gms | German Medical Science

Indications for resection of brain stem CM include, (1) progressive neurological deficits; (2) (sub)acute hemorrhage with mass effect; (3) surgically accessible location of the lesion. The diameter of the parenchymal layer over the lesion, the CM´s spatial relation to nuclei, tracts, or adjacent cranial nerves and vessels can particularly complicate, or even prevent, the surgical approach. We reviewed the surgical treatment and clinical course of 10 patients with 11 brain stem CM with special regard to MRI imaging and its consequences on the choice of surgical approach.

All patients were evaluated pre- and postoperatively neurologically and by conventional MRI (T1 ± Gd, T2, FLAIR) and 3D constructive interference in steady-state (3D-CISS) MRI. Surgery was performed under microsurgical conditions with use of neurophysiological monitoring in all patients. No attempt was made to remove hemosiderin stained gliotic tissue and associated venous anomalies.

The mean age was 27.7 years, mean follow-up was 7.5 months. Eight CM were located in the pons/pontomesencephalic region, operated via the lateral suboccipital approach, 3 CM were located near the floor of IV. ventricle and operated via the median suboccipital approach with total removal of all CM. Results of surgery were excellent/good in 8 patients, one patient suffered from a transient swallowing deficit with temporary tracheostoma, one patient showed slight new hemiataxia. While both, the conventional and 3D-CISS MRI allowed sufficient judgement on the diameter of the parenchymal layer over the lesion, 3D-CISS MRI evolved to be superior in demonstrating the spatial relation of the CM to the fairly safe entry zones as between the VII./VIII. group and the trigeminal nerve by displaying the margin between the CSF, nerves and vessels in detail.

Surgical treatment of brain stem CM is recommended in symptomatic patients, in whom the CM seems to reach the surface. Especially in patients with lesions situated ventrolaterally, 3D-CISS MRI seems to be a valuable method in identifying the cavernoma´s relation to "safe" entry zones, thereby facilitating the surgical approach.