The main symptoms are a rapid and intense decrease in vision in either or both eyes including:
or symptoms of spinal cord dysfunction:
Usually, as the disease progresses, both visual and spinal cord symptoms develop.
The course of Devic's disease is highly variable. It largely depends on whether there is a tendency for relapses to occur after the initial flurry of symptoms that leads to the diagnosis.
In general, attacks of Devic's disease tend to be more frequent and severe than they are in MS. The major risk to patients is severe damage to the upper spinal cord, which can lead to inability to breathe on one's own. This may be fatal. However, some patients with Devic's disease seem to enter a long period of time where the disease remains stable. Devic's disease has not been studied in large enough populations to predict the outcome of individual cases with great certainty.
Permanent blindness may occur in one or both eyes. Permanent loss of strength or sensation in the arms or legs may occur. Inability to control the bowel or bladder function may also occur.
At any point in this disease, patients may develop sudden brief, repetitive spasms. These spasms may also occur in MS, but they are considerably more common in Devic's disease. With these spasms, patients develop prolonged tightening of arms and legs that last for 15 seconds to 2 minutes. They may be painful and recur several times a day. In most cases, they respond very successfully to treatment with an anticonvulsant medication.