Surgical treatment of brainstem cavernous malformations
Authors: Zeng Lang , Zeng Lingcheng , Chen Kun , Chen Rudong , Li Hua , Yu Jiasheng , Yang Hongkuan 
Published: August 2023

Abstract
Objective: The brainstem cavernous malformations (BSCMs) are associated with higher morbidity and mortality compared with cavernous malformations (CMs), and selection of an optimal surgical strategy for BSCMs remains challengeable. The clinical manifestations, decision-making processes, surgical procedures, and postoperative outcomes of specific neurological deficits were evaluated based on our experience in the surgical treatment of BSCMs. Our experiences on surgical indications, approaches, timing, and microsurgical techniques were summarized through this evaluation.
Methods: A total of 50 patients with BSCMs underwent surgical treatment according to individual surgical indications, approaches, timing, and microsurgical techniques. All patients experienced one or multiple instances of hemorrhaging. Follow-up was conducted on all patients, with magnetic resonance imaging (MRI) scan taking place at 3, 6, 12, and 24 months post-surgery. The modified Rankin Scale (mRS) score was used to evaluate the neurological status preoperatively and postoperatively, and which could be differentiated as favorable outcome (mRS, 0-2 points) or unfavorable outcome (mRS, 3-6 points).
Results: A total of 50 patients suffered from one or more hemorrhages, 38 patients experienced 1 hemorrhage, 10 patients experienced 2 hemorrhages, and 2 patients experienced 3 hemorrhages. The clinical manifestations were categorized into 4 groups: 24 patients presented with cranial nerve deficits, 43 displayed conductive tracts dysfunction, 23 complained of cerebellar signs, and 12 patients suffered from symptoms related to intracranial hypertension. The preoperative magnetic resonance imaging (MRI) confirmed that 12 lesions were located at midbrain, 25 in the pons, and 13 in the medulla oblongata. The selection of surgical approach was based on the patient’s characteristics. Among patients with brainstem cavernous malformations (BSCMs), 32 underwent suboccipital approach, 5 underwent subtemporal approach, 8 underwent retrosigmoid approach, and 5 underwent far lateral approach. Gross-total resection (GTR) was achieved in 48 patients, while subtotal resection (STR) was achieved in 2 patients. Besides, 2 GTR patients experienced rehemorrhage episodes, requiring secondary surgeries for both. Notably, all patients with BSCMs involving the pons in our series achieved favorable outcomes, as measured by the mRS score. The mean mRS score was 0.84±0.10 at 12-month and 0.45±0.07 at 24-month. Importantly, all patients maintained favorable outcomes even at 24-monthk.
Conclusion: BSCMs can result in significant symptoms and signs, and favorable outcomes are typically achieved through surgical treatment. Opting for GTR is the most appropriate option, while it requires careful consideration of appropriate indications, timing, optimal approaches, and skilled microsurgical techniques. Additionally, modern neurosurgical techniques, such as electrophysiological monitoring and functional MRI can be beneficial during the surgical procedure.