Surgical treatment of cerebellopontine angle meningiomas in elderly patients.

BACKGROUND: The aim of this study is to assess the morbidity and mortality of meningioma surgery in patients over 70 years of age harbouring a tumour at the cerebellopontine angle as one representative location of the posterior fossa in comparison with a matched group of young patients. METHOD: A retrospective analysis based on clinical charts, surgical records, histological records, imaging studies and follow up records was conducted to select patients over 70 years who underwent surgery for cerebellopontine angle meningiomas. Tumours with comparable size and location were matched with the younger group. FINDINGS: There were 421 meningiomas located in the cerebellopontine angle, 21 patients were older than 70 years (range 70-84). Median Karnofsky-Index at presentation was 80 (50-90), 16 patients had a physical status grading ASA 2 and 5 patients ASA 3. The average length of hospital stay was 22 days (7-99 days). The postoperative median Karnofsky score at time of discharge was 80 (50-90). The most common medical complication was postoperative pneumonia in 4 patients, among them 3 patients had lower cranial nerve disturbances postoperatively. There were 56 younger patients (mean age 52.4 years; range 24.5-69.75 years) with corresponding tumour size and location. Pre-op Karnofsky score was 80 (70-90), 53 patients were graded as ASA 2 and 3 patients as ASA 3. Length of hospital stay was 13.6 days (8-32 days). Post-op Karnofsky score was 80 (50-90). Among 5 patients with postoperative lower cranial nerve disturbances no patient had pneumonia postoperatively. There was no peri-operative mortality in either group. CONCLUSIONS: With modern neurosurgical techniques and neuro-anesthesia elderly patients with CPA meningiomas can be operated on with acceptable low morbidity and good neurological outcome but recovery from surgery lasts longer compared to younger patients. However, postoperative lower cranial nerve deficits in elderly patients may not be well tolerated compared with younger patients.

Natural history of chondroid skull base lesions--case report and review.

Long-term follow-up reports on chondroid lesions of the skull base are rarely presented in the literature. There are virtually no data on natural growth rates of these tumors based on MRI obtained over a period of 10 years or longer. We followed a patient who has had such a lesion for more than 12 years. A non-progressive, slight abducens palsy has been the only associated symptom so far. Even though the patient was operated on for an additional intracranial arterio-venous malformation, clinical features and chromosomal testing excluded Maffucci's syndrome. The MRI follow-up in this case provides an extraordinary perspective on the natural history of chondroid skull base tumors.

Intracerebral epidermoid tumor: a case report and review of the literature.

BACKGROUND: Intracerebral epidermoid cysts are rare lesions and may account for only 1.5% of intracranial epidermoid tumors. Cell entrapment from the mesectodermal origin of the neural crest within the primitive cerebral hemisphere may lead to the formation of such rare intracerebral lesions. METHODS: An intracerebral epidermoid cyst located in the right temporal lobe that was surgically treated is presented. The origin, clinical course, radiological features, and surgical treatment of such uncommon lesions are discussed based on a review of the literature. RESULTS: Intraoperative findings revealed an epidermoid tumor. The postoperative course was uneventful and the patient was discharged with no neurological deficits. On long-term follow-up (2 years), there were no signs of recurrence. CONCLUSIONS: Truly intracerebral epidermoid tumors are rarely found. Cells originating from mesectodermal lines may migrate and remain trapped within the primitive cerebral hemisphere while the neural tube is closing, leading to the formation of such intraparenchymal epidermoid tumors. Accurate preoperative diagnosis can be very difficult due to the radiological similarities to other common intracerebral cysts (e.g., astrocytomas or gliomas). Magnetic resonance imaging (MRI) studies, especially with diffusion-weighted images, allow greater accuracy in the preoperative differential diagnosis. Radical surgical removal should be attempted, but a less aggressive surgical strategy should be considered if there is strong adherence between the tumor capsule and the brain tissue, particularly in eloquent areas.

Solitary follicular thyroid carcinoma of the skull base and its differentiation from ectopic adenoma--review, use of galectin-3 and report of a new case.

With only four histologically proven cases in the literature, solitary skull base metastasis of thyroid carcinoma is extremely rare. Having treated another patient harboring a lesion with osseous destruction in the petroclival region and downward soft tissue extension we analyzed this case in conjunction with previous reports. In contrast to parenchymal brain metastasis that usually consists of the papillary type, histological examination revealed differentiated follicular tumors in all cases. All were located around the clivus. The radiographic picture resembled that of chordomas or chondrosarcomas. In the tissue obtained during thyroidectomy no evidence of primary malignancy was found in any of the cases according to standard histological criteria. In our case, a recently developed immunocytological marker - galectin-3 - was applied to differentiate between ectopic thyroid adenoma and carcinoma. The results were indicative of anaplastic growth. Tumor remnants responded well to postoperative 131I internal radiation and TSH suppression therapy. Distant metastasis of follicular thyroid carcinoma has to be considered in the differential diagnosis of destructive skull base lesions. Histological evaluation should include immunohistochemistry or clonal analysis to differentiate between adenomatous and carcinomatous growth and initiate effective radiotherapy early. Prognosis is by far not as poor as in brain metastases and appears to depend largely on location, size and histological appearance.

