Clinical Analysis of Distal Posterior Inferior Cerebellar Artery Aneurysm

Baek, In Hyun; Park, Keun Young; Lee, Jae Whan; Huh, Seung Kon; Kim, Dong Joon; Kim, Dong Ik; Lee, Kyu Chang

Abstract

OBJECTIVE
This study was designed to determine the clinical characteristics of patients with aneurysms that are located at the distal posterior inferior cerebellar artery (dPICA). PATIENTS & METHODS: From September 1976 to June 2007, 54 consecutive patients with PICA aneurysms were treated at our institute. Among them, 19 patients had PICA aneurysms distal to the junction of the vertebral artery-PICA. We retrospectively reviewed the database and imaging studies as sources of information for analysis.
RESULTS
Five patients were male and 14 patients were female. The mean age was 44.6 years old (range: 23-70). Sixteen patients had ruptured lesions: 1 patient was Hunt and Hess Grade I, 4 were Grade II, 5 were Grade III, 4 were Grade IV and 2 were Grade V. Intraventricular hemorrhage or intracerebral hemorrhage was identified in 5 patients on the initial computed tomography (CT). Three patients had unruptured lesions. The locations of aneurysm were the lateral medullary segment in 10 patients, the tonsillomedullary segment in 1 patient, the telovelotonsillar segment in 5 patients and the cortical segment in 3 patients. Most aneurysms (17) were the saccular shape. Seventeen aneurysms were small and 2 were large or giant. The mean diameter of aneurysm was 6.5 mm (range: 2.0-28.0) and the mean diameter of the ruptured aneurysm was 4.8 mm (range: 2.0-12.0). Two patients had mirror aneurysms. Post-hemorrhagic hydrocephalus was identified in 10 patients on the initial CT and shunt surgery was performed on 3 patients. The obliteration methods of the aneurysms were microsurgery in 15 patients (midline suboccipital approach: 9, lateral suboccipital approach: 6) and endovascular surgery in 4 patients (therapeutic distal PICA occlusion: 3, intra-aneurysmal coiling: 1). Early surgery was performed on 2 patients, intermediate surgery (days between rupture: 4-10) was performed on 4 patients and delayed surgery was performed on 10 patients. The mean post-treatment follow up period was 49.5 months (range: 7-156). The clinical outcome was assessed using the modified Glasgow Outcome Scale. All the patients showed favorable outcomes. Five patients suffered from treatmentrelated complications (a CSF collection requiring wound revision for dura repair: 2, shunt surgery: 1 and transient hemiparesis due to impairment of the blood flow distal to the aneurysm: 2).
CONCLUSIONS
In our series, distal PICA aneurysms had the characteristics of a female predominance, they more often presented with intraventricular hemorrhage and the rupture was of a relatively small size. Both microsurgery and endovascular surgery can be troublesome due to the small size, wide neck and tortuosity of the proximal parent artery and the location of aneurysms at a branching site. The surgeons should be careful for preserving vessel patency and insuring watertight dura repair.