A Ruptured Aneurysm in Aplastic or Twig-like Middle Cerebral Artery: A Case Report with Histological Investigation.

Aplastic or twig-like middle cerebral artery (Ap/T-MCA) is a rare vascular anomaly that can cause a hemorrhagic or ischemic event. We report a 38-year-old man who presented with intracerebral hemorrhage from a ruptured aneurysm associated with an Ap/T-MCA. After aneurysm trapping and resection, histopathological examination revealed an internal elastic lamina (IEL) disruption and a thin aneurysmal wall. The patient recovered well after surgery and rehabilitation. No hemorrhagic or ischemic events have occurred during 2 years of follow-up. Ap/T-MCA-associated aneurysms exhibit a disrupted IEL and thin wall, which demonstrates the fragility of the "twig-like" vessels.