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.

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.

An experimental approach to image guided skull base surgery employing a microscope-based neuronavigation system.

INTRODUCTION: A cadaveric study was undertaken to investigate the usefulness and reliability of a microscope based navigation system (NS) for skull base surgery. MATERIAL AND METHODS: CT-scans (1 mm slices) were performed in 10 fixed cadaver heads after implantation of fiducials. There upon, various skull base dissections were undertaken: transethmoidal-transsphenoidal approach to sella and clivus, retrosigmoidal approach to the internal auditory canal (IAC) and to the posterior semicircular canal (PSCC). The navigated dissections were performed with the MKM, a microscope based navigation system of Carl Zeiss (Oberkochen, Germany). RESULTS: The registration assessment by the NS yielded a mean deviation of 0.23 mm +/- 0.03 mm (mean +/- SD, n = 7, range 0.19 to 0.27 mm). The real anatomical deviation during dissection was 0.67 mm +/- 0.2 mm for navigation to the IAC and 0.71 mm +/- 0.37 mm to the PSCC. This accuracy was achieved with three fiducials (4 x 1 mm titanium screws) arranged as a triangle (side length 4-6 cm) nearby the surgical field. Navigation data on current position, direction and distance to a target structure were helpful in the transethmoidal-transsphenoidal approach to the clivus, as well as for accessing deep seated structures (C1-C2 junction, petrous bone tip). The contouring feature was beneficial for identifying structures embedded in the bone. However, due to inaccurate 3-D modelling this feature has a restricted reliability. DISCUSSION: Our cadaveric skull base study has shown that the MKM is a reliable tool with high anatomical accuracy and usefulness of most navigation features. However, in order to effectively and reliably use any NS the surgeon must be familiar with its potential features and limitations as is demonstrated in this study.

Ossified and de novo cavernous malformations in the same patient.

We report the case of a 44-year-old patient with a MRI scan showing a newly developed cavernoma after two highly calcified lesions had been excised surgically. Six other cavernous malformations had been followed by MR imaging over a 2-year period. The coexistence of the two extremes of cavernous malformations in terms of lesions development--de novo and ossified lesions has not been reported previously and has implications for both the follow-up and the natural history of these malformations. The potential for developing new cavernous malformations persists and does not seem to be related to the evolutional stage of pre-existing lesions. It is suggested that these patients need to be followed up by MRI on a regular basis.

Cystic meningiomas resembling glial tumors.

BACKGROUND: Meningiomas can be associated with peripheral or intratumoral cysts. Meningiomas with intratumoral cysts, also called "true cystic" meningiomas, are rare and can frequently be confused with glial or metastatic tumors. METHODS: We report three cases of "true cystic" meningiomas and discuss the preoperative evaluation, etiology, and surgical treatment of these cystic lesions with reference to the literature. RESULTS: Magnetic resonance imaging (MRI) and computed tomography (CT) studies usually display a cystic lesion close to the dura with or without enhancement of the cyst wall. Multiplanar MRI scans are very useful to show the presence of a solid tumor or some dural enhancement. Some cases of "true cystic" meningiomas however, are still erroneously preoperatively diagnosed. Complete surgical removal of the tumors and of the entire cyst wall was performed in our cases. Despite the absence of a typical ring enhancement of the cystic lesion in two cases, histopathologic studies displayed the presence of tumor cells on the cyst wall of both cases. CONCLUSIONS: Tumor cells can be present on the cyst wall and therefore can be one of the causes of tumor recurrence if not totally removed. Accurate preoperative radiologic diagnosis (multiplanar MR images) and intraoperative histopathologic studies are fundamental in that they will definitely influence the surgical strategy and outcome.

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.

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.

Management of petroclival meningiomas: a critical analysis of surgical treatment.

Treatment of petroclival meningiomas have been a matter of discussion in neurosurgery. Since the advent of microsurgery, and with development of new skull base approaches more recently, the treatment of these tumours has become standardised, and the post-operative results considerably improved. However, potential complications have been related with the surgical removal of these lesions. The authors describe their experience and summarise the major reports of the literature on this subject.

Suprasellar meningioma with expression of glial fibrillary acidic protein: a peculiar variant.

A 24-year-old female presented with a 3-year history of a suprasellar and intraventricular solid midline process measuring about 3 x 4 cm. At surgery, this tumour was sharply delineated and of stone-like firmness and was removed completely. Histology suggested meningioma, featuring nests and cords of epithelium-like cells with prominent cytoplasm amidst abundant fibrous stroma with prominent lymphoplasmocellular infiltration. Immunocytochemically, the tumour cells expressed vimentin, S-100 protein, epithelial membrane antigen, cytokeratins, and most surprisingly, glial fibrillary acidic protein (GFAP). Ultrastructural investigation revealed abundant intermediate filaments and occasionally dense secretory granules in tumour cells with short, finger-like cytoplasmic processes joined by very rare small, but well-developed desmosomes. This tumour most likely represents a peculiar variant of meningioma with prominent production of GFAP, as previously described [Budka H (1986) Acta Neuropathol (Berl) 72: 43-54].

