Hypermotor syndrome in obstructive sleep apnea often misdiagnosed as parasomnias or seizures

   Sumaiya Salim, MD, New Jersey Neuroscience Institute at JFK Medical Center, Edison, N.J., and colleagues, reported on a case series of nocturnal hypermotor syndrome in obstructive sleep apnea (OSA) mistaken for seizures and parasomnias.

   A known cause of rhythmic movements in sleep, OSA-related arousals may also provoke complex movements and behaviors in sleep. Seven patients were referred for unusual movements and behavior in sleep with initial suspicion for parasomnias or seizures. A 41-year-old man had rhythmic, side-to-side leg rolling at 2-3 Hz, left greater than right. A 41-year-old woman had flailing movements of the limbs. A 63-year-old woman had various complex movements (ankle, knee, and hip flexion followed by extension and repetitive hip abduction). A 54-year-old man had body rolling movements with repetitive left wrist flexion-extension followed by rhythmic leg rolling. A 51-year-old man and a 71-year-old woman had complex periodic leg movements. 

   According to the researchers, in all cases polysomnography (PSG) with additional muscle and electroencephalographic (EEG) channels showed these movements being triggered by respiratory events in sleep. A 49-year old woman had a history of violent behavior in sleep, with no recollection on awakening. Her PSG showed bizarre complex movements (rhythmic abduction-adduction of legs, flexion, and extension of hips and knees, raising her leg up in the air at 90 degrees, fiddling with wires and clothing, sitting up confused, bending her right arm behind her head and tapping her abdomen, as well as sitting up in bed, drinking a soda, and speaking with the technician while asleep), induced by sleep-disordered breathing. In all cases, these movements responded to upper airway pressurization.