Received December 8, 1994; accepted after revision January 31 , 1995. 1 Both authors: Mallinckrodt Institute of Radiology, 510 S. Kingshighway Blvd., St. Louis, MO 631 10. Address correspondence to M. J. Siegel. 175 AJR 1995;165:175-176 0361-803X/95/1651-175 ©American Roentgen Ray Society Sinus Pericranii : Sonographic Findings Gary D. Luker1 and Marilyn J. Siegel Case Report Sinus pemicmanii consists of abnormal extmacnanial veins on venous hemangiomas that communicate directly with an intracranial dunal venous sinus via emissary and diploic veins of various sizes. Clinically, this lesion can mimic other cystic or vascular lesions of the scalp or brain. Identification of sinus pemicranii is important because this lesion, unlike other vascular lesions, does not usually require surgery. We recently encountered two patients with sinus pemicnanii in whom the diagnosis was established by sonogmaphy. Case Report A 6-month-old girl had a soft, bluish-tinged mass that had been present since birth over the posterior right parietal bone. With gray- ity dependence or crying, the mass increased in size. A small under- lying bone defect was palpable. Findings on physical and neurologic examination were otherwise normal, and she had no significant medical history. Gray-scale sonography of the scalp in the region of the mass showed a hypoechoic mass superficial to the parietal bone (Fig. 1A). The mass communicated with an approximately 1-mm defect in the underlying bone. Longitudinal color Doppler images showed blood flow extending from the superior sagittal sinus through the cal- varial defect into an extracranial lesion (Figs. lB and 1C). MR imag- ing showed numerous dilated subcutaneous veins but did not show the communication between these veins and the superior sagittal sinus. No surgical repair was done at this time. We subsequently encountered a second patient with sinus pen- cranii. The sonographic findings in this child were similar to those just described. Discussion Sinus penicmanii is an extracranial collection of nonmuscu- lam veins that are closely adherent to the skull and that con- nect directly with an intracranial venous channel. The superior sagittal and transverse sinuses are the most f me- quent sites of communication [1]. Three possible causes of sinus pericranii have been described: congenital, spontaneous, and posttraumatic. Congen- ital cases may have other associated vascular abnormalities such as cavernous hemangioma and aneurysmal malformation of the internal cerebral vein [2]. A spontaneous origin of this lesion has been attributed to development of an extracranial venous varix with secondary pressure erosion of the skull [3]. Sinus pericmanii may also be caused by skull fractures with tear- ing of an emissary vein or direct injuryto a dural venous sinus [4]. Patients with sinus pemicmanii can present at any age, but most are less than 30 years old at the time of diagnosis [4]. Although the lesion may cause headache, vague fullness, vertigo, or nausea, most patients are asymptomatic and present with a mound, fluctuant mass. The mass chamactemis- tidally enlarges with increased intracranial pressure such as crying, a Valsalva maneuver, or dependent positioning. It decreases in size with direct compression or head elevation. Sinus pemicmanii most commonly affects the frontal bone (40%) near the central and posterior thirds of the superior sagittal sinus. However, the parietal (34%), occipital (23%), and temporal (4%) bones may be affected, and lateral loca- tions have also been reported [5]. A palpable bone defect may be present beneath the mass.