Preoperative characterization of brain anatomy by magnetic resonance imaging and intraoperative functional characterization of the nervous system is essential in patients undergoing radical resection of brain tumors. A novel integrated system was developed combining conventional bipolar forceps with an electric stimulator and an oscilloscope. The system consists of a mechanical switching circuit allowing a wide range of electric characteristics and was designed to perform intraoperative electrophysiological studies, including functional mapping and measurements of motor evoked potentials (MEPs) and somatosensory evoked potentials (SEPs). This system achieved a significant reduction in exchange time (from 3.63 ± 1.00 sec to 1.12 ± 0.42 sec) between coagulation and stimulation, and reproducible measurement of MEPs from porcine limbs by cortical stimulation using the bipolar forceps. Functional mapping under awake craniotomy was carried out by cortical stimulation in patients with glioblastoma, and median nerve SEPs with high signal-to-noise ratio were elicited from the bipolar forceps on the sensory cortex of patients under general anesthesia. This integrated system is technically easy to operate and allows functional monitoring of an area that would otherwise be difficult to access using conventional methods. This three-way bipolar forceps system may reduce postoperative complications in patients undergoing neurosurgical procedures.
Surgical treatment of vestibular schwannoma is targeted at complete removal with preserved neurological function. Complete removal may cause significant deficits, whereas subtotal tumor removal is associated with a high recurrence rate. The present study assessed the risk of tumor recurrence and postoperative facial nerve function in relation to the extent of surgical resection by reviewing the clinical records and radiological findings of 116 patients with vestibular schwannoma treated between 1990 and 1999. The extent of resection was classified as follows: gross total resection (GTR), near total resection (NTR), and subtotal resection (STR). Facial nerve function was graded using the modified House-Brackmann grade, and patients grouped into good (grades 1-2) and intermediate or poor (grades 3-6). Of the 116 patients, 26 (22%) underwent GTR, 32 (28%) NTR, and 58 (50%) STR. The recurrence rates were 3.8% (1/26 cases), 9.4% (3/32), and 27.6% (16/58) for GTR, NTR, and STR, respectively. GTR and NTR showed no statistically significant difference in terms of recurrence rate (p = 0.620). However, recurrence was significantly less after NTR than STR (p = 0.043). Immediately postoperative facial nerve function was good in 15.4% of patients after GTR, 40.6% after NTR, and 46.6% after STR. The STR and NTR carried a lower risk of facial nerve palsy than GTR in the immediately postoperative stage (p = 0.006 and 0.036, respectively). Nevertheless, no statistical significance was observed in extent of resection and postoperative facial nerve outcome between the groups at last follow up (p = 0.227). GTR is the ideal surgical treatment for vestibular schwannoma, but NTR is a good option, with better facial nerve function preservation than GTR without significantly increasing the risk of recurrence.
A 25-year-old man presented with intractable post-traumatic seizures after suffering cerebral contusion in a traffic accident at age 5 years. Cerebral hemispherotomy was performed to transect the neuronal fibers to interrupt connections between seizure foci in wide areas of the brain, and to minimize the resected brain parenchyma. His seizures resolved and behavioral disorders improved, which had been impaired since age 8 years. Increased glucose metabolism in the normal frontal lobe detected by interictal fluorodeoxyglucose-positron emission tomography was correlated with the improvements in behavioral disorders. These findings suggest that the effects of seizures may be reversible in brain areas connected with, but remote from, the epileptogenic cortex.
A 43-year-old female was treated with gamma knife radiosurgery (GKS) for right frontal arteriovenous malformation (AVM) manifesting as absence seizures. Complete nidus obliteration was confirmed on angiography 4 years after GKS. However, she experienced recurrence of her previous seizures and delayed hemorrhage occurred within the treated nidus, despite absence of abnormalities by repeated angiography 81 months after GKS. She was treated conservatively and discharged home without neurological deficits. The risk of hemorrhage from obliterated AVM is significantly reduced but not eliminated after radiosurgery. Recanalization of thrombus that is too small to detect by neuroimaging may result in delayed hemorrhage.
