2024 Workshop Handout Bundle-W55C Myopathies An Electrodiagnostic (EDX) Approach Kushlaf

W55C Myopathies An Electrodiagnostic (EDX) Approach Kushlaf

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The workshop "Myopathies: An Electrodiagnostic (EDX) Approach" by Dr. Hani Kushlaf at the 2024 AANEM Annual Meeting discusses the role and methods of electrodiagnostic studies in diagnosing myopathies. Myopathies include conditions characterized by muscle weakness, hyperCKemia (elevated creatine kinase levels), muscle stiffness, muscle pain, rhabdomyolysis, twitching, and atrophy. <br /><br />Electrodiagnostic studies begin with nerve conduction studies to confirm the diagnosis, assess severity, and identify muscles for biopsy. Sensory nerve conduction studies are usually normal unless there is a coexisting condition like polyneuropathy. Motor nerve conduction studies remain normal except in cases like inclusion body myositis and myotonic dystrophy type 1. Critical Illness Myopathy (CIM) is indicated by prolonged compound muscle action potential (CMAP) duration due to the reduced excitability of muscle fiber membranes.<br /><br />Needle electromyography, crucial for examining weak muscles, involves selecting various muscles including proximal, distal, and thoracic paraspinal muscles. This method assesses spontaneous activity and motor unit action potentials (MUAPs). In chronic myopathies, reinnervation leads to long-duration, high amplitude, polyphasic MUAPs, mixed with short-duration, small amplitude, polyphasic MUAPs. Decreased MUAP duration and early recruitment are significant indicators of myopathy. The electrodiagnostic studies help confirm myopathic diagnosis, delineate muscle involvement, and guide further procedures like muscle biopsy.<br /><br />Specific myopathies might require advanced testing, such as short and long exercise tests for myotonic disorders and periodic paralyses, or repetitive nerve stimulation for neuromuscular junction disorders. The workshop highlights the importance of specialized protocols and tools, proper muscle selection for examination, and the significance of clinical presentations in guiding the diagnostic process.<br /><br />Dr. Kushlaf emphasizes that while electrodiagnostic findings can strongly suggest myopathies, further confirmation through muscle biopsy is often necessary, highlighting the interplay between clinical and electrodiagnostic evaluations.

Keywords

Myopathies

Electrodiagnostic

EDX

Nerve conduction studies

ncs

Needle electromyography

MUAPs

Critical Illness Myopathy

Muscle biopsy

Myotonic disorders

Neuromuscular junction

nmj

nerve conduction studies

nerve conduction study

ncs

nmj

neuromuscular junction