Xenon/CT CBF measurements as valuable diagnostic tool in a case of bilateral occlusive cerebrovascular disease associated with intracranial aneurysm.

A patient with the coincidental occurrence of a right internal carotid artery (ICA) stenosis and asymptomatic ipsilateral infraclinoidal ICA aneurysm is presented. CBF measurements including testing of the cerebrovascular reserve capacity (CRC) demonstrated a compromise of cerebral blood flow (CBF) within the anterior circulation of the affected side. We treated the patient in one operation by aneurysm clipping and subsequent carotid endarterectomy (CEA). 10 months later she presented with an occlusion of the contralateral ICA. CBF measurements showed sufficient resting flow and CRC on both sides. One year later repeat measurements disclosed a lowered resting CBF and diminished CRC on the affected side. Extracranial/Intracranial (EC/IC) artery bypass improved both symptoms and CBF/CRC values. The authors propose to treat symptomatic ICA stenosis and concurrent silent ipsilateral intracranial aneurysms at once if the patient is eligible for aneurysm surgery. CBF measurements should be performed before surgery. In a medically compromised patient carotid endarterectomy alone appears to be justifiable. In cases of symptomatic aneurysm and concurrent ICA stenosis a CEA can be added to aneurysm clipping to improve the hemodynamic situation for a better postoperative management. Xenon/CT investigations are suitable to provide important cerebral blood flow information. Together with angiography and clinical judgment it allows to identify patients with hemodynamic insufficiency. These are suitable candidates for an operative procedure to augment cerebral blood flow and to improve symptoms.

Microsurgery of midbrain lesions.

Of 41 patients with midbrain lesions, 25 underwent definitive surgical exploration. In 16 patients surgical exploration was not warranted, since the patients had only slight neurological deficits and longstanding histories or consent was not given. The infratentorial supracerebellar approach proved to be the ideal method of exposure in 20 patients, in whom the lesion was located in the more dorsal aspect of the midbrain. In 6 of these patients the mass lesion extended from the cerebellum into the midbrain and, therefore, a transcerebellar route was also needed for exposure. In 5 patients the subtemporal approach was chosen. Three patients died as a result of the operation, but in the other 22 patients no increase in morbidity after surgery was apparent and the immediate postoperative course was normal. Five patients with malignant tumors died from recurrence despite radiotherapy. The remaining 17 patients have been doing well up to 14 years after surgery, but 3 had only limited follow-up. This experience with surgical exploration and total resection or evacuation of midbrain lesions in 25 patients should prove the safety of modern microsurgical techniques. Emphasis is placed on the benefit of microtopographic considerations in the choice of the most suitable approach to these deep-seated lesions.

Serum melatonin levels: a new neurodiagnostic tool in pineal region tumors?

The pineal hormone melatonin (MLT) is secreted in a circadian rhythm with high serum levels during nighttime and low serum levels during daytime. Several authors have reported an altered secretion pattern of MLT in patients with pineal tumors and have proposed that MLT may be used as a tumor marker. In nine patients, a pineal region tumor was diagnosed by computer-assisted tomography. Before and after surgical removal of the tumor, several day- and nighttime serum samples were collected and MLT concentrations were estimated by radioimmunoassay. Before operation, five patients presented a normal circadian pattern of MLT secretion. In the remaining four subjects, MLT levels were undetectable or at the limit of detection, with no signs of a circadian secretion pattern. Eight patients were reexamined after tumor resection, when all but one had undetectable or very low MLT levels. The remaining subject, with a pineomesencephalic pilocytic astrocytoma, dislocating but not involving the pineal gland, presented a normal circadian secretion pattern of MLT after operation; in this case, tumor resection was possible without damaging the pineal gland. Thus, before operation, MLT deficiency rather than exaggerated serum levels may be used as a marker for pineal tumors that destroy the pineal gland. After tumor resection, serum MLT may serve to demonstrate complete pinealectomy.

External ventricular drainage for treatment of rapidly progressive posthemorrhagic hydrocephalus.

Twenty-seven newborn infants (birth weight, 1503 +/- 776 g; gestational age, 31 +/- 3 wk) (mean +/- standard deviation) with rapidly progressive posthemorrhagic hydrocephalus and increased intracranial pressure were treated by external ventricular drainage. The progression of hydrocephalus was arrested during the drainage period in each patient. The drainage was kept in place for 23 +/- 9 days, the longest drainage period being 48 days. In 16 of 23 surviving patients, progressive ventricular dilation recurred after removal of the drainage, requiring a definitive shunt implantation (nine ventriculoatrial, seven ventriculoperitoneal). For the remaining seven infants, no further therapy was necessary. Implantation of the permanent shunt was done days 28 to 88 (body weight, 2400 +/- 950 g). Bacterial cultures from cerebrospinal fluid and/or the tip of the ventriculostomy catheter were negative in 175 instances and positive in 11 instances (7 patients). No clinical or biochemical evidence of ventriculitis was noted. Four of the 27 patients died of causes unrelated to external ventricular drainage. Twenty-three infants survived. Seventeen of 23 survivors suffered from intraventricular hemorrhage Grade 3; in 7, neurological and developmental outcomes were classified as normal; 9 patients experienced mild to moderate paresis and/or mild to moderate developmental delay; and only 1 patient was severely retarded. Six patients with parenchymal lesions had severe motor and/or developmental handicaps. We consider external ventricular drainage an effective and safe therapy in newborn infants with rapidly progressive posthemorrhagic hydrocephalus and increased intracranial pressure. The ultimate outcome, however, depends mainly on the mode and the extent of the primary brain lesion.

