Association between features of tremor and volumetric analysis of brain magnetic resonance images of patients with essential tremor and idiopathic parkinson's disease

Objective: Determining common and disease-specific structural changes in certain brain regions in Essential Tremor (ET) and Parkinson's Disease (PD) and their relationship with tremor features. Methods: A total of 73 individuals, including 25 ET, 25 PD, and 23 healthy controls (HC), were included in the study. Tremorogenic drug use, cognitive impairment and existence of any other neurological signs were the exclusion criterias. Volumetric analysis results were obtained by using T1-weighted sequences of all participants taken with a 3.0 Tesla MRI scanner. Tremor recordings of 15 ET and 15 PH patients who underwent volumetric analysis were obtained with a triaxial accelerometer from the dorsum of the hand at rest, with the arms extended forward and carrying a 1 kg load in the same position. Results: There was no statistically significant volumetric difference between ET and PH patients and HC. No significant volumetric difference was detected between ET patients and HC in pairwise comparision analyses. In ET patients, tremor analysis results did not correlate with each other, with tremor characteristics or the volume values. There was a significant decrease in bilateral putamen, cerebellum gray matter and right thalamus volumes in PD patients compared to HC. In the tremor analysis, a negative correlation was found between postural tremor (PT) amplitude and frequency and the volumes of the cerebellum and motor cortical areas in PD patients. Discussion: The absence of significant volumetric difference between ET patients and HC suggests that the mechanisms involved in the pathophysiology of ET are not degenerative. The volumetric change seen in PD patients and its correlation with the tremor features support that the basal ganglia act as a possible generator and the cerebellothalamocortical networks act as a modulator in the tremor circuit, and cortical involvement begins at an advanced stage in PD. Keywords: Essential Tremor, Parkinson's Disease, Volumetry, Accelerometry