What is a Lhermitte Sign?
Lhermitte Sign is a symptom which is characterized by an intense electric shock like sensation that tends to travel from the head to the foot traveling through the arms and legs. This symptom can more often than not be reproduced when the neck is flexed and is brought close to the chest.
A Lhermitte sign is a sign of a dysfunctional dorsal column of the cervical spinal cord. This part of the spinal cord is responsible for sending signals to the brain pertaining to information about a sense of touch, proprioception, and vibration. Studies suggest that Lhermitte sign is the first signal that an individual may be having multiple sclerosis. As such, when an individual presents to a healthcare provider with a positive Lhermitte sign then the first thing that the physician does is to conduct tests to rule out multiple sclerosis as a cause of Lhermitte Sign.
What are the Causes or Triggers of a Lhermitte Sign?
Multiple Sclerosis: Coming to what causes Lhermitte Sign, as stated above multiple sclerosis is the most common cause of an individual having Lhermitte Sign. This is a neurological disorder in which the myelin, which is a protective sheath that protects the nerve fibers, start to degenerate, and gradually as the myelin starts to wear away from the nerve fibers, there is formation of scar tissue over the nerves which blocks the signals that travels from the spinal cord to the brain. This results in symptoms such as Lhermitte Sign.
Vitamin B12 Deficiency: Vitamin B12 deficiency is yet another cause that may lead to production of Lhermitte Sign. Vitamin B12 plays an important role in regulation of the nervous system of the body. A deficiency in vitamin B12 may lead to an impaired nervous system and gradually it takes the shape of a demyelinating disorder which eats away the myelin sheath protecting the nerve fibers causing the classic symptom of a Lhermitte Sign.
Transverse Myelitis: This is a condition in which there is inflammation on both sides of the spinal cord. As a result of this inflammation, there is significant damage done to the myelin thus blocking the signals that is being sent from the spinal cord to the brain causing the classic symptom of Lhermitte Sign.
Cervical Spinal Cord Tumors: This is yet another cause for Lhermitte Sign. Any type of tumor whether benign or malignant in the cervical spinal cord which impairs the functioning of the nerves within the spinal cord causes the classic symptom of Lhermitte Sign.
Cervical Spondylosis: This condition is also a common cause for Lhermitte Sign. Cervical spondylosis is a condition in which there is chronic degeneration of the cervical disc. As the disease condition advances, the disc starts to impinge on the nerves thus causing damage to the nerves which result in the nerves not being able to transmit information from the spinal cord to the brain. This is what causes Lhermitte Sign.
In summary, while multiple sclerosis is the primary cause for Lhermitte Sign, there are various other medical conditions which tend to damage the nerves, especially of the cervical spinal cord triggering what we call as Lhermitte Sign.