Sympathetic neural outflow directly recorded in patients with primary autonomic failure: clinical observations, microneurography, and histopathology

We evaluated 2 patients with primary autonomic failure, without clinical peripheral neuropathy. One had primary autonomic failure alone (PAF), and the other had autonomic failure and multiple system atrophy (MSA). Direct intraneural recordings demonstrated a marked reduction of sympathetic efferent nerve impulse activity in the PAF patient. The patient with MSA had spontaneous bursts of sympathetic nerve impulses that confirmed the functional integrity of post-ganglionic sympathetic efferent neurons. Neurosecretory activity of these neurons correlated with the electrophysiologic findings. The PAF patient had markedly reduced supine norepinephrine (NE) levels that did not rise upon standing. The supine NE level in the MSA patient was normal. Morphometric study of biopsied sural nerve in the MSA patient showed that unmyelinated fibers were normal, whereas the nerve of the PAF patient showed clear evidence of past degeneration. We suggest that the primary preganglionic sympathetic defect in MSA releases viable postganglionic sympathetic efferents from central control. Decentralized postganglionic elements may fire spontaneously, thus activating peripheral effectors and providing potentially useful signs and symptoms for differential diagnosis.     

Antibody in the CSF of patients with multiple system atrophy reacts specifically with rat locus ceruleus.

Idiopathic chronic autonomic dysfunction may occur as pure autonomic failure (PAF) or in association with multiple system atrophy (MSA). CSF immunoreactivity to rat locus ceruleus occurred in a significantly greater number of samples from MSA patients compared to control subjects or patients with PAF. Other brain regions infrequently showed immunoreactivity. These findings suggest that degeneration in MSA may release antigen(s) that induce antibodies against locus ceruleus neurons. Further studies are required to determine whether immune abnormalities play a pathogenetic role in MSA. Lack of CSF immunoreactivity in PAF is consistent with primarily peripheral involvement.     

Multiple system atrophy. Clinical aspects, pathophysiology, and treatment

Progressive autonomic failure is a clinical syndrome of autonomic dysfunction that may occur in isolation as in idiopathic orthostatic hypotension (IOH) or in association with a central neurologic disorder, multiple system atrophy (MSA). MSA and IOH can be distinguished on the basis of biochemical and pharmacologic tests. Plasma norepinephrine levels are low in IOH and normal in MSA; neither group increases the plasma norepinephrine level adequately in response to postural change. Both MSA and IOH manifest an exaggerated pressor response to administered norepinephrine. However, only patients with IOH have true adrenergic receptor supersensitivity. The autonomic dysfunction in IOH primarily involves the peripheral autonomic neurons whereas the defect in MSA is the failure to activate appropriately an intact distal sympathetic nervous system. Neuropathologic studies reveal a multisystem degeneration in MSA; the few postmortem examinations of the central nervous system in IOH reveal lesions confined to the intermediolateral columns of the spinal cord. Orthostatic hypotension may be treated with a number of medications although supine hypertension limits the usefulness of these drugs. Further development and testing of a sympathetic neural prosthesis may help to resolve this therapeutic dilemma. Only the parkinsonian features in MSA respond to treatment with anticholinergic drugs.     

Cerebrovascular pathology and misdiagnosis of multiple system atrophy: An autopsy study

