The inferior petrosal sinus: assessment by transcranial Doppler ultrasound using the suboccipital approach.

Recently, intracranial veins and sinuses have been successfully insonated using the transtemporal and transoccipital approaches by transcranial Doppler ultrasound. The purpose of this study was to prove the capacity of the Doppler method to evaluate the inferior petrosal sinus via the suboccipital approach. Venous transcranial ultrasound was performed with a range-gated 2-MHz transducer in 80 healthy volunteers and patients without central nervous system disorders ranging in age from 15-84 years (mean +/- standard deviation [SD], 37.6 +/- 15.2 years). A venous signal with a flow directed toward the probe was considered to originate from the inferior petrosal sinus because of its proximity to the basilar artery. The inferior petrosal sinus was insonated in 96.3% of the cases at least on one side. It was found bilaterally in 48 (60%), on the right side in 74 (92.5%), and on the left side in 51 (63.8%) subjects, respectively. Mean blood flow velocity ranged from 8-53 cm/s (mean +/- SD, 19.6 +/- 8.7 cm/s). A significant age dependency of venous velocities was found. Weak but significant side-to-side differences were observed, reflecting the known right-sided predominance of venous outflow in humans. Using the suboccipital approach, the inferior petrosal sinus can be insonated in a high percentage of subjects without major difficulties and is defined by its vicinity to the basilar artery.