Cephaloceles - experience with 42 patients.

Forty-two patients with 44 cephaloceles treated between 1966 and 1993 are presented. Eighteen lesions were occipital, 2 parietal, 1 at the anterior fontanelle, 11 sincipital, and 12 basal. In recent years computerized tomography (CT) and magnetic resonance imaging (MRI) provided better information on the site and nature of the lesion as well as on associated malformations. Different malformations were associated more frequently with the cranial vault lesions. Cerebrospinal fluid (CSF)-rhinorrhea was the most frequent clinical sign in the basal lesions. Excision of the cele was performed in all but one case. The age at the time of surgical treatment ranged from 1 day to 11 years. Seven patients were shunted. Post-operative complications were persisting CSF-leaks in 5 patients needing operative revision and 2 infections. The outcome was good in the anterior lesions and in the occipital meningoceles.

[Dural arteriovenous fistula as a rare cause of intracerebral hemorrhage]. / Durale arteriovenöse Fistel als seltene Ursache einer intrazerebralen Blutung.

Dural arteriovenous fistulas are rare vascular malformations presenting with very different clinical signs, depending on the pattern of venous drainage. Retrograde leptomeningeal venous drainage is significantly correlated with a progressive neurological presentation. A case of a dural arteriovenous fistula with cortical venous drainage is presented. The draining vein was frankly aneurysmal dilated. Rupture of this venous aneurysm caused an intracerebral hemorrhage. The venous varix and the hematoma were microsurgically resected and evacuated.

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.

Clentiazem protects against chronic cerebral vasospasm in rabbit basilar artery.

BACKGROUND AND PURPOSE: Experiments were carried out in rabbits to determine whether clentiazem (8-chlorodiltiazem), a cerebrovascular-selective calcium channel blocker, administered 24 hours before subarachnoid hemorrhage influenced the subsequent cerebral vasospasm. METHODS: Subarachnoid hemorrhage was induced by multiple injections of blood into the prepontine cisterns of 35 male New Zealand White rabbits, and clentiazem (5 mg/kg) was administered 4 times daily until sacrifice. Cerebral artery diameter was assessed in vivo by angiography. Functional features of basilar arteries were measured using conventional in vitro methodology. RESULTS: Clentiazem reduced the angiographic narrowing seen on days 2 and 5 from 35% and 34%, respectively (sham control, 1.42 +/- 0.31 mm [n = 22]), to 8% and 11%, respectively, and prevented the narrowing (32%) that occurred on day 9. Narrowing in the untreated rabbits was only partly reversed by papaverine; all narrowing in clentiazem-treated animals was papaverine sensitive. Clentiazem prevented or reduced many of the changes in the basilar artery caused by the subarachnoid hemorrhage. Of particular relevance to arterial narrowing were the increased wall stiffness, the transient spontaneous changes in wall force, and the reduction in relaxation to acetylcholine. Reduction of the changes in wall force induced by agonists and by stimulation of intramural sympathetic nerves was observed. CONCLUSIONS: The vascular damage associated with chronic cerebral vasospasm is related to calcium entry into the smooth muscle and endothelial cells, and possibly sympathetic nerve terminals, through calcium channels sensitive to clentiazem, which suggests that clentiazem may be of value in the management of chronic cerebral vasospasm.

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.

Longitudinal in vivo and in vitro time-course study of chronic cerebrovasospasm in the rabbit basilar artery.

Subarachnoid hemorrhage (SAH) was induced by multiple injections of autologous blood into the prepontine cistern in the rabbit. Long-lasting angiographic narrowing was recorded over a period of nine days after SAH. Papaverine (PPV) reversed angiographic narrowing in the first three days after SAH. Vasospasm was refractory to PPV from day five to day nine after SAH. PPV - refractoriness (in vivo) was positively correlated with decreased vessel wall distensibility (in vitro). Arterial segments showed spontaneous increases in tone in the first two days after SAH. Other alterations observed include a marked gradual reduction in the capacity of the vessel wall to contract, reduction in constrictor nerve influences on vascular tone, and impaired acetylcholine - induced vasorelaxation. Tonic contraction to the maximum dose of serotonin was increased in acute spasm and decreased in chronic spasm. It is suggested that the initial cause of arterial narrowing after SAH is the action of vasoactive substances released in the close vicinity of the arterial wall; this then leads to abnormal tone, tissue damage, and structural changes.

Two indices of functional damage of the artery wall parallel the time course of irreversible narrowing in experimental vasospasm in the rabbit.

Autologous blood placed around the basilar artery caused angiographic narrowing with a biphasic time course. The first immediate phase was reversed by intraarterial papaverine; the second exhibited an increasing component of narrowing which was papaverine-resistant. In vitro studies showed that vessels became increasingly stiffer, less capable to develop active tone, and less responsive to vasoconstrictors and vasodilators. The papaverine-resistant component of angiographic narrowing (in vivo) could be directly correlated with loss of contractility and increased artery wall stiffness (in vitro).