BackgroundMultiple system atrophy (MSA) is a progressive neurodegenerative disease characterized by a combination of dysautonomia, parkinsonism, and cerebellar ataxia. Other disorders can mimic MSA, but it is unknown whether cerebrovascular pathology, so-called “vascular parkinsonism,” can mimic MSA. This study aimed to determine the clinicopathological features and red flags for vascular parkinsonism masquerading as MSA.MethodsUsing a brain bank database, we screened 270 patients with an antemortem diagnosis of MSA, who did not have pathologic evidence of MSA, but rather cerebrovascular pathology, including leukoencephalopathy, lacunar infarcts, and microinfarcts. Histologic sections from the neocortex, basal ganglia, thalamus, brainstem, and cerebellum were reviewed. Medical records were reviewed to characterize the clinical features. The probability of a clinical diagnosis of MSA was assigned retrospectively, guided by current consensus criteria.ResultsFour patients had cerebrovascular pathology without neurodegenerative processes. Chronic ischemic changes in periventricular white matter, subcortical leukoencephalopathy, lacunar infarcts, or microinfarcts were detected in basal ganglia of all patients. Cerebrovascular pathology that might contribute to autonomic failure was not identified. Clinically, two patients were diagnosed with possible MSA-parkinsonism, one with probable MSA-parkinsonism, and one with possible MSA-cerebellar type; however, they also had one or more non-supporting features of MSA (e.g., onset >75-years of age, dementia), vascular risk factors, and other etiologies (e.g., autonomic neuropathy) that could cause autonomic failure.ConclusionsWhen combined with cerebrovascular risk factors and comorbidities, cerebrovascular pathology may masquerade as MSA. The important lesson from this study is that the diagnosis of MSA requires exclusion of other causes, including cerebrovascular disease.     

Modelling progressive autonomic failure in MSA: where are we now?

Multiple system atrophy (MSA) is a fatal late-onset α-synucleinopathy that presents with features of ataxia, Parkinsonism, and pyramidal dysfunction in any combination. Over the last decade, efforts have been made to develop preclinical MSA testbeds for novel interventional strategies. The main focus has been on murine analogues of MSA-linked motor features and their underlying brainstem, cerebellar and basal ganglia pathology. Although progressive autonomic failure (AF) is a prominent clinical feature of patients with MSA, reflecting a disruption of both central and peripheral autonomic networks controlling cardiovascular, respiratory, urogenital, gastrointestinal and sudomotor functions, attempts of modelling this aspect of the human disease have been limited. However, emerging evidence suggests that AF-like features may occur in transgenic MSA models reflecting α-synucleinopathy lesions in distributed autonomic networks. Further research is needed to fully characterize both autonomic and motor features in optimized preclinical MSA models.     

Autonomic nervous system testing may not distinguish multiple system atrophy from Parkinson's disease

BACKGROUND: Formal laboratory testing of autonomic function is reported to distinguish between patients with Parkinson's disease and those with multiple system atrophy (MSA), but such studies segregate patients according to clinical criteria that select those with autonomic dysfunction for the MSA category. OBJECTIVE: To characterise the profiles of autonomic disturbances in patients in whom the diagnosis of Parkinson's disease or MSA used criteria other than autonomic dysfunction. METHODS: 47 patients with parkinsonism and autonomic symptoms who had undergone autonomic laboratory testing were identified and their case records reviewed for non-autonomic features. They were classified clinically into three diagnostic groups: Parkinson's disease (19), MSA (14), and uncertain (14). The performance of the patients with Parkinson's disease was compared with that of the MSA patients on five autonomic tests: RR variation on deep breathing, heart rate changes with the Valsalva manoeuvre, tilt table testing, the sudomotor axon reflex test, and thermoregulatory sweat testing. RESULTS: None of the tests distinguished one group from the other with any statistical significance, alone or in combination. Parkinson's disease and MSA patients showed similar patterns of autonomic dysfunction on formal testing of cardiac sympathetic and parasympathetic, vasomotor, and central and peripheral sudomotor functions. CONCLUSIONS: This study supports the clinical observation that Parkinson's disease is often indistinguishable from MSA when it involves the autonomic nervous system. The clinical combination of parkinsonism and dysautonomia is as likely to be caused by Parkinson's disease as by MSA. Current clinical criteria for Parkinson's disease and MSA that direct patients with dysautonomia into the MSA group may be inappropriate.     

Central and peripheral effects of arecoline in patients with autonomic failure.

