Lhermitte's sign is classically associated with which condition?

• A. Multiple sclerosis
• B. Osteoarthritis
• C. Rotator cuff tear
• D. Carpal tunnel syndrome

Answer: (A)

Lhermitte's sign is the electric shock–like sensation that travels down the spine and into the limbs when the neck is flexed. This happens because neck flexion stretches a demyelinated cervical spinal cord, making the dorsal columns more excitable. The most classic association is with multiple sclerosis, where demyelinating plaques commonly involve the cervical spinal cord, producing this relief-seeking, transient shock with neck flexion. The other options affect joints or peripheral nerves and don’t produce this neck-flexion–induced spinal shock, so they’re not typical associations. In practice, a positive Lhermite sign strongly points toward a cervical myelopathy process such as MS, and prompts imaging to look for demyelination or other cervical cord pathology.