Singer, Wolfgang

The course of patients with multiple system atrophy (MSA) who undergo deep brain stimulation (DBS) is unclear. In a retrospective review of 1,496 patients with MSA evaluated at our institutions from 1998–2021, 12 patients underwent DBS; 9 had a diagnosis of Parkinson’s disease at the time of surgery. Nine patients reported initial improvement in at least one symptom and 7 experienced overall worsening following DBS. All patients had at least one red flag sign or symptom suggesting atypical parkinsonism prior to surgery. Considering overall poor outcomes of DBS in MSA, we recommend careful consideration of red flags in patient selection.

Injury of the afferent limb of the baroreflex from neck radiation causes radiation-induced afferent baroreflex failure (R-ABF). Identification and management of R-ABF is challenging. We aimed to investigate the pattern of autonomic dysfunction on standardized autonomic testing in patients with probable R-ABF. We retrospectively analyzed all autonomic reflex screens performed at Mayo Clinic in Rochester, MN, between 2000 and 2020 in patients with probable R-ABF. Additional tests reviewed included ambulatory blood pressure monitoring, plasma norepinephrine, and thermoregulatory sweat test. We identified 90 patients with probable R-ABF. Median total composite autonomic severity score (range, 0–10) was 7 (interquartile range, 6–7). Cardiovascular adrenergic impairment was seen in 85 patients (94.4%), increased blood pressure recovery time after Valsalva maneuver in 71 patients (78.9%; median 17.4 seconds), and orthostatic hypotension in 68 patients (75.6%). Cardiovagal impairment was demonstrated by abnormal heart rate responses to deep breathing (79.5%), Valsalva ratio (87.2%), and vagal baroreflex sensitivity (57.9%). Plasma norepinephrine was elevated and rose appropriately upon standing (722–1207 pg/mL). Ambulatory blood pressure monitoring revealed hypertension, postural hypotension, hypertensive surges, tachycardia, and absence of nocturnal dipping. Blood pressure lability correlated with impaired vagal baroreflex function. Postganglionic sympathetic sudomotor function was normal in most cases; the most frequent thermoregulatory sweat test finding was focal neck anhidrosis (78.9%). Standardized autonomic testing in R-ABF demonstrates cardiovascular adrenergic impairment with orthostatic hypotension, blood pressure lability, and elevated plasma norepinephrine. Cardiovagal impairment is common, while sudomotor deficits are limited to direct radiation effects.

Objective To explore the role of alpha‐synuclein (αSyn) oligomers and neurofilament light chain (NfL) in cerebrospinal fluid (CSF) of patients with pure autonomic failure (PAF) as markers of future phenoconversion to multiple system atrophy (MSA). Methods Well‐characterized patients with PAF (n = 32) were enrolled between June 2016 and February 2019 at Mayo Clinic Rochester and followed prospectively with annual visits to determine future phenoconversion to MSA, Parkinson's disease (PD), or dementia with Lewy bodies (DLB). ELISA was utilized to measure NfL and protein misfolding cyclic amplification (PMCA) to detect αSyn oligomers in CSF collected at baseline. Results Patients were followed for a median of 3.9 years. Five patients converted to MSA, 2 to PD, and 2 to DLB. NfL at baseline was elevated only in patients who later developed MSA, perfectly separating those from future PD and DLB converters as well as non‐converters. ASyn‐PMCA was positive in all but two cases (94%). The PMCA reaction was markedly different in five samples with maximum fluorescence and reaction kinetics previously described in MSA patients; all of these patients later developed MSA. Interpretation αSyn‐PMCA is almost invariably positive in the CSF of patients with PAF establishing this condition as α‐synucleinopathy. Both NfL and the magnitude and reaction kinetics of αSyn PMCA faithfully predict which PAF patients will eventually phenoconvert to MSA. This finding has important implications not only for prognostication, but also for future trials of disease modifying therapies, allowing for differentiation of MSA from Lewy body synucleinopathies before motor symptoms develop. ANN NEUROL 2021;89:1212–1220

Abstract Study Objectives Multiple system atrophy (MSA) is associated with disturbances in cardiovascular, sleep and respiratory control. The lateral paragigantocellular nucleus (LPGi) in the ventrolateral medulla (VLM) contains GABAergic neurons that participate in control of rapid eye movement (REM) sleep and cardiovagal responses. We sought to determine whether there was loss of putative GABAergic neurons in the LPGi and adjacent regions in MSA. Methods Sections of the medulla were processed for GAD65/67 immunoreactivity in eight subjects with clinical and neuropathological diagnosis of MSA and in six control subjects. These putative GABAergic LPGi neurons were mapped based on their relationship to adjacent monoaminergic VLM groups. Results There were markedly decreased numbers of GAD-immunoreactive neurons in the LPGi and adjacent VLM regions in MSA. Conclusions There is loss of GABAergic neurons in the VLM, including the LPGi in patients with MSA. Whereas these findings provide a possible mechanistic substrate, given the few cases included, further studies are necessary to determine whether they contribute to REM sleep-related cardiovagal and possibly respiratory dysregulation in MSA.

