Biomedical subjects

D Van Roost

Publications and source records attributed to D Van Roost.

15 recordsLinked to original sources

PubMed1999

Minimally invasive stereotactically-guided extirpation of brain stem cavernoma with the aid of electrophysiological methods.

The surgical extirpation of brain stem cavernomas always includes a risk of neurological deficits. To minimize the risk of deficits and control the motor and sensory function intraoperative monitoring of SEP and MEP seems to be helpful. The high density of motor and sensory fibers within the brain stem makes bilateral intraoperative monitoring necessary. The following case demonstrates a stereotactically-guided supratentorial, transventricular approach for extirpation of a brain stem cavernoma. Sensory and motoric functions were observed by transcranial recording of SEP's and by transcranial stimulation of motor cortex.

Adult↗

PubMed1999

Prediction of postoperative seizure control by hippocampal event-related potentials.

PURPOSE: In spite of unequivocal results of the presurgical evaluation, between 10 and 30% of patients with medial temporal lobe epilepsy (MTLE) do not become seizure free by temporal lobe surgery. Because event-related potentials (ERPs) recorded within the hippocampal formation have been shown to be sensitive to the epileptogenic process, we examined whether ERPs can help to improve the prediction of postoperative seizure control. METHODS: We recorded ERPs to words from bilateral intrahippocaampal electrodes by using a visual word-recognition paradigm in 70 patients with unilateral hippocampal pathology and related these measurements to seizure outcome after temporal lobe surgery. RESULTS: Words elicited N400 potentials, which were reduced in amplitude on repetition on the side contralateral to hippocampal sclerosis. This contralateral repetition effect, however, was significantly diminished in the group of patients who experienced seizure recurrence after the operation. Contralateral repetition effects thus permitted correct prediction of postoperative seizure control in 94% of all patients. CONCLUSIONS: Recording ERPs to words within the medial temporal lobes can improve the prediction of postoperative seizure control. Reduced repetition effects contralateral to the side of hippocampal sclerosis may indicate bilateral epileptogenicity.

Adolescent↗

PubMed1998

Limbic ERPs predict verbal memory after left-sided hippocampectomy.

Surgical removal of the dominant medial temporal lobe regions runs a considerable risk of verbal memory deficits which may be compensated for postoperatively by corresponding regions in the non-dominant medial temporal lobe. We examined this possibility by recording event-related potentials (ERPs) to words from the medial temporal lobes of patients with left-sided temporal lobe epilepsy (TLE) undergoing presurgical evaluation. N400 amplitudes in the right anterior medial temporal lobe predicted the postoperative verbal recall performance of individual patients with surprising accuracy, indicating that intracranial recordings can be used to quantify the functional capacities of the right hemisphere that can compensate for the verbal memory deficits after loss of medial temporal lobe structures in the left hemisphere.

Adolescent↗

PubMed1998

Depth electrode implantation in the length axis of the hippocampus for the presurgical evaluation of medial temporal lobe epilepsy: a computed tomography-based stereotactic insertion technique and its accuracy.

OBJECTIVE: An individualized computed tomography-based stereotactic technique for the longitudinal insertion of intrahippocampal electrodes is presented and its accuracy described. METHODS: The technique makes use of one well reproducible target in the hippocampal head and of the approximate inclination of the anteroposterior length axis of the hippocampus, for which the orbital floor is taken as an auxiliary landmark. It was used in 141 patients with medically intractable complex partial seizures. In 106 patients, magnetic resonance imaging (MRI) was available for assessment of implantation accuracy. Each of the 212 electrodes was plotted on topographic drawings and its goodness of fit rated. RESULTS: Whereas hippocampal head and body were hit by 97 and 96% of the electrodes, respectively, the amygdala was hit by only 75% of the electrodes and mainly at its basal margin. For 93% of the electrodes, the inclination in a sagittal plane corresponded exactly to that of the hippocampus. The implantation morbidity amounted to 5.7%, whereas permanent neurological deficit occurred in one (0.7%) of the 141 patients. CONCLUSION: This computed tomography-based protocol proved to be reliable and hence can be considered as an adequate alternative to MRI-based stereotactic implantation if MRI is not available or if a single MRI-based stereotactic set-up is unreliable because of intolerable distortions.

Amygdala↗

PubMed1997

Surgical management of brain-stem cavernomas.

