Biomedical subjects

E A Karol

Publications and source records attributed to E A Karol.

9 recordsLinked to original sources

PubMed1999

The micrometric multiarray technique for percutaneous thermocoagulation of trigeminal neuralgia. Preliminary report.

This report describes the technical features and preliminary results of a multiple electrode array system designed to provide access to four different sites within one or more selected trigeminal divisions. At each segment, multiple clinical sensory and motor data are correlated with radiological landmarks in the individual patient with trigeminal neuralgia. The system consists of an outer needle, through which a multielectrode array is introduced. Four successive 2.9 mm caps at the distal end of the multielectrode protrude from the tip of the outer needle into the cerebrospinal fluid of the post-gasserian fibers. The outer needle is always introduced fluoroscopically or tomographically into the inner third of the oval foramen. No blind punctures or suboptimal positions are accepted. After correlating clinical verbal and motor responses at each cap and inter se, the safest location is selected, with a precise knowledge of the segment of the division lying in front and behind the target. Lesions in the first division, the motor division, and segments not involved with pain are avoided. A thermocouple fitted with a micromanipulator allows the placement of the active tip at the center of the chosen target. The maximal size of the lesion cannot exceed the size of the target. Data from 117 consecutive procedures were systematically recorded in a computerized protocol for future analysis. Corneal anesthesia and deafferentation pain were not observed in this series. Preliminary data suggests that the micrometric technique may significantly minimize the residual morbidity from percutaneous thermocoagulation of trigeminal neuralgia.

Anesthesia, Local↗

PubMed1993

A micrometric multiple electrode array for the exploration of gasserian and retrogasserian trigeminal fibers: preliminary report. Technical note.

The determination of the target for percutaneous thermocoagulation of the trigeminal rootlets has been generally based on the analysis of subjective clinical verbal and motor responses as assessed by freehand displacement of an electrode active at its straight or curved distal tip. In a previous report, we demonstrated that sensory and motor trigeminal evoked potentials are of practical value when attempting to localize the position of trigeminal electrodes. This report describes the technical features of a multiple electrode array designed to provide simultaneous access to various segments along a chosen trigeminal division or divisions, correlating at each segment clinical and electrophysiological data with radiological landmarks in the individual patient. The system consists of an outer needle with four windows at a distance of 15 mm from the tip. A multiple electrode array occludes the windows with four isolated caps for stimulation and recording. After correlating clinical verbal and motor responses with sensory and motor evoked potentials at each window and inter se, a target window is selected. A thermocouple fitted with a micromanipulator allows the accurate placement of the center of the active tip at the center of the chosen window. Preliminary data from 25 patients indicate that the technique provides a reliable sequential analysis of clinical, electrophysiological, and radiological data along the explored tract.

Aged↗

PubMed1991

Sensory and motor trigeminal evoked potentials to localize the position of trigeminal electrodes.

Analysis of verbal responses to electrical stimulation of the trigeminal ganglion and rootlets has been the only method available so far to localize the electrode tip in the most appropriate trigeminal division or division segment, prior to thermocoagulation during percutaneous treatment for trigeminal neuralgia. A diversity of factors may lead to unreliable verbal responses, resulting in increased morbidity or even therapeutic failure. In an attempt to enhance the accuracy of electrode localization during Sweet's procedure, we describe an electrophysiological method complementary to clinical responses. Sensory trigeminal evoked potentials (STEPs) induced by separate successive orthodromic cutaneous stimulation of the three trigeminal divisions and recorded by the isolated tip of a transoval thermocouple electrode, together with motor trigeminal evoked potentials (MTEPs) elicited by stimulation of the trigeminal ganglion and recorded in the ipsilateral temporal muscle, were sequentially examined in six patients undergoing percutaneous tic treatment during gradual rostro-caudal electrode withdrawal. STEPs and MTEPs showed appropriate correlation with verbal and clinical motor responses at each electrode site. General anaesthesia failed to affect STEPs. Systematic exploration in the awake patient of both verbal and clinical motor responses, together with STEPs and MTEPs, is therefore recommended prior to the induction of radiofrequency lesions in the course of percutaneous treatment for trigeminal neuralgia.

Adult↗

PubMed1973