Objective: To investigate the indications, technical considerations, and effects of neuronavigation and electrocorticography (ECOG) monitoring in resection of brain cavernous malformations (CM).
Methods: From 1997 to 2003, 70 patients with CM, 53 males and 17 females, aged 33 (8 - 62), underwent resection of CM using neuronavigation and neurophysiological monitoring. The first episodes included hemorrhage (31 cases, 44.3%), seizure (29 cases, 41.4%), headache (5 cases, 7.1%), and focal neurological deficit (4 cases, 5.7%). One case was asymptomatic (1.4%), only discovered during physical examination. The size of CM focus was 21 mm (5-50 mm). The depth of tumor measured from the surface was 3-70 mm. Six patients had multiple lesions. The foci were located deep in the white matter of hemispheres in 39 cases, within the brainstem in 9 cases, within the basal ganglia or thalamus in 11 cases, within the cerebellum in 5 cases, and within the optic nerve in 1 case. Preoperatively a MRI procedure using 5 skin markers was performed with the data transferred to a neuronavigation workstation, thus reconstructing a three-dimensional image of the tumor. Supratentorial subcortical lobar cavernomas underwent microsurgery through sulcus and fissure approach. ECOG monitoring was performed on 29 patients with seizure during the operation and bipolar electrocoagulation on functional cortex was conducted. Follow-up was conducted for 19.4 months (6-24 months).
Results: No intraoperative death was found. Postoperative disability rate was 8.6%. Complete removal of the lesion demonstrated by postoperative MRI was obtained in all patients. New transitory neurological deficits occurred in 4 patients after operation and recovered within 1 month. Hemiparesis developed in 1 patient with thalamus CM (1.4%) and facial paralysis developed in 1 patient with pons CM, and both recovered in 6 mouths. Nineteen out of the 24 patients with preoperative seizure history (79.2%) were postoperatively free of seizure, five (20.8%) of them showed improvement.
Conclusion: Patients with asymptomatic CM can be kept under observation. CM deep in brain after the first bleeding is the indication of surgical treatment. Combination of neuronavigation and neurophysiological monitoring contributes to safety of operation and decrease of postoperative disability rate.