Increased plasma adrenalin (A) levels following arecoline in normal subjects and patients with multiple system atrophy (MSA) may result from nicotinic adrenal stimulation. Lack of this response in patients with pure autonomic failure (PAF) is consistent with peripheral sympathetic dysfunction. The mechanisms underlying diminished plasma corticotropin (ACTH) responses to arecoline may differ in patients with autonomic failure. Hypothalamic, cholinergic degeneration could prevent the response in MSA whereas patients with PAF do not manifest the normal increase in A which may be required to elicit an ACTH response. The appearance and exacerbation of tremor, vertigo, and pathological affect in the MSA group suggest that some central cholinergic receptors remain functional.     

Evolution of sporadic olivopontocerebellar atrophy into multiple system atrophy

OBJECTIVE: To determine the percentage of sporadic olivopontocerebellar atrophy (sOPCA) patients who later develop multiple system atrophy (MSA). METHODS: Observations of the course of 51 sOPCA patients 20 years of age or older initially evaluated in an ataxia clinic over 14 years and followed at 3- to 6-month intervals for 3 months to 10 years (median 2.5 years, interquartile range 5 months to 4 years). RESULTS: Seventeen patients evolved to develop MSA, whereas the remaining 34 manifested only progressively worsening cerebellar ataxia. The features of the MSA cases included autonomic failure and parkinsonism in 10 patients, autonomic failure without parkinsonism in six, and parkinsonism without autonomic failure in one. Using survival analysis methods, the authors estimated that 24% of subjects in this population will evolve to MSA within 5 years of the onset of sOPCA symptoms (95% CI 10% to 36%). An older age at onset of symptoms and a shorter time from onset of symptoms to first presentation in a neurology specialty clinic were both highly predictive of evolution to MSA. Six of the 17 patients who evolved to MSA died 4 months to 5 years after they had met diagnostic criteria for MSA. The estimated median survival time from time of transition was 3.5 years. In contrast, death occurred in only one of the 34 patients with sOPCA who did not evolve to MSA. Autopsy examination of all six patients with MSA who died confirmed the diagnosis. CONCLUSIONS: Approximately one-fourth of sporadic olivopontocerebellar atrophy patients will evolve to multiple system atrophy within 5 years, and this transition carries a poor prognosis for survival. Older age at onset of ataxia and earlier presentation in a neurologic specialty clinic predicted transition to MSA.     

Somatic and autonomic function in progressive autonomic failure and multiple system atrophy

We studied 62 consecutive patients with progressive autonomic failure (PAF) or multiple system atrophy (MSA) (26 PAF; 36 MSA). Patients were well matched in age (67 vs 66 years), duration (39 vs 36 months), and severity of autonomic failure (median values for PAF and MSA). Peripheral somatic neuropathy occurred in 2 patients with PAF and 7 patients with MSA. Postganglionic sudomotor and vasomotor functions were studied using the quantitative sudomotor axon reflex test and supine plasma norepinephrine. The extent and severity of autonomic failure were assessed by the thermoregulatory sweat test, by heart rate responses to deep breathing and the Valsalva maneuver, and by blood pressure recordings. Severe and widespread anhidrosis was found in both PAF and MSA patients. Postganglionic sudomotor failure occurred at the forearm in 50% each of PAF and MSA patients and at the foot in 69% and 66% of PAF and MSA patients, respectively. However, postganglionic sudomotor function was preserved in some patients with anhidrosis on thermoregulatory sweat test, indicating a preganglionic lesion. Vagal abnormalities were found in 77% and 81% of PAF and MSA patients. Supine plasma free norepinephrine values were significantly reduced in PAF (p less than 0.001), but not in MSA, patients. Standing plasma norepinephrine values were reduced in both PAF (p less than 0.001) and MSA (p less than 0.001) patients. We conclude the following: (1) PAF is characterized by combined postganglionic sudomotor and adrenergic failure. (2) MSA is associated with a similar frequency of postganglionic sudomotor failure, but postganglionic adrenergic denervation was uncommon. (3) Preganglionic neuron is also involved in both disorders, but more severely in MSA. (4) Somatic neuropathy may occur.     

