Amyotrophic lateral sclerosis causes small fiber pathology

Area of Science:

• Neurology
• Neuroscience
• Pathology

Background:

• Amyotrophic lateral sclerosis (ALS) is a progressive neurodegenerative disease.
• Small fiber neuropathy is a potential comorbidity in neurological disorders.
• The relationship between small fiber loss and ALS progression is not well understood.

Purpose of the Study:

• To investigate the correlation between small fiber loss and amyotrophic lateral sclerosis (ALS).
• To examine the association of small fiber loss with disease onset, phenotype, genotype, duration, severity, and sensory findings in ALS patients.

Main Methods:

• Consecutive patients with suspected ALS were evaluated.
• Sural nerve conduction studies (NCS) and skin biopsies for intraepidermal nerve fiber (IENF) density quantification were performed.
• Genetic analysis and clinical assessments including the ALS Functional Rating Scale-Revised were conducted.

Main Results:

• Reduced IENF density was observed in a majority of ALS patients (75.4%) and facial onset sensory and motor neuronopathy (FOSMN) patients (50%).
• No significant correlation was found between IENF density and ALS onset, phenotype, genotype, disease duration, or severity.
• Sensory disturbances were reported by a subset of ALS and FOSMN patients, with normal sural NCS in most cases.

Conclusions:

• Intraepidermal nerve fiber loss is a prevalent finding in most ALS patients.
• Small fiber loss in ALS does not correlate with disease characteristics and lacks clinical or prognostic utility as a biomarker.