Integration of multimodality imaging and surgical navigation in the management of patients with refractory epilepsy. A pilot study using a new minimally invasive reference and head-fixation system.

OBJECTIVE: To review the experience with a new system (VBH system) for minimally invasive frameless stereotactic guidance, acting as a common platform to provide multimodal image integration and surgical navigation in a consecutive series of 25 patients who underwent surgery for drug-resistant seizures. METHODS: The usefulness of the VBH system for integrating all images to produce one dataset and for intraoperative instrument guidance and navigation was judged semiquantitatively in a three-tiered scale (+, ++, +++). Seizure outcome was classified according to Engel. RESULTS: The presurgical evaluation extended over 21.2 months (mean). A total of 141 registrations of images were performed (mean 5.6 per patient, range: 2 to 16). In 19 (76%) of 25 patients structural data fused with functional data were used for the presurgical workup. Six patients proceeded directly to navigated resection. Nineteen patients (76%) underwent invasive recording, of whom 13 underwent resective surgery. In seven patients (28%) the combination of multimodal image fusion and intra-operative stereotactic guidance was judged "essential" (+++) to remove the epileptogenic zone. Integration of all images to form one dataset was "essential" (+++) for decision making in 15 and "helpful" (++) in 4 patients (overall 76% of patients). Intraoperative use of frameless neuronavigation was "essential" (+++) in ten and "helpful" (++) in all remaining patients. Eighty percent of the patients achieved satisfactory seizure outcome after 1 year. CONCLUSION: The VBH system is a safe and effective non-invasive tool for repetitive imaging, multimodal image fusion and frameless stereotactic surgical navigation in candidates for epilepsy surgery.

Neuroendoscopy based on computer assisted adjustment of the endoscope holder in the laboratory.

OBJECTIVE: We present our initial clinical experience with a novel technique of frameless stereotactic neuroendoscopy using a neuronavigation system, a specially designed aiming device (endoscope holder/targeting device) combined with a vacuum-mouthpiece based head holder. Due to the reproducibility of patient immobilization in the fixation system, the endoscope holder can be adjusted in the laboratory in the absence of the patient. METHODS: An individual vacuum-mouthpiece was fabricated. The patients were scanned with an external reference frame attached to this mouthpiece and the images were transferred to the neuronavigation system. Determination of the path, mouthpiece-based registration and adjustment of the targeting device were performed the day before surgery in the absence of the patient. In the OR the patient was repositioned and the endoscope was introduced through the preadjusted aiming device to the precalculated depth. RESULTS: The novel technique was successfully used for frameless endoscopic navigation in five patients. Three endoscopic third ventriculostomies in adults, one endoscopic septostomy due to unilateral hydrocephalus in an adult female patient and one endoscopic ventriculo-cysto cisternostomy in a 20-month-old girl with a suprasellar arachnoid cyst, were performed with excellent clinical results and without technical complications. CONCLUSION: Our initial experience indicates that frameless stereotaxy, in combination with a relocatable head holder and a special targeting device, allows for precise and preplanned advancement of the neuroendoscope, reducing or even eliminating intraoperative registration and endoscope trajectory adjustments, thus substantially reducing OR time. Due to the non-invasive but rigid immobilization method, neuronavigation can also be performed in children under 2 years of age.

Virtual endoscopy for planning neuro-endoscopic intraventricular surgery.

To evaluate the usefulness of virtual endoscopy (VE) in planning neuroendoscopic intraventricular surgeries, the technique was applied in 20 of 22 consecutive procedures. Thirteen endoscopic third ventriculostomies (ETV) in 12 patients, 3 endoscopic colloid cyst removals, 1 third ventricular arachnoidal cyst fenestration, 1 endoscopic ventricul-cysto-cisternostomy (suprasellar arachnoidal cyst), 1 endoscopic tumor biopsy, one third ventricular gross total tumor removal and 2 septostomies at the foramen of Monro due the septal occlusion were performed. Contrast medium-enhanced MR images (3DMPRAGE, Siemens, Germany) were semi-automatically segmented with a surface-rendering technique ("Navigator" software, General Electric Medical, Buc, France) to produce the virtual endoluminal views. Surgery was performed with cerebral ventriculoscopes by Wolf (Richard Wolf, Knittlingen, Germany). VE was feasible in all patients and the virtual endoscopic images were comparable with the real intraventricular views obtained by standard rod lens systems. After contrast medium administration intra- and paraventricular vessels such as the thalamocaudate vein, the septal veins, the basilar artery and its branches (distal BA complex) and the choroid plexus were identified on the virtual endoscopic images. In 8 patients, the additional anatomic information provided by VE profoundly influenced surgical planning. VE provides the neurosurgeon with additional morphological information supporting the planning process of neuroendoscopic intraventricular surgeries, contributing to the safety of the procedures.

