A modified Hodgkin–Huxley model to show the effect of motor cortex stimulation on the trigeminal neuralgia network

Abstract

Background Trigeminal neuralgia (TN) is a severe neuropathic pain, which has an electric shock-like characteristic. There are some common treatments for this pain such as medicine, microvascular decompression or radio frequency. In this regard, transcranial direct current stimulation (tDCS) is another therapeutic method to reduce pain, which has been recently attracting the therapists’ attention. The positive effect of tDCS on TN was shown in many previous studies. However, the mechanism of the tDCS effect has remained unclear. Objective This study aims to model the neuronal behavior of the main known regions of the brain participating in TN pathways to study the effect of transcranial direct current stimulation. Method The proposed model consists of several blocks: (1) trigeminal nerve, (2) trigeminal ganglion, (3) PAG (periaqueductal gray in the brainstem), (4) thalamus, (5) motor cortex (M1) and (6) somatosensory cortex (S1). Each of these components is represented by a modified Hodgkin-Huxley (HH) model. The modification of the HH model was done based on some neurological facts of pain sodium channels. The input of the model involves any stimuli to the ‘trigeminal nerve,’ which cause the pain, and the output is the activity of the somatosensory cortex. An external current, which is considered as an electrical current, was applied to the motor cortex block of the model. Result The results showed that by decreasing the conductivity of the slow sodium channels (pain channels) and applying tDCS over the M1, the activity of the somatosensory cortex would be reduced. This reduction can cause pain relief. Conclusion The proposed model provided some possible suggestions about the relationship between the effects of tDCS and associated components in TN, and also the relationship between the pain measurement index, somatosensory cortex activity, and the strength of tDCS.

A Comparative Review of the Outcome Following MVD and PBC in Patients with Trigeminal Neuralgia

“…59,60 PBC evenly compresses the structures of the trigeminal ganglion. [61][62][63] The ganglion consist of neuron somata, which cannot regenerate once destroyed. Theoretically, an appropriate compression may selectively damage the pain-sensing neurons and preserve others as far as possible.…”

Rol de los canales de sodio voltaje dependientes en la fisiopatología de la neuralgia del trigémino.

“…4 Según el modelo computarizado de Hodgkin-Huxley modificado, se ha observado que el ingreso constante de estímulos nociceptivos en el ganglio trigeminal y el aumento en el flujo de sodio de los canales lentos de Nav1.8 producen un incremento en la actividad de la corteza somatosensorial generando y perpetuando el dolor de la NT. 23 Un estudio realizado por Tanaka et al, muestra los cambios biofísicos causados en el VGSC por la sustitución de la metionina 136 por valina en el segmento transmembrana 1 del dominio 1. Dichos autores sostienen que la sustitución genera un aumento significativo en las corrientes pico transitorias y resurgentes (confiere hiperexcitabilidad) del canal Nav1.6 y que también reduce el umbral para el potencial de acción en las neuronas del ganglio del trigémino, activando a las neuronas implicadas más rápidamente.…”

Estimation of the Motor Threshold for Near‐Rectangular Stimuli Using the Hodgkin–Huxley Model

“…e HH equations have been widely used in the modeling of several neuromodulation modalities and neuronal behavior [12][13][14]. In this study, for the computational modeling of cortical neurons, a Hodgkin-Huxley type model is selected, including four conductances (the voltage-dependent sodium, potassium, slow potassium, and resting (leak) membrane conductance) and the TMS-induced current density.…”