We present a series of seven patients who were operated on for symptomatic brain-stem cavernomas. The following approaches were used: medial suboccipital (N = 4), lateral suboccipital (N = 1), subtemporal-transtentorial (N = 1), and frontal transcortical-transventricular-subchorioidal-trans velum interpositum (N = 1). Intraoperative motor (N = 4) and somatosensory (N = 1) evoked potential monitoring revealed temporary changes in 3 patients. Immediately postoperatively, the following additional deficits were observed in 6 patients: oculomotor nerve paresis (N = 2), abducens nerve paresis (N = 3), facial nerve paresis (N = 2), deafness (N = 1), and increased ataxia (N = 3). One patient died due to septic complications not related to surgery. After a mean observation time of 2 years, 2 patients had improved, 3 were unchanged, and 1 patient deteriorated as compared to his preoperative status. In conclusion, surgical treatment of brain-stem cavernomas, although carrying a significant risk of temporary neurological deterioration is recommended in symptomatic patients in whom the cavernoma seems to reach the surface of the brain-stem. Intraoperative functional topographic mapping and monitoring have proven useful tools lowering the surgical risks in these patients.

Adult↗

PubMed1997

Human temporal lobe potentials in verbal learning and memory processes.

Animal experiments and lesion studies have shown the importance of temporal lobe structures for language and memory. We recorded intracranial cognitive potentials from the human lateral and medial temporal lobe in 26 patients with temporal lobe epilepsy undergoing presurgical evaluation, using a word- and a picture-recognition paradigm. Neuropsychological testing included word fluency, verbal reasoning, sustained attention and a verbal learning memory test (VLMT), which was an adapted version of the Rey auditory verbal learning test. Word-specific N400-potentials elicited in the middle temporal gyrus of the dominant left hemisphere (LTL-N400) predicted immediate recall performance after learning, whereas N400s, elicited by words but not pictures in the left anterior medial temporal lobe (AMTL-N400), predicted delayed recall. The number of words that were learned but forgotten after a 30-min delay correlated only with N400s elicited by words in the left anterior medial temporal lobe. Thus, intracranial recordings indicated that different electrophysiological responses in different temporal lobe structures were linked to memory scores from specific neuropsychological tests.

Adolescent↗

PubMed1997

Intracerebral capillary telangiectasia and venous malformation: a rare association.

BACKGROUND: The vascular malformations of the brain have been classified into arteriovenous, venous, cavernous, and capillary malformations as four discrete entities. Various combinations of two discrete malformations in one lesion have been reported, some of which can be considered as established associations, while others appear to be very rare. Mixed vascular malformations evoke reflections on possible interrelations in the pathogenesis of the discrete components. CASE DESCRIPTIONS: We report a case of intracerebral capillary telangiectasia associated with a venous malformation in a supratentorial paraventricular location in a 45-year-old woman with a history of headache. The capillary telangiectasia was diagnosed by stereotactic biopsy. Magnetic resonance imaging (MRI) and magnetic resonance angiography (MRA) strongly suggested the presence of a venous malformation by demonstrating a transcerebral draining vein running through the center of the capillary telangiectasia. The association of capillary telangiectasia and venous malformation has been reported only twice before and exclusively in the posterior fossa, as opposed to the more frequent, established associations of capillary telangiectasia and cavernous malformation, and venous malformation and cavernous malformation, respectively. CONCLUSIONS: Against the background of the established associations, this rare observation possibly places capillary telangiectasias, cavernous malformations, and venous malformations within the spectrum of a single disease. The common pathogenetic role of a focal venous outflow obstruction is discussed.

Capillaries↗

PubMed1997

Safety of intrahippocampal depth electrodes for presurgical evaluation of patients with intractable epilepsy.

PURPOSE: Intracerebral depth electrodes are used in preoperative evaluation of selected patients with intractable epilepsies. In spite of their usefulness, safety of depth electrodes is disputed, and the number of insertions is decreasing. This study examined retrospectively possible deleterious effects such as perioperative complications, induction of epileptogenesis, and neuropsychologic deficits. METHODS: Clinical course and neuroradiologic findings of 115 patients with bilaterally inserted longitudinal intrahippocampal depth electrodes (IDEs) were analyzed. Hippocampal resection specimens were examined histopathologically. To detect newly developed epileptogenic areas, EEG recordings, seizure control, and semiology after standardized resection procedures were compared between patients who received IDEs and those who did not. To demonstrate functional deficits caused by IDE insertion into an unaffected hippocampus of the speech-dominant hemisphere, changes of verbal learning and memory performances before and after right amygdalohippocampectomy were compared between patients evaluated with and without IDEs. RESULTS: Five significant complications without any permanent neurologic deficit were noted, and only one was specifically linked to IDE insertion. The tissue damage associated with the insertion was minimal and sharply circumscribed. No differences of seizure outcome after standardized resections were identified between patients with and without IDEs. In postoperative EEG recordings, there was no evidence of new epileptogenic areas. No verbal memory deficit caused by IDE implantation into the hippocampus of the speech-dominant hemisphere was detectable. CONCLUSIONS: Results indicate that it is safe to implant these IDEs in selected patients.

