Chronic subdural hematoma (CSDH) after posterior fossa surgery is rare but may occur. A 70-year-old man with trigeminal neuralgia underwent microvascular decompression. The patient took several medications for trigeminal neuralgia and tremor for a long time. The patient tended to bleed easily and did not stop well, but the bleeding was thoroughly controlled intraoperatively. A month later, he presented with left side weakness, and brain computed tomography showed huge amount of CSDH in the right cerebral convex with midline shifting. Although CSDH was completely drained via burr hole trephination, the brain was not fully expanded, and the CSDH recurred a month later. CSDH was evacuated, but there was still considerable subdural space and remained small CSDH in another superficial subdural space. We considered that the patient was at high risk of recurrence of CSDH and performed middle meningeal artery (MMA) embolization. Afterward, he did not suffer a recurrence. Here, we reviewed the risk factors of CSDH recurrence and the usefulness of MMA embolization in the treatment of CSDH, and we recommend upfront MMA embolization as an effective adjuvant to treat CSDH in patients at a high risk of recurrence of CSDH.

Chronic subdural hematoma (CSDH) after posterior fossa surgery is rare but may occur. A 70-year-old man with trigeminal neuralgia underwent microvascular decompression. The patient took several medications for trigeminal neuralgia and tremor for a long time. The patient tended to bleed easily and did not stop well, but the bleeding was thoroughly controlled intraoperatively. A month later, he presented with left side weakness, and brain computed tomography showed huge amount of CSDH in the right cerebral convex with midline shifting. Although CSDH was completely drained via burr hole trephination, the brain was not fully expanded, and the CSDH recurred a month later. CSDH was evacuated, but there was still considerable subdural space and remained small CSDH in another superficial subdural space. We considered that the patient was at high risk of recurrence of CSDH and performed middle meningeal artery (MMA) embolization. Afterward, he did not suffer a recurrence. Here, we reviewed the risk factors of CSDH recurrence and the usefulness of MMA embolization in the treatment of CSDH, and we recommend upfront MMA embolization as an effective adjuvant to treat CSDH in patients at a high risk of recurrence of CSDH.

It is critical to identify the ruptured cerebral arteriovenous malformations (AVMs) for secondary prevention. However, there are rare cases unidentified on the radiological evaluation. We report on a patient with the delayed appearance of radiologically occult AVM as a probable cause of the previous intracerebral hemorrhage (ICH). An 18-year-old male patient presented with a right temporal ICH. The preoperative radiological examination did not reveal any causative lesions. Because of the intraoperative findings suggesting an AVM, however, only hematoma was evacuated. Disappointedly, there were no abnormal findings on postoperative and follow-up radiographic examinations. Eleven years later, the patient presented with an epileptic seizure, and an AVM was identified in the right temporal lobe where ICH had occurred before. The patient underwent partial glue embolization followed by total surgical resection of the AVM and anterior temporal lobe. Based on the literature review published in the era of magnetic resonance imaging, common clinical presentation of radiologically occult AVMs included headache and seizure. Most of them were confirmed by pathologic examination after surgery. In cases of the ICH of unknown etiology in young patients, long-term follow-up should be considered.

Objective: Non-aneurysmal spontaneous subarachnoid hemorrhage (NASAH) has a good prognosis, but its cause has not been clearly identified. In this study, we assessed the clinical and radiological features of NASAH and suggested an anatomical relationship between the basilar tip anatomy and NASAH. Methods: From August 2013 to May 2020, 21 patients were diagnosed with NASAH at our institution. We evaluated the clinical features of NASAH. NASAH was classified into a perimesencephalic pattern and aneurysmal pattern according to the distribution of hemorrhage based on initial brain computed tomography. Digital subtraction angiography was used to classify the basilar tip anatomy into symmetric cranial fusion, symmetric caudal fusion, or asymmetric fusion types. Results: Of the 21 patients, twenty patients had a good clinical outcome (modified Rankin Scale (mRS) 1–2; Glasgow Outcome Scale (GOS) 4–5). These patients showed improvement in mRS and Glasgow Coma Scale (GCS) at the last follow-up (P=.003 and P=.016, respectively). Eighteen patients with NASAH (85.7%) had the caudal fusion type, and only three patients with NASAH (14.3%) had the cranial fusion type. Seven patients with the perimesencephalic pattern (77.8%) had the caudal fusion type, and eleven patients with the aneurysmal pattern (91.7%) had the caudal fusion type. Conclusions In NASAH patients, the caudal fusion tends to occur frequently among patients with basilar tip anatomy. In the case of the caudal fusion, the perforators around the basilar tip would be more susceptible to hemodynamic stress, which could contribute to the occurrence of NASAH.