Sleep apnea and nocturnal hypoventilation after western equine encephalitis.

That viral encephalitis can produce daytime hypoventilation is well appreciated, but an association of this infection with the development of a prolonged disturbance of breathing during sleep once the ventilatory disorder during wakefulness has resolved, has not been reported. We describe a young male who required assisted mechanical ventilation in association with western equine encephalitis. Normal waking ventilation returned over 3 to 4 wk, but frequent apneas and severe hypoventilation persisted during sleep with a near absence of waking ventilatory response to chemical stimuli. Over 3 months there was considerable improvement in breathing during sleep associated with an increase in both hypoxic and hypercapnic ventilatory responsiveness.