Unveiling autonomic failure in synucleinopathies: Significance in diagnosis and treatment.

Autonomic failure is frequently encountered in synucleinopathies such as multiple system atrophy (MSA), Parkinson's disease (PD), Lewy body disease, and pure autonomic failure (PAF). Cardiovascular autonomic failure affects quality of life and can be life threatening due to the risk of falls and the increased incidence of myocardial infarction, stroke, and heart failure. In PD and PAF, pathogenic involvement is mainly post-ganglionic, while in MSA, the involvement is mainly pre-ganglionic. Cardiovascular tests exploring the autonomic nervous system (ANS) are based on the analysis of continuous, non-invasive recordings of heart rate and digital blood pressure (BP). They assess facets of sympathetic and parasympathetic activities and provide indications on the integrity of the baroreflex arc. The tilt test is widely used in clinical practice. It can be combined with catecholamine level measurement and analysis of baroreflex activity and cardiac variability for a detailed analysis of cardiovascular damage. MIBG myocardial scintigraphy is the most sensitive test for early detection of autonomic dysfunction. It provides a useful measure of post-ganglionic sympathetic fiber integrity and function and is therefore an effective tool for distinguishing PD from other parkinsonian syndromes such as MSA. Autonomic cardiovascular investigations differentiate between certain parkinsonian syndromes that would otherwise be difficult to segregate, particularly in the early stages of the disease. Exploring autonomic failure by gathering information about residual sympathetic tone, low plasma norepinephrine levels, and supine hypertension can guide therapeutic management of orthostatic hypotension (OH).

An overview on pure autonomic failure.

Pure autonomic failure (PAF) is a neurodegenerative disease affecting the sympathetic component of the autonomic nervous system and presenting as orthostatic hypotension (OH). It is a rare, sporadic disease of adults. Although OH is the primary symptom, the autonomic dysfunction may be more generalised, leading to genitourinary and intestinal dysfunction and sweating disorders. Autonomic symptoms in PAF may be similar to those observed in other autonomic neuropathies that need to be ruled out. PAF belongs to the group of α synucleinopathies and is characterised by predominant peripheral deposition of α-synuclein in autonomic ganglia and nerves. However, in a significant number of cases, PAF may convert into another synucleinopathy with central nervous system involvement with varying prognosis: Parkinson's disease (PD), multiple system atrophy (MSA), or dementia with Lewy bodies (DLB). The clinical features, the main differential diagnoses, the risk factors for "phenoconversion" to another synucleinopathy as well as an overview of treatment will be discussed.

Pure Autonomic Failure: A Case Report of Recurrent Orthostatic Hypotension.

Pure autonomic failure is a neurodegenerative disorder affecting the autonomic nervous system which clinically presents with orthostatic hypotension. It is a diagnosis of exclusion after detailed clinical examinations and relevant investigations. Here, we discuss a case of 68 years old male who had complaints of multiple episodes of loss of consciousness on standing from a sitting position for the last 3 years. The diagnosis was considered by clinical examinations revealing autonomic dysfunctions with normal appropriate investigations. The patient was treated successfully with midodrine, fludrocortisone, and other non-pharmacological interventions. We focused on doing various autonomic dysfunction tests in the evaluation of a patient with recurrent orthostatic hypotension. We suspect that pure autonomic failure might not have been considered in the differential diagnosis of recurrent orthostatic hypotension and suggest that it is to be kept as a differential in such a scenario. Midodrine has an effective role in syncope due to sympathetic vasoconstrictor failure.

Pure Autonomic Failure.

Pure autonomic failure (PAF) is a neurodegenerative disorder of the autonomic nervous system clinically characterized by orthostatic hypotension. The disorder has also been known as Bradbury-Eggleston syndrome, named for the authors of the 1925 seminal description. Patients typically present in midlife or later with orthostatic hypotension or syncope. Autonomic failure may also manifest as genitourinary, bowel, and thermoregulatory dysfunction. With widespread involvement, patients may present to a variety of different specialties and require multidisciplinary treatment approaches. Pathologically, PAF is characterized by predominantly peripheral deposition of α-synuclein. However, patients with PAF may progress into other synucleinopathies with central nervous system involvement.

Diagnosis of multiple system atrophy.

Multiple system atrophy (MSA) may be difficult to distinguish clinically from other disorders, particularly in the early stages of the disease. An autonomic-only presentation can be indistinguishable from pure autonomic failure. Patients presenting with parkinsonism may be misdiagnosed as having Parkinson disease. Patients presenting with the cerebellar phenotype of MSA can mimic other adult-onset ataxias due to alcohol, chemotherapeutic agents, lead, lithium, and toluene, or vitamin E deficiency, as well as paraneoplastic, autoimmune, or genetic ataxias. A careful medical history and meticulous neurological examination remain the cornerstone for the accurate diagnosis of MSA. Ancillary investigations are helpful to support the diagnosis, rule out potential mimics, and define therapeutic strategies. This review summarizes diagnostic investigations useful in the differential diagnosis of patients with suspected MSA. Currently used techniques include structural and functional brain imaging, cardiac sympathetic imaging, cardiovascular autonomic testing, olfactory testing, sleep study, urological evaluation, and dysphagia and cognitive assessments. Despite advances in the diagnostic tools for MSA in recent years and the availability of consensus criteria for clinical diagnosis, the diagnostic accuracy of MSA remains sub-optimal. As other diagnostic tools emerge, including skin biopsy, retinal biomarkers, blood and cerebrospinal fluid biomarkers, and advanced genetic testing, a more accurate and earlier recognition of MSA should be possible, even in the prodromal stages. This has important implications as misdiagnosis can result in inappropriate treatment, patient and family distress, and erroneous eligibility for clinical trials of disease-modifying drugs.