A 34-year-old man with hemophilia type A presented with a huge intracerebral hematoma (ICH) in the left frontoparietal lobe due to rupture of an arteriovenous malformation (AVM). Angiography demonstrated the AVM in the frontoparietal lobe fed by the anterior cerebral arteries and the middle cerebral arteries, with a vein draining into the superior sagittal sinus. He developed signs of cerebral herniation due to the huge ICH. An emergent operation was performed to reduce intracranial pressure and to stop bleeding from the AVM under continuous administration of factor VIII. To prevent postoperative hemorrhage, aggressive blood pressure control and continuous administration of factor VIII were performed for 10 days. His neurological status improved so that he could hold a simple conversation. Continuous administration of factor VIII during surgery and intensive intra- and postoperative therapy resulted in a favorable outcome for this patient with hemophilia type A.
A 31-year-old man presented with typical trigeminal neuralgia caused by an anomalous variant type of anterior inferior cerebellar artery (AICA) directly branching from the primitive trigeminal artery (PTA). Three-dimensional computed tomography angiography, magnetic resonance angiography, and magnetic resonance cisternography disclosed that this anomalous artery originated from the PTA and coursed to the AICA territory of the cerebellum. Microvascular decompression surgery disclosed the trigeminal nerve compressed by this AICA variant together with the superior cerebellar artery. These arteries were successfully transpositioned to decompress the nerve. Careful and thorough inspection around the trigeminal nerve verified that the PTA did not conflict with the nerve. This unusual case was caused by compression of the trigeminal nerve from the AICA directly originating from the PTA, without the more common involvement of the PTA.
A 30-year-old man presented with a supratentorial malignant glioma manifesting as isolated progressive left oculomotor nerve paresis. Computed tomography and magnetic resonance imaging showed an intra-axial tumor in the left temporal lobe, extending to the basal and prepontine cisterns, and compressing the brainstem. The tumor was removed subtotally. The histological diagnosis was anaplastic astrocytoma. Malignant glioma with exophytic growth in the temporal lobe should be considered in the differential diagnosis of isolated oculomotor nerve paresis.
A 38-year-old man presented with progressive cervical myelopathy due to atlas hypoplasia associated with non-traumatic retro-odontoid mass. The neuroimaging findings suggested hypertrophy of the transverse ligament of the atlas. No histological confirmation of the retro-odontoid mass was obtained. Clinical manifestations improved after posterior decompression. Decompressive laminectomy of the atlas with or without fusion can achieve a good outcome in such cases.
A 15-year-old boy presented with a dermoid cyst in the left temporal lobe manifesting as complex partial seizures. Magnetic resonance imaging demonstrated a tumor with mixed signal intensity in the left anterior temporal subdural area, but no evidence of rupture. Intraoperatively, the tumor was located mainly in the deep sylvian fissure, adjacent to the amygdala, and had compressed the hippocampus. Intraoperative electrocorticography (ECoG) showed sporadic interictal spikes in both the adjacent areas of the tumor and over the anterior segment of the hippocampus. Total removal of the tumor and gliotic area of the surrounding tissue including the amygdala was performed. The hippocampal epileptic region was treated by transection of the pyramidal layer to preserve verbal memory function. Histological examination showed the dermoid tumor was closely attached to the brain parenchyma. The complex partial seizures ceased completely after surgery. Intraoperative recording of ECoG from the hippocampus and other limbic structures was very important to determine the epileptogenic area even if the tumor did not directly invade the hippocampus.
Dynamic computed tomography (CT) myelography was conducted in 15 patients with cervical degenerative disease to assess the lesions responsible for their symptoms. CT myelography was performed using a multi-detector row helical CT system in dynamic positions (flexion or extension or both) in addition to the neutral position. Fine sagittal reconstructed images could be obtained in addition to axial images. This method provided static information including cervical vertebral body deformities, and good contrast images of the spinal cord, nerve roots, and cerebrospinal fluid space. In addition, laterality of the offending lesion and changes exaggerated by cervical motion were clearly shown in both axial and sagittal images. Ten of 15 patients demonstrated dynamic changes including dynamic canal stenosis or spinal cord impingement. The operative strategies were changed based on dynamic CT myelography findings in three of the 15 patients. Dynamic CT myelography can provide the axial and sagittal images required for flexion-extension studies, and in combination with conventional imaging modalities, provides valuable information for determining treatment strategies and objectives.