ObjectiveTo explore the role of alpha‐synuclein (αSyn) oligomers and neurofilament light chain (NFL) in cerebrospinal fluid (CSF) as markers of early multiple system atrophy (MSA) and to contrast findings with Lewy body synucleinopathies.MethodsIn a discovery cohort of well‐characterized early MSA patients (n = 24) and matched healthy controls (CON, n = 14), we utilized enzyme‐linked immunosorbent assay to measure NFL and protein misfolding cyclic amplification (PMCA) to detect αSyn oligomers in CSF. We confirmed findings in a separate prospectively enrolled cohort of patients with early MSA (n = 38), Parkinson disease (PD, n = 16), and dementia with Lewy bodies (DLB, n = 13), and CON subjects (n = 15).ResultsIn the discovery cohort, NFL was markedly elevated in MSA patients, with perfect separation from CON. αSyn‐PMCA was nonreactive in all CON, whereas all MSA samples were positive. In the confirmatory cohort, NFL again perfectly separated MSA from CON, and was significantly lower in PD and DLB compared to MSA. PMCA was again nonreactive in all CON, and positive in all but 2 MSA cases. All PD and all but 2 DLB samples were also positive for αSyn aggregates but with markedly different reaction kinetics from MSA; aggregation occurred later, but maximum fluorescence was higher, allowing for perfect separation of reactive samples between MSA and Lewy body synucleinopathies.InterpretationNFL and αSyn oligomers in CSF faithfully differentiate early MSA not only from CON but also from Lewy body synucleinopathies. The findings support the role of these markers as diagnostic biomarkers, and have important implications for understanding pathophysiologic mechanisms underlying the synucleinopathies. ANN NEUROL 2020;88:503–512

Abstract Introduction REM-sleep behavior disorder (RBD) is a common finding among patients with synucleinopathies. We aimed to determine the degree of autonomic dysfunction in patients presenting with idiopathic RBD (iRBD), and the predictive value of autonomic dysfunction for phenoconversion to a defined neurodegenerative disease. Methods We searched our electronic medical record for patients diagnosed with iRBD who also underwent standardized autonomic function testing within 6 months of iRBD diagnosis, and who had clinical follow-up of at least 3 years following iRBD diagnosis. Patients who received a diagnosis of phenoconversion within 3 months of autonomic testing were excluded. The composite autonomic severity score (CASS) was derived and compared between phenoconverters and non-converters using chi-square and Wilcoxon rank-sum tests. Results We identified 18 patients who fulfilled in- and exclusion criteria. Average age at autonomic testing was 67 ± 6.6 years. Twelve (67%) patients phenoconverted during the follow-up period; 6 developed PD, the other 6 DLB. Fifteen (83%) patients had at least mild autonomic dysfunction. There were no significant differences between overall converters and non-converters in total CASS or CASS subscores. However, iRBD patients who developed DLB had significantly higher total and cardiovagal CASS scores compared with those who developed PD (p <0.05), and a trend for higher adrenergic CASS scores compared to those who developed PD and those who did not phenoconvert (p=0.08 for each). Conclusion Autonomic dysfunction was seen in 83% of iRBD patients, and more severe baseline cardiovagal and adrenergic autonomic dysfunction in iRBD was associated with phenoconversion to DLB but not PD. Prospective studies are needed to confirm the value of autonomic testing for predicting phenoconversion and disease phenotype in iRBD. Support

Abstract Background Multiple system atrophy (MSA) is a neurodegenerative disorder from α‐synuclein aggregation. in vitro studies suggest vitamin B12 may interrupt α‐synuclein‐mediated neurodegeneration. The objective of this study was to determine whether serum vitamin B12 level at MSA diagnosis is associated with survival. Methods One hundred eighty‐two MSA patients evaluated at Mayo Clinic with vitamin B12 testing were studied. We determined the risk of death in relationship to serum vitamin B12 levels at MSA diagnosis, adjusting for predictors of poor survival. Results Predictors of shorter survival included vitamin B12 < 367 ng/L (HR, 1.8; 95% CI, 1.3–2.7), falls within 3 years of MSA diagnosis (HR, 1.6; 95% CI, 1.1–2.3), bladder symptoms (HR, 1.6; 95% CI, 1.0–2.6), urinary catheter requirement (HR, 1.7; 95% CI, 1.0–2.8), male sex (HR, 1.4; 95% CI, 1.0–2.0), and MSA‐P subtype (HR, 1.5; 95% CI, 1.0–2.0). Conclusions Low vitamin B12 levels are associated with shorter survival in MSA. Additional studies to explore this observation and assess the potential role of vitamin B12 as a modifiable survival factor are needed. © 2020 International Parkinson and Movement Disorder Society

AbstractBackgroundThe relationship between cardiovascular and gastrointestinal (ie, plasma pancreatic polypeptide [PP] response to modified sham feeding [MSF]) indices of vagal function is unclear. Hyperglycemia inhibits PP secretion via vagally mediated mechanisms. Our aims were to (a) compare the PP response, (b) its relationship with glycemia, and (c) the relationship between PP response to MSF, gastric emptying (GE) of solids, and symptoms during GE study in healthy controls, patients with diabetic gastroenteropathy (DM), and non‐ulcer dyspepsia (NUD).MethodsIn 24 healthy controls, 40 DM, and 40 NUD patients, we measured plasma PP concentrations during MSF, cardiovagal functions, GE, and symptoms during a GE study.Key ResultsBaseline PP concentrations were higher in DM than in controls and NUD (P = .01), and in type 2 than in type 1 DM patients (P < .01). The PP increment during MSF was normal (≥20 pg/mL) in 70% of controls, 54% of DM, and 47% of NUD patients. Overall, the PP response and cardiovagal tests were concordant (P = .01). Among patients with a reduced PP increment with MSF, 7/10 of T1DM and 1/7 of T2DM patients had moderate or severe cardiovagal dysfunctions (P < .05). The PP response to MSF was not associated with GE.Conclusions & InferencesUp to 30% of healthy controls have a reduced PP increment during MSF, limiting the utility of this test to detect vagal injury. The PP response is more useful when it is normal than abnormal. A reduced PP response is more likely to be associated with cardiovagal dysfunctions in T1DM than in T2DM.