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Andrea Szelényi

Publications and source records attributed to Andrea Szelényi.

7 recordsLinked to original sources
PubMed2006

Monitoring of muscle motor evoked potentials during cerebral aneurysm surgery: intraoperative changes and postoperative outcome.

OBJECT: The authors in this study evaluated muscle motor evoked potentials (MMEPs) elicited by transcranial electrical stimulation (TES) and direct cortical stimulation as a means of monitoring during cerebral aneurysm surgery. The analysis focused on the value and frequencies of any intraoperative changes and their correlation to the postoperative motor status. METHODS: One hundred nineteen patients undergoing surgery for 148 cerebral aneurysms were included in the study. Muscle motor evoked potentials were elicited by a train of five constant-current anodal stimuli with an individual pulse duration of 0.5 msec and a stimulation rate of 2 Hz. Stimulation intensity was up to 240 mA for TES and up to 33 mA for direct cortical stimulation. The MMEPs were continuously recorded from the abductor pollicis brevis and tibialis anterior muscles bilaterally and from the biceps brachii and extensor digitorum communis muscles contralateral to the surgical side. The motor status was evaluated immediately after surgery and 7 days later. In 97% of the patients MMEPs were recordable for continuous neurophysiological monitoring of the vascular territory of interest throughout the surgery. In 14 patients significant intraoperative MMEP changes occurred, resulting in a transient motor deficit in one patient and a permanent motor deficit in six. The permanent loss of MMEPs in three patients was followed by a permanent severe motor deficit in one patient and severe clinical deterioration in the other two. CONCLUSIONS: Data in this study demonstrated that MMEPs are a useful means of intraoperative neurophysiological monitoring of motor pathway integrity and predicting postoperative motor status. The intraoperative loss of MMEPs reliably predicts both severe and permanent postoperative motor deficits.

Adolescent↗
PubMed2005

Motor evoked potential monitoring during cerebral aneurysm surgery: technical aspects and comparison of transcranial and direct cortical stimulation.

OBJECTIVE: This study evaluates technical aspects, handling, and safety of intraoperatively applied transcranial electrical stimulation (TES) and direct cortical stimulation (DCS) for eliciting muscle motor evoked potentials (mMEPs) during cerebral aneurysm surgery. METHODS: In 119 patients undergoing cerebral aneurysm surgery, mMEPs were evoked by a train of five stimuli with individual pulse duration of 0.5 milliseconds, a repetition rate of 2 Hz, and constant current anodal stimulation. The maximal stimulation intensity was 240 mA for transcranial and 33 mA for direct stimulation. mMEPs were recorded continuously from the abductor pollicis brevis, from tibial anterior muscles bilaterally, and from the biceps brachii and extensor digitorum communis muscles contralateral to the side operated on. RESULTS: In 118 (99%) of 119 patients, transcranially evoked mMEPs were monitorable for the vascular territory of interest. DCS was performed successfully in 95 (95%) of 100 patients. In 86 (99%) of 87 patients with internal carotid artery, middle cerebral artery, or posterior circulation aneurysms, mMEPs from upper-extremity muscles were obtained with DCS. In 11 (55%) of 20 patients with anterior communicating artery, anterior cerebral artery, or pericallosal aneurysms, mMEPs from the lower-extremity muscles could be recorded. The incidence of seizures was 0.84% for TES and 1% for DCS. Minor and inconsequential subdural bleeding after positioning of the strip electrode occurred in 2%. CONCLUSION: The cogent comprehensive combination of transcranial and direct cortical electrical stimulation allows for the continuous mMEP monitoring of the cerebral vascular territory of interest in 99% of the patients with cerebral aneurysms. Unwarranted effects of electrode placement and stimulation are rare and without clinical consequences.

Adolescent↗
PubMed2004

Functional magnetic resonance imaging-integrated neuronavigation: correlation between lesion-to-motor cortex distance and outcome.

OBJECTIVE: The integration of functional magnetic resonance imaging (fMRI) data into neuronavigation is a new concept for surgery adjacent to the motor cortex. However, the clinical value remains to be defined. In this study, we investigated the correlation between the lesion-to-fMRI activation distance and the occurrence of a new postoperative deficit. METHODS: fMRI-integrated "functional" neuronavigation was used for surgery around the motor strip in 54 patients. During standardized paradigms for hand, foot, and tongue movements, echo-planar imaging T2* blood oxygen level-dependent sequences were acquired and processed with BrainVoyager 2000 software (Brain Innovation, Maastricht, The Netherlands). Neuronavigation was performed with the VectorVision(2) system (BrainLAB, Heimstetten, Germany). For outcome analysis, patient age, histological findings, size of lesion, distance to the fMRI areas, preoperative and postoperative Karnofsky index, postoperative motor deficit, and type of resection were analyzed. RESULTS: In 45 patients, a gross total resection (>95%) was performed, and for 9 lesions (low-grade glioma, 4; glioblastoma, 5), a subtotal resection (80-95%) was achieved. The neurological outcome improved in 16 patients (29.6%), was unchanged in 29 patients (53.7%), and deteriorated in 9 patients (16.7%). Significant predictors of a new neurological deficit were a lesion-to-activation distance of less than 5 mm (P < 0.01) and incomplete resection (P < 0.05). CONCLUSION: fMRI-integrated neuronavigation is a useful concept to assess the risk of a new motor deficit after surgery. Our data suggest that a lesion-to-activation distance of less than 5 mm is associated with a higher risk of neurological deterioration. Within a 10-mm range, cortical stimulation should be performed. For a lesion-to-activation distance of more than 10 mm, a complete resection can be achieved safely. The visualization of fiber tracks is desirable to complete the representation of the motor system.

