Symptomatic brainstem cavernous malformations carry a high risk of permanent neurological deficit related to recurrent hemorrhage, which justifies aggressive management. Detailed knowledge of the microscopic and surface anatomy is important for understanding the clinical presentation, predicting possible surgical complications, and formulating an adequate surgical plan 1).
A systematic review and meta-analysis of 25 studies show that the incidence of symptomatic hemorrhage or rehemorrhage is higher in brainstem lesions. First symptomatic hemorrhage increases the chance of symptomatic rehemorrhage, which decreases after 2 years 2). But reported variance in the literature may also be due to study limitations along with selection, patient and disease-specific; follow-up; and recall bias. An accurate assessment of hemorrhagic risk along with evaluation of patient and lesion-specific characteristics is critical in the decision-making process for potential intervention, as microsurgical intervention can significantly decrease the risk of future hemorrhage, but may be associated with significant complications 3).
Rather than developing a grading system for all cerebral cavernous malformations that is weak with BSCMs, Garcia et al. propose a system for the patients who need it most. The BSCM grading system differentiates patients who might expect favorable surgical outcomes and offers guidance to neurosurgeons forced to select these patients 4).
Brainstem cavernous malformations are associated with a considerable risk of hemorrhage and subsequent morbidity, with significant focal impairment caused by hemorrhages leading to facial nerves damage 5).
Favorable surgical outcomes can be predicted in brainstem CM patients with early age at presentation, pontine cavernous malformationlocation of the cavernoma, favorable preoperative mRS and those undergoing early surgery. The outcomes at long-term follow-up were associated with location of the CM in the brainstem, size of the CM and the preoperative mRS 6).
Patients who had undergone surgery of symptomatic BSCMs were evaluated pre- and postoperatively both neurologically and neuroradiologically supplemented by telephone interviews. Additionally, patients were scored according to the Scandinavian Stroke Scale. Multiple uni- and multivariate analyses of possible clinical and radiological prognostic factors were conducted. The study population comprised 35 patients. Mean age at operation was 39.3 ± 13.0 years with microsurgical resection of a total of 37 different BSCMs between 2002 and 2011. Median clinical follow-up was 44.0 months (range 8-116 months). Postoperative MRI showed eventually complete resection of all BSCMs. Postoperative overall outcome revealed complete resolution of neurological symptoms for 5/35 patients, 14/35 improved and 9/35 remained unchanged. 7/35 suffered from a postoperative new and permanent neurological deficit, mostly affecting the facial nerve or hemipareses with mild impairment. Pre- and postoperative Scandinavian Stroke Scale scores were 11.0 ± 2.4 and 11.4 ± 2.2 (p = 0.55). None of the analyzed factors were found to significantly correlate with patients' clinical outcome. Complete resection of brainstem cavernous malformations can be achieved with an acceptable risk for long-term morbidity and surgery-related new deficits (~20 %). Neurological outcome is mainly determined within the first 6 months after surgery 7).