Masamichi Tomonaga

Flexible Endoneurosurgical Therapy for Aqueductal Stenosis

We successfully managed 11 patients with aqueductal stenosis of adult or adolescent onset, with no mortality or significant morbidity, by using a flexible ventriculoscope to perform either a third ventriculostomy or an aqueductal plasty. A flexible fiberoptic ventriculoscope and its accessories were newly developed, and surgical techniques were improved. For all patients, cinemagnetic resonance imaging was a critical part of the preoperative and postoperative evaluation of cerebrospinal fluid flow in the third ventricle and in the aqueduct of Sylvius. All of the 11 patients showed patency to cerebrospinal fluid flow at the aqueduct of Sylvius and the floor of the third ventricle. Only one patient subsequently required a lumboperitoneal shunt. Flexible endoneurosurgical management is simple and safe and allows in situ observation and the ability to perform biopsies. Therefore, flexible endoneurosurgical third ventriculostomy and aqueductal plasty are now considered our treatment of choice for aqueductal stenosis in adults and adolescents.

Cerebral blood flow and autoregulation in normal pressure hydrocephalus.

OBJECTIVE We tried to identify indications for cerebrospinal fluid shunting in patients with normal pressure hydrocephalus. METHODS We studied the cerebral blood flow (CBF) and vascular response to acetazolamide in the white matter, cortex, and thalamus of 21 patients with normal pressure hydrocephalus, comparing patients who improved clinically after shunting with those who did not. We used xenon-enhanced computed tomography for the CBF measurements. RESULTS Preoperatively, both groups had globally reduced CBF, but the reduction was more pronounced in the unimproved patients. The vascular response was impaired only in the white matter of the patients who improved later. After shunting, restoration of CBF, more marked in the white matter, and recovery of vascular response in the white matter paralleled clinical improvement and a reduction in ventricular dilation and periventricular lucency on computed tomographic scans in nine patients. The CBF reduction, however, deteriorated in the 12 patients who did not improve clinically. CONCLUSION We conclude that the underlying disease in the improved patients was ischemia, with a loss of autoregulatory capacity in the periventricular white matter caused by cerebrospinal fluid diffusion. Those who did not improve had irreversible brain damage in which the CBF reduction was secondary to metabolic depression and autoregulation was preserved. We also conclude that patients suspected of having normal pressure hydrocephalus will improve clinically after shunting if preoperative hemispheric CBF is greater than 20 ml/100 g per minute and the vascular response to acetazolamide is impaired only in the periventricular white matter. They will not improve, however, if the preoperative CBF is less than 20 ml/100 g per minute and the vascular response to acetazolamide is intact.

The significance of artificial cerebrospinal fluid as perfusate and endoneurosurgery.

To compare the benefits of physiological saline solution and artificial cerebrospinal fluid (CSF) as perfusates, we investigated 12 patients with presumed symptomatic aqueductal stenosis by clinical course and CSF analysis. In all patients, endoneurosurgical third ventriculostomy and cine magnetic resonance imaging confirmed the patency of ventriculostomy. After endoneurosurgery, patients who received the saline solution experienced high fever, headaches, and elevated cell count in lumbar CSF. Saline solution provoked a striking inflammatory reaction in the CSF. In contrast, the artificial CSF reduced these conditions to a minimum. Artificial CSF used as a physiological perfusate during endoneurosurgery can suppress host reactions within the CSF pathway and is also available for routine neurosurgical procedures.

Giant Cell Tumor of the Sphenoid Bone: Long-term Follow-up of Two Cases after Chemotherapy

BACKGROUND Giant cell tumors rarely occur in the sphenoid bone. When they do occur in the base of the skull, surgical treatment is frequently difficult and therefore, the use of adjuvant therapy is important. However, there remains no optimal management regimen for giant cell tumors of the sphenoid bone. CASE DESCRIPTION Two cases of a giant cell tumor involving the sphenoid bone that responded well to chemotherapy using adriamycin after a partial removal of the tumor are presented. In the first patient, the tumor was partially removed via a transcranial subfrontal approach and a transnasal transsphenoidal approach. In the second patient, the tumor was partially removed through a transcranial subfrontal approach. Both tumors demonstrated histologic features typical of giant cell tumors. The patients subsequently received adjuvant chemotherapy using adriamycin alone in the first patient, and chemotherapy combined with radiotherapy in the second patient. Partial regression of the tumors was later confirmed on a computed tomography (CT) scan after chemotherapy. In both patients, tumors have been stable for more than 12 years despite an incomplete removal of the tumors. CONCLUSION Based on the above findings, postoperative adjuvant chemotherapy using adriamycin may be effective for incompletely resected giant cell tumors of the sphenoid bone.

Endoneurosurgical treatment for hydrocephalus caused by intraventricular tumors

A flexible therapeutic ventriculoscope allowing for the use of a variety of different instruments has been developed. Endoneurosurgical instruments are composed of an endoscopic contact YAG laser endoprobe, grasping forceps and a punctured needle. Endoneurosurgical procedures include biopsies, III ventriculostomy, fenestration of the septum pellucidum, aspirations of cysts and excisions of tumors in the cerebrospinal fluid pathways. Our ventriculoscope allows the initial treatment for progressive hydrocephalus caused by intraventricular tumors to take the form of reducing ventricular size and decreasing intracranial pressure, and it can also be used to perform biopsy examinations, so that acceptable neurological outcomes and an accurate histological diagnosis can be obtained with fewer side effects. The subsequent therapies for hydrocephalus caused by intraventricular tumors include radical surgery for benign tumors, irradiation for radiosensitive tumors, and irradiation and/or chemotherapy for either malignant or disseminated tumors. We have tried to avoid the sequelae of shunt surgery and have achieved maximum effects with the minimum of procedures by using our ventriculoscope.

