Aim: Cardiovascular autonomic and peripheral sensory neuropathy is a known complication of chronic alcoholic and non-alcoholic liver diseases. We aimed to assess the prevalence and risk factors for peripheral sensory nerve and autonomic dysfunction using sensitive methods in patients with primary biliary cirrhosis (PBC).
Methods: Twenty-four AMA M2 positive female patients with clinical, biochemical and histological evidence of PBC and 20 age matched healthy female subjects were studied. Five standard cardiovascular reflex tests and 24-h heart rate variability (HRV) analysis were performed to define autonomic function. Peripheral sensory nerve function on median and peroneal nerves was characterized by current perception threshold (CPT), measured by a neuroselective diagnostic stimulator (Neurotron, Baltimore, MD).
Results: Fourteen of 24 patients (58%) had at least one abnormal cardiovascular reflex test and thirteen (54%) had peripheral sensory neuropathy. Lower heart rate response to deep breathing (P = 0.001), standing (P = 0.03) and Valsalva manoeuvre (P = 0.01), and more profound decrease of blood pressure after standing (P = 0.03) was found in PBC patients than in controls. As a novel finding we proved that both time domain and frequency domain parameters of 24-h HRV were significantly reduced in PBC patients compared to controls. Each patient had at least one abnormal parameter of HRV. Lower CPT values indicated hyperaesthesia as a characteristic feature at peroneal nerve testing at three frequencies (2000 Hz: P = 0.005; 250 Hz: P = 0.002; 5 Hz: P = 0.004) in PBC compared to controls. Correlation of autonomic dysfunction with the severity and duration of the disease was observed. Lower total power of HRV correlated with lower CPT values at median nerve testing at 250 Hz (P = 0.0001) and at 5 Hz (P = 0.002), as well as with those at peroneal nerve testing at 2000 Hz (P = 0.01).
Conclusion: Autonomic and sensory nerve dysfunctions are frequent in PBC. Twenty-four-hour HRV analysis is more sensitive than standard cardiovascular tests for detecting of both parasympathetic and sympathetic impairments. Our novel data suggest that hyperaesthesia is a characteristic feature of peripheral sensory neuropathy and might contribute to itching in PBC. Autonomic dysfunction is related to the duration and severity of PBC.