The Physiology of Painīecause EMG is an electrophysiologic measure, it is important to consider the physiology of pain itself, which is perhaps best studied in myofascial pain. 11 For patients in pain caused by median neuropathies, or for example from wrist arthritis leading to the compression, an accurate pain-free study may be quite helpful. Neuromuscular ultrasound is accurate for diagnosis of median neuropathy at the wrist, and level A evidence suggests it may be offered for this diagnosis. 10 A more frequently used “pain-free” electrodiagnostic test is neuromuscular ultrasound, which is used to diagnose neuropathies and focal deficits and monitor muscle health. An evidence-based review from the American Association of Neuromuscular and Electrodiagnostic Medicine (AANEM) suggests there is class C evidence that sEMG may be helpful in diagnosing neuromuscular diseases it is rarely used for this purpose, and that is likely to remain so until further studies are done. Currently, sEMG is mostly used to evaluate nonneurologic diagnoses. Muscle signals are examined with surface electrodes in sEMG rather than through the traditional needle electrode. 9 Although these are extremely uncommon, the risks warrant at least ensuring that the study is necessary before referring.Įlectrodiagnostic tests that are painless may also be considered for diagnosing neuromuscular diseases including surface EMG (sEMG), which can complement a nerve conduction study and/or needle examination. EMGs carry intrinsic hazards, including the rare cases of electrical injury, bleeding, or infection. It is also important to remember that pain is not the only risk of the study. 8 It is important that referrals include clear descriptions of symptoms and a thoughtful diagnostic question for the electromyographer to evaluate (Box). A study found that 82% of patients said the test was “not as bad as they expected,” and most patients noted only mild pain. 7 Although the procedure may induce pain, it is important to note that it is not a severely painful experience for most patients. 3Īccurate muscle selection is an important and modifiable aspect of the pain caused by EMG, making it crucial that electromyographers perform accurate muscle selection. Women have more pain during EMG or at least acknowledge and report it. Some studies have found women having nerve conduction studies perceived less pain when they were given informational handouts prior to the study, although this did not apply to the needle portion of the exam and the effect was not seen in men. 6 Giving information before the test may be helpful. In a study of new patients at an EMG lab, 52.1% of patients had either no information or incorrect information about EMG, and only 28.2% were considered informed. Patients have varied levels of understanding and perceptions of EMG. 4 There have been attempts to alleviate pain during EMG with pharmacologic interventions (eg, skin sprays or oral analgesics) and with nonpharmacologic interventions (eg, calming music and/or providing preprocedure information about the test to alleviate anxiety). Patients who report higher pretest pain and anxiety typically report more pain during the procedure. It is crucial to discuss and understand a patient's pain before referring to EMG because stopping midstudy because of pain sacrifices patients' resources, adds to their discomfort, and creates the challenge of interpretation from limited data for the electromyographer. 3 The study is typically well tolerated but for some patients it is nearly unbearable. Most surveys find pain more common in the needle portion. Pain is the most common complication of EMG 2 causing some level of discomfort in all patients either from the nerve conduction portion or the needle examination. 1 This review addresses the types of patients and pain that warrant referral to EMG and when to consider this a useful diagnostic study. Choosing which patients to refer for EMG is important because there are costs of patient time, money, and perhaps most importantly, pain intrinsically associated with EMG itself. EMG can be considered an extension of the clinical neurologic examination, rather than simply a test, and is ordered by many healthcare providers from all specialties. Nerve conduction and EMG studies are an important procedure for evaluating possible peripheral nervous system (PNS) disorders.
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