Sleep disturbances in essential tremor: an investigation of associated brain microstructural changes using diffusion tensor imaging

Essential tremor (ET) is a complex, neurodegenerative disorder that includes motor and non-motor symptoms. There is growing interest in its non-motor features, including sleep disturbances (SD). There are no studies evaluating the brain structural correlates of SD in ET. We aimed to identify brain microstructural changes related to SD in ET. SD was evaluated using the Pittsburg sleep quality index (PSQI). Diffusion tensor imaging (DTI), with reported measures being fractional anisotropy (FA) and apparent diffusion coefficient (ADC), was used to evaluate microstructural brain changes. DTI data were compared in ET patients with vs. without SD. The mean age of 40 ET patients was 49.20 ± 21.06 years. The mean PSQI score was 6.13 ± 3.99, and 18 (45.0%) patients had SD. The mean PSQI score of patients with vs. without SD was 9.78 ± 2.98 vs. 3.14 ± 1.28 (p < 0.001). Patients with vs. without SD differed significantly with respect to several DTI findings: right (R) superior cerebellar peduncle ADC (p = 0.04), left (L) dorsolateral prefrontal cortex FA (p < 0.01), L frontooccipital fasciculus FA (p = 0.02), R posterior corona radiata (RPCR) FA (p = 0.01), L posterior corona radiata FA (p = 0.04), R posterior thalamic radiation (RPTR) FA (p = 0.02), and fornix FA (p = 0.03) Significant correlations between PSQI scores and RPCR FA (r = − 0.50, p = 0.02) and RPTR FA (r = − 0.67, p = 0.001) were also observed. Our findings suggest that certain brain changes may be associated with the clinical expression of SD in ET. These changes are discussed in terms of their possible neuroanatomical and physiological significance.