Follow the Venous Path to the Hidden Lesion: A Technical Trick in Brainstem Cavernous Malformation Surgery

OBJECTIVE: Deep-seated brainstem cavernous malformations (BSCMs) pose a particular challenge for brainstem entry intraoperatively and their treatment can require comprehensive application of neuronavigation, electrophysiological brainstem mapping and monitoring, and full knowledge of safe brainstem entry zones. In the present report, we have introduced a supplementary technical trick for localizing a hidden tiny lesion inside the brainstem when a developmental venous anomaly (DVA) is present on the brainstem surface. METHODS: A retrospective analysis of a 74-case cohort treated surgically from January 2011 to December 2019 was conducted. We identified 11 patients (14.9%) whose deepseated BSCMs were exposed and removed following a brainstem surface DVA path as a supplementary technical trick. We have presented 2 typical cases to illustrate the operative nuances. RESULTS: Of the 11 patients, 5 were male and 6 were female. Their average age was 38.0 +/- 14.0 years (range, 15e62 years). Most BSCMs were located in the pons (n = 5; 45.5%), followed by the pontomesencephalic area (n = 3; 27.3%), midbrain (n = 2; 18.2%), and medulla oblongata (n = 1; 9.1%). All BSCMs were successfully located and completely removed. In 5 cases, the DVA was impaired after lesion removal (45.5%). However, no aggravated postoperative brainstem edema occurred in any of the 11 patients. After 3.6 +/- 2.0 years of follow-up (2 patients were lost to follow-up; follow-up rate, 81.8%), no rebleeding was found, and the modified Rankin scale score of the patients had improved from 2.7 +/- 1.1 preoperatively to 1.7 +/- 0.9 at follow-up (P = 0.031). CONCLUSIONS: The presented method could help surgeons trace deep-seated BSCMs with minimal brainstem parenchyma impairment, avoiding unnecessary aggressive exploration.