Diagnostic and Treatment Approaches for Amyotrophic Lateral Sclerosis (ALS)

Diagnostic Approach

• The diagnosis of ALS requires evidence of both upper and lower motor neuron degeneration, progressive spread of symptoms, and exclusion of other conditions through a combination of clinical evaluation, electrophysiological studies, and neuroimaging 1, 2
• ALS presents with mixed upper motor neuron signs and lower motor neuron signs 2
• Approximately 80% of patients with bulbar-onset ALS develop dysarthria and dysphagia 2
• Electromyography (EMG) and nerve conduction velocity (NCV) studies are cornerstone tests for diagnosing ALS, detecting lower motor neuron degeneration and distinguishing ALS from other conditions 1
• MRI of the brain without IV contrast is recommended for initial imaging to exclude other conditions 3, 1
• MRI of the spine without IV contrast may be appropriate in certain cases to exclude structural, infectious, or neoplastic etiologies 3, 1
• Complete blood count (CBC) to evaluate for infectious or inflammatory conditions 1
• Blood chemistry profile including glucose, electrolytes, kidney function, and liver enzymes 1
• Thyroid function tests to rule out thyroid disorders that can cause weakness 1
• Vitamin B12, folate, and vitamin E levels to exclude deficiencies 1
• Serum protein electrophoresis to rule out paraproteinemic neuropathies 1
• Anti-ganglioside antibodies to exclude immune-mediated motor neuropathies 1
• Paraneoplastic antibody panel to exclude paraneoplastic syndromes 1
• Anti-acetylcholine receptor and anti-MuSK antibodies to rule out myasthenia gravis 1
• CSF analysis including cell count, protein, glucose, IgG index, oligoclonal bands, and cytology to exclude infectious, inflammatory, or neoplastic causes 1
• Consider genetic testing for ALS-associated genes (e.g., C9orf72, SOD1, FUS, TARDBP), especially in cases with family history 1

Swallowing Evaluation in ALS

• Structured questionnaires (e.g., EAT-10) can help identify patients with unsafe airway protection during swallowing (sensitivity 86%, specificity 76%) 4
• Volume-Viscosity Swallow Test (V-VST) has high sensitivity (92%) and specificity (80%) for detecting dysphagia in ALS patients 5
• Videofluoroscopy is recommended in the clinical evaluation of dysphagia at diagnosis 5

Treatment Approach

• Nutritional support is essential for patients with dysphagia and weight loss 2
• Regular swallowing evaluations (recommended every 3 months) to monitor dysphagia progression 4
• Early referral to palliative services is recommended to establish relationships with staff and address end-of-life issues before communication becomes limited 2

Prognosis

• Mean survival of typical ALS patients is 3-5 years after symptom onset 2
• Only 5-10% of patients live longer than 10 years 2
• Respiratory failure due to respiratory muscle weakness is the most common cause of death 2

Important Considerations

• Support for caregivers is crucial, as they often experience significant burden 2

Dysphagia Screening and Management in Amyotrophic Lateral Sclerosis (ALS)

Screening Tools and Diagnostic Accuracy

• In newly diagnosed ALS patients, the EAT‑10 questionnaire is recommended for initial dysphagia screening; it demonstrates 86 % sensitivity and 76 % specificity for detecting aspiration. (Clinical Nutrition, 2018) 6
• Videofluoroscopic swallow study should be performed at diagnosis to identify early dysphagia signs and silent aspiration in ALS. (Clinical Nutrition, 2018) 7

Comprehensive Clinical Assessment

• A structured clinical examination at ALS diagnosis should evaluate lip closure, saliva pooling, tongue strength and mobility, chewing capacity, palatal movement, cough quality and strength, and phoniatric function to detect subtle swallowing deficits. (Clinical Nutrition, 2018) 6

Follow‑up Frequency and Prognostic Context

• Dysphagia evaluations are advised every 3 months after ALS diagnosis, reflecting a median survival of 18–28 months and a high risk of nutritional compromise in this population. (Clinical Nutrition, 2018) 6

Prevalence of Subclinical Dysphagia

• Even when ALS patients report “normal eating habits” on clinical scales, approximately 66.7 % exhibit swallowing alterations on objective testing. (Clinical Nutrition, 2018) 7

Imaging Strategies for Differentiating ALS from Mimics

Critical Structural Mimics – Cervical Spine Imaging

• Cervical spondylotic myelopathy is the most important structural mimic of ALS because it can produce both upper‑ and lower‑motor‑neuron signs and requires surgical decompression rather than ALS‑directed therapy (American College of Radiology recommendation) 8.
• MRI of the cervical spine without contrast is essential to rule out compressive myelopathy, syrinx, or intramedullary tumors that can masquerade as ALS (American College of Radiology recommendation) 8.
• Spinal cord lesions such as syringomyelia, intramedullary neoplasms, and radiation‑induced myelopathy must be excluded with dedicated spine MRI (American College of Radiology recommendation) 8.

Initial Brain Imaging to Exclude ALS Mimics

• MRI of the brain without contrast is the first‑line study to eliminate structural, demyelinating, and vascular conditions that can mimic ALS (American College of Radiology recommendation) 8.
• T2/FLAIR sequences evaluate corticospinal‑tract hyperintensity in the posterior limb of the internal capsule and cerebral peduncles; presence of these hyperintensities supports an ALS diagnosis (American College of Radiology recommendation) 8.
• T2* (susceptibility‑weighted imaging) detects precentral‑gyrus hypointensity, a finding that is ~86 % sensitive and highly specific for ALS (American College of Radiology recommendation) 8.

Cervical/Thoracic Spine MRI Indications in Suspected ALS

• MRI of the cervical and thoracic spine without contrast should be performed when patients exhibit sensory symptoms, neck or radicular pain, or predominant upper‑extremity weakness (American College of Radiology recommendation) 8.

Strength of evidence: The cited source does not specify a formal evidence grade; recommendations are based on expert consensus from the American College of Radiology.