Posttraumatic subgaleal herniation of an intracranial cerebral arterial segment
Published in Baylor University Medical Center Proceedings, 2019
Manav Bhalla, John L. Ulmer, Andrew P. Klein, Kieran E. McAvoy, Namrata M. Bhalla
The MCA has four segments: M1 (sphenoidal: MCA origin to insular genu), M2 (insular: limen insulae to circular sulcus), M3 (opercular: circular sulcus to sylvian fissure surface), and M4 (cortical: sylvian surface to cortical branches over lateral hemisphere). Cortical branches may arise from superior, inferior, or intermediate trunks, are two to eight in number, and have a mean diameter of 0.44 to 2.47 mm.3 The diameters of M1, M2–M3, and cortical branches range from 2.5 to 4 mm, 1 to 2 mm, and 1 mm, respectively.4 Situated in the subarachnoid space, the cortical branches enter the brain by perforating the pia mater. The diagnostic utility of CTA relies on optimal image acquisition with respect to contrast bolus.5 The smallest arterial size detected on CTA and DSA is 0.7 and 0.4 mm, respectively.6 No normal caliber arteries in the subgaleal space are visible with current CTA resolution.