Neurodegenerative diseases comprise a large number of disorders with high impact 
on human health. Neurodegenerative processes are caused by various etiological 
factors and differ in their clinical presentation. Neuroinflammation is widely 
discussed as both a cause and a consequence in the manifestation of these 
disorders. The interplay between the two entities is considered as a major 
contributor to the ongoing disease progression. An attentive search and 
implementation of new and reliable markers specific for the processes of 
inflammation and degeneration is still needed. YKL-40 is a secreted glycoprotein 
produced by activated glial cells during neuroinflammation. Neuron-specific 
enolase (NSE), expressed mainly by neuronal cells, is a long-standing marker for 
neuronal damage. The aim of this review is to summarize, clarify, and evaluate 
the potential significance and relationship between YKL-40 and NSE as biomarkers 
in the monitoring and prognosis of a set of neurological diseases, such as 
Alzheimer's disease, Parkinson's disease, Huntington's disease, and multiple 
sclerosis. YKL-40 appears to be a more reliable biomarker in neurological 
diseases than NSE. The more prominent expression pattern of YKL-40 could be 
explained with the more obvious involvement of glial cells in pathological 
processes accompanying each neurodegenerative disease, whereas reduced NSE 
levels are likely related to low metabolic activity and increased death of 
neurons.