Tremor after solid organ transplantation: Results from the TransplantLines Biobank and Cohort Study

Abstract

Background and purpose: Tremor is a frequent complaint of solid organ transplant recipients. We report on the largest population investigated with clinical neurophysiological methods. Our aim is to objectively establish the tremor prevalence and syndrome in the largest population of solid organ transplant recipients.

Methods: Tremor was measured in heart, kidney, liver, and lung recipients, using accelerometers during rest, postural, and weight-loaded conditions. The 95th percentile of healthy kidney donors' tremor amplitude was used as the cutoff to determine the presence of tremor in transplant recipients. Tremor frequency, frequency variability, and effect of loading were used to investigate enhanced physiological tremor as the likely tremor syndrome. Impact on activities of daily life was assessed, and correlations with tacrolimus blood levels were investigated.

Results: Tremor was present in 52% of 246 transplant recipients, typically in postural positions. Mean tremor frequency was 6.1 (±2.0) Hz; mean tremor variability was 2.6 (±1.8) Hz. A frequency decrease upon loading was found in 83% of patients with tremor. Sixty-five percent of patients met formal clinical neurophysiological criteria for enhanced physiological tremor. Tremor-related impairment was present in 55% and correlated with tremor amplitude (ρ = 0.23, p ≤ 0.001). In a binominal regression analysis, tacrolimus blood levels were independently associated with tremor prevalence (p = 0.009).

Conclusions: More than half of solid organ transplant recipients experience a tremor that best fits the syndrome of enhanced physiological tremor. This is the first objective study on tremor that has established a better understanding of the neurophysiological mechanisms of tremor in a large population of solid organ transplant recipients.

Keywords: enhanced physiological tremor; solid organ transplantation; tacrolimus; tremor.