Objective: We aim to investigate the relationship between sonographic abnormalities of the substantia nigra, vagus nerve cross-sectional area and clinical features of PD in different stages.

Background: Both transcranial sonography (TCS) of the substantia nigra (SN) and sonography of the vagus nerve (VN) have been suggested to be useful for the diagnosis of Parkinson’s disease (PD). TCS shows an increased echogenic size of the substantia nigra, known as substantia nigra hyperechogenicity (SNH), in 90% of patients with a PD diagnosis. Vagus nerve nuclei, especially the dorsal motor nucleus, show neuronal loss even in early stages of PD.

Method: Aged subjects were screened for parkinsonian symptoms through the Tanner questionnaire (Tanner et al, 2012), then evaluated for parkinsonian syndromes by a neurologist specialized in movement disorders. Twenty people positive for parkinsonian syndromes (PD+), and eight age-matched controls (C) were evaluated for REM-sleep Behavior Disorder (RBD), tilt-test, evacuation frequency, and MDS-UPDRS III, then submitted to TCS and VN sonography. PD+ and C were aged 68,8±7 and 68,3±5,5 years, respectively. PD+ group was subdivided into probable PD (n=2), subtle parkinsonism (n=4), established PD (n=2), subtle parkinsonism+RBD (n=7), and RBD (n=6).

Results: 4PD+ and 3C had absent temporal window for TCS. Total mesencephalic areas were 4,86±0,5cm² PD+ and 5,02±1,3cm² C. One patient with established PD showed SN hyperechogenicity of 0,88cm². The VN areas were of 0,02±0,0066cm² PD+ and 0,0271±0,0049cm² C. Most individuals with NV areas under 0,02cm² were positive for tilt test (decrease in systolic BP ≥20 mmHg and/or diastolic BP ≥10 mmHg from supine to upright position). Evacuation frequency of PD+ and C was 5,47±1,9 and 6,5±1,06 times/week. UPDRS III was of 1,47±1,4 PD+ and 0,37±0,7 C.

Conclusion: These preliminary data point to a possible relation between VN transactional area and autonomic changes in PD, and SNH was observed in established PD but not in other stages. Further investigations are needed to investigate if these methods could be useful for general application in the diagnosis of PD.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/transcranial-sonography-of-the-substantia-nigra-and-vagus-nerve-ultrasonography-as-complementary-diagnosis-for-parkinsons-disease/