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H J Reulen

Publications and source records attributed to H J Reulen.

At least 73 records · Page 4Linked to original sources
PubMed1997

The transcallosal interforniceal approach to the third ventricle: anatomic and microsurgical aspects.

OBJECTIVE: The ability to visualize median-sagittal brain structures by magnetic resonance imaging improves planning for surgery to treat lesions of the third ventricle. The most appropriate path to the third ventricle is the transcallosal approach. The present study was undertaken to describe the surgical anatomy and landmarks encountered during this approach. METHODS: The transcallosal-interforniceal approach was undertaken in 30 formalin-fixed brains using an operating microscope. The surface landmarks for the approach pathway were the two points, P5 and P7, located 5 and 7 cm anterior to the central sulcus, respectively. Using these two points on the cortical surface as references, a variety of measurements were made to provide quantitative information about distances between brain structures that are encountered during the surgical approach. Measurements that were made include the following: 1) the distance between P5 and the cingulate sulcus, 2) the distance between the cingulate sulcus and the corpus callosum, 3) the height of the corpus callosum, 4) the distance between the anterior commissure and the foramen of Monro, and 5) the distance between the lower margin of the corpus callosum and the fornix. RESULTS: Mean values for these key measurements were as follows: 1) 23.96 mm (range, 15.0-32.0 mm); 2) 13.50 mm (range, 8.0-20.0 mm) with reference to P5 and 12.73 mm (range, 16.0-18.0 mm) with reference to P7; 3) 6.12 mm (range, 4.0-8.0 mm) with reference to P5 and 6.60 mm (range, 4.0-9.0 mm) with reference to P7; 4) 4.96 mm (range, 2.5-10.0 mm), independent of P5 and P7; and 5) 8.46 mm (range, 3.0-16.0 mm) with reference to P5 and 11.04 mm (range, 6.0-22.0 mm) with reference to P7. CONCLUSION: The detailed quantitative information obtained in this study about the interforniceal approach permitted definition of surgical approach pathways that preserve important anatomic structures, such as the motor strip, genu of the corpus callosum, fornical commissure (hippocampal commissure), anterior commissure, and fornical columns. The approach through this surgical corridor can easily be planned and performed in individual cases using median-sagittal magnetic resonance imaging scans.

Adult↗
PubMed1997

Postoperative spiral computed tomography and magnetic resonance angiography after aneurysm clipping with titanium clips.

OBJECTIVE: To reduce morbidity and mortality after subarachnoid hemorrhage, it is imperative to evaluate the results of the surgical treatment of cerebral aneurysms. We investigated the usefulness of spiral computed tomography (CT) and magnetic resonance angiography as postoperative control examinations after cerebral aneurysms were clipped with titanium clips. METHODS: Eleven patients with 13 treated aneurysms were studied prospectively with postoperative digital subtraction angiography, spiral CT, and magnetic resonance angiography. The occlusion of the dome of the aneurysm, the presence of a remnant of the neck, the patency of the parent vessels and other major vessels, and the presence of vasospasm were investigated. RESULTS: The different parameters could all be well evaluated by postoperative spiral CT. The artifacts caused by the titanium clips, although relatively small compared with artifacts from other clips, precluded evaluating the dome and the neck of the aneurysm with magnetic resonance angiography. CONCLUSION: In our opinion, spiral CT promises to become a valuable aid in in the postoperative evaluation of clipped aneurysms, and we recommend its routine performance. Postoperative digital subtraction angiography remains the gold standard and has to be performed when spiral CT reveals abnormalities, when the neck of the aneurysm cannot be evaluated because the clip overlays it, or when, intraoperatively, imperfect clipping is suspected and intraoperative angiography cannot be performed.

Adolescent↗
PubMed1997

Radical resection of meningiomas and arteriovenous fistulas involving critical dural sinus segments: experience with intraoperative sinus pressure monitoring and elective sinus reconstruction in 10 patients.

