TERMINATION OF THE INFERIOR PETROSAL SINUS - AN ANATOMICAL VARIANT

Unusual caudal terminations of the inferior petrosal sinus (IPS) chara cterized by an extracranial extension joining the internal jugular vei n up to 40 mm below the external skull base are reported. This variati on was observed bilaterally on an anatomical specimen and unilaterally on four patients during diagnostic cerebral angiography. It may be co nsidered an accessory internal jugular vein and, if present, may allow for an alternate endovascular access to the IPS. (C) 1997 Wiley-Liss, Inc.