Adult↗

PubMed1997

Can neuronavigation contribute to standardization of selective amygdalohippocampectomy?

Tailored selective amygdalohippocampal resections seem to be an interesting application for neuronavigation. The accuracy of freehand frameless neuronavigation was assessed in 28 patients for its ability to determine the hippocampal resection length, as compared to postoperative MRI. Brain collapse due to CSF displacement caused an expected error of navigation at the brain surface, but almost no error at the tentorial notch. Yet, the hippocampal resection length was overestimated by navigation to an extent of 3 +/- 2 mm. The discrepancy is explained by an anterior-posterior component of brain collapse in a tilted head. Horizontal positioning of the head or navigational marking prior to the occurrence of brain collapse may overcome the problem.

Adult↗

PubMed1997

Intravascular papillary endothelial hyperplasia of the sellar region. Report of three cases and review of the literature.

Intravascular papillary endothelial hyperplasia (IPEH) is considered a reactive proliferation of endothelium associated with thrombosis. The occurrence of IPEH in the cranial cavity is exceedingly rare. In this article, the authors report three cases of IPEH that originated from the cavernous sinus and extended into the sellar contents. The lesions were resected incompletely in two cases and completely in one case. The IPEH in one of the patients was incompletely resected and exhibited further growth on magnetic resonance imaging 3 months postoperatively; local radiation therapy was instituted. This led to shrinkage of the lesion over an additional follow-up period of 3.5 years. In a review of the literature, the authors located seven other cases of intracranial IPEH. The authors conclude that clinically symptomatic intracranial IPEH should be completely resected whenever possible, because it can cause considerable morbidity and mortality and because it is prone to progression or recurrence.

Adult↗

PubMed1996

A flexible metal ventricular catheter for treatment of complicated and protracted infections of the cerebrospinal fluid spaces: preliminary experiences.

In the management of shunt infection, the use of ventricular catheters made of silicone rubber for the temporary external drainage of cerebrospinal fluid (CSF) is general practice. However, the eradication of the primary source of infection may be hindered by the affinity of bacteria to silicone-based material. Compared to silicone catheters, a metal drainage device for temporary ventriculostomy appears to offer more favourable conditions for successful eradication of the infection. Since metal needles cannot be implanted permanently and since their screw-type fixation precludes attachment to the skulls of infants or small children, we developed a flexible metal catheter. This catheter was used exclusively for the treatment of particularly serious or chronic infections of the CSF spaces. The catheter is made of implantation steel and consists of a corrugated tube that renders it flexible. Cerebrospinal fluid drains into a receptable bulb at the tip of the tube. Tubing of other materials may be connected to the end of the metal catheter for either external or internal drainage. It was implanted as a temporary and later permanent CSF drainage in 7 male patients aged from 4 to 60 years, who suffered from chronic, recurrent ventriculitis (n = 5) with an average of 7 previous surgical revisions, as well as from complex infections (n = 2; basal tuberculous meningitis, brain abscess). The infections were successfully eliminated in 6 patients. In the remaining patient, the metal catheter for external ventriculostomy had to be removed after 4 days due a leakage of CSF; it was replaced by a silicone catheter and later on by a needle drainage. Other complications, such as secondary infection or intracerebral haemorrhage, did not occur. The average duration of external CSF drainage via the flexible metal catheter was 27 days (range 4-50 days). In 4 patients, the CSF drainage was converted to a permanent ventriculoperitoneal shunt using a new flexible metal catheter. At the time of post-operative follow-up examination (average = 34 weeks), all shunts were functioning and there was no evidence of infection. In cases of especially complicated and protracted CSF infections, the flexible metal ventricular catheter is a promising device for treatment.

Adolescent↗

PubMed1996

Presence and removal of arteriovenous malformation: Impact of regional cerebral blood flow, as assessed with xenon/CT.

