Neuroimaging of the brainstem in parasomnia overlap disorder

History A 40-year-old woman developed acute rhombencephalitis with cerebellar ataxia, a facial palsy, diplopia, right hearing loss, dysphagia, and dysarthria [1]. She reported vivid dreams associated with vigorous movements while asleep. On examination, she had right third, fifth, sixth, seventh, eighth, ninth, and tenth nerve palsies plus a right internuclear ophthalmoplegia, and a static cerebellar ataxia. Brain magnetic resonance imaging (MRI) suggested diffuse inflammatory lesions (Figure 44.1). The patient was treated with high-dose corticosteroids and improved within five weeks, except for the cerebellar ataxia and the anterior internuclear ophthalmoplegia. Six months after the episode, she developed an acute C2-7 and D5-6 myelitis; the brain and spinal MRI were unchanged. Two years later she developed abnormal sleep behaviors. Every night while asleep, and several times per night, she would speak, sing, have arm and leg jerks, and walk, open doors, walk into the kitchen or her son’s room, but did not hurt herself and had no recall of any associated mental content. While dreaming of giving him a spanking she slapped her son. She was mainly amnestic for the episodes the next morning. One year after the first neurological episode, she underwent video-polysomnography (Figure 44.2). Slow-wave sleep was interrupted by sudden arousals without any abnormal movement but she had nightly recurrent, quiet, sleep-associated walking episodes without dream recall suggestive of sleepwalking as an arousal disorder rather than as a rapid eye movement (REM) sleep behavior disorder (RBD). Clonazepam was not beneficial but a 9 mg melatonin dose partially improved the frequency and severity of RBD and sleepwalking.