Clinical Autonomic Research最新文献

Purpose: We compared locus coeruleus (LC) structural integrity, as measured by neuromelanin-sensitive magnetic resonance imaging (NM-MRI), between patients with Parkinson's disease (PD) and those with multiple system atrophy (MSA) and tested whether orthostatic hypotension (OH) impacted differences in LC volume between PD and MSA. Substantia nigra (SNc) volumes were compared between these groups to determine whether effects observed in LC were specific to that structure. Last, we tested whether LC integrity is associated with orthostatic hemodynamic responses.

Methods: Presence or absence of (±)OH was determined with active stand testing. Automated segmentation of LC and SNc volumes took place using NM-MRI. Structural volumes were first compared between PD and MSA groups and, second, after stratification by OH status. Last, correlations between LC volumes and orthostatic vitals were calculated.

Results: Of 71 patients with PD, 19 were (+)OH. Of 19 patients with MSA, 12 were (+)OH. LC volumes were larger in PD than MSA (p = 0.002), and LC volumes in PD(-)OH were larger than PD(+)OH and MSA(±)OH (p < 0.05). All comparisons involving SNc were nonsignificant. Primarily in PD(-)OH, LC volumes correlated negatively with supine mean arterial pressure (MAP) and positively with supine heart rate. In PD(+OH) and MSA(+)OH, lower LC volumes were correlated with greater orthostatic falls in MAP.

Conclusions: Similar levels of LC neurodegeneration were observed in PD(+)OH and MSA(±)OH. Therefore, LC measurement may be useful to differentiate PD(-)OH from MSA. Lower LC volumes additionally correlated with greater drops in MAP in both PD(+)OH and MSA(+)OH, suggesting that LC neurodegeneration may contribute to OH in both conditions.

Purpose: Despite the central role of exercise in treating postural orthostatic tachycardia syndrome (POTS) there have been no studies on the subjective experience of exercise interventions and/or recommendations among this patient population. The purpose of this mixed-methods study was to provide greater understanding of the perceived barriers, preferences, perceptions of exercise, and experiences implementing exercise recommendations for adults with POTS in order to optimize treatment recommendations and intervention design.

Methods: This study consisted of a series of focus groups (n = 29) and an online survey of adults with POTS (n = 255) focusing on exercise engagement, beliefs, barriers, and facilitators. Qualitative data were analyzed using an iterative inductive-deductive approach, informed by social cognitive theory, which resulted in a conceptual framework and a series of themes.

Results: Survey results showed that participants reported a wide range of exercise frequency prior to the onset of POTS symptoms, and overall lower exercise engagement post-POTS. In both survey results and qualitative findings, participants reported believing that exercise is important in managing POTS, but identified barriers to exercise training, including most saliently, their symptom burden. Participants also identified important needs and facilitating factors that could support them in engaging in regular exercise to help manage their condition.

Conclusion: These findings shed light on the patient experience of exercise in POTS, which can inform both the tailoring of exercise recommendations and the design of interventions to support exercise engagement specific to the POTS population.

Purpose: Establish the minimally clinically important difference (MCID) for the Orthostatic Hypotension Questionnaire (OHQ).

Background: Neurogenic orthostatic hypotension (nOH) causes disabling symptoms that impair daily function and quality of life. The OHQ is a validated patient-reported outcome with a symptom assessment (OHSA) and daily activity scale (OHDAS), widely used in clinical trials, despite the MCID being unestablished.

Methods: We analyzed data from two phase 3, randomized placebo-controlled trials (SEQUOIA and REDWOOD), evaluating ampreloxetine for symptomatic nOH in patients with Parkinson disease, multiple system atrophy, and pure autonomic failure. Using anchor-based and distribution-based methods, we calculated the MCID for the total OHQ score, OHSA and OHDAS composite subscales, and for the single dizziness/lightheadedness question (OHSA1).

