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Neurogenic orthostatic hypotension (nOH) is common in patients with neurodegenerative disorders such as Parkinson’s disease, multiple system atrophy, pure autonomic failure, dementia with Lewy bodies, and peripheral neuropathies including amyloid or diabetic neuropathy. Due to the frequency of nOH in the aging population, clinicians need to be well informed about its diagnosis and management. To date, studies of nOH have used different outcome measures and various methods of diagnosis, thereby preventing the generation of evidence-based guidelines to direct clinicians towards ‘best practices’ when treating patients with nOH and associated supine hypertension. To address these issues, the American Autonomic Society and the National Parkinson Foundation initiated a project to develop a statement of recommendations beginning with a consensus panel meeting in Boston on November 7, 2015, with continued communications and contributions to the recommendations through October of 2016. This paper summarizes the panel members’ discussions held during the initial meeting along with continued deliberations among the panel members and provides essential recommendations based upon best available evidence as well as expert opinion for the (1) screening, (2) diagnosis, (3) treatment of nOH, and (4) diagnosis and treatment of associated supine hypertension.Electronic supplementary materialThe online version of this article (doi:10.1007/s00415-016-8375-x) contains supplementary material, which is available to authorized users.

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Objective To define the clinical features and biomarkers that predict which patients with pure autonomic failure will develop Parkinson disease, dementia with Lewy bodies, or multiple system atrophy. Methods One hundred patients who presented with pure autonomic failure were recruited at 5 medical centers in the U.S. Seventy-four patients agreed to be followed prospectively. Patients underwent clinical evaluations including neurological rating scales, sleep questionnaires, smell test, and sympathetic and parasympathetic cardiovascular autonomic function tests. Results At enrollment, patients were 68(12) years old [(median (interquartile range)] and had had autonomic failure for 5(7) years. Within 4-years of follow-up, 25 of 74 subjects (34%) developed dementia with Lewy bodies (in 13), Parkinson disease (in 6), or multiple system atrophy (in 6). The presence of probable REM sleep behavior disorder was strongly associated with the development of a manifest CNS synucleinopathy (odds ratio=7.1). Patients who phenoconverted to multiple system atrophy had younger age at onset of autonomic failure, severe bladder/bowel dysfunction, preserved olfaction, and a cardiac chronotrophic response upon tilt >10 beats per minute. Those who phenoconverted to Parkinson disease or dementia with Lewy bodies had decreased olfaction, a lesser chronotrophic response to tilt, and a longer duration of illness. The small group of patients retaining the pure autonomic failure phenotype had very low plasma norepinephrine levels, slow resting heart rate, no REM sleep behavior disorder, and preserved smell. Interpretation Patients presenting with pure autonomic failure are at high risk of phenoconverting to a manifest CNS synucleinopathy. Specific clinical features predict future diagnosis.

Treatment-induced neuropathy in diabetes (also referred to as insulin neuritis) is considered a rare iatrogenic small fibre neuropathy caused by an abrupt improvement in glycaemic control in the setting of chronic hyperglycaemia. The prevalence and risk factors of this disorder are not known. In a retrospective review of all individuals referred to a tertiary care diabetic neuropathy clinic over 5 years, we define the proportion of individuals that present with and the risk factors for development of treatment-induced neuropathy in diabetes. Nine hundred and fifty-four individuals were evaluated for a possible diabetic neuropathy. Treatment-induced neuropathy in diabetes was defined as the acute onset of neuropathic pain and/or autonomic dysfunction within 8 weeks of a large improvement in glycaemic control-specified as a decrease in glycosylated haemoglobin A1C (HbA1c) of ≥2% points over 3 months. Detailed structured neurologic examinations, glucose control logs, pain scores, autonomic symptoms and other microvascular complications were measured every 3-6 months for the duration of follow-up. Of 954 patients evaluated for diabetic neuropathy, 104/954 subjects (10.9%) met criteria for treatment-induced neuropathy in diabetes with an acute increase in neuropathic or autonomic symptoms or signs coinciding with a substantial decrease in HbA1c. Individuals with a decrease in HbA1c had a much greater risk of developing a painful or autonomic neuropathy than those individuals with no change in HbA1c (P < 0.001), but also had a higher risk of developing retinopathy (P < 0.001) and microalbuminuria (P < 0.001). There was a strong correlation between the magnitude of decrease in HbA1c, the severity of neuropathic pain (R = 0.84, P < 0.001), the degree of parasympathetic dysfunction (R = -0.52, P < 0.01) and impairment of sympathetic adrenergic function as measured by fall in blood pressure on tilt-table testing (R = -0.63, P < 0.001). With a decrease in HbA1c of 2-3% points over 3 months there was a 20% absolute risk of developing treatment-induced neuropathy in diabetes, with a decrease in HbA1c of >4% points over 3 months the absolute risk of developing treatment-induced neuropathy in diabetes exceeded 80%. Treatment-induced neuropathy of diabetes is an underestimated iatrogenic disorder associated with diffuse microvascular complications. Rapid glycaemic change in patients with uncontrolled diabetes increases the risk of this complication.

