Pain is more common in MS than has been recognized previously. The rates of pain vary in different studies, from 44% to 80%, depending on the sample and specific questions used to assess the incidence and severity of pain. Osterberg et al studied pain syndromes in 429 patients with definite MS; 58% of the patients reported pain during the course of their disease. One hundred patients (28%) had central pain, including 18 patients (5%) with trigeminal neuralgia. The majority of patients (87%) with central pain had symptoms located in the lower extremities, while 31% were in the upper extremities. It was mostly bilateral (76%) and constant. Aching, burning, and pricking were common qualities.
Other reported pain syndromes in MS include, Lhermitte’s sign, dysesthetic pain, back pain, headache and painful tonic spasms. Chronic pain in MS was found to have no significant relationship to gender, age of onset, disease duration or disease course. Chronic pain can have a significant negative impact on functions in persons with MS, such as the ability to engage in household work and psychological functioning. Chronic pain is significantly related to anxiety and depression in females. In the long-term care facility, residents with MS are more physically disabled and have more frequent pain. There also is a higher prevalence of pressure ulcers and depression than residents without MS.
Though pain is common, it is frequently overlooked in MS patients, and only one-third of MS pain patients are treated for pain.
Cannabis is now legally used in several states in the USA to treat pain, European studies indicate that cannabis-based medicines are effective in reducing pain and sleep disturbance in patients with multiple sclerosis-related central neuropathic pain and are mostly well tolerated. Oral ketamine, an NMDA receptor antagonist, has also been reported to be effective in the treatment of pain and allodynia associated with MS.