During a 13-year period from August 1997 to August 2010, 41 patients with vascular lesions were treated surgically with a transsylvian-transinsular approach. The mean patient age was 36 years (range 11–68 years), with 20 men and 21 women. This cohort included 24 patients with AVMs () and 17 patients with CMs (). All patients were operated on by the senior author (MTL).
Summary of patients with arteriovenous malformations.
Summary of patients with cavernous malformations.
Sensorimotor deficits related to hemorrhage were the most common presenting symptoms. Overall, 18 patients with AVMs (75%) and 12 patients with CMs (71%) presented with clinical findings and radiographic evidence of hemorrhage. Seizures were the next most common presentation in 7 patients. Patients with AVMs presented with more significant deficits than patients with CMs, with mean preoperative mRS scores of 2.5 and 1.6, respectively. Three AVM patients presented in coma after AVM rupture.
AVMs were predominantly located in the insula (18 patients, 75%), whereas CMs were located deeper – 8 in the basal ganglia (47%), 7 in the insula (41%), and 2 in both (12%). The mean diameter was 2.4 cm for AVMs and 2.3 cm for CMs. AVM grading is shown in . AVMs were fed predominantly by MCA branches, with minor contributions from insular and lenticulostriate perforators.
Grading of insular and basal ganglia arteriovenous malformations.
Surgical Management of AVMs
Four patients had previous interventions related to their AVMs. Three of these patients had prior surgery, including one hematoma evacuation, one decompressive hemicraniectomy, and one partial resection. Two of these operated patients were treated subsequently with stereotactic radiosurgery. One additional patient was treated with radiosurgery. Of the three patients treated radiosurgically, two patients hemorrhaged during the latency period and one had incomplete AVM obliteration.
Fifteen patients (62%) underwent preoperative embolization. The anterior transsylvian-transinsular approach was performed in 10 AVM patients (42%) ( and ) and the posterior approach was performed in 14 AVM patients (58%). Selection of the anterior versus posterior approach was based on AVM location. There were no significant differences in subgroups with regard to patient age, preoperative neurological condition, or AVM anatomy with the exception of side – all of the anterior approaches but only half of the posterior approaches were performed on the left side. Language mapping was used in one patient and frameless navigation was used in 4 patients (BrainLab North America, Westchester, IL).
Figure 4 Patient 5 presented comatose with a ruptured left anterior insular and basal ganglia AVM. (A) Axial computed tomography angiography demonstrated a large hematoma in the basal ganglia with midline shift. She underwent emergency decompressive hemicraniectomy, (more ...)
Figure 5 (A) Widely splitting the left proximal Sylvian fissure exposed the draining venous varix, MCA branches, supraclinoid ICA, and optic nerve (Patient 5). (B) Retraction of the varix exposed the MCA bifurcation and its branches, and the inferior margin of (more ...)
Complete AVM resection was accomplished in 21 patients and confirmed with postoperative angiography. Three patients required two planned surgical stages, and two patients had unexpected residual AVM that hemorrhaged postoperatively, necessitating a second operation. Three patients had small, ventricular AVM remnants that were incompletely resected and subsequently treated with Gamma Knife radiosurgery. Of these, two were obliterated completely and one is within the latency period.
Surgical Management of CMs
Only one patient had undergone previous treatment of her CM and presented with a recurrence. The anterior transsylvian-transinsular approach was used in 9 patients (53%) and the posterior approach was used in 8 patients (47%) ( and ). There were no significant differences in subgroups with regard to patient age, preoperative neurological condition, or CM anatomy. Language mapping was used in one patient and motor mapping was used in one patient. In contrast to AVMs, frameless navigation was used in all patients with CMs. Complete resection was achieved in all but one patient (94%), and was confirmed with late magnetic resonance imaging 12 months postoperatively. The incomplete resection was a large, atypical CM that bled significantly during the surgery, had neoplastic features pathologically, and required subsequent radiosurgery.
Figure 6 Patient 40 presented with seizures from this left insular cavernous malformation, seen on (A) axial T2-weighted, (B) sagittal T1-weighted, and (C) coronal T1-weighted MR images. The CM was resected completely through a posterior transsylvian-transinsular (more ...)
Figure 7 (A) The absence of overlying Sylvian veins facilitated splitting the distal Sylvian fissure, (B) which exposed the opercular segments of MCA (Patient 40). (C) The cavernous malformation came to the surface of the long gyrus and was apparent under the (more ...)
There was no surgical mortality in this patient series. Six patients were neurologically worse after surgery, of whom 4 patients recovered completely (transient neurological morbidity, 9.8%) and 2 patients did not (permanent neurological morbidity, 4.9%). Both of these patients had AVMs; one deteriorated after a postoperative hemorrhage from unexpected residual AVM and the other had new hemiparesis after resecting an insular/basal ganglia AVM adjacent to the internal capsule. There were no new language deficits in patients with dominant hemisphere lesions. Overall, good outcomes (mRS 0-2) were observed in 34 patients (83%) and poor outcomes (mRS 3-4) in 7 patients (17%). Relative to neurological baseline, 39 patients (95%) were improved or unchanged after treatment. The mean length of post-operative follow-up for all patients was 19.3 months.
Patient outcomes after CM resection with the anterior transsylvian-transinsular approach were not significantly different from those with the posterior approach (). With AVMs, neurological morbidity was similar with anterior and posterior approaches, but patients were more likely to improve after the anterior approach.
Summary of neurological outcomes after anterior and posterior transsylvian-transinsular approaches.