Unexpected REM sleep excess associated with a pontine lesion in multiple sclerosis

Sleep disorders are prevalent in patients with multiple sclerosis. In contrast, a frank increase of rapid eye movement (REM) sleep time is a rare phenomenon, mostly described in the context of REM sleep rebound (after sleep deprivation, abrupt withdrawal of antidepressants or neuroleptics, and during the first night of ventilation for severe sleep apnea), but not in link with specific brain lesions.We incidentally found an isolated,marked increase inREMsleep time (200min, 40%of total sleep time, normative values: 18.2-20.3%) and in rapid eye movements density during REM sleep in a patient with a secondary progressive multiple sclerosis, associated with an anterior pontine demyelinating lesion on magnetic resonance imaging. This result suggests that a network blocking REM sleep in the pons has been damaged.