Somatosensory evoked potentials following trigeminal nerve stimulation in trigeminal neuralgia

Abstract

The examination of somatosensory evoked potentials following trigeminal nerve stimulation in 20 subjects with idiopathic trigeminal neuralgia revealed a pathological increase in latency of the first positive component on the involved side in 7 (41%) of the 17 patients without antecedent surgical treatment. The mean difference in latency between the two sides was 1.3 msec (2p greater than or equal to 0.005). These results are indicative of microtraumatization of the trigeminal nerve in the posterior fossa by blood vessels, for example, leading to local demyelinization. The method seems to be of diagnostic value in selecting patients for more decompression by posterior fossa operations.

Somatosensory Trigeminal Evoked Potential Amplitudes Following Low Level Laser and Sham Irradiation Over Time

“…When subjected to an analysis of variance, no significant difference was observed between the two groups at base-line (p = 0.202; Table 1). The STEP amplitudes of N1-P1 in the study by Stohr et al, [8] revealed a mean of 2.6 + 1.1 microvolts, which compared to the overall mean amplitude of 2.89 + 1.1 in this current study (N=24). …”

“…These authors concluded that the STEP would provide a valid and reliable tool for monitoring trigeminal nerve components. The short duration, far field latencies of 18-24 ms are described [6,7] as the initial responses in the facial area of the somatosensory cortex. The N44 and longer latencies are considered to be derived from the associative cortex, possibly involving attentional, perceptual, and cognitive processing [8].…”

Comparative Study of the Electromyographic Activity of the Lips Orbicular Muscle in Patients with and without Cleft Palate

“…This problem is not limited to electromyography, and could be appreciated in many imaging studies like blood pressure or glycosylated hemoglobin 22,23 . Blair and Smith in 1986, mention that the surface electrodes have two advantages over the needle eletrodes to analize the electromiographic activity of orbicular muscle of the lips, the first is that it is not invasive and the second is that this muscle is constituted by the union of left and right muscle fibers.…”

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“…Segundo Jannetta 55 , esse método de investigação não demonstra claramente a compressão neurovascular. No passado, o estudo angiográfico encefálico foi muito útil para a detecção de lesões expansivas intracranianas 55 ; atualmente é indicado para o diagnóstico de afecções vasculares e, eventualmente, de tumores 23,63,71,74,78,95,114 . São encontradas anormalidades eletromiográficas da musculatura temporal e do masseter, especialmente em casos de neuralgia sintomática, mesmo quando o exame clínico é normal 43,53,60,76,77,89 .…”

“…São encontradas anormalidades eletromiográficas da musculatura temporal e do masseter, especialmente em casos de neuralgia sintomática, mesmo quando o exame clínico é normal 43,53,60,76,77,89 . O estudo eletrofisiológico do reflexo do piscamento e do reflexo mentoniano 11,43,60 e potencial evocado somatossensitivo podem sofrer alterações em muitos doentes com dor facial 11,12,95 . O exame do líquido cerebrospinal é utilizado para o diagnóstico de processos expansivos intracranianos intra e extra-axiais 5,15,61,63 .…”