Reverse Lhermitte's phenomenon provoked by cervical cord compression.

PURPOSE Lhermitte's phenomenon (LP) is a rare manifestation, which is defined when a sudden electric-shock sensation transmitted down the spine induced by neck flexion; however, the reverse LP is defined when symptoms are induced by neck extension, not flexion. Because reports of LP are limited in the Taiwan literature, we report this case. CASE REPORT A 74-year-old woman presented to our emergency department with sudden onset of right neck pain when extending the neck. The pain mimicked an electric shock and radiated to the left shoulder. Imaging showed spondylosis and spondylolisthesis without any spinal canal stenosis. A neck collar was recommended, and the strange phenomenon did not recur over the following year. However, long-term follow-up and aggressive workup are recommended to rule in or rule out the possibility of multiple sclerosis in the future. CONCLUSION Although LP represents spinal demyelination disorders, reverse LP is induced by extrinsic compression of the cervical cord, and neck collar immobilization rather than intravenous or oral medication is recommended.