Multiple orofacial indices in amyotrophic lateral sclerosis

Area of Science:

• Neurology
• Speech-Language Pathology

Background:

• Amyotrophic lateral sclerosis (ALS) is a neurodegenerative disease impacting motor neurons, leading to progressive muscle weakness.
• Orofacial muscle weakness, affecting speech and swallowing, is a hallmark of ALS, but its functional significance and relation to motor neuron loss remain unclear.

Purpose of the Study:

• To investigate the relationship between specific orofacial muscle strength measures and speech dysfunction in early-stage ALS.
• To determine if static (maximum voluntary contraction - MVC) and dynamic (peak rate of change of force - PRCF) measures, alongside upper motor neuron (UMN) index and functional disability score (FDS), enhance understanding of ALS-related speech impairment.

Main Methods:

• Studied ten males with sporadic ALS and mild speech impairment, compared to ten matched controls.
• Assessed tongue, lip, and jaw MVC and PRCF, UMN index, and FDS in participants.

Main Results:

• Tongue MVC and PRCF were significantly more impaired than lip and jaw measures in ALS patients.
• Disproportionate tongue impairment may be linked to UMN deficits, though contraction rate impairments were not.
• Tongue weakness and specific PRCF measures correlated with speech severity, but not speech intelligibility.

Conclusions:

• Orofacial muscle strength measures, especially for the tongue, are valuable in characterizing early ALS bulbar impairment.
• While muscle weakness relates to speech severity, speech intelligibility may not be a reliable early indicator of orofacial involvement in ALS.