Objective tests for upper motor neuron involvement in amyotrophic lateral sclerosis (ALS).

Area of Science:

• Neurology
• Neuroscience
• Biomarkers

Background:

• Amyotrophic lateral sclerosis (ALS) is a progressive neurodegenerative disease affecting motor neurons.
• Accurate diagnosis and monitoring of upper motor neuron (UMN) involvement are crucial for ALS management.
• Objective biomarkers are needed to supplement clinical assessment in ALS.

Purpose of the Study:

• To evaluate the diagnostic value of single-voxel MR spectroscopy (MRS) and transcranial magnetic stimulation (TMS) for detecting UMN involvement in ALS patients.
• To determine the sensitivity and specificity of MRS and TMS in identifying UMN signs.
• To explore the correlation between MRS findings and clinical UMN signs.

Main Methods:

• Analysis of MRS and/or TMS test results from 164 ALS patients.
• Inclusion of 11 autopsy examinations for pathological correlation.
• Categorization of patients based on clinical signs (UMN involvement or solely LMN signs).

Main Results:

• Abnormal MRS and TMS results consistent with UMN involvement were observed in a high percentage of patients with clinical UMN signs.
• MRS showed higher sensitivity (86%) compared to TMS (77%) in detecting UMN involvement.
• Abnormal N-acetyl aspartate/creatine ratios on MRS significantly correlated with the degree of UMN signs (p = 0.01).

Conclusions:

• MRS is a highly sensitive tool for detecting UMN involvement in ALS, outperforming TMS.
• Combining MRS and TMS, with further refinement, may enhance early ALS diagnosis.
• Pathological UMN abnormalities were confirmed at autopsy, even in cases with normal in-life MRS or TMS findings.