Vagus nerve stimulation (VNS) is gaining increasing popularity and credibility as a treatment option for patients with intractable epilepsy. VNS is a relatively recent innovation, however, and like many other incipient developments, it has engendered a number of unresolved controversies and perplexities. Limitations in our current understanding of how VNS works lie at the crux of these uncertainties. In this article, we present our clinical experience with VNS and review the fundamental issues which remain unsettled, such as the mechanism of VNS action, the factors underlying variability in patient outcome, and the selection of ideal candidates for VNS therapy. Although many enigmas persist, VNS has proven to be a safe, feasible, and potentially effective method of reducing seizures in select patient populations. It offers several advantages over extant treatments and, as a result, holds much promise for future therapy of medically refractory epilepsy.

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The somatostatin analog octreotide was administered prior to transsphenoidal surgery in three patients with tumors that extended to the suprasellar space and one side of the cavernous sinus. Octreotide, 100 μg twice a day, was subcutaneously injected for 2 weeks. Octreotide administration reduced the serum growth hormone (GH) levels in these patients from 82 to 22 ng/ml, from 148 to 12 ng/ml, and from 129 to 9 ng/ml. The tumor size shrank by about 50%, and the suprasellar extension disappeared in two patients. The main tumor was sharply dissected from the normal pituitary gland at surgery. Intracavernous portions were removed using a curette. Postoperatively, GH levels were less than 5 ng/ml in two patients, and 8.5 ng/ml in one patient. Follow-up magnetic resonance imaging revealed a small residual tumor in one side of the cavernous sinus in all patients. Follow-up GH levels were less than 5 ng/ml in one patient, and less than 2 ng/ml in two patients treated with bromocriptine. Preoperative administration of octreotide for 2 weeks reduced tumor volume and allowed near-total surgical resection of invasive macroadenomas without compromising the treatment course. Residual tumor due to intracavernous extension can be managed with bromocriptine or gamma knife radiosurgery.

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Image-guided procedures, such as computed tomography (CT)-guided stereotactic and ultrasoundguided methods, can assist neurosurgeons in localizing the relevant pathology. The characteristics of image-guided procedures are important for their appropriate use, especially in brain biopsy. This study reviewed the results of various image-guided brain biopsies to ascertain the advantages and disadvantages. Brain biopsies assisted by CT-guided stereotactic, ultrasound-guided, Neuronavigator-guided, and the combination of ultrasound and Neuronavigator-guided procedures were carried out in seven, eight, one, and three patients, respectively. Four patients underwent open biopsy without a guiding system. Twenty of 23 patients had a satisfactory diagnosis after the initial biopsy. Three patients failed to have a definitive diagnosis after the initial procedure, one due to insufficient volume sampling after CT-guided procedure, and two due to localization failure by ultrasound because the lesions were nonechogenic. All patients who underwent biopsy using the combination of ultrasound and Neuronavigator-guided methods had a satisfactory result. The CT-guided procedure provided an efficient method of approaching any intracranial target and was appropriate for the diagnosis of hypodense lesions, but tissue sampling was sometimes not sufficient to achieve a satisfactory diagnosis. The ultrasound-guided procedure was suitable for the investigation of hyperdense lesions, but was difficult to localize nonechogenic lesions. The combination of ultrasound and Neuronavigator methods improved the diagnostic accuracy even in nonechogenic lesions such as malignant lymphoma. Therefore, it is essential to choose the most appropriate guiding method for brain biopsy according to the radiological nature of the lesions.

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The clinicopathological features of atypical teratoid/rhabdoid tumor, a new entity among malignant pediatric brain tumors, and the differential diagnosis from primitive neuroectodermal tumor (PNET)/ medulloblastoma, and germ cell tumor are described. Histologically, atypical teratoid/rhabdoid tumor is defined as a polymorphous neoplasm often featuring rhabdoid, PNET, epithelial, and mesenchymal components. Atypical teratoid/rhabdoid tumors usually include PNET components and occur mainly in the posterior fossa, so mimic medulloblastoma. Atypical teratoid/rhabdoid tumor is characterized by the cytogenetic finding of monosomy 22 rather than i(17q). The tumor is similarly mistaken for PNET at supratentorial sites. Germ cell tumors also enter into the differential diagnosis due to their histological immunophenotypic diversity, particularly features indicative of epithelial and mesenchymal differentiation. Nonetheless, the remarkable spectrum of tissues that typify teratoma is absent in atypical teratoid/rhabdoid tumor. The same is true of germ cell marker in tumor tissues and serum. The prognosis of atypical teratoid/rhabdoid tumor is far less favorable than that of PNET/medulloblastoma of malignant or germ cell tumor. Meta-analysis of 133 cases, including 15 new and 118 reported cases, confirm that atypical teratoid/rhabdoid tumor is as a clinicopathological entity and emphasizes the necessity for distinguishing this unique tumor from other pediatric central nervous system neoplasms.