OBJECTIVE: Radical resection of meningiomas and dural arteriovenous fistulas involving functional major dural sinuses entails the risk of intracranial hypertension and venous infarction. Surgical reconstruction of dural sinuses and bridging veins increases the spectrum of dural sinus conditions that can be treated by complete resection, but indications for venous reconstructions and associated risks are still not well defined. We report our experience with sinus reconstruction based on the intraoperative assessment of collateral venous flow. METHODS: Radical resection of meningiomas (n = 5) or dural arteriovenous fistulas (n = 5) involving critical segments of dural sinuses was performed in 10 patients. All but two patients were suffering from recurrent disease after incomplete treatment. Tolerance of sinus occlusion was assessed intraoperatively by measuring stump pressure in the superior sagittal sinus during test clamping of the involved sinus segment. RESULTS: In five patients, the results of pressure monitoring suggested that occlusion of the sinus might not be tolerated. In two other patients, major bridging veins entered the diseased segment. In these patients, the resected sinus segment was reconstructed and bridging veins were reinserted as far as possible. Postoperative graft occlusion occurred in two patients. One patient who was managed without reconstruction sustained a transient postoperative neurological deficit resulting from venous congestion in the vein of Labbé. Postoperative imaging confirmed total elimination of the pathological process in all 10 patients. There was no recurrence of disease during follow-up periods of up to 8 years. CONCLUSION: The monitoring of sinus pressure, together with the possible reconstruction of the diseased sinus, allows complete surgical treatment of dural sinus abnormalities and involves acceptable risk.

Adolescent↗
PubMed1997

Preoperative activation and intraoperative stimulation of language-related areas in patients with glioma.

OBJECTIVE: Evaluation of the accuracy of preoperative localization of language-related cortex by magnetic resonance imaging-guided positron emission tomography. METHODS: Patients with gliomas in the left dominant hemisphere were examined preoperatively with magnetic resonance imaging-guided positron emission tomography and intraoperatively by electrical stimulation of cortex. RESULTS: A verb generation task yielded more intense and better lateralized local increases of cerebral blood flow in the positron emission tomographic examination than did a naming task. Significant correspondence of preoperative and intraoperative findings was observed for the verb generation task. Cortical sites with aphasic disturbance during electrical stimulation had a significantly higher cerebral blood flow increase during preoperative activation than did sites without intraoperative language impairment. Areas with cerebral blood flow increases above an optimum threshold had 73% sensitivity and 81% specificity to predict aphasic disturbance during intraoperative stimulation. CONCLUSION: The data suggest that with further technical improvements, imaging of language function may become a preoperative diagnostic tool for patients with tumors close to language-related brain structures.

Adult↗
PubMed1997

Superior neuroprotective efficacy of a novel antioxidant (U-101033E) with improved blood-brain barrier permeability in focal cerebral ischemia.

BACKGROUND AND PURPOSE: The vascular endothelium and parenchyma of the brain have the potential to generate free radicals under pathological conditions, but it is unclear which of these two sites prevails in the production of free radicals and should be the primary target of therapeutic intervention. To clarify this issue, we compared the neuroprotective properties of a 21-aminosteroid (U-74389G) that acts on the microvasculature and a pyrrolopyrimidine (U-101033E), a novel antioxidant compound that has significantly improved potential to enter the brain parenchyma. METHODS: In Sprague-Dawley rats the middle cerebral artery was occluded for 90 minutes by an intraluminal filament. Local cortical blood flow was recorded by bilateral laser Doppler flowmetry throughout ischemia and 1 hour of reperfusion. Three groups of rats were studied: controls that received vehicle only and animals that received either U-74389G or U-101033E. Neurological examinations were performed daily, and infarct size was assessed histologically 7 days after ischemia. RESULTS: U-101033E reduced infarct volume significantly by 51%, whereas U-74389G led to a nonsignificant decrease in infarct volume. U-101033E improved neurological function immediately after ischemia, whereas U-74389G led to improvement only at the end of the observation period. Laser Doppler measurements showed no significant difference in local cortical blood flow among the treatment groups. CONCLUSIONS: We conclude that for treatment of transient focal ischemia, an antioxidant that crosses the blood-brain barrier might be superior to agents that predominantly act on the endothelium of the cerebral microvasculature.

Animals↗
PubMed1996

Seizure control following surgery in supratentorial cavernous malformations: a retrospective study in 77 patients.

Of 168 patients operated on consecutively for a supratentorial cavernous malformation, 77 had seizures as the initial symptom. The effectiveness of surgery in controlling seizures and the risk of surgery were evaluated by retrospective review of the patients' charts. The follow-up period was 1 to 9 years (mean 39 months) and the review period totalled 284 lesion-years. Only two patients showed postoperative deterioration in neurological status (morbidity risk: 2.6%), no patient died (mortality: 0%). Sixty-eight (88.3%) patients were seizure-free after operation and five (6.5%) showed a marked reduction in the frequency of their seizures. This corresponds to an overall positive effect of surgery of 94.8% of the patients. There was no substantial evidence that excision of the haemosiderin-stained tissue around the cavernoma along with the lesion itself provided better results than resection of only the cavernoma. Better results with regard to seizure control, however, were associated with shorter duration of symptoms before surgery.

