Lhermitte’s sign is a sudden, transient, electric shock–like sensation radiating down the spine and into the extremities, precipitated by forward flexion of the neck. It is commonly associated with multiple sclerosis (MS), cervical spinal cord degeneration, and cervical spinal cord injury.

Pathophysiology

• Normal physiology:

  • Spinal cord tracts conduct sensory and motor signals without abnormal excitation during neck flexion.

• Abnormal physiology:

  • Demyelination or irritation of cervical spinal cord fibers (especially dorsal columns) leads to abnormal electrical conduction.

  • Forward flexion stretches the cord, triggering paroxysmal “shock-like” sensations down the spine and extremities.

• Associated conditions:

  • Multiple sclerosis (demyelination)

  • Cervical spondylotic myelopathy

  • Traumatic cervical spinal cord injury

  • Vitamin B12 deficiency–related subacute combined degeneration

Examination Technique

1. Patient positioning: Have the patient sit or stand upright.

2. Neck flexion: Ask the patient to bend the head forward slowly toward the chest.

3. Observation: Note electric shock-like sensations radiating down the spine and into arms or legs.

4. Documentation: Record distribution, severity, triggers, and presence of other neurologic signs (weakness, numbness, hyperreflexia).

Clinical Features

Differential Diagnosis

Special Populations

• Multiple sclerosis patients:

  • Lhermitte’s sign can be an early or relapsing symptom.

• Elderly:

  • More likely due to cervical spondylosis or degenerative myelopathy.

• Trauma patients:

  • May indicate cord instability or injury; urgent evaluation required.

Limitations

• The sign is subjective; relies on patient reporting.

• Can be confused with peripheral neuropathy or radiculopathy.

• Not pathognomonic; must be interpreted in the context of neurologic exam and imaging.

Patient Counseling

• Explain that the “electric shock” sensation is due to nerve or spinal cord irritation, not a primary muscle or joint problem.

• Advise careful neck movement to avoid triggering discomfort or exacerbating underlying pathology.

• Emphasize the need for neurological evaluation and imaging if recurrent or associated with other neurologic deficits.

• Discuss potential underlying causes such as multiple sclerosis, spinal degeneration, or vitamin deficiency.

Conclusion

Lhermitte’s sign is a transient, electric shock–like sensation induced by neck flexion, most commonly seen in demyelinating disorders, cervical myelopathy, and spinal cord injury. Recognizing this sign can facilitate early diagnosis of serious neurologic conditions and guide further work-up and management.

References

1. Compston A, Coles A. Multiple sclerosis. Lancet. 2008;372:1502–1517.

2. Ropper AH, Samuels MA, Klein JP. Adams and Victor’s Principles of Neurology. 11th ed. New York, NY: McGraw-Hill; 2021.

3. Koller WC, Glatt S. Neurologic examination in parkinsonism and myelopathy. Neurol Clin. 1987;5:35–54.

4. Lhermitte J. [Original description of the sign]. Rev Neurol. 1924;2:75–79.