Endoscope-assisted interlaminar removal of an ependymoma of the cauda equina.

In oder to reduce surgical trauma to the lumbar spine during a multilevel laminectomy procedure we performed a multilevel, bilateral and interlaminar approach, with microsurgical and endoscopic techniques for removal of a large ependymoma of the lumbar spine in a 33-year-old female patient. Complete tumor removal has been achieved, while at the same time, the major elements that form the posterior spinal column could be preserved. The follow-up time is 4 years.

Use of neuronavigation and electrophysiology in surgery of subcortically located lesions in the sensorimotor strip.

OBJECTIVES: Subcortical lesions in the sensorimotor strip are often considered to be inoperable. The purpose of this study was to evaluate the usefulness of a combined approach for surgery in this region, aided by a robotic neuronavigation system under electrophysiological control. METHODS: In a prospective study on 10 patients, space occupying lesions in the sensorimotor central area were removed using the Surgiscope robotic navigation system and the Nicolet Viking IV electrophysiological system. RESULTS: Precise tumour localisation with the neuronavigation system and the information on the patient's cortical motor distribution obtained by bipolar cortical stimulation led to postoperative improvement in motor function in all but one patient. Seven of the patients had focal, defined pathology (four metastases; two cavernoma; one aspergilloma). CONCLUSION: Due to the implementation of two recent technologies, surgery of lesions in the subcortical sensorimotor region can be performed with greater confidence.

Quality of life in patients after meningioma resection.

OBJECTIVES: To evaluate quality of life in patients after tumour resection, to assess different dimensions of quality of life, to compare a newly designed questionnaire with the Nottingham Health Profile. SUBJECTIVE: A non-selected neurosurgically treated series of patients with meningiomas was investigated with reference to quality of life as a judgement of one's own needs and concerns and subjective disease dependent perception. METHODS: A postal survey was sent out to 155 patients who underwent resection of a meningioma between 1977 and 1993 at our clinic. The survey consisted of the specifically designed "Innsbruck Health Dimensions Questionnaire for Neurosurgical Patients" IHD(NS) and the Nottingham Health Profile NHP. The data were put into categories and analysed statistically (Chi-square, Mann Whitney U, Kruaskal-Wallis H-tests). RESULTS: 82 patients (53 female, 29 male) responded (response rate 59%). 10 had died and 7 had moved. The majority of patients (50/61% on NHP and 49/59.7% on IHD) had mild to moderate impairment of quality of life. 20% of the patients showed moderate to severe impairment of the dimensions: physical handicap and energy level. Physical impairment correlated to tumour size. This group was characterised by mainly belonging to the over 70ies age group and taking anti-epileptics. CONCLUSIONS: The quality of life impairments in most patients after tumour resection can be classified as mild to moderate. However, other disease and age effects are difficult to distinguish without a control group. The IHD(NS) correlated well with the NHP questionnaire.

Computer-assisted neurosurgery by using a noninvasive vacuum-affixed dental cast that acts as a reference base: another step toward a unified approach in the treatment of brain tumors.

OBJECT: The purpose of the study was to evaluate the use of the Vogele-Bale-Hohner (VBH) mouthpiece, which is attached to the patient's upper jaw by negative pressure, for patient-image registration and for tracking the patient's head during image-guided neurosurgery. METHODS: A dynamic reference frame (DRF) is reproducibly mounted on the mouthpiece. Reference points, optimally distributed and attached to the mouthpiece, are used for registration in the patient's absence on the day before surgery. In the operating room, the mouthpiece and DRF are precisely repositioned using a vacuum, and the patient's anatomical structures are automatically registered to corresponding ones on the image. Experimental studies and clinical experiences in 10 patients confirmed repeated (rigid body) localization accuracy in the range of 0 to 2 mm, throughout the entire surgery despite movements by the patient. CONCLUSIONS: Because of its noninvasive, rigid, reliable, and reproducible connection to the patient's head, the VBH vacuum-affixed mouthpiece grants the registration device an accuracy comparable to invasive fiducial markers.

Virtual endoscopy for planning endoscopic third ventriculostomy procedures.

