Intermuscular coherence as a candidate biomarker for primary lateral sclerosis

Area of Science:

• Neurophysiology
• Biomarker Discovery
• Neuromuscular Disorders

Background:

• Upper motor neuron (UMN) dysfunction requires reliable and accessible neurophysiological biomarkers.
• Primary Lateral Sclerosis (PLS) is a rare UMN disease lacking definitive diagnostic markers.

Purpose of the Study:

• To investigate intermuscular coherence in the beta-gamma frequency range (IMCβγ) and its imaginary component (ICOHβγ) as potential biomarkers for PLS.
• To assess the diagnostic accuracy of IMCβγ and ICOHβγ in differentiating PLS patients from neurotypical controls.

Main Methods:

• IMCβγ and ICOHβγ were measured in upper and lower limb muscle pairs of 21 PLS patients and 42 controls.
• Clinical evaluations included deep tendon reflex assessment and manual muscle strength testing.
• Receiver operating characteristic (ROC) curve analysis was used to determine diagnostic performance.

Main Results:

• IMCβγ and ICOHβγ were significantly reduced in PLS patients compared to controls in both arms and legs.
• ROC analysis showed areas under the curve ranging from 0.71 to 0.77 for single-limb measurements.
• A diagnostic test using abnormal coherence in any two limbs achieved 0.76 sensitivity, 0.86 specificity, and 0.83 accuracy for PLS.

Conclusions:

• IMCβγ in arms and ICOHβγ in legs effectively distinguish PLS patients from neurotypical individuals.
• These coherence measures demonstrate potential as accessible biomarkers for UMN dysfunction in PLS.
• Further validation may establish IMCβγ and ICOHβγ as valuable tools in diagnosing and monitoring PLS.