SRS for Cavernous Malformations: Myths and Realities.

The optimal management of cavernous malformations (CMs) remains controversial. Over the past decade, stereotactic radiosurgery (SRS) has gained wider acceptance in the management of CMs, especially in those with deep location, eloquence, and where surgery is of high risk. Unlike arteriovenous malformations (AVMs), there is no imaging surrogate endpoint to confirm CM obliteration. Clinical response to SRS can only be gauged by a reduction in long-term CM hemorrhage rates. There is concern that the long-term benefits of SRS and the reduced rehemorrhage rate after a latency period of 2 years may only be a reflection of natural history. Of further concern is the development of adverse radiation effects (AREs), which were significant in the early experimental studies. The lessons learnt from that era have led to the progressive development of well-defined, lower marginal dose treatment protocols that have reported less toxicity (5%-7%) and consequently reduced morbidity. Currently, there is at least Class II, Level B evidence for use of SRS in solitary CMs with previous symptomatic hemorrhage in eloquent areas with high surgical risk. Recent prospective cohort studies observing untreated brainstem and thalamic CMs report significantly higher hemorrhage rates and neurological sequelae than the rates reported from contemporary pooled large natural history meta-analyses. Furthermore, this strengthens our recommendation for early proactive SRS in symptomatic deep-seated CMs due to the higher morbidity associated with observation and microsurgery. The key to successful outcomes for any surgical intervention is patient selection. We hope that our precis on contemporary SRS techniques in the management of CMs will assist this process.