Cortical asymmetry of REM sleep EEG following unilateral pontine hemorrhage. A 24-year-old woman with a left pontine hematoma showed marked asymmetry in the EEG of REM sleep, suggesting that a unilateral pontine lesion is sufficient to disrupt normal REM sleep EEG in the ipsilateral hemisphere. Other REM sleep characteristics (rapid eye movements, muscle atonia) were unaffected by this lesion. 