Clinical studies of autonomic function and dysfunction

A discussion of progressive autonomic failure in man. This is one of the few neurological diseases disrupting cardiovascular function. Both central and peripheral pathways are involved. Means of diagnosing defects in autonomic reactions are described. Abnormalities in responses due to multiple system atrophy (MSA) are discussed most extensively.     

Functional imaging with positron emission tomography in multiple system atrophy

Summary. Although the current guidelines for the clinical diagnosis of multiple system atrophy (MSA) do not require structural or functional brain imaging, investigations utilizing positron emission tomography (PET) have been helpful diagnostically in differentiating between MSA and primary autonomic failure; idiopathic Parkinson’s disease; and sporadic olivopontocerebellar atrophy. These investigations have demonstrated different patterns of cerebral glucose utilization and of nigrostriatal projection abnormalities among these disorders and between the cerebellar and parkinsonian forms of MSA. Most of the studies have focused upon patients with well-established disease and none have examined the utility of PET imaging in early stage patients with follow-up of clinical course and autopsy verification to ensure accuracy of diagnosis and to determine the sensitivity and specificity of PET techniques for diagnosis. Recent PET studies have revealed denervation of myocardial post-ganglionic sympathetic neurons in some MSA patients, indicating that this disorder can affect the peripheral autonomic as well as the central nervous system. Investigations utilizing ligands to quantify central nervous system dopaminergic and cholinergic terminals have begun to provide insight into the neurochemical disorders that may underlie two of the sleep disturbances common in MSA, rapid eye movement sleep behavior disorder and obstructive sleep apnea.     

Hereditary neuropathy with upper motor-neuron, visual pathway, and autonomic disorders

A 42-year-old man had progressive distal weakness and muscle atrophy, stocking-type sensory loss, upper motor-neuron and visual pathway lesions, and dysautonomia. Electrodiagnostic tests revealed a generalized sensorimotor peripheral neuropathy that largely involved axons. Low recumbent and upright norepinephrine levels implied a peripheral autonomic defect. Sural nerve biopsy showed mild abnormalities of medium and small size fibers. The patient's mother and two brothers were also affected. Other causes of peripheral motor, sensory, and autonomic failure were eliminated. This kinship does not fit any generally accepted classification of hereditary neuropathies.     

The nature of the autonomic dysfunction in multiple system atrophy

The concept that multiple system atrophy (MSA, Shy-Drager syndrome) is a disorder of the autonomic nervous system is several decades old. While there has been renewed interest in the movement disorder associated with MSA, two recent consensus statements confirm the centrality of the autonomic disorder to the diagnosis. Here, we reexamine the autonomic pathophysiology in MSA. Whereas MSA is often thought of as “autonomic failure”, new evidence indicates substantial persistence of functioning sympathetic and parasympathetic nerves even in clinically advanced disease. These findings help explain some of the previously poorly understood features of MSA. Recognition that MSA entails persistent, constitutive autonomic tone requires a significant revision of our concepts of its diagnosis and therapy. We will review recent evidence bearing on autonomic tone in MSA and discuss their therapeutic implications, particularly in terms of the possible development of a bionic baroreflex for better control of blood pressure.     