Adolescent↗
PubMed1996

Evidence for peroxidative damage by nitric oxide in experimental chronic cerebral vasospasm.

Recent data has suggested a role for the nitric oxide metabolite peroxynitrite in peroxidative injury to endothelium associated with atherosclerosis. The present experiments were designed to elucidate whether such a mechanism might be involved in the morphological changes observed during chronic vasospasm after subarachnoid hemorrhage. For this purpose, chronic vasospasm was induced in male Wistar rats by an injection of autologous blood (100 microliters) in the cisterna magna followed by a second injection 24 hours later. Vasospasm was verified by pressure controlled internal carotid angiography after retrograde cannulation of the external carotid artery 7 days after the second injection. Animals were then perfusion fixed and the brains removed for immunohistochemical assessment of nitrotyrosine, the peroxidation product of peroxynitrite with tyrosine contained in tissue proteins. Staining for nitrotyrosine was quantified by microscopy in 40 microns coronal floating sections. The brains of rats with angiographic vasospasm revealed nitrotyrosine predominantly located with a perivascular distribution and in the pia. We conclude that peroxidation of membrane proteins by the nitric oxide metabolite peroxynitrite may contribute to the morphological damage evident in chronic vasospasm.

Animals↗
PubMed1996

Microsurgical anatomy of the lateral approach to extraforaminal lumbar disc herniations.

OBJECTIVE: During the "lateral" approach to extraforaminal lumbar disc herniations, the surgeon may be confronted with considerable variations in anatomy, making this approach extremely difficult in some patients. An anatomic study, therefore, was undertaken to examine the bony boundaries of the operative target, the medial intertransverse space. METHODS: In 31 lumbar spine specimens taken from cadavers of people who had been between 30 and 93 years old at death, the relevant distances and proportions of the operative window were measured at the levels L1-L2 to L5-S1. RESULTS: Measurements revealed that the operative window in a systematic fashion becomes progressively smaller as the approach moves from L1-L2 toward L5-S1: 1) from L1 to L5, the medial boundary, the isthmus laminae, gradually extends farther laterally and eventually covers the waist of the respective vertebral body; 2) the lower boundary, the facet joint, gradually overlaps the disc space in an upward and lateral direction; 3) the upper boundary, the transverse process, gradually moves downward. Anatomic variations and abnormalities are found particularly often at the L5-S1 level. CONCLUSION: The anatomic findings led to important conclusions regarding the microsurgical approach to extraforaminal lumbar disc herniations; at levels L1-L2 to L3-L4, the midline approach with lateral retraction of the paraspinal muscles allows for efficient exposure of the lateral neural foramen and avoidance of trauma to the facet joint. Often at level L4-L5, and nearly always at level L5-S1, a tangential route through a paramedian transmuscular approach offers many advantages.

Adult↗
PubMed1996

The Neurosurgical Clinic at the Ludwig-Maximilians University in Munich.

ThE NEUROSURGICAL CLINIC at the Ludwig-Maximilians University in Munich began as a small unit of the university's surgical clinic. Eduard Weber, who in 1952 became the first surgeon fully trained in the specialty of neurosurgery to join the surgical clinic's faculty, worked, until his death in 1962, to advance the new specialty. Neurosurgery became an independent department of the university in 1965, and the neurosurgical clinic moved to a new location at Beethovenplatz. Further expansion led the neurosurgical clinic to move again, in 1975, to the newly constructed Klinikum Grosshadern at the periphery of Munich. Frank Marguth, chairman of the department of neurosurgery from 1964 to 1991, had superb skill as an organizer and greatly enhanced the reputation of the department of neurosurgery. Today, the faculty of the department consists of 10 full-time staff members, 10 joint appointment staff members, and 16 residents and fellows. Annually, 2200 to 2300 procedures are performed in the neurosurgical clinic. The current philosophy in the department places heavy emphasis on subspecialization and academic training. Political and economic changes in Germany during recent years have affected the nation's public health system and pose major challenges to the department of neurosurgery.

Academic Medical Centers↗
PubMed1995

Space-occupying lesions of the sensori-motor region.

