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As medicine advances, more critically ill patients are surviving longer ICU admission. Many of these patients will have difficulty weaning off the ventilator or will complain of profound weakness after extubation despite appropriate treatments and medical intervention. Although not often performed, the gold standard for the diagnosis of critical illness myopathy remains electrodiagnostic testing, which includes nerve conduction studies and needle electromyography. This activity outlines and reviews the importance of electrodiagnostic testing in the evaluation of critical illness myopathy (CIM) and highlights the role of the interprofessional team in improving care for these patients. Objectives: Identify the indications for electrodiagnostic testing in critically ill patients. Describe the nerve conduction study findings in a patient with critical illness myopathy. Review the electromyographic findings in a patient with critical illness myopathy. Outline the importance of communication among the interprofessional team to enhance the delivery of care for patients with critical illness myopathy. Access free multiple choice questions on this topic.

As survival rates of the critically ill increase with the advancement of modern medicine, the incidence of neuromuscular disturbances in these patients becomes a profound complication that needs further attention.  “Intensive care unit acquired weakness” (ICUAW) is a spectrum of underdiagnosed conditions that includes both critical illness neuropathy (CIN) (also referred to as critical illness polyneuropathy (CIP)) and critical illness myopathy (CIM). While studies show that pure neuropathy is rare, patients more often develop a combination of both CIN and CIM, or they can develop a pure CIM. Therefore, it is imperative to understand the key features and electrodiagnostic findings of each condition to ensure prompt recognition, prevent further disability, and ensure better patient outcomes. Prognostically, while patients with critical illness neuropathy often suffer from a long-term impairment, those with a pure critical illness myopathy have been shown to improve relatively rapidly with minimal residual disturbance.[1] While the conditions are often underdiagnosed, studies show that the incidence of ICUAW in patients with greater than seven days of mechanical ventilation may range from 25% to 83%.[2][3] Some of the risk factors for developing CIM include high-dose glucocorticoid use, neuromuscular blocking agents, COPD or asthma exacerbation, and hyperglycemia.[4] The pathophysiology of CIM is theoretically a combination of microvascular, metabolic, and electrical alteration, which leads to an inflammatory cascade. The atrophy is proposed to be due to increased muscle proteolysis coupled with a decrease in muscle protein synthesis. These processes result in myosin loss, as well as thick fiber necrosis and apparent muscle atrophy, which may be evident in a muscle biopsy.[5][6] Creatine kinase may be normal or transiently elevated in a patient with CIM. It bears mention that steroid myopathy may mimic the symptoms of CIM by similarly affecting proximal muscles with profound weakness. However, steroid myopathies affect type 2B muscle fibers, and therefore EMG testing in steroid myopathy will be grossly normal because the test evaluates only the faster, type 1 motor units.[7]

Often patients with a prolonged ICU admission will develop profound weakness or failure to wean off a ventilator. Intensivists, physiatrists, and neurologists must recognize that further evaluation with electrodiagnostic testing is warranted in these circumstances. As healthcare professionals, appropriate disease recognition and diagnosis of critical illness myopathy will help expedite patient recovery and can improve long term quality of life. While there is a vast differential in the patient with weakness which develops in the ICU, NCS and EMG studies may be able to identify the etiology and further guide the management. After arriving at the diagnosis of CIM, the interprofessional team must include a team of physicians, physical therapists, occupational therapists, speech therapists, nutritionists, social workers, and case managers. These professionals can work together to coordinate early mobilization and aggressive multifaceted rehabilitation. Typically, there is a long and challenging recovery ahead for patients with CIM upon leaving the critical care setting. Only with a coordinated effort between the various medical disciplines and departments will the best outcomes for patients be achieved.[14][15][16]