Virtual endoscopy was used to plan 10 endoscopic third ventriculostomy procedures in 9 patients suffering from occlusive hydrocephalus due to idiopathic aqueductal stenosis and tumors. The patients were 4 children (4-14 years, mean age: 9 years) and 5 adults (21-38 years, mean age: 29 years). The aim of the study was to preoperatively evaluate the individual intraventricular and vascular endoscopic anatomy at the floor of the third ventricle based on virtual endoscopic images. The virtual views were correlated with the real endoscopic images, intraoperatively obtained by a standard ventriculoscope (Wolf, Knittlingen, Germany) during endoscopic third ventriculostomy procedures. Contrast-medium-enhanced MR images (3D-MPRAGE; Siemens, Germany) were semiautomatically segmented with a surface-rendering technique ('Navigator' software; General Electric Medical, Buc, France) to produce the virtual endoluminal views. The virtual endoscopic images were comparable with the real intraoperative endoscopic view in 8 of 9 patients. Virtual endoscopy can display the position of the basilar artery, the posterior cerebral arteries and the posterior communicating arteries in their relationship to the mammillary bodies and the clivus. Preoperative virtual endoscopy planning can intraoperatively assist the neurosurgeon to find a safe location for third ventriculostomy.

Suboccipital decompressive surgery in cerebellar infarction.

In a retrospective study 100 consecutive patients with cerebellar apoplexy were evaluated with regard to presenting symptoms, diagnostic and therapeutic strategies according to changes in the clinical condition of the patients. The results of decompressive suboccipital craniectomy in patients with a cerebellar infarction is also evaluated in this retrospective study as the valency from use the Glasgow-Coma-Score as prognostical factor and monitoring instrument in patients with a cerebellar stroke. Different therapeutic modalities were critically analyzed. Outcome was sgnificantly influenced by age (p = 0.003), localisation and size of the lesion (p = 0.004), space-occupying character on computed tomography (p < 0.001), the progressive appearance of brainstem dysfunction and reduction of the level of consciousness as measured with the Glasgow Coma Scale (p < 0.001). We were able to show that the GCS is a valid instrument for the evaluation of the clinical course of patients with cerebellar stroke since a statistically significant relationship exists between the GCS prior to surgical intervention and outcome. In patient with a GCS < 12 a reduction of mortality by 15% was obtained by surgical intervention and the outcome as measured by the GOS was significantly improved.

Posterior-fossa haemorrhage after supratentorial surgery--report of three cases and review of the literature.

We present clinical details of three patients with posterior fossa haemorrhage after supratentorial surgery and discuss possible pathomechanisms of this rare complication. All patients were males of advanced age. Two patients presented with a history of hypertension. In all patients the occurrence of haemorrhage was associated with loss/removal of large amounts of cerebrospinal fluid (CSF) either intra-operatively (one patient undergoing aneurysm surgery) or postoperatively (all three patients: drainage of subdural hygromas or chronic subdural haematomas in two, external ventricular drainage in one patient). Treatment consisted in haematoma evacuation and/or external ventricular drainage. Two patients died, one patient recovered completely. Although haematomas distant from a craniotomy site are a well known entity, a review of the literature identified only 25 published cases of posterior fossa haemorrhage after supratentorial procedures in the CT era. Most often disturbances of coagulation, positioning of the patient and episodes of hypertension have been associated with this complication. Only one author described the occurrence of a haemorrhage after drainage of a supratentorial hygroma. We suggest that the loss of large amounts of CSF intra-operatively and post-operatively may lead to parenchymal shifts or a critical increase of transmural venous pressure with subsequent vascular disruption and haemorrhage.

Three-dimensional computer assisted magnetic resonance imaging for neurosurgical planning in parasagittal and parafalcine central region tumors.

Usually, conventional magnetic resonance spin echo images (MRI) are sufficient to establish the diagnosis of intracranial pathology. Planning and executing a neurosurgical procedure requires the ability of the neurosurgeon to transform these two-dimensional MRI into a three-dimensional (3-D) virtual image of the pathology and the surrounding neuronal anatomy. Such mentally performed transformations after sequential observation of the individual two-dimensional slices (i.e., MRI and angiography) may be virtual tasks that are very difficult or sometimes impossible to achieve. Using 3-D MRI data sets and a semiautomatic computer assisted segmentation technique, we tried to simulate intraoperative situs-based 3-D MRI reconstructions of parasagittal and parafalcine central region tumors. The MRI reconstructions were integrated into the neurosurgical planning procedure as an additional tool. They proved to be an important adjunct in determining the distinct anatomy of the intracranial pathology in its relation to the surrounding and overlying brain and vascular (especially venous) anatomy. With 10 patients with central region parasagittal and parafalcine tumors, we found that the 3-D MRI reconstructions revealed additional information compared to conventional cross-sectional images and had an influence on neurosurgical planning and strategy, improving neurosurgical performance and patient outcome.

