EMG Master of Neuroscience 2021 PDF

Master of Neuroscience 2021 Electromyography Dr R Strijers, neurologist Dpt of Clinical Neurophysiology VU Medical Center Neurophysiology Nerves and muscles produce electrical current (action potentials, IPSP/EPSP, sodium/potassium pump) Electrical current can be recorded; EEG, EMG (Instantane...

Master of Neuroscience 2021 Electromyography Dr R Strijers, neurologist Dpt of Clinical Neurophysiology VU Medical Center Neurophysiology Nerves and muscles produce electrical current (action potentials, IPSP/EPSP, sodium/potassium pump) Electrical current can be recorded; EEG, EMG (Instantaneously, spontaneously, superficially, subcutaneously) Electrical current can activate nerves and muscles Electromyography, a test for the peripheral nervous system  The speed of propagation increases with larger axonal diameter and in the presence of a myelin sheath. In myelinated axons the AP is propagated from node to node by saltatory conduction.  Psychogalvanic response or Lie Detector Test Meet The Parents Robert de Niro, Ben Stiller Unmyelinated nerves Latency 1,8 sec (1800 msec) Knee jerk, patellar tendon reflex, latency 20 msec (mainly myelinated nerves) Motor nerve conduction, schematic (hypothenar muscle, ulnar nerve) Sensory nerve conduction in practice, cutaneus nerve in lower arm training video made by Sanjeev Nandedkar Nerve conduction influences -Temperature - Age What can go wrong in motor nerve conduction In your document…  Carpal tunnel syndrome 45 year female with complaints of paraesthesia in the first 3 fingers of the right hand; she wakes up every night after 1-2 hours sleep Dig IV Dig IV Dig III Dig III Carpal tunnel syndrome, treatment Polyneuropathy Man 31 y with complaints of numbness in his lower legs and problems with walking Conduction velocity 38 m/sec Conduction velocity 25 m/sec Conduction velocity 34 m/sec Male, 31 yr, demyelinating neuropathy (PHARC syndrome) Needle examination  Concentric needle examination SFAP -> MUAP; amplitude, duration, number of phases Needle examination; normal bi- and triphasic MUAPs during contraction, 20 different potentials Abnormal needle examination: Fibrillation potentials and positive sharp waves at rest 50 μV 10 msec. Needle examination; abnormal MUAPs: upper row polyphasic potentials with high amplitude (raw sound), lower row polyphasic potentials with low voltage amplitude (crispy sound) Patiënt with loss of strength in fingerflexors, after a shooting incident with hail. Which nerve is damaged?  Patiënt with loss of strength in fingerflexors, after a shooting incident with hail. Which nerve is damaged? Spontaneous act +/++/+++ Voluntary contraction Max contr Muscle L/R fibr psw fas crd Dur. ms Ampl mV polyfas SP-MP-IP Ampl mV m. interosseus dorsalis I (Uln) R + + 0,6 - SP m. flexor dig. Profundus (Med) R + +++ 0,2 - SP m. Brachioradialis (Rad) R - - 0,5 +/- MP Intra operative nerve monitoring * FCR ADQ At start of surgery, stimulation of a nerve proximal from the tumor in the shoulder region; apparently the ulnar nerve is involved FCR ADQ After removing the tumor and transection of the ulnar nerve, stimulation of the median nerve. Note the respons in an ulnar muscle (so called Martin Gruber anastomosis) Summary Good reasons for an Electromyographic test Neuropathy - Diffuse neuropathy: - type (axonal/demyelinating), severity, monitoring - Local neuropathy: - compression (CTS) - trauma - Nerve root damage: Lumbar disc protrusion - ALS (amyotrophic lateral sclerosis) - combination of peripheral and central nervous system disease Myopathy/Neuro-muscular junction disease IONM (intra operative nerve monitoring)