11/13/2023 0 Comments Als emg findings![]() ![]() 5 While late stage disease is relatively easy to identify, early disease can be much more difficult to diagnose on clinical examination alone. Chio and colleagues examined the phenotypes of over 1300 ALS patients and described eight common presentations: Classic, bulbar, flail arm, flail leg, pyramidal, pure LMN, pure UMN, and respiratory. Phenotypic presentation can be markedly varied in ALS, making early diagnosis more complicated. Signs at presentation may be limited to UMN or LMN loss. The spread of symptoms is so typical of ALS that it is required for diagnosis. In the late stages, mechanical ventilation and nutritional support may be required. Symptoms most typically begin at one anatomic site and spread, with the disease progressing until the patient loses volitional control of skeletal muscles, transitioning from independence to dependence. General Approach to the Electrodiagnostic Evaluation of the Patient with ALSĬlinically, ALS causes muscle atrophy and weakness. Electrodiagnostic evaluation is key to establishing the diagnostic certainty of ALS once other disease processes have been excluded. Laboratory testing, neuroimaging, and muscle biopsy are all potentially helpful in focusing the differential diagnosis and excluding processes that mimic ALS ( Table 1). Thus, a process of exclusion is used to determine the diagnosis. 4 Limited DNA analysis is available and can identify the etiology for some patients with familial ALS (10-15% of all ALS patients), as well as those with SMA and spinal bulbar muscular atrophy (SBMA) but for the majority of patients with symptoms of MND, diagnosis is complicated by the lack of disease biomarkers. Individually, the motor neuron diseases are rare with the prevalence of ALS being approximately 5-7 per 100,000 people. 2, 3 Because prognosis and survival can be vastly different among the motor neuron disorders, differentiating among these disorders and making an accurate and timely diagnosis are paramount. 1 However, while ALS is characterized by the rapid degeneration of motor neurons throughout the neuraxis and by definition requires both upper motor neuron (UMN) and lower motor neuron (LMN) signs to confirm the clinical diagnosis, other motor neuron diseases such as spinal muscular atrophy (SMA) or the atypical motor neuron variants, progressive muscular atrophy (PMA), primary lateral sclerosis(PLS), and progressive bulbar palsy (PBP), have more focal involvement or only UMN or LMN involvement, at least initially. ALS is the most common adult MND worldwide and is considered the prototypical disorder of this class, as demonstrated by the often-interchangeable use of the terms ALS and MND. These changes, strategies for the design and implementation of an effective electrodiagnostic evaluation, and additional electrophysiologic techniques and their relationship to the evaluation of a patient with ALS are reviewed and discussed.Īmyotrophic lateral sclerosis (ALS) is a progressive and inevitably fatal neurodegenerative disease belonging to a heterogeneous group of disorders known as motor neuron diseases. In addition, electrophysiologic evidence is now considered equivalent to clinical signs and symptoms in reaching diagnostic certainty of ALS. The recent changes in the revised El Escorial criteria, recommended by the Awaji-shima consensus group, have increased the diagnostic significance of fasciculation potentials to equal that of fibrillation and positive sharp wave potentials in the needle EMG examination of the patient suspected of having ALS. ![]() The electrodiagnostic study should include peripheral nerve conduction studies (NCS) and needle electromyography (EMG) to both exclude treatable disease and gather evidence toward a diagnosis of amyotrophic lateral sclerosis (ALS). Electrophysiology remains an important tool in the evaluation of patients presenting with signs and symptoms of motor neuron disease (MND). ![]()
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