[Magnetic resonance angiography of intracranial aneurysms after subarachnoid hemorrhage]. / Magnetresonanzangiographie intrakranieller Aneurysmen nach Subarachnoidalblutungen.

Magnetic resonance angiography is now commercially available for a variety of scanners and is being increasingly applied in the diagnosis of cerebrovascular disorders. Considering the clinical consequences, especially in intracranial aneurysms, studies to determine the sensitivity and specificity of the method are essential. Here we report our experience with a 3D-FISH time-of-flight magnetic resonance angiography protocol in 52 patients who have suffered an acute subarachnoid hemorrhage. In 26 of the 52 patients, conventional angiography identified 31 aneurysms (3-20 mm) that were confirmed during surgery or autopsy. Magnetic resonance angiography correctly identified 28 of the 31 aneurysms (sensitivity 90.3%) and missed one ruptured (3 mm) and two incidental aneurysms (3 mm) in patients with multiple aneurysms. The sensitivity for a ruptured aneurysm was 96%. The 26 patients who suffered subarachnoid hemorrhage without evidence of an intracranial aneurysm on repeated angiography served as a control group. Magnetic resonance angiography revealed no false-positive findings, resulting in a specificity of 100%. In correlation with the literature, we conclude that magnetic resonance angiography is not sensitive enough for the management of acute subarachnoid hemorrhage. However, the method provides important complementary information for definition of the bleeding site in patients with multiple aneurysms. In addition, the calculation of projections not possible with conventional angiography can aid surgical planning. Since only very small aneurysms were missed by magnetic resonance angiography, the sensitivity seems appropriate to screen asymptomatic patients who are at risk for intracranial aneurysms.

Toxic shock syndrome in transsphenoidal neurosurgery.

An overlooked toxic shock syndrome (TSS) may lead to a fatal outcome. In neurosurgery a transsphenoidal approach with post-operative nasal tamponade may promote toxic shock syndrome without signs of local wound infection. By discussing the case history of a patient after hypophysectomy by the transsphenoidal route, we propose that after the appearance of the first signs of toxic shock syndrome, quick removal of the nasal tamponade is a life saving procedure.

CT-guided stereolithography as a new tool in craniofacial surgery.

CT-guided stereolithography provides an acrylic model which exactly replicates the original structure. It allows optimal preoperative planning and intraoperative management. This application proved advantageous in surgical correction of a wide midline craniofacial cleft in a baby.

Peracute surgery of aneurysms with intracerebral hematomas.

Out of a series of 252 patients who underwent aneurysm surgery, 19 (7.5%) were operated on in a "peracute stage" in the poor grades Hunt & Hess IV (n = 11), IV-V (n = 2), and V (n = 6). All patients suffered from large aneurysmal intracerebral hematomas which were evacuated after decompressive craniotomies, all aneurysms (ACA: n = 1, ACoA: n = 4, MCA: n = 12, ICA: n = 2) could be clipped. 4 patients died within the first 3 postoperative days, 6 patients reached a poor result remaining in an apallic syndrome or a state of high invalidity, 8 obtained a fair result with personal autonomity, and 1 patient recovered completely. Although this kind of aneurysm bleeding is combined with high mortality and morbidity, we nevertheless emphasize its surgical treatment as soon as possible because of the lack of other efficient therapeutical procedures.

Familial cavernous angiomas of the brain: observations in a four generation family.

A family with a history of cavernous angiomas of the brain was investigated by MRI. The disease was present in four generations of the family and is consistent with autosomal dominant inheritance. Among affected individuals, there was considerable variability in the extent of intraparenchymal cavernomas and neurological symptoms as a result of bleeding events. Three siblings manifested with seizures, two affected persons were symptom free at the time of investigation, and one sibling had neurological symptoms without certain correlation with cavernomas. The disease appeared to have an earlier onset in younger generations.

[Chronic subdural hematoma as a cause for blindness]. / Ein chronisches Subduralhämatom als Erblindungsursache.

The uncommon complication of bilateral blindness resulting from a decompressive neurosurgical procedure is presented by the case of a 51-year old patient suffering from a traumatic chronic subdural haematoma. A breakdown of the altered vasoregulation of the optic nerves due to papilledema at the time of intracranial pressure drop is supposed to be the etiological background of optic atrophy and consequent amaurosis. The causal relationship of accident trauma and blindness in the presented case is pointed out.