Management of brainstem cavernous malformations

The risk of hemorrhage from brainstem cavernous malformations (BSCMs) ranges between 2.33 % and 4.1 % per patient-year across natural history studies and between 2.68 % and 6.8 % per patient-year across surgical series. The recurrent hemorrhage rate from BSCMs ranges between 5 % and 60 % per patient-year. Asymptomatic BSCMs tend to have a benign course, whereas symptomatic lesions often have a more aggressive course and carry an increasing risk of hemorrhage with subsequent bleeds. Hemorrhagic presentation, female gender, family history, and associating venous anomalies have been correlated with an increased risk of hemorrhage from BSCMs. MRI is the diagnostic imaging method of choice for the detection of CMs. Preoperative T1-weighted MRI can help assess the proximity of the lesion to the pial or ependymal surface of the brainstem and is thus essential to operative planning. Fluid attenuated inversion recovery (FLAIR) sequences can detect inflammatory activity and perilesional gliosis and may therefore correlate with an increased biological activity in the CM. This might help predict the aggressiveness of these lesions and their clinical activity. Due to the potential risks of surgery, conservative management with close follow-up should be the primary treatment option for patients with BSCMs. At least two clinically significant hemorrhagic episodes and an anatomical pial representation of the lesion are required before considering surgical intervention as an option because of the potential irreversible neurological damage to the patient. Life-threatening bleeds and rapidly progressive neurological deterioration are also potential indications for surgery. Complete removal of BSCMs when feasible is crucial to the prevention of future hemorrhage from BSCMs. An intraoperative ultrasound and a post-operative MRI can be used to rule out any unnoticed residual lesion. Minimizing the risk of surgery can be achieved by undergoing a case-based selection of the optimal surgical approach that allows for easy access to the lesion with minimal manipulation of normal neural tissues. Preserving any associated venous anomaly during surgery is crucial in order to avoid any undesirable hemorrhagic infarction. Advanced imaging techniques, such as diffusion tensor imaging integrated with intra-operative neuronavigation MRI, can be used to determine the anatomical relation between BSCM and the surrounding eloquent structures. Radiosurgery is not considered an effective treatment option for BSCMs. It is reserved only for extremely biologically aggressive lesions that cannot be accessed surgically.