Central neurogenic hyperventilation

Abstract

Central neurogenic hyperventilation (CNH), for which there is no effective therapy, can eventually result in respiratory fatigue and death. This report describes a patient with CNH due to a brainstem anaplastic astrocytoma who also exhibited disturbances of sleep and ocular motor function. The CNH responded clinically to morphine sulfate and methadone. Analysis of ventilatory response to CO₂ before and after morphine demonstrated a depression of ventilatory response (49 to 53% of baseline) and occlusion pressure response (35 to 50% of baseline) to CO₂, with a requirement for high doses of naloxone (10 mg IV) to reverse the effect. Polysomnography revealed sustained hyperventilation, elevated O₂ saturation, and low end-tidal CO₂ throughout all stages of non-rapid eye movement (NREM) sleep, and absence of rapid eye movement (REM) sleep. Ocular motor evaluation disclosed absence of horizontal and reflexive saccades with compensatory head thrusts. Correlation of the clinical and physiologic data with the MRI abnormalities suggested that the lesion responsible for CNH in this patient might reside in the medial tegmental parapontine reticular formation. Since recurrent episodes of hyperventilation responded in a sustained fashion to IV and oral opiates, this treatment may warrant consideration in other patients with CNH.