Resection of brainstem cavernous malformations via lateral approaches

Objective To explore the surgical indications and efficacy of lateral approaches in the removal of brainstem cavernous malformations retrospectively. Methods From July 1999 to June 2008, 10cases of brainstem cavernous malformations were removed via lateral approaches. Four of them had reached the lateral pial surface and 6 were covered by parenchyma or glial tissue. Three lesions were located dorsal to the cranial nerve roots and 4 lesions rostral to the facial nerve root. All 7 lesions were removed via the retrosigmoidal approach. Far lateral approach was used for 2 cases with the lesions ventral or caudal to the posterior cranial nerves. Subtemporal approach was adopted in 1 patient with the lesion ventral and rostral to the trigeminal nerve. The preoperative visual reality technique, in combination with intraoperative neuronavigation, was employed in the recent 3 cases to select a safe entry point on the surface of brainstem and a surgical corridor so as to maintain minimal damage to the surrounding fiber tracts and cranial nerve nuclei. Results Total lesion removal was achieved in all patients. Four cases of associated venous malformation were all preserved. The mean NIHSS score was 1.1 after a mean post-operative follow-up of 41months. Eight patients improved, 1 worsened and 1 remained unchanged versus the preoperative state.Conclusion Lateral approaches are recommended for lesions reaching the lateral glial surface or accessible via the lateral safe entry zone approaches. Key words: Brain Stem;  Hemangioma;  Cavernous