Interactive image-guided techniques used in conjunction with three-dimensional images allow accurate planning and performance of a variety of neurosurgical procedures. The frameless stereotactic Viewing Wand System was used to provide real-time correlation of the operating field and computerized images in over 22 neurosurgical operations carried out for intractable epilepsy. The overall results of the surgery demonstrated favorable results, with class 1 + class 2 outcomes in 86.4% of the present series. Our experience shows that the Viewing Wand System is most helpful as an adjunctive navigational device in the microsurgical treatment of epilepsy.
The relationship between hyperperfusion and temporary clipping was evaluated to determine the safe limit for the duration of temporary clipping in aneurysm surgery. Twenty-one patients surgically treated for a ruptured aneurysm were examined using xenon-enhanced computed tomography on postoperative days 4 to 13. Eight of the 16 patients undergoing temporary clipping had focal hyperperfusion; whereas the five patients without temporary clipping had no hyperperfusion. Mean total temporary clipping time in patients with hyperperfusion was significantly longer than that in patients without (31.9 vs. 13.9 minutes, p = 0.0157) and mean maximum single temporary clipping time in patients with hyperperfusion was also significantly longer than in patients without (18.4 vs. 8.6 minutes, p = 0.0313). Moreover, cerebral infarction was related to hyperperfusion (p = 0.0027). These results support the hypothesis that temporary clipping during aneurysm surgery causes postoperative hyperperfusion and cerebral infarction. Temporary clipping may be harmful when performed for more than 20 minutes of total duration, since postoperative hyperperfusion was seen under this condition.
Histological changes in and around the arterial walls of rats were investigated following simultaneous topical application of cotton sheet and cyanoacrylate glue. The bilateral common carotid arteries were exposed using sterile techniques, and the test materials were applied to the right artery. The left artery served as a control. Changes in arterial histology were evaluated at 2 weeks, 1 month, 2 months, and 3 months after surgery. Extensive inflammation consisting primarily of histiocytes and multinuclear giant cells was observed around the materials, but tended to decrease by 3 months. Necrosis in the media and fibrosis in the adventitia initially appeared around 2 weeks, and became advanced by 2-3 months. At 2-3 months, disruption of elastic fibers and marked fibrosis in the media were seen, and endothelial proliferation in the intima appeared. Intimal proliferation was observed at both the experimental and other sites of the vessels. The present results suggest that simultaneous use of the test materials can cause the arterial occlusive lesions observed following aneurysmal surgery.
The clinical usefulness of diffusion-weighted echo planar imaging (DW-EPI) was studied in 55 patients with acute brain ischemia. Ischemic lesions were identified on DW-EPI as hyperintense regions in all patients before changes were detected by conventional magnetic resonance imaging techniques in 12 cases studied earlier than 6 hours after onset. The earliest case was verified on DW-EPI at 50 minutes after onset. The ultra-fast imaging technique took less than 2 minutes to perform even for restless patients. Three patients had cardioembolic middle cerebral artery occlusion, and emergent percutaneous transluminal recanalization was carried out. Chronological changes in the signal of brain ischemia on DW-EPI depended on the site and size of the lesion, lacunar infarct of basal ganglia, and/or massive infarct due to major vessel occlusion, and were affected by associated hemorrhagic events. Coronal DW-EPI could more easily demarcate ischemia in the brainstem and/or cerebellum than axial scans when susceptibility artifacts were present. Coronal scans also demonstrated the site and direction of the pyramidal tract and its anatomical correlation with the lesions. DW-EPI has potential for the diagnostic and therapeutic planning of patients with acute brain ischemia.
The morphometric characteristics of nerve fibers of the human optic nerve in the chiasmatic region were measured with the combination of an image analyzer and a computer, using the Luxol fast blueperiodic acid-Schiff-hematoxylin discriminative staining method. The mean axonal transverse area of the human optic nerve fibers was 0.644 ± 0.361 µm2. Comparison of the size of the axon of the human optic nerve fiber with that of various other human nerves showed optic nerve fibers were definitely thinner than the other nerve fibers, and were surrounded by a thinner myelin sheath. Optic nerves may be more liable to mechanical damage at surgery that previously believed.
