The previous understanding of multiple sclerosis was solely related to neuroinflammation and its harmful effects; however, countless data indicate the importance of some inflammation-independent, neurodegenerative mechanisms associated with mitochondria malfunction, iron deposition and oxidative stress. Recently, it has been postulated that glutamate excitotoxicity, a phenomenon that takes place when an excessive amount of glutamate overactivates its cellular receptors and induces cell death, could be a missing link between inflammatory and neurodegenerative processes evident in multiple sclerosis. Glutamate is the major excitatory neurotransmitter of the central nervous system, which has been proven to have a central role in a complex communication network established between all residential brain cells, including neurons, astrocytes, oligodendrocytes and microglia. Thus, the disturbance of glutamate homeostasis could affect practically all physiological functions and interactions of brain cells, leading to heterogeneity of pathological events. The understanding of glutamate excitotoxicity as a valid mechanism of central nervous system damage in multiple sclerosis, requires the revision of the current knowledge about a source of elevated extracellular glutamate, glutamate receptor alterations, alterations of glutamate transporters and metabolizing enzymes, as well as molecular mechanism of excitotoxic damage.

Immunoinflammatory-mediated demyelination, the main pathological feature of multiple sclerosis (MS), is regularly accompanied by neurodegenerative processes, mostly in the form of axonal degeneration, which could be initiated by glutamate excitotoxicity. In the current study, the relationship between Th17-mediated inflammatory and excitotoxic events was investigated during an active phase of MS. Cerebrospinal fluid (CSF) of patients with MS and control subjects was collected, and IL-17A and glutamate levels were determined. IL-17A level was significantly higher in patients with MS; whereas no statistically significant changes in glutamate concentrations were found. There was a direct correlation between IL-17A and glutamate levels; IL-17A levels were also associated with the neutrophil expansion in CSF and blood-brain barrier disruption. However, IL-17A level and the number of neutrophils tended to fall with disease duration. The results suggest that Th17 cells might enhance and use glutamate excitotoxicity as an effector mechanism in the MS pathogenesis. Furthermore, Th17 immune response, as well as neutrophils, could be more important for MS onset rather than further disease development and progression, what could explain why some MS clinical trials, targeting Th17 cells in the later stage of the disease, failed to provide any clinical benefit.

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Diagnostically, it is crucial to recognize this uncommon histological variant because malignant Triton tumor has a worse prognosis than classic malignant peripheral nerve sheath tumor does. The use of the immunohistochemistry is essential in making the correct diagnosis. Only appropriate pathological evaluation supported by immunostaining with S-100 protein and desmin confirmed the diagnosis. Aggressive surgical management treatment improves the prognosis of such cases with adjuvant radiotherapy.