Results: The analysis included 184 subjects from SEQUOIA and 128 from REDWOOD. The total OHQ MCID for improvement was a reduction of 0.9-1.2 points and for worsening was an increase of 0.7-1.1 points. The MCID for the OHSA composite ranged from a reduction of 0.9-1.3 points for improvement and an increase of 0.7-1.1 points for worsening. For the single-item OHSA1, the MCID was a reduction of 2.0-3.0 points for improvement and an increase of 1.0 point for worsening. Owing to poor correlation with the symptom-based anchors, a reliable MCID for the OHDAS component was not established.

Conclusions: These MCID thresholds for the OHQ, OHSA and OHSA item 1 alone, enhance the interpretability of scores and support their use in evaluating clinical benefit.

Background and objective: The association between blood pressure variability (BPV) or heart rate variability (HRV) and the baroreflex is well established. However, the role of the vestibular-autonomic reflex in regulating BP and HR stability has primarily been explored only in experimental studies. We aimed to delineate the association of BPV and HRV with otolith function in postural orthostatic tachycardia syndrome (POTS).

Methods: We retrospectively analyzed data from consecutive patients with POTS recruited between April 2021 and April 2025 at a tertiary referral-based hospital in South Korea. All patients underwent a head-up tilt table test using a Finometer^® device and cervical (cVEMP) and ocular vestibular evoked-myogenic potentials (oVEMP). The Finometer data were analyzed using a power spectral analysis. The Finometer, cVEMP, and oVEMP data were compared with those of 32 age- and sex-matched healthy participants.

Results: A total of 47 patients with POTS (mean age $\pm$ standard deviation [SD] = 33 $\pm$ 10 years; 30 female patients) and 32 age- and sex-matched healthy participants were included for analysis. The n1-p1 amplitude of oVEMP was larger in patients with POTS than in healthy participants (p = 0.002). p13 latency was negatively correlated with the SD of heart rate in the supine position in patients with POTS (p = 0.001), a trend not observed in healthy participants. The n1-p1 amplitude (odds ratio [95% confidence interval] = 1.27 [1.08-1.49], p = 0.004) and root mean square of successive differences (RMSSD) during tilting (0.82 [0.72-0.93], p = 0.001) were associated with POTS after adjusting for other covariates.

Conclusions: Otolithic function may play a role in accentuating BPV and HRV in POTS by contributing to enhanced sympathetic outflow.

Purpose: Spontaneous indices have been widely used to assess baroreflex gain despite their numerous limitations and concerns regarding their validity, reliability, and reproducibility. In this retrospective study, we investigated whether spontaneous baroreflex indices reflect cardiovagal baroreflex gain assessed by the neck-chamber technique in those with spinal cord injury (SCI) and in uninjured individuals. SCI represents a model of preserved cardiovagal baroreflex control coupled with impaired sympathetic effects on the vasculature.

Methods: We derived three spontaneous indices of baroreflex sensitivity (sequence method, low-frequency (LF), and high-frequency (HF) transfer function) and compared them with baroreflex gain obtained via the neck-chamber technique in adults with SCI (n = 29; neurological level C1-T10, ≤ 2 years since injury) and uninjured adults (n = 14).

Results: In both groups, spontaneous indices were highly correlated with each other (all p < 0.01). In uninjured participants, neck suction baroreflex gain did not relate to any spontaneous index. In individuals with SCI, neck-chamber gain correlated significantly with spontaneous indices (all r > 0.43, p < 0.05); these relationships were significantly stronger in individuals with neurologically complete injuries (sequence: r = 0.67, p < 0.01; LF: r = 0.79, p < 0.001; HF: r = 0.76, p < 0.001). However, Bland-Altman analysis revealed a strong proportional bias, with spontaneous indices consistently and progressively overestimating neck-chamber gain (all r > 0.91, p < 0.001).

Conclusions: These results suggest that sympathetic activity is largely responsible for the lack of correspondence between spontaneous and neck-chamber baroreflex gains. However, even in individuals with a neurologically complete SCI, where sympathetic influences are minimal, spontaneous indices may not consistently reflect baroreflex gain derived from other methods.