How are fasciculations in Amyotrophic Lateral Sclerosis (ALS) managed?

Management of Fasciculations in Amyotrophic Lateral Sclerosis (ALS)

Fasciculations in ALS are a diagnostic hallmark but do not require specific treatment beyond the management of the underlying disease with riluzole, which is the only FDA-approved medication shown to extend survival in ALS patients.

Characteristics of Fasciculations in ALS

• Fasciculations are spontaneous discharges of entire motor units originating from the motor neuron or along the axon, presenting with an irregular pattern that sounds like "raindrops on a tin roof" 1
• Fasciculations are a nearly universal feature in people with ALS but have diagnostic rather than prognostic utility in patient care 2
• In early ALS, fasciculations tend to be more stable and can often be voluntarily recruited, while in later stages they become more unstable, complex, and less likely to be voluntarily recruited 3
• The frequency of fasciculations increases as limb strength deteriorates, particularly when physical activity is maintained 2
• Complex fasciculations, especially "combined fasciculations" (consisting of two or more components that occur both independently and in combination), are distinctive in ALS and may reflect dysfunction of descending motor pathways 4

Assessment of Fasciculations

• Fasciculations can be detected through clinical observation, surface electromyography, or high-density surface EMG (HDSEMG) 5
• Videofluoroscopy is recommended in the clinical evaluation of dysphagia in ALS patients at diagnosis, which can help identify fasciculations affecting bulbar musculature 1
• When evaluating fasciculations, it's important to differentiate them from "contraction fasciculation," which is a remnant of large voluntary motor unit potentials 6
• The key distinguishing feature of true fasciculations is their low-frequency and irregular firing pattern, often showing clustering of discharges 6

Management Approaches

• There is no specific treatment for fasciculations in ALS; management focuses on the underlying disease 1, 7
• Riluzole (50 mg twice daily) is indicated for the treatment of ALS and has been shown to extend survival by approximately 60-90 days in clinical trials 8
• Although riluzole improves survival, it does not show benefits on measures of muscle strength or neurological function, including fasciculations 8
• For patients with bulbar-onset ALS where fasciculations affect swallowing:
  • Videofluoroscopy study is recommended to detect early signs of dysphagia 1
  • Dietetic counseling should focus on adapting food texture to facilitate swallowing 1
  • Postural maneuvers such as chin-tuck posture can help protect the airway during swallowing 1

Monitoring and Follow-up

• Regular screening for malnutrition (BMI, weight loss) is recommended at diagnosis and every 3 months during follow-up 1
• Weight loss >5-10% of habitual weight is associated with decreased survival in ALS patients 1
• For patients with bulbar symptoms affecting swallowing, regular assessment using tools like the Volume-Viscosity Swallow Test (V-VST) may be considered 9
• Monitoring for respiratory complications is essential, as respiratory failure is a common cause of mortality in ALS 9

Common Pitfalls and Caveats

• Fasciculation frequency alone cannot predict disease duration or progression in ALS 2
• Do not confuse benign fasciculations (which have high firing rates and normal morphologic parameters) with the more complex and unstable fasciculations seen in ALS 3
• In weak muscles in ALS, fasciculations are generally more unstable than in other neurogenic disorders 3
• When evaluating a patient with fasciculations, remember that they arise proximally early in ALS and distally in later stages of the disease 3