Visual Dysfunction
Although optic neuritis, the most common visual symptom, usually is transient and associated with good recovery, some patients have persisting and occasionally progressive deficits and may benefit from referral to a low vision clinic. Involuntary eye movement disorders, such as nystagmus and oscillopsia, also cause distressing visual disturbance. These symptoms may be helped by the use of prisms, and there is anecdotal evidence to suggest the use of a number of medications including baclofen, gabapentin, and isoniazid. A small study has evaluated the role of the glutamate agonist memantine in pendular nystagmus, and all 11 patients treated with this agent were reported as showing a positive response.

Vertigo
Dizziness or vertigo may occur as part of a brain stem relapse and may be accompanied by nystagmus and ataxia, resulting in a profound reduction in mobility and safety. Prochlorperazine may be helpful in acute vertigo, while physiotherapy, including Cawthorne-Cooksey exercises, together with cinnarizine, may be helpful when symptoms are chronic.

Swallowing, Speech, and Respiratory Dysfunction
Dysphagia is not uncommon in MS, and suggestive symptoms have been reported in up to 43 percent of the MS population. These symptoms included coughing when eating, choking, anxiety about swallowing, and change in swallowing function. Such symptoms are often overlooked until the patient has a severe choking episode. Mild dysphagia usually is easily managed with assessment and advice from a speech therapist. There is an unquantified risk of aspiration pneumonia in more severe cases, and investigation may include videofluoroscopy. Percutaneous gastrostomy may be required if swallowing is unsafe or intake is inadequate.

Speech disturbance in MS usually is due to dysarthria, although dysphasia does occasionally occur, usually in patients with severe cognitive deficits. Again, assessment and management by a speech therapist is helpful, and a communication aid may be useful in very severe dysarthria.

Respiratory insufficiency may occur in advanced MS but also may complicate acute brain stem episodes. Respiratory muscle weakness, including diaphragmatic weakness, is the most common cause. Respiratory support may be required in an acute event, while in more chronic situations the patient may be taught to incorporate the diaphragm when talking.

Temperature Sensitivity
Many patients report a worsening of symptoms associated with an increase in temperature or exercise, particularly in relation to visual function (Uhthoff’s phenomenon). The drug 4-aminopyridine has been reported to be particularly beneficial in patients with temperature sensitivity. Practical advice about airconditioning systems may be helpful, and the use of a cooling suit might be considered if the symptoms are very severe (see Chapter 5). A recent randomized, double-blind, controlled study of cooling therapy has been reported. It included 84 patients with mild to moderate disability, together with heat sensitivity, and looked at the benefit of a single dose of cooling therapy and at more sustained therapy over a month. Some benefits were seen in mobility and visual testing in both the acute and sustained treatment, and benefit in fatigue was reported in the latter group.