Nocturnal carbon dioxide monitoring in patients with idiopathic intracranial hypertension.
BACKGROUND
Idiopathic intracranial hypertension may be associated with sleep apnea. This study evaluated the incidence of sleep breathing disorders in patients with idiopathic intracranial hypertension.


METHODS
Overnight respiratory monitoring was performed in 22 untreated patients with idiopathic intracranial pressure diagnosed at a tertiary medical center over a two-year period and 12 sex- and age-matched control subjects. Breathing measures included heart rate, respiratory rate,oxygen saturation, and continuous end-tidal capnography. Sleep quality and daily fatigue were assessed by self-report questionnaires.


RESULTS
Mean age of the study group was 32.6±12.2 years and of the control group, 37.0±12.9 years. Neither group had significant findings of hypoxia or hypercarbia during sleep, and there were no between-group differences in mean carbon dioxide level (patients, 35.8±4.41 mmHg; controls, 37.6±4.38 mmHg; p>0.02) or minimal oxygen saturation (96.35±1.99% and 5.69±1.71%, respectively; p>0.02). The study group had significantly more events of apnea (CO2) per hour of sleep than the control group (1.21±1.38 and 0.92±0.56, respectively; p=0.02), although values were still within normal range (<5/hr).


CONCLUSIONS
Idiopathic intracranial hypertension is not associated with a clinically significant nocturnal breathing abnormality, and hypercarbia is apparently not involved in the pathogenesis. However, it is possible that a subtle increase in paroxysmal sleep apnea (CO2) events might be sufficient to cause vasodilatation of the cerebral blood vessels, thereby increasing intracranial pressure. Screening for sleep apnea may be appropriate in idiopathic intracranial hypertension patients, and further studies are needed to clarify this issue.
Department of Neurology, Rabin Medical Center, Beilinson Hospital, Petach Tikva, Israel. alonabmail@gmail.com
Alon
A
Abraham
Nir
N
Peled
Alexander
A
Khlebtovsky
Felix
F
Benninger
Israel
I
Steiner
Hadas
H
Stiebel-Kalish
Ruth
R
Djaldetti
D000328:Adult; D000368:Aged; D019296:Capnography; D002248:Carbon Monoxide / Q000097:blood*; D005221:Fatigue / Q000175:diagnosis / Q000209:etiology / Q000523:psychology; D005260:Female; D006339:Heart Rate / Q000502:physiology; D006801:Humans; D019586:Intracranial Hypertension / Q000097:blood*; D008297:Male; D008875:Middle Aged; D008991:Monitoring, Physiologic; D010101:Oxygen Consumption / Q000502:physiology; D017286:Polysomnography; D012891:Sleep Apnea Syndromes / Q000097:blood / Q000175:diagnosis; D020181:Sleep Apnea, Obstructive / Q000097:blood / Q000503:physiopathology; D011795:Surveys and Questionnaires
D002248:Carbon Monoxide
Hypercarbia; Idiopathic intracranial hypertension; Obstructive sleep apnea