Functional results after microsurgical resection of brain stem cavernous malformations (retrospective study of a 12 patient series and review of the recent literature)

Background. Since advent of MRI, brain stem Cavernous Malformations (CM) can be easily diagnosed, and their curative surgical resection considered under precise conditions. The authors report a consecutive series of twelve patients with CMs surgically treated and histopathologically confirmed. Eleven of the cases had bled (six more than once). In this study special emphasis has been put on the pre and post-operative functional status of the patients, by using the 100 Karnofsky scale (KS). Method. Surgical approaches were: 1 degrees) supra-occipital transtentorial for 1 thalamomesencephalic and 1 quadrigeminal plate CM, 2 degrees) suboccipital infratentorial supracerebellar for 1 dorsolateral mesencephalic CM, 3 degrees) retrosigmoid through the cerebello-pontine angle for 3 pontine and/or medullary CM, 4 degrees) suboccipital intertonsillar for 6 CM located under the floor of the IVth ventricle. Completeness of removal was checked by postoperatoire MRI. It was complete in 11 cases and only partial in 1 (i.e., in the case with the progressing mass-effect presentation). There was no post-op death. Follow-up ranged from 1 to 7 years. Findings. Preoperatively: 2 patients were operated on in a comatose state (KS less than or equal to 20), 5 were in state of functional dependance (K less than or equal to 60) and Shad severe neurological deficits but were still of independant functional status (KS greater than or equal to 60). At one year after surgery: 3 patients had a KS greater than or equal to 80 (i.e., they could resume their prior normal life), 6 had a KS between 60 and 80 (i.e., they were independant) and 3 had a KS below 60 (i.e., they were dependant especially for walking). Interpretation. Our results, as well as the data harvested from the literature, plead for advocating radical surgical resection at least in patients with exophytic CMs having bled. As a matter of fact, study of the natural history shows that in brain stem CMs, the bleeding risk amounts to 21% per year per patient. Review of literature shows evidence that radiosurgery did not prove effective and/or even innoccuous.