Adult↗
PubMed2003

Neurophysiological criteria for intraoperative prediction of pure motor hemiplegia during aneurysm surgery. Case report.

The value of motor evoked potentials (MEPs) as an intraoperative neurophysiological monitoring tool for detecting selective subcortical ischemia of the motor pathways during intracerebral aneurysm repair is described and the use of such measures to predict postoperative motor status is discussed. The authors present the case of a 64-year-old woman in whom there was an incidental finding of two right middle cerebral artery (MCA) aneurysms. During the aneurysm clipping procedure, an intraoperative MEP loss in the left abductor pollicis brevis and tibial anterior muscles occurred during an attempt at permanent clip placement. There were no concurrent changes in somatosensory evoked potentials. Postoperatively, the patient demonstrated a left hemiplegia with intact sensation. A computerized tomography scan revealed an infarct in the anterior division of the MCA territory, including the posterior limb of the internal capsule. In this patient, intraoperative neurophysiological monitoring with MEPs has been shown to be a sensitive tool for indicating subcortical ischemia affecting selective motor pathways in the internal capsule. Therefore, intraoperative loss of MEPs can be used to predict postoperative motor deficits.

Aneurysm↗
PubMed2002

Neurophysiological evaluation of the corticospinal tract by D-wave recordings in young children.

OBJECTIVE: The objective was to neurophysiologically evaluate corticospinal tract (CT) maturation in children younger than 36 months by recording D-waves. METHODS: In 19 children, D-wave recordings were attempted during resection of intramedullary spinal cord tumors (imSCTs). D-waves were elicited by transcranial electrical stimulation (TES; single pulse, anodal stimulation) and recorded from a catheter-electrode inserted into the epidural space caudal to the imSCTs. The presence of the D-wave was analyzed in respect of the patients' age. RESULTS: A D-wave was present in 7 children (21-36 months) and absent in the remaining 12 children (8-31 months). In the youngest child (21 months) the D-wave was recorded from the lower thoracic spinal cord. CONCLUSION: These D-wave recordings indicate that in the immature CT a synchronized descending volley via fast conducting fibers is evoked by TES and can be recorded as a D-wave from the lower thoracic spinal cord at 21 months. As all D-waves have been recorded caudal to the imSCTs, it is difficult to distinguish the contributing factor affecting the D-wave recordings in children older than 21 months: the prolonged CT maturation for the lower extremities, the individual variability of CT maturation or the influence of the imSCT.

Cerebral Cortex↗
PubMed2002

Brain tissue oxygenation monitoring supplementary to somatosensory evoked potential monitoring for aneurysm surgery. Initial clinical experience.

The object of the study was to evaluate brain tissue oxygenation (p(ti)O2) for intra-operative monitoring of critical ischemic events during early cerebral aneurysm surgery of the anterior circulation supplementary to somatosensory evoked potentials (SEPs). P(ti)O2 was continuously evaluated during surgery for an intracranial aneurysm in 28 patients. Standard cortical SEP monitoring was simultaneously performed. The two monitoring methods were compared by evaluating their respective responses to intra-operative events (particularly temporary vessel occlusion), clinical and neuroradiological outcome. P(ti)O2 and SEPs were reliably used for monitoring in 16 patients. Seven patients were excluded due to too high or too low p(ti)O2 readings or initial absence of SEPs (six patients). Of 64 intra-operative events 19 events (eight patients) were associated with a significant decrease in p(ti)O2 (below 10 mmHg), 22 events (13 patients) were associated with a significant change in SEP amplitude (< 50% decrease related to baseline). Temporary vessel occlusion (six SEP andp(ti)O2 changes each in eightpatients) and surgical dissection were most likely to be followed by significant changes in a monitoring method. Intra-operative p(ti)O2 was found to be a safe, rapid method for documenting ischemic events. P(ti)O2 was found to supplement SEP monitoring. The use of p(ti)O2 measurement as a routine monitoring method in aneurysm surgery is limited by its focal spatial resolution. Nevertheless, it might be helpful as an adjunct in situations when SEPs are absent at baseline, in aneurysms when parent vessel anatomy is complex or if temporary vessel occlusion is planned.

Adult↗