Glioblastoma developing at the site of a cerebellar medulloblastoma treated 6 years earlier. Case report.

The authors report the highly unusual development of a glioblastoma multiforme at the site of excision of a medulloblastoma 6 years earlier. The patient was operated on for a cerebellar medulloblastoma at the age of 13 years. Postoperative treatment included irradiation and chemotherapy. Six years later, a glioblastoma multiforme was found at the original site of the medulloblastoma. Intensive multimodality treatment is considered the likely cause for the later tumor development.

Longitudinal time course of reversible and irreversible components of chronic cerebrovasospasm of the rabbit basilar artery.

Multiple injections of autologous blood were made around the basilar artery of rabbits through a silicone catheter placed into the prepontine cistern. The total blood injected was 3 ml/kg in aliquots of 0.5 to 0.8 ml over a 4-hour period. Control angiograms were obtained 7 days before this procedure. Groups of animals were examined by angiography on each of 9 days after the injections of blood. An angiogram was obtained 15 minutes after the first injection of blood, 20 seconds after the intra-arterial injection of a maximum dilating dose of papaverine. All surviving animals showed basilar artery narrowing, which was greatest 24 hours after the hemorrhage, when the vessel diameter was reduced to 54% of the control value. The narrowing then decreased to a reduction of about 30%, which was maintained throughout the rest of the study period. A papaverine-resistant component of narrowing was not seen until the 3rd day. It increased progressively to Day 9 when it represented 63% of the total. This model has a number of features that are reminiscent of human cerebrovasospasm, including the fact that there is an initial phase of narrowing that is completely reversed by an intra-arterially administered vasodilator, and a second phase beginning on Day 3 which exhibits a progressively increasing papaverine-resistant component.

Meningiomas of the tentorial notch: surgical anatomy and management.

Twenty-five meningiomas located at the tentorial notch were surgically treated between 1978 and 1993 at the Neurosurgical Department of Nordstadt Hospital in Hannover, Germany. Nineteen meningiomas were classified as originating from the lateral tentorial incisura (Group I) and six were from the posteromedial tentorial incisura (Group II). Clinically, the most common symptom was trigeminal neuralgia, followed by headache. Neuroradiologically, 64% of the meningiomas were larger than 30 X 30 mm. Further evaluation revealed signs of brainstem compression in 88% of the patients. Radical surgical removal (Simpson I and II) was achieved in 88% of the cases. There was no mortality. Follow up revealed that 80% of patients were able to return to their premorbid activity. Surgical approaches to the tentorial notch included the suboccipital retrosigmoidal or the combined subtemporal-presigmoidal approach for Group I tentorial notch meningiomas; and the supracerebellar-infratentorial or the suboccipital-transtentorial approaches for Group II meningiomas. Because the best surgical approach to the tentorial incisura is still a matter of debate, the anatomy of the tentorial incisura, the clinical presentation of the patients, diagnostic indications, surgical findings, and follow up are discussed, with reference to the literature.

Reconstruction of the facial nerve in acoustic neurinoma surgery. Juxtapontine-intratemporal nerve graft.

Five cases of large acoustic neurinomas (diameter 2.5 cm) with involvement of the facial nerve in the tumour capsule are presented. The preoperative function of the facial nerve was normal. During surgery, in order to achieve a radical tumour removal, the facial nerve was severed juxtapontine. Reconstruction was performed at the same procedure using a 5-6 cm long sural nerve graft. Thus the central juxtapontine stump was joined to the peripheral stump in the facial nerve canal of the petrous bone. After six months, all five patients exhibited a well functioning mimic and a good eyelid function. At the one year control four patients had normal nerve function clinically and one patient still showed asymmetrical mimic.

Technical considerations regarding accuracy of the MKM navigation system. An experimental study on impact factors.

The purpose of this study was to investigate experimentally, factors determining the navigation accuracy of the MKM navigation system by Zeiss. The MKM consists of an operating microscope mounted to a six-axis motor-driven robot arm and an alpha-workstation. The image-guided surgery device provides navigation information based on calculation of the cartesian coordinates of the robot arm, and coordinates of the focus point assessed by laser assisted measurement. Navigation information (current position, direction and distance to a previously selected target) is optically projected into the microscopic field. Following factors were examined in an experimental setting for their impact on accuracy of the MKM: optical system, mechanical precision of the robot arm, and registration procedure. The robot arm and the optical system of the microscope allow high precision measurements of any focus point (error < 2 mm if the following aspects are considered: the use of auto-focus function instead of manual focusing, positioning of the registration points as a square or a triangle focus point should be selected on a surface that is perpendicular to the optical axis.

De novo formation of an aneurysm in a case of unusual intracranial fibromuscular dysplasia.

Intracranial fibromuscular dysplasia (FMD) is a vascular disease of unknown origin occurring predominantly in young women. The internal carotid artery is most often involved, but other cerebral arteries may also be affected. We report the case of a young woman presenting with an unusual angiographic appearance of intracranial FMD of the internal carotid artery (ICA) that could not be categorized into any type of the Osborn-Anderson classification. During follow up the patient presented with an intracerebral and subarachnoid hemorrhage. Repeated angiography revealed multiple aneurysms in the pathologic segment of the vessel. The patient underwent surgical treatment with clipping of the aneurysms, wrapping of the pathologic segment of the ICA and biopsy of the superficial temporal artery. Histopathological sections revealed FMD of the intimal type. alpha(1)-antitrypsin blood levels were normal. Cases of intracranial FMD previously reported in the literature are reviewed and various aspects of this rare disease are discussed.