Vagal cross-sectional area correlates with parasympathetic dysfunction in Parkinson's disease

Abstract

The aim of this prospective study was to investigate autonomic function in Parkinson’s disease with a multidimensional approach including clinical evaluation tools, head-up tilt test and morphological studies of the vagus nerve. Head-up tilt test parameters including high frequency power of the heart frequency interval, the ratio of low frequency power of the distance between two consecutive R waves in electrocardiogram (RR interval) to the high frequency and low frequency power of systolic blood pressure were used to evaluate parasympathetic, cardiac sympathetic and vasomotor sympathetic functions, respectively in 80 patients with Parkinson´s disease. We examined the cross-sectional area of the vagus nerves bilaterally using nerve ultrasound and compared mean values with a control group of healthy subjects (n=40) as well as patients with chronic inflammatory demyelinating polyneuropathy (n= 76). The cross-sectional area of right/left vagus nerve of Parkinson´s patients was significantly lower compared to the right/left vagus nerve of the control group and of chronic demyelinating polyneuropathy patients. Furthermore, the cross-sectional area of the right vagus nerve was significantly larger from the one of the left vagus nerve for all groups. Based on tilt test, 43 patients (disease duration 7 ± 5, age at evaluation 71 ± 9, Hoehn & Yahr score 2.8 ± 8) were diagnosed with autonomic dysfunction (orthostatic hypertension n=11, chronotropic incompetence n=31, postural orthostatic tachycardia syndrome n=1). Patients with orthostatic hypotension showed significantly higher Unified Parkinson’s Disease Rating Scale-III values than those with chronotropic incompetence. The cross-sectional-area of the vagus nerve correlated inversely with heart rate in rest and supine position and positively with tilt test parameters representing parasympathetic modulation through vagal activity (high frequency power of the distance between two consecutive R waves in electrocardiogram (RR-Interval)) at rest. We demonstrate for the first time that morphological characteristics of the vagus nerve correlate with parameters of parasympathetic function from the spectral analysis of cardiovascular parameters in tilt test for Parkinson´s patients. This correlation reveals the impact of the atrophy of vagal atrophy for autonomic function in Parkinson´s disease. Nerve ultrasound of the vagus nerve could potentially be used as an adjunct to tilt table examination to diagnose autonomic dysfunction.

Ultrasonic detection of vagus, accessory, and phrenic nerve atrophy in amyotrophic lateral sclerosis: Relation to impairment and mortality

“…Parkinson disease [20,41]. Taken together, these findings support the view that predominantly somatomotor nerve fibers of cranial nerves degenerate in ALS.…”

“…Another study that involved patients with a wider range of ALS duration (up to 84 months) demonstrated a negative correlation of VN CSA with ALS duration, and positive correlation with ALSFRS‐R score, but no association with autonomic function measures [10]. In contrast, ultrasonic VN atrophy correlated with parasympathetic cardiovascular dysfunction in patients with Parkinson disease [20, 41]. Taken together, these findings support the view that predominantly somatomotor nerve fibers of cranial nerves degenerate in ALS.…”

Nerve ultrasound for the diagnosis and follow-up of peripheral neuropathies

“…The CSA increase of the vagus nerve in GBS patients also provides a crucial sonological marker, which correlates with autonomic dysfunction and improves after disease [11]. Currently, studies on the correlation of the vagal autonomic function in tilt-test and sonographical findings for patients with extrapyramidal disorders are emerging showing a reduction of the nerve CSA correlating with autonomic dysfunction [49 ▪ ].…”

Unveiling the Journey from the Gut to the Brain: Decoding Neurodegeneration–Gut Connection in Parkinson’s Disease

“…This strongly correlates to a putative reason for increased neurotoxic forms of astrocytes in both the gut and the brain of PD patients, and astrogliosis is strongly correlated to α-syn aggregation and consequently dopaminergic cell death. − Thus, in popular notion, it can be said that microbial alterations, their products, and a resultant increase in intestinal inflammation contribute to retrograde transfer of products and abnormal aggregates of α-syn via the vagus nerve to the brain and the spread of pathology in the brain (see Figure ), thus strongly cementing the concept of gut-to-brain communication in PD. To much disarray, it is a debatable topic whether the cross-sectional area of the vagus nerve changes in PD; ultrasound of the vagus nerve was considered to be a diagnostic tool to assess autonomic changes in PD . However, some studies have expressed the opposite view that there are no diagnosable changes in the vagus nerve in PD patients .…”

“…To much disarray, it is a debatable topic whether the cross-sectional area of the vagus nerve changes in PD; ultrasound of the vagus nerve was considered to be a diagnostic tool to assess autonomic changes in PD. 134 However, some studies have expressed the opposite view that there are no diagnosable changes in the vagus nerve in PD patients. 135 Nevertheless, vagal nerve stimulation (VNS) has borne positive fruits in terms of PD patient functional outcomes; noninvasive stimulation of the vagus nerve in the cervical region caused recovery of the subthalamic beta activity in patients.…”