Neuropathology of multiple system atrophy: New thoughts about pathogenesis

Multiple system atrophy (MSA) is a fatal adult‐onset neurodegenerative disorder of uncertain etiology, clinically manifesting with autonomic failure associated with parkinsonism, cerebellar dysfunction, and pyramidal signs in variable combination. The pathological process affects central autonomic, striatonigral, and olivopontocerebellar systems. These show varying degrees of neurodegeneration and underlie the stratification of the heterogenous disorder into MSA‐P and MSA‐C clinical variants, which correlate to the morphologic phenotypes of striatonigral degeneration and olivopontocerebellar atrophy (MSA‐C). The lesions are not limited to these most consistently and severely affected systems but may involve many other parts of the central, peripheral, and autonomic nervous systems, underpinning the multisystem character of MSA. The histological core feature are glial cytoplasmic inclusions (GCIs, Papp‐Lantos bodies) in all types of oligodendroglia that contain aggregates of misfolded α‐Synuclein (α‐Syn). In addition to the ectopic appearance of α‐Syn in oligodendrocytes and other cells, oxidative stress, proteasomal and mitochondrial dysfunction, excitotoxiciy, neuroinflammation, metabolic changes, and energy failure are important contributors to the pathogenesis of MSA, as shown by various neurotoxic and transgenic animal models. Although the basic mechanisms of α‐Syn–triggered neurodegeneration are not completely understood, neuron‐to‐oligodendrocyte transfer of α‐Syn by prion‐like spreading, inducing oligodendroglial and myelin dysfunction associated with chronic neuroinflammation, are suggested finally to lead to a system‐specific pattern of neurodegeneration. © 2014 International Parkinson and Movement Disorder Society     

Non-motor multiple system atrophy associated with sudden death: pathological observations of autonomic nuclei

Multiple system atrophy (MSA) manifests as a combination of dysautonomia and motor symptoms/signs. However, rare cases presenting with autonomic failures in absence of motor symptoms/signs until their deaths have been reported and are referred to as non-motor MSA. To clarify pathological findings underlying non-motor MSA patients, we analyzed consecutively autopsied 161 patients with MSA. In results, four patients were identified as having non-motor MSA, who showed isolated autonomic disorders throughout their lives and had minimal pathological changes in the motor systems. We also identified two patients with pathologically minimal MSA, who had minimal pathological involvement in the motor systems and presented with definite parkinsonism and dysautonomia. Survival durations of the non-motor MSA patients were much shorter (1.3–2.0 years) than those of the classical MSA patients (3.0–7.0 years), and the causes of death were all sudden death. The medullary serotonergic neurons were severely involved in the non-motor MSA patients in comparison with the classical MSA patients. Also, one of the pathologically minimal MSA patients had died suddenly and exhibited marked involvement of the medullary serotonergic neurons. The involvement of the medullary catecholaminergic or cholinergic neurons did not differ in severities among the groups. We conclude that non-motor MSA may be a pathological variant of MSA that preferentially involves the medullary serotonergic neurons and autonomic systems in association with poor prognosis.     

Assessment of cardiovascular autonomic dysfunction in multiple system atrophy

Because heart rate is controlled mainly by the autonomic nervous system, cardiovascular autonimic dysfunction may contribute to the prognosis of patients with multiple system atrophy (MSA). To clarify cardiovascular autonomic dysfunctions in MSA, the authors investigated the relation between blood pressure (BP) and pulse rate (PR), and assessed a power spectral analysis of heart rate variability (HRV) during the clinical course using ambulatory BP and a heart rate monitor for 24 hours. The authors studied seven patients with MSA (five men and two women, aged 61.0±5.8 years) and seven healthy volunteers (four men and three women, aged 58.0±6.6 years) without hypertension, heart disease, or intracranial lesions. The MSA group showed abnormal circadian variations of BP and PR and a significantly decreased correlation coefficient between BP and PR. A significant decrease and altered circadian variation also existed in the number of changes in successive R-R intervals greater than 50 msec (RR50) and in the power of the high- and low-frequency component of HRV. The authors observed a significant negative correlation between the duration of illness and the number of changes in successive R-R intervals greater than 50 msec. The characteristic dysautonomia in MSA was a decrease in sympathetic and parasympathetic activity, with an abnormal circadian rhythm of BP and HRV. The balance between sympathetic and parasympathetic activity was also impaired. The parasympathetic modulation represented by RR50 worsened according to the development of the illness. Those autonomic dysfunctions may have affected the cardiovascular systems, which may indicate a poor prognosis in patients with MSA. An analysis of HRV and the circadian rhythm of BP and HRV are useful in evaluating cardiac autonomic dysfunctions in MSA.     

