Trigeminal Neuralgia
Causes
The exact cause of trigeminal is not known. Normally, there are several different types of nerve fibers within the trigeminal nerve that carry different sensations, e.g., pain, touch, heat, etc. These nerve fibers are encased by a layer of insulation, called myelin, which keeps different types of nerve signals separate from each other. If this insulation is damaged, nerve signals can blend together, and the brain can then interpret sensations produced by light touch as pain. In essence, damage to the nerve fibers produces a “short circuit” in electrical conduction that leads to pain.
The most popular and widely-held theory is that TN is caused by vascular (blood vessel) compression of the nerve near the point at which the nerve enters the brainstem (trigeminal root entry zone). This theory in fact forms the basis for one of the most frequently performed operations for treatment of TN, namely microvascular decompression (MVD) (see below). Most commonly, this is due to compression of the nerve by an artery (or arteries), and less commonly by a vein. This form of trigeminal neuralgia has been termed “idiopathic” (no known cause), although this is not a good term and should probably not be used since the cause is actually known (compression by a blood vessel). It is believed that over time, repeated arterial pulsations lead to internal abnormalities in electrical conduction of the trigeminal nerve which is turn produce the pain that is felt by the patient. It is now actually possible, by taking a special “photograph” of the brain known as an MRI, to accurately see blood vessels compressing the trigeminal nerve.
Trigeminal neuralgia can also occur in association with other underlying conditions. Trigeminal neuralgia occurs in about 1% of patients who suffer from multiple sclerosis. Multiple sclerosis causes damage to myelin and this in turn leads to pain production. Rarely, trigeminal neuralgia can be caused by other abnormalities that compress the trigeminal nerve such as tumors, aneurysms, etc.
The most popular and widely-held theory is that TN is caused by vascular (blood vessel) compression of the nerve near the point at which the nerve enters the brainstem (trigeminal root entry zone). This theory in fact forms the basis for one of the most frequently performed operations for treatment of TN, namely microvascular decompression (MVD) (see below). Most commonly, this is due to compression of the nerve by an artery (or arteries), and less commonly by a vein. This form of trigeminal neuralgia has been termed “idiopathic” (no known cause), although this is not a good term and should probably not be used since the cause is actually known (compression by a blood vessel). It is believed that over time, repeated arterial pulsations lead to internal abnormalities in electrical conduction of the trigeminal nerve which is turn produce the pain that is felt by the patient. It is now actually possible, by taking a special “photograph” of the brain known as an MRI, to accurately see blood vessels compressing the trigeminal nerve.
Trigeminal neuralgia can also occur in association with other underlying conditions. Trigeminal neuralgia occurs in about 1% of patients who suffer from multiple sclerosis. Multiple sclerosis causes damage to myelin and this in turn leads to pain production. Rarely, trigeminal neuralgia can be caused by other abnormalities that compress the trigeminal nerve such as tumors, aneurysms, etc.