Symptomatic therapy of multiple system atrophy.

Multiple system atrophy is a progressive neurodegenerative disease characterized by the association of autonomic failure and a movement disorder that consist of either a hypokinetic movement disorder or a cerebellar syndrome or both. In addition to these core characteristics other movement disorders (e.g. dystonia, myoclonus, spasticity), and neuropsychiatric symptoms (e.g. depression, cognitive dysfunction) may occur in the course of the disease and can severely impair patients' quality of live. To date no causal therapy is available and therefore symptomatic treatment plays a pivotal role in patient care. In this article we provide an overview of frequent clinical symptoms and their symptomatic treatment options.

Pure autonomic failure.

Pure autonomic failure is a degenerative disorder of the peripheral autonomic nervous system. Patients experience symptomatic hypotension that requires them to sit, squat or lie down to prevent syncope. It is associated with characteristic histopathological findings, resulting in neuronal cytoplasmic inclusions in the peripheral autonomic nerves. These lesions are responsible for defects in the synthesis and release of norepinephrine from sympathetic nerve terminals, resulting in significant hypotension. Patients with autonomic failure also have exaggerated blood pressure responses to common stimuli such as food or fluid intake, heat, exercise and medications. Tilt table (head-up) testing is probably the test most commonly used to establish the diagnosis. However, simple office testing is also useful, such as having the patient stand after lying supine with blood pressure monitoring. Treatment options range from simply increasing fluid and salt intake, and using compressive garments, to medications administered orally, subcutaneously or intravenously in more severe cases.

Is ambulatory blood pressure monitoring useful in patients with chronic autonomic failure?

Management of blood pressure (BP) abnormalities in patients with autonomic failure is usually based on office BP readings. It is uncertain, whether office readings reflect actual BP's [corrected] during a typical day. Therefore, in 45 patients with autonomic failure, we compared office BP values during a tilt test with those captured on a 24-h BP [corrected] ambulatory monitor. Office BP values while supine predicted well the level of nighttime hypertension. However, in only 33% of patients, office values during tilt test accurately reflected hypotension during a typical day. Therefore, BP [corrected] ambulatory monitoring is useful to gauge the true severity of hypotension in patients with autonomic failure.

Limelight on alpha-synuclein: pathological and mechanistic implications in neurodegeneration.

The pathogenesis of many neurodegenerative disorders arises in association with the misfolding and accumulation of a wide variety of proteins. Much emphasis has been placed on understanding the nature of these protein accumulations, including their composition, the process by which they are formed and the physiological impact they impose at cellular and, ultimately, organismal levels. Alpha-synuclein (ASYN) is the major component of protein inclusions known as Lewy bodies and Lewy neurites, which are the typical pathological hallmarks in disorders referred to as synucleinopathies. In addition, mutations or multiplications in the gene encoding for ASYN have also been shown to cause familial cases of PD, the most common synucleinopathy. Although the precise function of ASYN remains unclear, it appears to be involved in a vast array of cellular processes. Here, we review, in depth, a spectrum of cellular and molecular mechanisms that have been implicated in synucleinopathies. Importantly, detailed understanding of the biology/pathobiology of ASYN may enable the development of novel avenues for diagnosis and/or therapeutic intervention in synucleinopathies.

Pharmacotherapy of autonomic failure.

The clinical picture of autonomic failure is characterized by severe and disabling orthostatic hypotension. These disorders can develop as a result of damage of central neural pathways or peripheral autonomic nerves, caused either by a primary autonomic neurodegenerative disorder or secondary to systemic illness. Treatment should be focused on decreasing pre-syncopal symptoms instead of achieving blood pressure goals. Non-pharmacologic strategies such as physical counter-maneuvers, dietary changes (i.e. high salt diet, rapid water drinking or compression garments) are the first line therapy. Affected patients should be screened for co-morbid conditions such as post-prandial hypotension and supine hypertension that can worsen orthostatic hypotension if not treated. If symptoms are not controlled with these conservative measures the next step is to start pharmacological agents; these interventions should be aimed at increasing intravascular volume either by promoting water and salt retention (fludrocortisone) or by increasing red blood cell mass when anemia is present (recombinant erythropoietin). When pressor agents are needed, direct pressor agents (midodrine) or agents that potentiate sympathetic activity (atomoxetine, yohimbine, pyridostigmine) can be used. It is preferable to use short-acting pressor agents that can be taken on as needed basis in preparation for upright activities.