gms | German Medical Science

Objective: Spontaneous intracranial hypotension (SIH) is an increasingly recognized condition that commonly presents as orthostatic headache. The syndrome is caused by spontaneous loss of cerebrospinal fluid. There is some evidence that the optic nerve sheath diameter (ONSD) may be affected by this disease. We hypothesize that there is a change in ONSD from supine to upright position in symptomatic patients (i.e. with orthostatic headaches) as opposed to asymptomatic patients. We call this method of comparing supine and subsequent upright ONSD “dynamic ultrasound of optic nerve sheath Diameter” (d-ONSD).

Method: We performed a case control analysis. The change in ONSD was measured with a 7-15Mhz linear array transducer in transorbital B-mode ultrasound. The patient was examined first in supine position and subsequently in upright position. All patients with clinically suspected SIH received dynamic ultrasound as part of their workup.

Results: Dynamic ultrasound was performed in 44 patients. In 18 patients the leading symptom was orthostatic headaches (10 men, 8 women; mean age 51.9 years). The remaining 26 patients comprised the control group without orthostatic headaches (15 men, 11 women; mean age 61.9 years). Data from the two groups revealed no statistically significant difference of ONSD in supine position between patients with or without orthostatic headaches. The mean ONSD was significantly smaller in upright position among patients with orthostatic headaches (mean 0.484 cm) as compared to patients without orthostatic headaches (0.549 cm, p=0.036). The difference of ONSD between supine and upright position – the d-ONSD – was significantly larger in patients with orthostatic headaches (mean -0.048 cm) as compared to patients without orthostatic headaches (0.005 cm, p<0.001). Receiver operator characteristics revealed an area under the curve of 0.870.

Conclusions: In this report the difference of ONSD from supine to upright position was significantly larger in patients with orthostatic headaches. Therefore, transorbital dynamic ultrasound may provide a new method for confirming and detecting the diagnosis of SIH. Results of the current analysis are promising and suggest the need for a larger prospective series.