Headaches, shunts, and obstructive sleep apnea: Report of two cases

OBJECTIVE: This report describes two shunted patients evaluated with continuous intracranial pressure (ICP) monitors for worsening headaches and subsequently diagnosed with obstructive sleep apnea. CLINICAL PRESENTATION AND INTERVENTION: ICPs were monitored with strain-gauge sensors inserted into the frontal cortex. After the initial diagnosis of sleep apnea, 8-hour attended polysomnography was performed in each patient. Both patients showed apnea-hypopnea indices greater than 15. Consequently, a "split-night study" was performed to evaluate treatment with titrated nasal continuous positive airway pressure. Patient I was a 42-year-old woman (body mass index, 34.1) with a 16-year history of idiopathic intracranial hypertension treated with lumboperitoneal and ventriculoperitoneal shunts. Patient 2 was a 20-year-old man (body mass index, 64.4) with the Arnold-Chiari 11 malformation. The patient had had a low-pressure shunt since birth. Neurological examinations were normal or unchanged before evaluation. Neurophthalmological examinations were normal. Computed tomographic scans failed to show progressive ventriculomegaly. Awake ICPs were less than 15 mm Hg. Nighttime ICPs during rapid eye movement sleep showed multiple Lundberg A waves associated with obstructive sleep apnea and hypoxemia. Blood pressure did not change during these episodes. Polysomnography showed apnea-hypopnea indices of 31 and 41, respectively. Continuous positive airway pressure reduced apnea-hypopnea indices to 17 and 0, respectively; headaches resolved with outpatient therapy. CONCLUSION: These observations suggest adequate shunting with reduced cerebral compliance in both patients. Altered respiratory mechanics associated with hypoxemia may have triggered cerebral vasodilation and increases in cerebral blood volume, particularly during rapid eye movement sleep. In noncompliant systems, these changes precipitated sustained elevations in ICP and intermittent headaches relieved by continuous positive airway pressure. The clinical patterns also suggest that obstructive sleep apnea should be considered in shunted patients with isolated symptoms of increasing headaches.