ALS can be defined as a neurological, progressive and degenerative disease that progresses with the depletion of upper and lower motor neurons. For the general population, it is a disease that affects the neurons of the spinal cord and brain. The course of the disease, until the present moment, is inexorable, with survival ranging from 2-8 years after the onset of symptoms.

ALS can be defined as a neurological, progressive and degenerative disease that progresses with the depletion of upper and lower motor neurons. For the general population, it is a disease that affects the neurons of the spinal cord and brain. The course of the disease, until the present moment, is inexorable, with survival ranging from 2-8 years after the onset of symptoms.

In most cases (about 80%), the diagnosis is clinical, with associated involvement of these two populations of neurons. In others, neurologists need complementary tests to support the diagnosis - electroneuromyography, neuroimaging and laboratory tests (blood). In a few cases, withdrawal of spinal cord fluid (liquor) may be necessary. In suspected genetic cases, DNA extraction is performed, with approximately more than 66 mutations already described.

The use of light and heavy chain neurofilaments in the blood and CSF of patients with ALS is currently emerging. In addition to better managing the quality of life, survival and mishaps of the disease, we will introduce the patients early in randomized controlled clinical studies, double blind in several research centers, which can effectively change the catastrophic evolution of ALS. Reliable and robust biomarkers to accelerate ALS diagnosis and provide a means to monitor disease progression is what we need to bring hope and disease control.

More than 90% of the cell volume of the neuron is taken up by the axons and their building blocks: cytoskeleton (composed of three main structural components: Microtubules (the largest component of them), (Intermediate filaments), Microfilaments (the smallest component) and the intermediates - “neurofilaments” - these have already been captured as objects of several studies. These are subdivided into 4 units: Neurofilaments of light, medium and heavy chains and α-internexin in the central nervous system or peripherin in the peripheral nervous system.

In ALS patients, in addition to the death of motor neurons, there is massive destruction of axons. These die earlier. a fact already proven in biopsies containing motor neurons (the axons are found in large numbers and degraded in the areas surrounding the lesion). When axons begin to die (earlier than neurons), a very high concentration of neurofilaments is dumped into the blood and cerebrospinal fluid.

“The time for neurofilaments as a disease biomarker is not yet ripe - that's science's candid answer !” Patients who have a clinical diagnosis of ALS, in comparison with “healthy” individuals or with other diseases, but deeper studies are still needed, seeking the reliability of serum measurements in relation to CSF measurements, in addition to standardization of analytical methods. These biomarkers have diagnostic value in diferentiating ALS from clinically relevant ALS mimics. Plasma NFL levels can be used to diferentiate between clinical and genetic ALS subgroups. Other disorders also show an increase in neurofilaments in CSF and blood.

These discussion opens a window for a better understanding of the potentially heterogeneous pathogenetic processes underlying the different disease phenotypes.

In conclusion, biomarkers for the diagnosis of motoneuron diseases (MND) are urgently needed to improve the diagnostic pathway, patient stratification and monitoring.