Abstract
Amyotrophic lateral sclerosis (ALS) is a neurodegenerative condition characterized by the progressive degeneration of motor neurons, resulting in muscle weakness and paralysis. The neutrophil-to-lymphocyte ratio (NLR) has emerged as a potential marker for monitoring disease severity and progression in ALS, yet longitudinal analyses of NLR are limited. Our study conducts an in-depth examination of NLR dynamics from before diagnosis through the disease's progression to its end stage. We analyze the case of a 56-year-old Puerto Rican male with ALS, tracking his NLR over 13 years - six years before and seven years after his diagnosis - alongside assessments of clinical symptoms and lung function. Our findings indicate that NLR values were initially normal but significantly increased with the onset of symptoms. NLR remained elevated above the normal range, with a notable exception during a period of edaravone therapy when levels normalized. The study demonstrates a clear elevation in NLR associated with ALS progression and critical clinical events, such as symptom onset, diagnosis, and the initiation of respiratory support. This research is, to our knowledge, the first to provide a detailed characterization of NLR changes from the pre-diagnostic phase to end-stage ALS, showing its correlation with clinical deterioration, decreased pulmonary function, and key clinical events. Our results contribute to the body of evidence on NLR's role in ALS while enhancing our understanding of ALS's natural progression.