Bradykinesia in minimal hepatic encephalopathy is due to disturbances in movement initiation

Background: One of the predominant symptoms of early stages of hepatic encephalopathy (HE) is bradykinesia. Aims: To further analyze the pathophysiology of bradykinesia in HE. Methods: A three-dimensional computer-assisted movement analysis was performed in 36 cirrhotics with grade 0–I HE compared to 18 controls selected with regard to sex and age and 16 patients with Parkinsonʹs disease (PD). Four types of movement were studied: finger tapping, hand tapping, pronation/supination of the forearm and flexion/extension in the hip joint. Results: The patients with PD presented with a decrease of the maximal movement velocity (VMAX) and a prolongation of the time needed to reach VMAX (VTIME). In patients with minimal or grade I HE, the VMAX of all movements was unchanged compared to controls while the VTIME was significantly prolonged. This was caused by a delay before the beginning of each new part of the diadochokinetic movement cycle. Conclusions: The data suggest an impairment of movement initiation as main cause of bradykinesia in early HE.