Rupture of a pseudoaneurysm of the posterior meningeal artery at its anomalous origin from the posteroinferior cerebellar artery: case report.

OBJECTIVE

The posterior meningeal artery (PMA) normally arises from the vertebral artery; however, its origin varies considerably as the result of its embryological development. This gains clinical significance when associated with vascular pathology.

CLINICAL PRESENTATION: A 65-year-old man presented to his local hospital with a sudden-onset, severe headache. Computed tomography of the head revealed diffuse subarachnoid hemorrhage, mostly in the left posterior fossa. A computed tomographic angiogram demonstrated an anomalous origin of the PMA from the posteroinferior cerebellar artery (PICA). Cerebral angiography showed the PICA to be enlarged, with a reduced caliber at the takeoff of the PMA, which is consistent with possible dissection.

INTERVENTION: The patient was taken to the operating room for trapping of the dissecting segment of the PMA. A clip was placed across the PMA at its origin from the PICA, and the vessel was coagulated and transected. The PICA was wrapped in muslin gauze.

CONCLUSION

The variable origin of the PMA and PICA may be the result of the persistence of embryological anastomoses between the arteries, with regression of the normal channel. Physical stress at the junction of the anomalous PMA and the PICA may have contributed to the abnormality of the PMA, consistent with possible dissection. Because the PMA has multiple anastomoses with the arteries of the falx cerebri, the proximal PMA may be occluded with no compromise to its vascular territory.