Medical Student: EMG Basics-Dr. Izenberg Presentation

Dr. Izenberg Presentation

Pdf Summary

This document provides an overview of electromyography (EMG), which is the analysis of spontaneous and voluntary muscle activity using a needle electrode. The document discusses the equipment needed for EMG, including the needle electrode and cable, ground electrode, EMG headbox, amplifier, and computer. It also provides a basic approach to EMG, including the assessment of insertional and spontaneous activity and voluntary activity. <br /><br />The document then delves into the different types of spontaneous activity that can be observed during an EMG, including endplate noise and spikes, fibrillation potentials, positive sharp waves, myotonic discharges, complex repetitive discharges, fasciculation potentials, doublets and triplets, myokymic discharges, cramp potentials, and neuromyotonia. Each of these abnormalities is described in terms of its characteristic morphology, firing pattern, and associated pathologies.<br /><br />The document also discusses specialized studies that can be performed using EMG, such as repetitive nerve stimulation (RNS), blink studies, and short and long exercise studies. RNS is typically used to evaluate neuromuscular junction (NMJ) disorders, with low frequency stimulation used for post-synaptic disorders like myasthenia gravis and high frequency stimulation used for pre-synaptic conditions like Lambert-Eaton myasthenic syndrome (LEMS). Blink studies can help detect cranial nerve V and VII lesions, as well as generalized demyelinating neuropathies. Short and long exercise studies are used to evaluate muscle channelopathies, non-dystrophic myotonias, and periodic paralyses.<br /><br />Overall, the document provides a comprehensive overview of the basics of EMG and specialized studies, making it a valuable resource for individuals interested in understanding and performing electromyography.

Keywords

electromyography

EMG

muscle activity

needle electrode

spontaneous activity

voluntary activity

repetitive nerve stimulation

myasthenia gravis

Lambert-Eaton syndrome

muscle channelopathies