Giant fusiform aneurysm of the basilar artery: Consideration of its pathogenesis

BACKGROUND We tried to determine the pathogenesis of a fusiform aneurysm of the basilar artery based on the findings of two patients who had pontine infarctions due to thrombosis within the aneurysm. CASE REPORT The patients were female, aged 75 and 62 years. At autopsy of the first case, the dilated basilar artery was filled with fresh and old thrombus. The wall was extremely thin on the left side, where a fresh red thrombus was evident, and thick on the right side, where an old white thrombus appeared. The thick wall had a thickened and hyalinized intima, and a deposition of atheromatous plaque disrupted both the internal elastic lamina and muscle layer. The left vertebral artery was atherosclerotic and its lumen was severely compromised, but the right vertebral artery was hypoplastic. On angiogram of the second case, the dilated basilar artery presumably was filled with thrombus on the left side, contralateral to the dilated and tortuous vertebral artery. The left vertebral artery was hypoplastic. CONCLUSION Atherosclerosis may be the essential factor in the pathogenesis of a fusiform aneurysm of the basilar artery in elderly patients. The disrupted internal elastic lamina and muscle layer may be susceptible to mechanical injury by hemodynamic strain, causing progressive attenuation of the arterial wall. Stenosis of the vertebral artery on the dominant side probably produces a jet stream within the basilar artery on the stenotic side and a stagnant zone on the opposite side, promoting the initial thrombus formation.

Circulation of Red Blood Cells Having High Levels of 2,3-Bisphosphoglycerate Protects Rat Brain From Ischemic Metabolic Changes During Hemodilution

BACKGROUND AND PURPOSE We designed the present study to examine the effects of red blood cell oxygen-delivering capacity on ischemic brain metabolism during hemodilution with respect to red blood cell 2,3-bisphosphoglycerate content. METHODS A modification of red blood cell 2,3-bisphosphoglycerate content was achieved by an exchange transfusion of blood in which red blood cells were treated with either phospho(enol)pyruvate or inorganic phosphate in spontaneously hypertensive rats. Hematocrit values of circulating blood were varied from 30% to 20% during transfusion. Brain ischemia was produced in rats by bilateral carotid artery occlusion lasting 60 minutes. The concentrations of ATP and 2,3-bisphosphoglycerate in the blood and the ATP, phosphocreatine, and lactate concentrations in the brain were estimated by an enzymatic method. RESULTS Red blood cell 2,3-bisphosphoglycerate concentration increased to 200% of the pretransfusion level after the transfusion in which red blood cells were treated with phospho(enol)pyruvate, whereas the concentration decreased to 80% after the transfusion in which red blood cells were treated with phosphate. Red blood cell ATP content did not differ significantly between the phospho(enol)pyruvate- and phosphate-treated groups after transfusion. When hematocrit was approximately 30%, the ischemic brain ATP and lactate contents did not differ between the nonischemic and ischemic groups. However, as hematocrit was reduced to less than 25% the ischemic brain ATP content remarkably decreased and the lactate content substantially increased in the 2,3-bisphosphoglycerate-subnormal red blood cell group. In contrast, the ischemic brain ATP and phosphocreatine contents in the 2,3-bisphosphoglycerate-enriched red blood cell group were preserved and as high as those in the nonischemic group under the same conditions. CONCLUSIONS Cerebral ischemia was compensated with the increment of cerebral blood flow as a result of the reduction of hematocrit to optimal levels, but the extreme hemodilution induced insufficient oxygen supply to the brain tissue, resulting in a more marked impairment of brain metabolism despite an increase in cerebral blood flow. However, even in extreme hemodilution conditions the 2,3-bisphosphoglycerate-enriched red blood cells in circulating blood protected the brain from ischemic metabolic changes. These results suggest that the 2,3-bisphosphoglycerate-enriched red blood cells in the circulating blood may thus compensate for the insufficient oxygen supply in extremely anemic conditions by providing a sufficient supply of oxygen in the face of ischemic insult.

Intraventricular craniopharyngioma: Its characteristics in magnetic resonance imaging and successful total removal

We experienced a craniopharyngioma in the third ventricle which was removed totally by a staged operation through the lamina terminalis and then through the foramen of Monro using a transventricular approach. In magnetic resonance imaging, chiasmal thickening with pot-belly expansion and bilobed shape of the mass were found, and postoperative magnetic resonance imaging showed indentation of the chiasm and flattening of the floor of the third ventricle.

Percutaneous flexible neuroendoscopic ventriculostomy in patients with shunt malfunction as an alternative procedure to shunt revision

Three patients with shunt malfunction, who had previously undergone a shunting procedure for noncommunicating hydrocephalus of adolescent and adult onset, successfully underwent a percutaneous flexible neuroendoscopic ventriculostomy. This procedure was performed as an alternative treatment for shunt revision by the use of our newly developed flexible fiberoptic ventriculoscope. All patients were able to remain independent of the shunt system after the ventriculostomy. These results thus suggest that a percutaneous flexible neuroendoscopic ventriculostomy can be effective for the treatment of shunt-dependent patients with shunt malfunction in adolescents and adults.

Xanthoma in meckel's cave a case report

A case of xanthoma located within Meckels cave and the semilunar ganglion is described in a patient with a trigeminal nerve deficit. This is the first case of xanthoma in such a location. The distinctive morphological appearance is illustrated and the possible histogenesis is discussed.