Pain is another common symptom in MS and occurs in over 50 percent of patients, with considerable impact on their quality of life. The pain is acute and usually paroxysmal in 15 percent of patients, while in the vast majority of patients it is chronic in nature. Rarely, it may be the presenting symptom. Trigeminal neuralgia is the most common type of acute pain and occurs 300 times more frequently in the MS population than in patients without MS. Lhermitte’s symptom and painful tonic spasm may also be included in this category. Chronic pain consists mainly of low back pain resulting from proximal weakness and abnormal posture and gait, pain associated with spasticity, and spasm and dysesthetic extremity pain.

Carbamazepine is the mainstay of treatment of trigeminal neuralgia, whether MS-related or not. If this drug is ineffective or poorly tolerated, there is some evidence to suggest that other anticonvulsants may be useful, particularly phenytoin. Small studies of misoprostol, a prostaglandin E1 analogue, have suggested partial benefit in patients who respond poorly to carbamazepine. Gabapentin and lamotrigine also have been reported to be of some benefit. Pain becomes chronic in a small proportion of patients, and surgical intervention may be required in this group, particularly if drug therapy is less than adequate or poorly tolerated. Percutaneous procedures have shown benefit, although reinjection may be necessary. This approach has not been rigorously evaluated. Logically, microvascular decompression should not have a role, although recent studies have suggested benefit in about 50 percent of those selected for treatment. Chronic pain is more difficult to treat, although there is some evidence to support the use of amitriptyline in dysesthetic pain, followed by carbamazepine, clonazepam, and other anticonvulsant drugs. Physiotherapy to improve proximal stability and incorporate education on improved posture in standing and sitting is the cornerstone of treatment for low back pain. Nonsteroidal anti-inflammatory drugs, transcutaneous electrical nerve stimulation (TENS), and a heating pad may all play a useful subsidiary role. A recent pilot study of the oral synthetic delta-9-tetrahydrocannabinol dronabinol suggested some benefit in central pain in MS.

In the view of the Committee, acute paroxysmal pain usually responds to carbamazepine, and other drugs are also available. Chronic pain is more difficult to manage and is often undertreated. It frequently requires multidisciplinary input and, if severe, may benefit from the expertise of a pain clinic.