Successful surgery of the sensori-motor region requires precise pre- and intraoperative localization of the sensori-motor region and pyramidal tract. Important aids are the landmarks of cranio-cerebral topography, coronal suture and bregma and the sulcal anatomy of the sensori-motor region, which can be identified in CT or MR images. Due to considerable displacement and distortion of the anatomical structures, elicited by mass lesions, these aids often fail to render reliable support. In this situation, identification of the motor area can be achieved by electrical stimulation of the precentral gyrus in association with the recording of somatosensory evoked potentials of the pre- and postcentral gyrus. The localisation of the "motor mosaics" in relation to the lesion, enable determination of the direction of displacement of the motor strip and the fan of the pyramidal tract. Based on this information the most appropriate route of access to the lesion is selected, either transcortical or transsulcal. Lesion-specific operative techniques as well as location-specific approaches are discussed. With consequent application of these principles the risk of a new persistent motor deficit was as low as 4%. Thus, the indication for surgery in this area can now be set with greater confidence and far more generously than in the past.

Brain Abscess↗
PubMed1995

Topography of the cortical motor hand area: prospective study with functional MR imaging and direct motor mapping at surgery.

PURPOSE: To localize the cortical motor hand area with functional magnetic resonance (MR) imaging and electrical stimulation at surgery and to detect changes due to central lesions. MATERIALS AND METHODS: Fast-gradient-echo and functional MR images of the brain were acquired in four healthy volunteers and six patients with tumors in the central region before, during, and after repetitive opening and closing of the hand. Open brain surgery was performed, and the exposed cortex was stimulated. RESULTS: At functional MR imaging, circumscribed changes in signal intensity that correlated in time with the task were seen in the central region of the contralateral brain. In the healthy volunteers, the area of change was spotlike and projected into the posterior bank of the precentral gyrus. In four of the six patients, this area was diffuse and projected into the precentral gyrus. The locations of the cortical hand area as determined with intrasurgical mapping and functional MR imaging were identical. CONCLUSION: Identification of the cortical area responsible for motor hand function was similar with functional MR imaging and with direct stimulation at surgery. A space-occupying lesion can change the cortical representation of motor hand function.

Adult↗
PubMed1995

The mapping and continuous monitoring of the intrinsic motor nuclei during brain stem surgery.

A comprehensive technique was developed for continuous electrophysiological monitoring of intrinsic brain stem motor function during surgery to remove space-occupying lesions in the fourth ventricle and brain stem. The technique is analogous to that used during surgery in the cerebellopontine angle; motor nuclei and peripheral pontine fiber tracts of Cranial Nerves III-XII are identified by the electrical stimulation of structures in the operative field and the evaluation of the compound muscle action potentials recorded from the corresponding muscles of the head. Nerve function is monitored continuously by recording the ongoing electromyographic activity in these same muscles. Broadcasting electromyographic responses through a loudspeaker gives the surgeon immediate feedback on the status of the motor nuclei being monitored. Advantages of this technique include 1) the positive, objective identification of the nuclei and fiber tracts; 2) the continuous feedback on the status of these structures; 3) a safe approach through the fourth ventricle to the lesions in the brain stem; 4) the positive identification of the boundaries between the neoplasm and the motor structures of the rhomboid fossa; and 5) a warning to the surgeon of potentially harmful nerve manipulations (contact, dissection, transection) during surgery. After this technique was used in 16 consecutive operations to remove cavernomas (n = 9), gliomas (n = 4), and other types of tumors (n = 3), surgical and neurological results showed the method to be reliable and simple to perform.

Adult↗
PubMed1995

[Function-controlled neurosurgery. Neurophysiologic and neuropsychological monitoring during surgery of the nervous system].

Neuromonitoring of neural structures has become increasingly common during surgery near cortical areas representing sensorimotor and language function (epilepsia, tumors), in the brain stem and the spinal cord (tumors), near cranial nerves (cerebellopontine angle tumors, trigeminal neuralgia, hemifacial spasm), and in the cauda equina (tumors, tethered spinal cord). The technical spectrum to monitor these operations includes electrical cortical stimulation to evoke sensorimotor phenomena and language disturbances, electroneurography and -myography of the cauda equina, motor cranial nerves and nuclei, and somatosensory, motor and acoustic evoked potentials. The goals of intraoperative neuromonitoring are: (1) minimizing the risk of suffering neurological and neuropsychological injury as a result of surgery; (2) extending the surgical spectrum to lesions that have previously been considered inoperable or hazardous to operate upon; (3) intraoperative electrophysiological documentation that the goal of surgery has been achieved; (4) intraoperative basic research.