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The effectiveness of spinal surgery for lumbar canal stenosis was investigated in the elderly. 164 patients with lumbar canal stenosis were surgically treated over 8 years. 125 patients were followed up by letter questionnaire. The outcome and patient satisfaction with the surgical procedures were compared between the 73 younger patients (≤ 64 years of age) and the 52 elderly patients (≥ 65 years of age). Intermittent claudication was satisfactorily improved in both the younger and the elderly groups. Both simple laminectomy and laminectomy with fusion could equally improve the symptoms of intermittent claudication. Although statistically not significant, there was tendency that laminectomy plus fusion effectively improved the symptoms of back pain and leg pain in both groups. 75% of the younger patients and 67% of the elderly were pleased with the outcome. The present study shows that elderly patients with lumbar canal stenosis should be actively considered for surgical treatment.

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An 81-year-old male presented with right oculomotor nerve paresis and left hemiparesis caused by a mass effect of a large superior cerebellar artery aneurysm. Endovascular treatment was performed using Guglielmi detachable coils. The patient subsequently suffered aggravation of the mass effect 3 weeks after the embolization. Bilateral vertebral artery occlusion was performed, which decreased the cerebral edema surrounding the aneurysm, but his neurological symptoms did not improve. Parent artery occlusion is recommended as the first choice of treatment for an unclippable large or giant aneurysm causing a mass effect on the brainstem.

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A 46-year-old female presented with persistent bifrontal headache. Computed tomography revealed a large cystic tumor in the right temporoparietal area, which included a solid component. The tumor had no attachment to the dura. There was no peritumoral edema or mass effect usually found around cystic meningiomas. The solid component was totally removed. Histological examination indicated that the tumor was a fibrous meningioma. Intracerebral meningioma with a large cystic component without dural attachment should be considered in the differential diagnosis of cystic cerebral tumors.

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A 38-year-old male presented with an extremely rare primary osteogenic sarcoma, unassociated with Paget''s disease or late effects of radiation, involving the sella and sphenoid sinus region. Complete excision of the tumor was achieved through an extended frontobasal approach. Postoperatively, six cycles of combination chemotherapy (adriamycin, ifosphamide, and cisplatin) followed by a total of 55 Gy local radiotherapy in 33 fractions was given. Primary osteogenic sarcoma should be considered in the differential diagnosis of the central skull base tumors. Osteogenic sarcoma, in general, has a bad prognosis, and should be managed aggressively with multimodality treatment including gross total surgical resection, combination chemotherapy, and radiotherapy.

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A 51-year-old female presented with a rare case of synovial cyst at the cruciate ligament of the odontoid process associated with atlanto-axial dislocation, manifesting as a history of headache and numbness in her left extremities for 5 months, and progressive motor weakness of her left leg. Neuroimaging studies revealed a small cystic lesion behind the dens, which severely compressed the upper cervical cord, and atlanto-axial dislocation. The cyst was successfully removed via the transcondylar approach. C-1 laminectomy and foramen magnum decompression were also performed. Posterior craniocervical fusion was carried out to stabilize the atlanto-axial dislocation. The cyst contained mucinous material. Histological examination detected synovial cells lining the fibrocartilaginous capsule. Synovial cysts of this region do not have typical symptoms or characteristic radiographic features. Careful preoperative evaluation of the symptoms and a less invasive strategy for removal of the cyst are recommended.

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A neonate presented with Dandy-Walker syndrome associated with occipital meningocele and spinal lipoma, manifesting as soft masses on the skull and lumbosacral regions. Magnetic resonance imaging demonstrated a large posterior fossa cyst between the fourth ventricle and occipital meningocele, but the aqueduct was patent and there was no sign of hydrocephalus. A cyst-peritoneal shunt was emplaced at the age of 8 days followed by partial removal of the spinal lipoma and untethering of the cord at the 3 months. Follow-up examination of age 3 years found almost normal development, although the cyst still persisted.

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A new bipolar diathermy forceps system was developed to solve the problems of constant, pressurelimited flow rate, and one-sided irrigation. A roller pump, activated synchronously by pressing a foot switch, feeds dripping and flushing solution to the target tissue via the tip at both ends of the forceps. This system is volume-limited. Continuous compression of the foot switch first activates the flushing function, which continues for less than 1 second, during which time bleeding spots can be detected. The flow then changes automatically to the dripping function to suppress tip burning and prevent damage to the surrounding tissues from heat and current leakage. Repeated pressing of the foot switch initiates the jet irrigation function (continuous high flow rates), allowing irrigation of hematomas and removal of excess debris.

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