Amyotrophic lateral sclerosis

Background

Progressive muscle atrophy/weakness due to degeneration of upper and lower motor neurons
Patients will rarely present to the ED undiagnosed
Likely related to mutated superoxide dismutase (SOD1) gene
Involvement of the anterior horn cells

A man with ALS using a head-mounted laser pointer to comunicate. Note asymetic motor weakness.

Acute respiratory failure
- Predicted by forced VC <25 mL/kg or 50% decrease from normal
Aspiration pneumonia
Trauma related to extremity weakness
Asymmetric weakness without sensory findings with mixed upper and lower motor nerve findings

Neuromuscular weakness
- Upper motor neuron:
  - CVA
  - Hemorrhagic stroke
  - Multiple sclerosis
  - Amyotrophic Lateral Sclerosis (ALS) (UMN & LMN)
- Lower motor neuron:
  - Spinal and bulbar muscular atrophy (Kennedy's syndrome)
- Spinal cord disease:
  - Infection (Epidural abscess)
  - Infarction/ischemia
  - Trauma (Spinal Cord Syndromes)
  - Inflammation (Transverse Myelitis)
  - Degenerative (Spinal muscular atrophy)
  - Tumor
- Peripheral nerve disease:
  - Guillain-Barre syndrome
  - Toxins (Ciguatera)
  - Tick paralysis
  - Diabetic peripheral neuropathy
- NMJ disease:
- Muscle disease:
  - Rhabdomyolysis
  - Dermatomyositis
  - Polymyositis
  - Alcoholic myopathy
Non-neuromuscular weakness
- Can't miss diagnoses:
  - ACS
  - Arrhythmia/Syncope
  - Severe infection/Sepsis
  - Hypoglycemia
  - Periodic paralysis (electrolyte disturbance, K, Mg, Ca)
    - Hypokalemic periodic paralysis
    - Thyrotoxic periodic paralysis
  - Respiratory failure
- Emergent Diagnoses:
  - Symptomatic Anemia
  - Severe dehydration
  - Hypothyroidism
  - Polypharmacy
  - Malignancy
- Other causes of weakness and paralysis
  - Acute intermittent porphyria (ascending weakness)

MRI (axial FLAIR) demonstrates increased T2 signal within the posterior part of the internal capsule, consistent with the diagnosis of ALS.

Nebulized medications
Steroids
Antibiotics for infectious complications
Assisted ventilation / intubation if in respiratory failure and aligned with goals of care

Tintinalli's Emergency Medicine: A Comprehensive Study Guide, 7e (2010), Chapter 167. Chronic Neurologic Disorders

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