In 26 patients with supratentorial AVMs and 1 patient with a dural arteriovenous fistula, the regional cerebral blood flow (rCBF) was assessed by means of xenon-enhanced computed tomography (Xe/CT) before and after complete resective surgery. Each assessment comprised an acetazolamide challenge in order to check the cerebrovascular reserve capacity. While scanning through the AVM was purposely avoided, a single brain slice at the level of the basal ganglia was examined. Five regions of interest (ROIs) in gray matter of the AVM-bearing hemisphere were compared to the contralateral ROIs and categorized into 7 CBF groups. Interhemispherical differences exceeding 20% of the contralateral value in either direction were considered to the significant. AVM-related (AVM-R) and AVM-non-related (AVM-NR) ROIs were looked at separately. Before surgery, all possible rCBF patterns were found, including a normal rCBF as well as a reduced or an increased rCBF, either in AVM-R, AVM-NR, or both. After AVM removal, a rCBF increase in AVM-R is relatively rare, whereas a rCBF decrease is twice as frequent. A rCBF drop to a level of impaired reserve capacity correlates with the occurrence of post-operative neurological deficit.

Acetazolamide↗

PubMed1995

A characteristic ventricular shape in myelomeningocele-associated hydrocephalus? A CT stereology study.

We measured the volume of the supratentorial ventricles in 39 consecutive children with myelomeningocele (MMC) and associated hydrocephalus, using a stereological method based on the Cavalieri theorem of systematic sampling. We distinguished the following groups: newborns before and after cerebrospinal fluid shunting (14), a somewhat larger group of newborns with an untreated MMC-associated hydrocephalus (25) and a group of shunted children at a mean age of 1.5 years (28). We paid special attention to the shape of the lateral ventricles, looking separately at the anterior and posterior halves. The measurements were compared with a healthy control group (10) and with children with hydrocephalus unrelated to MMC (15). The average volume ratio of the posterior to the anterior half of the lateral ventricles was 1.05 +/- 0.39 in non-hydrocephalic children, 1.11 +/- 0.55 in untreated hydrocephalic children without MMC, and 2.15 +/- 0.65 in MMC-associated hydrocephalus prior to shunting. These ratios did not change significantly after shunting. This confirms our impression that MMC-associated hydrocephalus shows a characteristic shape, with a disproportionate enlargement of the posterior part of the lateral ventricles, in clear contrast to the normal-width frontal horns. This shape is reminiscent of the fetal ventricular shape. It reveals disturbance of brain development in children with MMC, which goes beyond the classic description of the Chiari malformation.

Arnold-Chiari Malformation↗

PubMed1995

Alterations of intrahippocampal cognitive potentials in temporal lobe epilepsy.

During presurgical evaluation event-related potentials were recorded with depth electrodes located longitudinally within the hippocampus in 25 patients suffering from unilateral temporal lobe epilepsy. Rare stimuli in a visual oddball paradigm elicited a pronounced negativity ("NO") in the hippocampal body. Amplitudes were significantly reduced on the side of the primary epileptogenic area. Visual presentations of words in a recognition paradigm evoked an earlier negativity ("ENW") in anterior and a later negativity ("LNW") in posterior hippocampal structures. Both were sensitive for recognition effects and showed reduced amplitudes on the side of the primary epileptogenic area. Relating the differences of left and right hippocampal "NO" and "ENW" amplitudes proved to be a sensitive method for topological diagnosis and allowed a correct lateralization of the primary epileptogenic area in all patients. Amplitudes of the hippocampal ENW, evoked in the dominant hemisphere by first presentations, strongly correlated with the recognition rate, when the primary epileptogenic area was situated in the contralateral temporal lobe. This correlation was reduced by the presence of ipsilateral epileptogenic foci.

Adolescent↗

PubMed1995

Tracing the planned probe trajectory on axial computed tomography slices: a computation-based support for stereotactic procedures. A computational tool for tracing of probe trajectories on CT slices.

Stereotactic frames are designed to hit point-like intracranial targets. Their routine performance does not include a display of the intended transcerebral probe path. Since the latter can render stereotactic procedures safer, more accurate and versatile, it has increasingly been implemented by potent computer systems. A low-cost alternative is presented in the form of a small extension of the computation program which is usually employed for the conversion of imaging coordinates to frame adjustments. It allows any desired point on the planned probe trajectory, in terms of its distance to the target, to be defined in Cartesian coordinates and thus to be traced on computed tomography. Thus, in biopsy procedures, for instance, instead of sampling tissue at the target only or in a 'blind' serial way, samples can be collected in a previewed and therefore safer and more purposeful way, thereby improving the yield of pathological tissue. The method seems particularly interesting for institutions that have a low to moderate number of stereotactic procedures and for which the investment of sophisticated computer systems for this purpose alone would not be economically feasible.

Biopsy↗