Lhermitte’s phenomenon is as a sign of cervical spinal cord demyelination. It is considered positive if flexion of the neck causes a tingling sensation moving down the limbs or trunk, and may be reported as a symptom or elicited as a sign. This is due to stretching of the dorsal column sensory fibers, the commonest cause of which is multiple sclerosis. Other causes include other myelopathies, such as B12 deficiency, radiation and toxic (due to chemotherapy) or idiopathic myelitis. Its sensitivity is low at 16%, but its specificity for myelopathy is high at 97%.
References
Kempster PA, Rollinson RD. The Lhermitte phenomenon: variant forms and their significance. J Clin Neurosci 2008;15(4):379–81.
Khare S, Seth D. Lhermitte's Sign: The current status. Ann Indian Acad Neurol. 2015 Apr-Jun; 18(2): 154-156.
