A diagnosis of severe obstructive sleep apnea was made after a 52-year
-old hypertensive man developed a large intracranial hemorrhage. Thera
peutic noninvasive positive pressure ventilation (NPPV) for obstructiv
e sleep apnea and hypoventilation was complicated by transient unilate
ral orbital herniation. As best as can be determined, this represents
a new, potentially deleterious side effect of NPPV.