The relationship between inflammatory markers in cerebrospinal fluid in healthy controls and in patients with severe essential tremor before and after deep brain stimulation

• Essential tremor is the most common movement disorder and the prevalence among individuals over 65 years old reaches 4.6%. • The tremors are most obvious in the hands with difficulties doing tasks as writing, drinking, and using different tools. • The underlying pathophysiology in essential tremor remains controversial. • There are at present two theories for tremor generation: it is an electric disorder or a neurodegenerative disorder. • Inflammatory proteins have gained support in the pathogenesis in several neurodegenerative diseases. The inflammatory mediator Macrophage migration inhibitory factor (MIF) appears to have a role in the modulation of neuroinflammation and neurodegeneration. • Our study displays significant alterations in inflammatory proteins in the cerebrospinal fluid of patients with severe Essential tremor compared to a control group. MIF is significantly increased in our patients supporting evidence that Essential tremor is likely to be a neurodegenerative disorder. Essential tremor (ET) is the most common movement disorder, with a prevalence of approximately 5% in individuals over 65 years old. The pathophysiology behind ET is still largely unknown but emerging evidence indicates that ET can be a neurodegenerative disorder. Our aim in this pilot study was to evaluate alterations in inflammatory cytokines in ET patients undergoing deep brain stimulation (DBS) compared to healthy controls. Ten patients with severe ET were included in this study. Cerebrospinal fluid was analyzed in healthy controls and in ET patients before and after deep brain stimulation. The samples were analyzed with a U-PLEX assay, based on an electrochemiluminescent detection method. Several cytokines were downregulated or upregulated in patients with ET compared to the healthy control group. Interestingly, macrophage migration inhibitory factor (MIF) was one of the significantly upregulated inflammatory mediators. There was no difference in the analyzed cytokines before and after DBS. Inflammatory proteins are altered in patients with ET compared to healthy individuals. The finding of an upregulation of MIF, an interesting cytokine that plays a role in other neurodegenerative disorders, suggests evidence for a neurodegenerative pathophysiology in ET. Inflammatory biomarkers might be promising to be future biomarkers and targets of therapeutics against several neurodegenerative disorders.