Autonomic dysfunction in different subtypes of multiple system atrophy

Multiple system atrophy (MSA) can clinically be divided into the cerebellar (MSA‐C) and the parkinsonian (MSA‐P) variant. However, till now, it is unknown whether autonomic dysfunction in these two entities differs regarding severity and profile. We compared the pattern of autonomic dysfunction in 12 patients with MSA‐C and 26 with MSA‐P in comparison with 27 age‐ and sex‐matched healthy controls using a standard battery of autonomic function tests and a structured anamnesis of the autonomic nervous system. MSA‐P patients complained significantly more often about the symptoms of autonomic dysfunctions than MSA‐C patients, especially regarding vasomotor, secretomotor, and gastrointestinal subsystems. However, regarding cardiovascular, sudomotor pupil, urogenital, and sleep subsystems, there were no significant quantitative or qualitative differences as analyzed by autonomic anamnesis and testing. Our results suggest that there are only minor differences in the pattern of autonomic dysfunction between the two clinical MSA phenotypes. © 2008 Movement Disorder Society     

Assessment of the Scopa-Aut questionnaire in multiple system atrophy: relation to UMSARS scores and progression over time

Autonomic failure is a key feature of multiple system atrophy (MSA). Moreover, early autonomic failure is an independent predictive factor for rapid disease progression and shorter survival. The assessment of autonomic failure is therefore important for both, the diagnosis and prognosis of MSA. Here, we evaluate autonomic dysfunction in MSA patients by the Scopa-Aut questionnaire. Potential associations between the Scopa-Aut questionnaire and established markers of disease progression - that is the Unified MSA Rating Scale (UMSARS) - were further assessed. The results confirm early and prominent autonomic failure in MSA patients. Relative scores were highest for the sexual and urinary subdomains. Surprisingly, relative scores in the cardiovascular subdomain were lowest suggesting that the Scopa-Aut questionnaire is suboptimal for the screening and evaluation of cardiovascular symptoms in MSA. A multivariate regression showed an association between total Scopa-Aut and UMSARS I scores. No significant changes in Scopa-Aut scores were observed during follow-up except for the urinary subdomain, while UMSARS I, II and IV scores significantly increased over time. In conclusion, Scopa-Aut can be used as a simple auto-questionnaire for the screening of autonomic symptoms in multiple system atrophy. It seems not useful as endpoint for disease-modification or neuroprotection trials.     

The pathophysiology and diagnosis of orthostatic hypotension

Orthostatic Hypotension (OH) is a common manifestation of blood pressure dysregulation. OH takes a heavy toll on quality of life. It has many potential etiologies, and many effects of aging can increase susceptibility to OH. Neurological disorders are especially likely to cause severe OH. In this brief review, the pathogenesis of OH is considered, particularly in terms of autonomic neuropathy, multiple system atrophy (MSA), pure autonomic failure, baroreflex failure, and dopamine beta hydroxylase deficiency. While OH is difficult to treat, its control greatly enhances the quality of life.     

Morphological substrate of autonomic failure and neurohormonal dysfunction in multiple system atrophy: impact on determining phenotype spectrum

Autonomic failure is a prominent clinical feature of patients with multiple system atrophy (MSA). Neurohormonal dysfunction is also a frequent accompaniment in patients with MSA. The determination of the pathological involvement of the autonomic neurons, which are responsible for circadian rhythms and responses to stress, provides new insight into autonomic failure and neurohormonal dysfunction in MSA. The disruptions of circadian rhythms and responses to stress may underlie the impairment of homeostatic integration responsible for cardiovascular and respiratory failures. These notions lead to the hypothesis that a pathological involvement of autonomic neurons is a significant factor of the poor prognosis of MSA. Beyond this perspective, endeavors to find the morphological phenotype that represents a predominant loss of autonomic neurons may elucidate the full spectrum of pathological involvements in MSA.