-like or electric sensations transmitted down the spine and into the limbs, typically triggered by neck flexion or rotation 1, 2
• Usually stereotyped in individual patients but characteristics vary widely between patients 1
• May present as variant forms:
  • Typical Lhermitte's phenomenon: tingling sensations moving down the limbs or trunk on neck flexion 2
  • Delayed Lhermitte's phenomenon: follows contusion of the spinal cord from neck trauma 2
  • Reverse Lhermitte's phenomenon: induced by neck extension, usually from extrinsic compression of the cervical spinal cord 2
  • Inverse Lhermitte's phenomenon: upward moving paresthesia with neck flexion, can be a sign of myelopathy from nitrous oxide inhalation 2

Etiology

• Multiple sclerosis (most common cause) - present in approximately 41% of MS patients 1
• Cervical spondylotic myelopathy 2
• Spinal cord tumors (both intrinsic and extrinsic) 3
• Vitamin B6 (pyridoxine) toxicity at doses ≥100 mg/day 4
• Medication-induced:
  • TNF antagonist therapy (may cause demyelinating diseases) 4
  • Cisplatin neurotoxicity 3
• Cervical radiation injury 3
• Neck trauma 3, 2

Diagnostic Workup

• MRI of the brain and cervical spinal cord is the preferred imaging modality when Lhermitte's sign is detected 4, 1
• Strong correlation exists between Lhermitte's sign and cervical spinal cord abnormalities on MRI, particularly in the posterior columns 1, 5
• Consider checking vitamin B6 levels if supplementation is suspected as a cause 4
• In patients receiving TNF antagonists, promptly evaluate for demyelinating disease 4

Management

General Approach

• Treatment should target the underlying cause 4, 6
• If associated with multiple sclerosis, management should follow MS treatment protocols 1
• For medication-induced cases:
  • Reduction of vitamin B6 supplementation if levels are excessive 4
  • Stopping TNF antagonist therapy if neurological symptoms develop 4

Specific Management Based on Etiology

• For spinal cord tumors: surgical removal may be indicated, as demonstrated in a case of ependymoma presenting with Lhermitte's sign 3
• For cervical spondylotic myelopathy: appropriate neurosurgical intervention based on the degree of compression 2
• For MS-related Lhermitte's sign:
  • Disease-modifying therapies for MS 1
  • Some case reports suggest weak electromagnetic field therapy may help resolve Lhermitte's sign in MS patients 6

Special Considerations

• Vitamin B6 supplementation should not exceed 100 mg/day to avoid neurological complications 4
• Lhermitte's sign may be an early indicator of MS, with 53% of MS patients who experience it reporting onset within the first three years of illness 1
• In 64% of MS patients with Lhermitte's sign, it began as an isolated symptom 1

Clinical Pearls

• Lhermitte's sign has high specificity for pathology affecting the posterior columns of the cervical spinal cord 5
• The presence of Lhermitte's sign warrants thorough neurological evaluation, especially MRI of the cervical spine 4, 1
• Rarely, Lhermitte's sign can be the presenting symptom of an intrinsic spinal cord tumor 3
• The natural course of Lhermitte's sign is variable, but it is typically a short-lasting sensation in all patients who experience it 1