Diagnostic Approach for Amyotrophic Lateral Sclerosis (ALS)

Essential Electrophysiological Studies

The American Academy of Neurology recommends EMG and nerve conduction velocity (NCV) studies as mandatory for detecting lower motor neuron degeneration and distinguishing ALS from other conditions 1, 2

Brain MRI without IV contrast is the primary imaging modality to exclude structural lesions, tumors, and inflammatory conditions that mimic ALS, according to the American College of Radiology 1, 2, 3
The American College of Radiology suggests looking for abnormal T2/FLAIR hyperintensity in the corticospinal tracts, particularly in the posterior limb of the internal capsule and cerebral peduncles 2, 3
T2*-weighted or susceptibility-weighted imaging may show abnormal hypointensity in the precentral gyrus, which can be highly sensitive and specific for ALS, as recommended by the American College of Radiology 2

The American Academy of Neurology recommends a complete blood count (CBC) to evaluate for infectious or inflammatory conditions 1, 2
The American College of Physicians suggests a comprehensive metabolic panel including glucose, electrolytes, kidney function, and liver enzymes 1, 2
The Endocrine Society recommends thyroid function tests (TSH, free T4) to exclude thyroid disorders causing weakness 1, 2
The American Academy of Neurology suggests testing for vitamin B12, folate, and vitamin E levels to identify deficiencies causing neurological symptoms 1, 2
The American Society for Clinical Pathology recommends serum protein electrophoresis to rule out paraproteinemic neuropathies 1, 2
The American Academy of Neurology suggests testing for anti-ganglioside antibodies (GM1, GD1a, GD1b) to exclude immune-mediated motor neuropathies like multifocal motor neuropathy 1, 2
The American College of Rheumatology recommends a paraneoplastic antibody panel to exclude paraneoplastic syndromes 1, 2
The American Academy of Neurology suggests testing for anti-acetylcholine receptor and anti-MuSK antibodies to rule out myasthenia gravis 1, 2

The American Academy of Neurology recommends CSF examination to exclude inflammatory/infectious mimics 1, 2
The American College of Physicians suggests ordering cell count, protein, glucose, IgG index, oligoclonal bands, and cytology 1, 2

The American Academy of Neurology recommends genetic testing for ALS-associated genes, particularly when there is a family history of ALS or frontotemporal dementia 1, 2
The American College of Medical Genetics suggests testing for key genes including C9orf72, SOD1, FUS, and TARDBP 1, 2

The American Speech-Language-Hearing Association recommends dysphagia screening at diagnosis and every 3 months thereafter as part of comprehensive evaluation 4, 1
The American Academy of Otolaryngology suggests using the EAT-10 questionnaire, which has 86% sensitivity and 76% specificity for identifying unsafe swallowing 4, 1
The American College of Gastroenterology recommends the Volume-Viscosity Swallow Test (V-VST), which demonstrates 92% sensitivity and 80% specificity for detecting dysphagia 4, 1
The American Society for Gastrointestinal Endoscopy suggests videofluoroscopy for instrumental assessment when dysphagia symptoms are present 4

The American Academy of Neurology recommends not relying solely on clinical examination, as up to 10% of patients initially diagnosed with ALS have a mimic disorder 1, 2
The American College of Physicians suggests not skipping the comprehensive laboratory panel, as several treatable conditions can present identically to ALS 1, 2
The American Academy of Neurology recommends not delaying genetic testing in familial cases, as approximately 10% of ALS is familial, and genetic counseling is important for family members 1, 2
The American Speech-Language-Hearing Association suggests not overlooking early dysphagia, as swallowing abnormalities can occur even without bulbar symptoms, and early detection prevents aspiration pneumonia 4, 1