Trigeminal neuralgia (TN) is a chronic pain condition that affects the trigeminal nerve, which is responsible for sensation in the face. It causes sudden, severe facial pain, often described as an electric shock. Multiple sclerosis (MS) is a chronic neurological disorder where the immune system mistakenly attacks the myelin, the protective covering of nerve fibers in the brain, spinal cord, and optic nerves. This attack disrupts communication between the brain and the body, leading to a variety of symptoms.
Understanding Trigeminal Neuralgia
Trigeminal neuralgia (TN) causes intense, sudden pain episodes in the face. This pain typically affects one side of the face, occurring in areas supplied by the trigeminal nerve like the cheek, jaw, teeth, gums, or lips. The pain is often described as shooting or jabbing, similar to an electric shock, and can last from a few seconds to several minutes.
Episodes of pain can be triggered by everyday activities such as touching the face, chewing, speaking, or brushing teeth. There are two main types of trigeminal neuralgia: classic (Type 1) and atypical (Type 2). Classic TN involves severe, sudden, shock-like pain, while atypical TN can present as a constant burning or aching sensation.
The Link Between Trigeminal Neuralgia and Multiple Sclerosis
Trigeminal neuralgia is significantly more common in individuals with multiple sclerosis, with an incidence approximately 15 times higher than in the general population. This strong association stems from the underlying pathology of MS, which involves demyelination—the damage to the myelin sheath protecting nerve fibers.
In MS, demyelinating lesions can form in the brainstem, specifically where the trigeminal nerve exits or at its root entry zone. This damage directly impairs the normal function of the trigeminal nerve, leading to the characteristic pain of TN. When TN is caused by MS, it is considered “symptomatic” because there is an identifiable cause related to the MS disease process.
Trigeminal neuralgia in MS patients often presents at a younger age than idiopathic TN. TN in MS is also more frequently bilateral, affecting both sides of the face. The longer a person has MS, the higher the likelihood of developing trigeminal neuralgia.
Symptoms and Diagnosis in MS Patients
Trigeminal neuralgia symptoms in MS patients can be more widespread or involve less typical triggers than in non-MS cases. While sudden, sharp facial pain remains a hallmark, it can affect the cheek, jaw, teeth, or lips, and sometimes the eye and forehead. Some individuals may also experience a dull burning or tingling sensation between attacks.
Diagnosing TN in MS patients involves a comprehensive neurological examination. The presence of other MS symptoms, such as vision problems, muscle weakness, or balance issues, provides a broader clinical picture. Magnetic Resonance Imaging (MRI) scans play a role in confirming the MS connection.
An MRI can identify demyelinating lesions in the brainstem or near the trigeminal nerve’s root entry zone, which helps differentiate MS-related TN from other causes like blood vessel compression. MRI helps confirm the specific damage linked to MS as the source of the facial pain.
Treatment Approaches for MS-Related Trigeminal Neuralgia
Managing trigeminal neuralgia caused by multiple sclerosis often begins with medications. Anticonvulsant medications are the primary approach, with carbamazepine being a first-line drug. Oxcarbazepine is another effective first-line option, often with fewer side effects. These medications work by modulating voltage-gated sodium channels to decrease neuronal activity and block pain signals.
If initial medications are not effective or cause intolerable side effects, other anticonvulsants like lamotrigine, gabapentin, or pregabalin may be used. Baclofen is also considered a second-line treatment. The aim is to find the lowest effective dose to manage pain while minimizing side effects.
When medication alone does not provide sufficient pain relief or is poorly tolerated, surgical options may be considered. Microvascular decompression (MVD) is a procedure that involves moving blood vessels away from the trigeminal nerve. Stereotactic radiosurgery uses focused radiation to damage the trigeminal nerve root to reduce pain signals. Percutaneous procedures, including glycerol injection or balloon compression, are also options that involve destroying nerve fibers to alleviate pain, though they may result in facial numbness.