Inneurology, Lhermitte phenomenon, also called the barber chair phenomenon, is an uncomfortable "electrical" sensation that runs down the back and into the limbs. The sensation can feel like it goes up or down the spine. It is painful for some, although others might simply feel strange sensations.[1]
In many people, it is elicited by bending the head forward.[2] It can also be evoked when a practitioner pounds on the cervical spine while the neck is flexed; this is caused by involvement of the posterior columns.
Lhermitte phenomenon is named after the French neurologist Jean Lhermitte.
The sign suggests a lesion or compression of the upper cervical spinal cord or lower brainstem—usually dorsal columns of the cervical cord or caudal medulla.[citation needed]
Delayed onset Lhermittes sign has been reported following head and/or neck trauma.[7][8] This occurs ~2 1/2 months following injury, without associated neurological symptoms or pain, and typically resolves within 1 year.[citation needed]
This sign is also sometimes seen as part of a "discontinuation syndrome" associated with certain psychotropic medications, such as selective serotonin reuptake inhibitors and serotonin norepinephrine reuptake inhibitors, particularly paroxetine and venlafaxine. Typically, it only occurs after having taken the medication for some duration, and then stopped or withdrawn rapidly or after administering reduced dose. Fluoxetine, given its very long half-life, can be given as a single small dose, and often avoid Lhermitte's sign and other withdrawal symptoms.[9]
In the dental field, three studies (Layzer 1978, Gutmann 1979, Blanco 1983) have identified Lhermitte sign among nitrous oxide abusers. This is likely due to nitrous oxide depletion of vitamin B12 leading to a very severe, rapid deficiency in the absence of supplementation.[citation needed]
Lhermitte sign is not attributed to its discoverer.[10] It was first described by Pierre Marie and Chatelin in 1917.[11]Jean Lhermitte, a French neurologist and neuropsychiatrist, did not publish his first report until 1920.[12] However, in 1924 he did publish the seminal article on the subject which resulted in it becoming well known.[13]
^Marie P, Chatelin C (1917).『Sur certains symptômes vraisemblablement d'origine radiculaire chez les blessés du crâne』[On certain symptoms presumably of root origin in skull injuries]. Revue Neurologique (in French). 31: 336.
^Lhermitte JJ, Bollak NM (1924).『Les douleurs à type décharge électrique consécutives à la flexion céphalique dans la sclérose en plaques. Un cas de la sclérose multiple』[Electric shock-like pain resulting from cephalic flexion in multiple sclerosis. A case of multiple sclerosis]. Revue neurologique (in French). 2: 56–57.