Lhermitte's sign in a patient with herpes zoster.

A 34-year-old, previously healthy man developed herpes zoster (shingles) involving the C4 dermatome. This was accompanied by Lhermitte's sign, i.e. an electric shock-like sensation radiating from the neck to the sacrum, elicited by flexion of the neck. Lhermitte's sign resolved in this patient after several days, and probably reflected acute inflammation together with changes in sensory axon excitability. This positive manifestation of dorsal column dysfunction can be present in the absence of fixed neurological deficits, and can reflect dorsal column dysfunction caused by a wide spectrum (demyelinating, traumatic, compressive, toxic/deficiency, infectious and inflammatory) of etiologies.