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Amyotrophic Lateral Sclerosis (ALS)

Nicholas Mallett

Background

  • Progressive weakness, often asymmetric and profound with no sensory loss

  • Combination of LMN and UMN findings

    • LMN findings: weakness, flaccidity, absent/decreased reflexes, fasciculations

    • UMN findings: weakness, spasticity, hyperreflexia, pathologic reflexes

  • Bulbar symptoms: dysphagia, increased saliva production (they are not swallowing it), changes in voice

  • Tongue fasciculations are best assessed while tongue rests in mouth and observed for ~30 seconds but can be hard to be certain of (symmetric movements are typically not fasciculations). A light can be helpful, and atrophy if present, can help differentiate from normal movements

  • Pseudobulbar affect (inappropriate laughing or crying) is relatively common in ALS and other neurodegenerative disorders.

  • FVC is an important respiratory marker for function.

Evaluation

  • EMG/NCV is gold standard using the El Escorial or Awaji Criteria for diagnosis

  • Exclude mimicking lesions, which may be treatable (see below)

Management

  • Pts with ALS are ideally treated with a multidisciplinary team of neurologists, pulmonologists, PT, OT, and SLP

  • Given the extensive, specialized care requirements, the Office of Outpt Referral Assistance can assist in getting uninsured pt established with specialists

  • Three medications have been shown to add a few months to survival:

    • Riluzole: PO, requires CBC/LFT monitoring, AE: GI distress and general weakness
    • Edaravone: IV, QD x2weeks every month, AE: headache, bruising
    • Sodium Phenylbutyrate: PO, recently approved by FDA (9/2022), shown to delay ventilator-dependence by ~7 months, AE: GI distress

  • Otherwise, symptomatic management

Mimics of ALS

  • Primary lateral sclerosis: UMN-only disease, less common than ALS with slower progression. Suspected to be on spectrum with ALS.

  • Cervical spine lesions: UMN changes in UE with LMN pattern in LE. MRI can reveal lesion

  • Multifocal motor neuropathy: rare autoimmune disorder with LMN-only signs. Responds to IVIG. Can be anti-GM1 Ab positive. EMG/NCV distinguishes from ALS.

  • Kennedy Disease: X-linked genetic disorder with progressive LMN pattern, endocrine disorders, and androgen-resistance symptoms (gynecomastia, defective spermatogenesis)

  • Inclusion body myositis: Can be asymmetric with grip weakness and quadriceps weakness. Biopsy and atrophy pattern usually distinguishes it. CPK typically runs 500-800.

  • Polymyositis/dermatomyositis: proximal weakness in BUE/BLE, CPK typically runs >1000, usually younger onset (30-40s), no UMN signs.