gms | German Medical Science

Objective: Burr hole evacuation of chronic subdural hematoma (cSDH) carries a relevant risk of recurrence. Recent evidence has suggested that endovascular middle meningeal artery (MMA) occlusion may help reduce this risk. However, endovascular MMA occlusion requires an additional intervention and is hampered by limited availability, increased cost and radiation exposure. On the other hand, a simple technique for reliable preoperative localization of the MMA that would permit direct MMA occlusion through a burr hole approach has not yet been described. Here, we performed a preclinical anatomic and prospective clinical study followed by a retrospective feasibility analysis to validate a simple, fast and cost-effective technique for reliable preoperative MMA localization.

Methods: We performed an anatomic cadaver study with 33 human skulls (66 hemispheres) to localize a frontal target point above the pterion, where the MMA can be accessed via burr hole trephination. Based on anatomic landmark measurements, we designed, cross-checked and tested the validity of a template in a prospective series of 10 patients undergoing elective pterional craniotomy using image guidance. Feasibility of the frontal target point localization was determined according to the hematoma extension in a retrospective series of 237 patients treated for cSDH between 2014-2018.

Results: In the anatomic study, the perpendicular distance from the zygomatic arch to the target point in the fronto-parietal bone was 4.1cm (95% CI 4-4.2). The mean length along the zygomatic arch from the external auditory canal to the point of perpendicular distance measurement was 2.3cm (95% CI 2.2-2.4). The template designed according to these measurements yielded high agreement between the template-based target point and the proximal MMA groove inside the fronto-parietal bone (right 90.9%; left 93.6%). In the clinical validation, we noted a mean distance of 4mm (95% CI 2.1-5.9) from the template-based target point to the actual MMA localization. In the retrospective series, 95% of all cSDH had primary frontal extension or frontal involvement and would have been accessible by the new target point localization.

Conclusion: In cSDH with frontal extension that require surgical evacuation, a template-based target point approach for MMA localization may serve as a simple, fast and cost-effective technique to permit surgical cSDH evacuation with MMA occlusion through the same burr hole in a single setting.