Ruptured aneurysm associated with a twig-like middle cerebral artery: An illustrative case report

Abstract

Background: Anomalies of the middle cerebral artery (MCA) are rare; among the different types of anomalies, the aplastic or twig-like (Ap/T) MCA is extremely rare and has been reported under various names, including aplastic, unfused, or rete type anomaly. The occurrence of a brain aneurysm associated with this anatomic variant is an even rare event, and probably their development and rupture are related to hemodynamic stress of the tinny wall of vessels forming the network.

Case description: We present a 43-year-old male patient with an explosive and persistent right orbitofrontal headache. A computed tomography showed a right frontobasal hematoma with intraventricular disruption. Magnetic resonance angiography showed a right MCA aneurysm and what seems to be a MCA trunk stenosis. Cerebral digital subtraction angiography demonstrated a plexiform arterial network and one aneurysm arising from the network. The patient was successfully treated by surgical clipping to evacuate the hematoma and to prevent further intracranial hemorrhages.

Conclusion: The Ap/T-MCA may be associated with hemodynamic stress with a significant effect through the tinny wall of the vessels causing hemorrhage or leading to the formation and rupture of cerebral aneurysms. Based on a correct diagnosis of the anomaly, treatment can be completed successfully through different standard methods.

Keywords: Aneurysm; Clipping surgery; MCA anomaly; Middle cerebral artery; Twiglike MCA.

Figure 1:

Illustrative case (a) A right frontobasal hematoma with ventricular extension is seen on noncontrast Computed tomography (CT) scan. (b and c) Cerebral DSA with rotational 3-D show the presence of a saccular aneurysm in the middle of the vascular network. (d) Intraoperative view. After evacuating the hematoma, the vascular network is exposed (T-MCA). Under the superficial vessels of the anomaly, the dome of the aneurysm is just visible. Distal M2 segment seems normal. (e) Postoperative DSA. The aneurysm is not visible. (f) CT-angio displays the clip position and the complete exclusion of the aneurysm. (g) Perfusion MRI showing the mean transit time (MTT) and regional cerebral blood volume (rCBV) images without ischemic areas (h) Illustration of the Ap/T MCA anomaly depicting the plexiform arterial network replacing the proximal M1 segment.