Brain↗
PubMed1995

[The motor hand area. Noninvasive detection with functional MRI and surgical validation with cortical stimulation].

In this study, activation of cortical sites by specific motor tasks (opening and closing of the hand) was examined by fMRI utilizing the blood-oxygen-level-dependent (BOLD) technique. fMRI was employed in five volunteers and in six patients with tumors in the vicinity of the central region. In the patients, the fMRI data and intraoperative cortical mapping were compared. Our results indicate good correlation of these two methods and that there are no significant differences in the localization of the motor hand area.

Adult↗
PubMed1994

Formation and resolution of human peritumoral brain edema.

In 16 patients with 21 metastatic brain tumors and 9 patients with a malignant glioma, tumor volume, volume of the edematous tissue, edema production, speed of edema propagation and edema resolution were examined by using the CT. Edema production was determined according to a technique described previously and ranged between 0.09 and 1.63 ml/h in metastases and between 0.42 and 3.49 ml/h in gliomas. The speed of edema propagation ranged from 0.2-2.2 mm/h. Edema resolution can take place within the tissue (i.e. reabsorption into blood) as well by drainage into the ventricular or subarachnoid CSF. In a few small metastases with a small perifocal edema (without contact to the ventricule or the subarachnoid space) the amount of edema resolution within the tissue could be determined and averaged 0.0086 ml/h/cm3. This probably represents the reabsorption of edema fluid into capillaries within the edematous tissue. If this value is used to calculate the edema reabsorption in larger tumors, the resulting data are considerable lower than the respective edema production rate of that tumor. This indicates, that in larger tumors the main fraction of the edema fluid is draining into the ventricular and/or subarachnoid CSF.

Blood-Brain Barrier↗
PubMed1994

Cavernous malformations of the brain stem. A review of 139 cases.

A retrospective analysis of 139 patients with brain stem cavernous malformations is presented. The material consists of 41 cases from Bern and Phoenix and 98 further well-documented cases from the literature. Sixty-eight patients were male, 70 were female. The average age was 31.8 + 11.8 years. Sixty-two percent of the cavernous malformations were in the pons, 14% were in the mesencephalon, 12% were in the pontomesencephalic and in the pontomedullary junction, and 5% were in the medulla. Eighty-eight percent of the patients showed evidence of recent or previous hemorrhage, 55% had one hemorrhage. 17% had two hemorrhages, and 17% had three or more hemorrhages. Twelve patients died from a hemorrhage, 5 with the first bleeding and 7 with a rebleeding. The minimum bleeding rate was 2.7% per year and the average rebleeding rate 21% per year and per lesion. Most lesions had a diameter between 10 and 30 mm. Increase in size was observed in 12 of the patients; this corresponds to about 21% when only patients with a follow-up of at least one year are considered. In 93 patients the cavernous malformation was removed operatively while in 30 patients the lesion was not removed. In the group with conservative management at the end of the observation period (up to 25 and 32 years), 66.6% had no or only a slight neurological deficit, 6.7% were moderately disabled, 6.7% were completely dependent, and 20% had died. In the group treated surgically 83.9% had no or only a slight neurological deficit, and 15% were moderately disabled. One patient remained severely disabled, no patient died. The limitations of the retrospective nature of this study are stressed.

Adolescent↗
PubMed1992

Are there typical localisations of lumbar disc herniations? A prospective study.

A prospective intra-operative analysis of the location of lumbar disc herniation was performed in 131 patients with verified 54% contained (incomplete) and 46% non-contained (complete) lumbar disc herniations. Bulging discs or protrusions are not included in this study. Complete disc herniations occurred more frequently in the upper lumbar spine. The localization of the lumbar disc herniations within its segment showed no correlation to the affected level. 64% of the disc herniations were located medio-laterally, 20% laterally, 12% within or lateral of the intervertebral compartment and 5% in the midline. Nearly one third of all herniations were found at the level of the disc space. Medio-lateral disc herniations were displaced more often in a caudal direction, lateral herniations were found displaced upwards and downwards with similar frequency while extraforminal herniations migrated significantly more often in a cranial direction. The pathomechanism and anatomical pathways of disc fragment migration are discussed on the basis of a new concept of the anterior extradural space.

Adult↗