Objective: To develop a cutaneous biomarker for Parkinson disease (PD).Methods: Twenty patients with PD and 14 age-and sex-matched control subjects underwent examinations, autonomic testing, and skin biopsies at the distal leg, distal thigh, and proximal thigh. a-Synuclein deposition and the density of intraepidermal, sudomotor, and pilomotor nerve fibers were measured. a-Synuclein deposition was normalized to nerve fiber density (the a-synuclein ratio). Results were compared with examination scores and autonomic function testing.Results: Patients with PD had a distal sensory and autonomic neuropathy characterized by loss of intraepidermal and pilomotor fibers (p , 0.05 vs controls, all sites) and morphologic changes to sudomotor nerve fibers. Patients with PD had greater a-synuclein deposition and higher a-synuclein ratios compared with controls within pilomotor nerves and sudomotor nerves (p , 0.01, all sites) but not sensory nerves. Higher a-synuclein ratios correlated with Hoehn and Yahr scores (r 5 0.58-0.71, p , 0.01), with sympathetic adrenergic function (r 5 20.40 to 20.66, p , 0.01), and with parasympathetic function (r 5 20.66 to 20.77, p . 0.01). Conclusions:We conclude that a-synuclein deposition is increased in cutaneous sympathetic adrenergic and sympathetic cholinergic fibers but not sensory fibers of patients with PD. Higher a-synuclein deposition is associated with greater autonomic dysfunction and more advanced PD. These data suggest that measures of a-synuclein deposition in cutaneous autonomic nerves may be a useful biomarker in patients with PD. Accumulating evidence suggests that a-synuclein deposition occurs early in the course of PD and may antedate the appearance of the clinical features of the disease.2 This has provided the rationale for the use of a-synuclein as a biomarker in PD. 3Skin punch biopsy could provide a simple means to measure a-synuclein deposition in the peripheral nervous system; however, preliminary studies used techniques optimized for CNS tissue, relied on small tissue volumes, and did not systematically study autonomic substructures, and therefore detected a-synuclein in only a minority of subjects with PD. [4][5][6][7][8] We recently reported novel methods to study the cutaneous autonomic innervation in skin biopsies of patients with peripheral nerve disease.9,10 We hypothesized, based on the prominent autonomic manifestations of PD, that a-synuclein deposition would be elevated in cutaneous structures with autonomic innervation.The aims of the study were to determine 1) whether a-synuclein was present in cutaneous sensory and autonomic nerves, 2) the relationship between cutaneous a-synuclein deposition and *These authors contributed equally to this work.

Sudomotor dysfunction is one of the earliest detectable neurophysiologic abnormalities in distal small fiber neuropathy. Traditional neurophysiologic measurements of sudomotor function include thermoregulatory sweat testing (TST), quantitative sudomotor axon reflex testing (QSART), silicone impressions, the sympathetic skin response (SSR), and the recent addition of quantitative direct and indirect axon reflex testing (QDIRT). These testing techniques, when used in combination, can detect and localized pre-and postganglionic lesions, can provide early diagnosis of sudomotor dysfunction and can monitor disease progression or disease recovery. In this article, we review the common tests available for assessment of sudomotor function, detail the testing methodology, review the limitations and provide examples of test results.

Objective-To describe the natural history, clinical, neurophysiological and histological features and outcomes of diabetic patients presenting with acute painful neuropathy associated with glycemic control, also referred to as 'insulin neuritis'.Methods-Sixteen subjects, presenting with acute painful neuropathy had neurological and retinal examinations, laboratory studies, autonomic testing and pain assessments over 18 months. Eight subjects had skin biopsies for evaluation of intra-epidermal nerve fiber density.Results-All subjects developed severe pain within 8 weeks of intensive glucose control. There was a high prevalence of autonomic cardiovascular, gastrointestinal, genitourinary, and sudomotor symptoms in all subjects. Orthostatic hypotension and parasympathetic dysfunction were seen in 69% of subjects. Retinopathy worsened in all subjects. Reduced intra-epidermal nerve fiber density (IENFD) was seen in all tested subjects. After 18 months of glycemic control, there were substantial improvements in pain, autonomic symptoms, autonomic test results and IENFD. Greater improvements were seen after 18 months in type 1 vs. type 2 diabetic subjects in autonomic symptoms (cardiovascular p<0.01; gastrointestinal p<0.01; genitourinary p<0.01) and autonomic function tests (p<0.01, sympathetic and parasympathetic function tests).Interpretation-Treatment induced neuropathy is characterized by acute, severe pain, peripheral nerve degeneration and autonomic dysfunction after intensive glycemic control. The neuropathy occurred in parallel with worsening diabetic retinopathy suggesting a common underlying pathophysiological mechanism. Clinical features and objective measures of small myelinated and unmyelinated nerve fibers can improve in these diabetic patients despite a prolonged history of poor glucose control, with greater improvement seen in patients with type 1 diabetes. Keywords diabetic neuropathy; painful neuropathy; autonomic neuropathyWhile chronic neuropathic pain occurs frequently in diabetic patients, acute severe neuropathic pain is rarely encountered. Several different acute painful syndromes occur: 1) Pain may appear shortly after the initiation of intensive glycemic control, sometimes referred to as 'insulin neuritis' or treatment induced neuropathy. 1-3 Characteristically, the painful neuropathy is preceded by rapid glycemic control. 2) Additional cases present in association with severe weight loss with or without a change in glycemic control, a disorder