A 23-year-old female presented with dural sinus thrombosis caused by protein S deficiency. She suffered superior sagittal sinus thrombosis 6 days after delivering her first child. Past history showed deep vein thrombosis at the age of 20. While conservative management was initiated because of the potential risk of increasing intracranial hemorrhage, several hours later she deteriorated rapidly because of severe brain swelling with massive hemorrhage. The patient died despite surgical decompression. Autopsy disclosed organized thrombus in the superior sagittal and transverse sinuses. Although the total concentration of protein S was normal, the free protein S concentration and protein S activity were decreased. Protein S deficiency is a rare cause of dural sinus thrombosis, but is associated with a high mortality rate, so accurate diagnosis and urgent intervention are required.
A 27-year-old female presented with dual origin of the left vertebral artery. Twenty-six cases of this rare congenital vascular anomaly have been reported. In general, the medial leg of the dual origin of the vertebral artery enters a higher transverse foramen (usually the fifth or less frequently the fourth) than the lateral leg, which usually enters the sixth. Exceptions to this rule occur when the medial and lateral legs of the right vertebral artery enter the right seventh and sixth transverse foramina, respectively. This congenital vascular anomaly has diagnostic and therapeutic implications in any intervention involving the proximal vertebral artery.
Metallic artifacts in magnetic resonance (MR) imaging occur mostly in patients who have received an implant at surgery. Similar artifacts are now increasingly recognized in patients in whom high-speed drills have been used. A 15-year-old male with neurofibromatosis 2 had undergone excision of acoustic neurofibroma on the left 1.5 years prior to the present admission. MR imaging to evaluate the acoustic neurofibroma on the right showed a metallic artifact at the site of the previous surgery. Computed tomography did not show any evidence of metal debris. The artifact was probably caused by metallic dust or debris from a high-speed drill during the first surgery. We suggest that care should be taken to prevent deposition of such debris in the operative field to prevent this complication.
Two patients with symptomatic intrasellar arachnoid cyst were successfully treated. A 67-year-old female with a cyst 20 mm in diameter developed headache and visual disturbance. She was treated by transsphenoidal surgery. A 59-year-old male with a cyst measuring 35 × 30 × 50 mm causing headache, visual disturbance, and deterioration of consciousness was managed by wide resection of the cyst wall via craniotomy. Postoperative courses in both patients were uneventful. Transsphenoidal surgery may be suitable for small to medium-sized cysts, although tight packing of the sella is mandatory to prevent leakage of cerebrospinal fluid. However, craniotomy is recommended for large intraand suprasellar arachnoid cysts to avoid this complication, and to achieve sufficient communication between the cyst and the subarachnoid cistern.
Three cases of skull metastasis of Ewing''s sarcoma were treated. The metastatic lesion was located at the midline of the skull above the superior sagittal sinus in all cases. Surgery was performed in two patients with solitary skull lesions involving short segments of the superior sagittal sinus without remarkable systemic metastasis, resulting in good outcome. The third patient had extensive, multiple tumors involving the superior sagittal sinus which could not be excised, and died due to intracranial hypertension. The surgical indication for skull metastasis of Ewing''s sarcoma depends on the location and length of the involved superior sagittal sinus, and general condition.
A 1-year 8-month-old boy presented with isolated fourth ventricle after ventriculoperitoneal shunting for hydrocephalus associated with ventricular and subarachnoid hemorrhage. The therapeutic endoscope was inserted through the thin left cerebellar hemisphere. Endoscopic aqueductal plasty was performed via the enlarged fourth ventricle under guidance from a navigating system. Endoscopic aqueductal plasty via the fourth ventricle under navigating system guidance is a useful procedure enabling less invasive surgery for isolated fourth ventricle associated with slit-like ventricle after shunt placement.