Evaluation of Relationship Between Laboratory, Electrodiagnostic, and Functional Parameters in Patients With Amyotrophic Lateral Sclerosis; A Cross Sectional Study

Background: Amyotrophic lateral sclerosis (ALS) is an adult-onset motor neuron disease which leads to limb and/or bulbar muscle degeneration with a poor prognosis. Several demographic and biological factors have prognostic importance, but little data exist on the relationship between clinical, electrodiagnostic, and laboratory markers as predictors of disease progression. We aimed to assess the relationships between different aspects of clinical, electrodiagnostic, and laboratory features of ALS patients with their level of functioning. Methods: We included 27 patients with ALS who were diagnosed within two years before enrolment. Clinical assessment and electrodiagnostic studies were done by a neurology resident. The motor unit number index (MUNIX) and compound motor action potential (CMAP) were used as measures of motor unit loss. Serum creatinine, urea, Albumin, and creatine kinase were measured as laboratory markers. We used the Persian version of ALS functional rating scale (ALS-FRS) as the main outcome measure. Data were analyzed using the SPSS software. Pearson's correlation coefficient was calculated to test for correlations. Results: None of the demographic or laboratory parameters correlated with ALS-FRS. Patients with the onset of disease in the limbs had a higher MUNIX score compared to patients with a bulbar onset. Also, increased body mass index was associated with lower CMAP and MUNIX scores (p-value:0.02). Higher serum creatinine levels were significantly associated with higher lower limb MUNIX (p value:0.04). Higher lower limb MUNIX was in turn associated with higher lower limb functional score (ALS-FRS). Conclusion: Decreased serum creatinine may possibly be an indicator of lower limb motor unit loss in patients with ALS. Also, MUNIX scores may be used as surrogates for ALS-FRS in ALS trials. Further research is needed to elucidate the clinical application of these findings.Methods: We included 27 patients with ALS who were diagnosed within two years before enrolment. Clinical assessment and electrodiagnostic studies were done by a neurology resident. The motor unit number index (MUNIX) and compound motor action potential (CMAP) were used as measures of motor unit loss. Serum creatinine, urea, Albumin, and creatine kinase were measured as laboratory markers. We used the Persian version of ALS functional rating scale (ALS-FRS) as the main outcome measure. Data were analyzed using the SPSS software. Pearson's correlation coefficient was calculated to test for correlations. Results: None of the demographic or laboratory parameters correlated with ALS-FRS. Patients with the onset of disease in the limbs had a higher MUNIX score compared to patients with a bulbar onset. Also, increased body mass index was associated with lower CMAP and MUNIX scores (p-value:0.02). Higher serum creatinine levels were significantly associated with higher lower limb MUNIX (p value:0.04). Higher lower limb MUNIX was in turn associated with higher lower limb functional score (ALS-FRS). Conclusion: Decreased serum creatinine may possibly be an indicator of lower limb motor unit loss in patients with ALS. Also, MUNIX scores may be used as surrogates for ALS-FRS in ALS trials. Further research is needed to elucidate the clinical application of these findings.