Faculty Bibliography

Background: Normally, during sleep, when cortical influences are minimized, blood pressure (BP) and heart rate (HR) fall (i.e., nocturnal dipping). In patients with afferent baroreflex failure, in whom BP and HR are highly dependent on cortical influences, this nocturnal dipping is usually preserved. There are, however, a number of patients with afferent baroreflex failure in whom BP does not dip at night. The reasons for this are unknown.
Method(s): We examined the 24-hour ambulatory BP profiles in 50 patients with afferent baroreflex failure of acquired (n = 6) or genetic origin (familial dysautonomia n = 44). BP and HR were captured at 30-minute intervals over a 24-h period. Nighttime sleep periods were identified from the patient's diary. Dipping was defined as a 10 % or greater fall in systolic and diastolic blood pressure at night.
Result(s): Normal BP nocturnal dipping was present in only 50 % of the patients; 33 % of patients had reversal of the circadian rhythm with higher blood pressures at night. In the remaining 17 %, nocturnal BP was similar to daytime BP. Patients with preserved nocturnal dipping had a significantly higher glomerular filtration rate (8430 mL/ min) than those that did not dip at night (6130 mL/min, p = 0.043).
Conclusion(s): Lack of nocturnal BP dipping in patients with afferent baroreflex failure was associated with impaired renal function. These findings suggest that in patients with FD, a non-dipping profile may involve abnormalities in extracellular volume and/or impaired regulation of vascular resistance (i.e., abnormal endothelial function)

Autoimmune autonomic ganglionopathy (AAG) is a rare condition characterized by acute-onset generalized autonomic failure. Some of these patients also develop severe sensory and motor deficits. Droxidopa, an oral norepinephrine precursor, has been previously reported as effective treatment of neurogenic orthostatic hypotension (nOH) in one patient with AAG. Here we report our experience using droxidopa to treat symptomatic nOH in 3 patients with suspected AAG. Patient #1 (35-year-old woman) presented with acute-onset recurrent syncope, urinary retention, constipation, dry mouth, and decreased sweating, but no motor or sensory deficits. Patient #2 (11 year-old boy) and patient #3 (43-year-old woman) presented with similar autonomic deficits as well as severe impairment in all sensory modalities, but patient #3 also had severe generalized muscle weakness and had been initially diagnosed with Guillain-Barre syndrome. In all three patients, autonomic testing showed severe nOH confirmed by absent phase IV blood pressure overshoot after release of the Valsalva strain and very low or undetectable plasma norepinephrine levels. Ganglionic acetylcholine receptor antibodies were not detected in any patient. Droxidopa increased blood pressure and improved symptoms in all three patients. After 1 year, patient #1 is still receiving droxidopa 200 mg three times/day with normalization of standing BP, and continued symptomatic improvement. During the initial droxidopa titration, patients #2 and #3 experienced nausea, abdominal pain, and severe hypertension (>180 mmHg) with dosages > 200 mg. Both have now been receiving 100 mg once/day for a year with improvement in orthostatic tolerance and BP, no side effects and no supine hypertension. In conclusion, droxidopa substantially increased blood pressure standing and reduced symptoms of orthostatic hypotension in adult and pediatric patients with suspected acute autonomic ganglionopathy

Physicians who specialize in autonomic disorders think in terms of orthostasis, synapses, catecholamines, ganglionopathies, and baroreflexes. Patients, on the other hand, inhabit a world of streaming, downloads, hashtags, tweets, and blogs. In an increasingly digital era, if we are to communicate effectively with patients, we must understand their language, including that of social media. The cultural revolution of social media opens new opportunities for autonomic medicine. First, social media can direct patients to specialists who have the expertise to evaluate and treat their disorders when such expertise is not available locally. Listing contact information on reputable dysautonomia websites is an effective way to facilitate these connections, as is creating practice websites to showcase unique expertise and resources. Secondly, online platforms can empower the patient population through education. In clinical practice, we see how frequently patients turn to the Internet for medical information. However, search engines alone are inadequate because of the sheer volume of available information, much of which is unmonitored. Patients can quickly be led down a path of misinformation about their particular condition. Dr. Google is frequently wrong. Moreover, it takes on average 2.5 clicks to get from a headache to a brain tumor. As experts in the field, we have an obligation to participate online in the translation and dissemination of accurate medical information. It is important to consider the demographics of the target audience and how best to reach them, be it Facebook, Twitter, Instagram or Snap Chat. By doing this we can assist patients in understanding their autonomic disorders and managing their symptoms. Thirdly, social media can be an important tool for research. Social media platforms can be used to recruit research subjects with rare disorders and as a tool to promote the need for research funding from the public. Social media is undoubtedly an effective way to spread news and can be used to disseminate new knowledge arising from research, which allows patients to keep abreast of current breakthroughs. Lastly, social media can be leveraged to raise public awareness about autonomic disorders and their treatment, build community, share experiences, and engage patient groups in partnership

Congenital insensitivity to pain with anhidrosis (CIPA, also known as hereditary sensory and autonomic neuropathy type IV) is a rare autosomal recessive disorder caused by mutations in the gene encoding for neurotrophic tyrosine kinase receptor type 1, a receptor for nerve growth factor (NTRK1-NGF). We recently described that patients with CIPA have very low or undetectable circulating norepinephrine levels. Since these mutations severely deplete the development of noradrenergic neurons in the periphery, they presumably also affect those in the central nervous system. Patients with CIPA have low IQ and behavioral problems including hyperactivity and reckless impulsivity, likely the result of a central deficiency in norepinephrine. We explored whether treatment with droxidopa, a synthetic norepinephrine precursor, which crosses the blood brain barrier, could improve behavioral features in a patient with CIPA. Our patient was a 29-year-old woman with a classic phenotype and molecular confirmation of a mutation in the NTRK1 gene (c360- 2A >C pathogenic variant). She had symptoms of attention deficit and hyperactivity and scored highly on the adult ADHD self-report scales (Scores Part A: 4/6 and Part B: 9/12). She had high scores in the attentional (17 and 4), motor (21 and 10), and planning (21 and 17) domains of Barratt impulsiveness scale. NICHQ Vanderbilt assessment scale also indicated attention deficits and hyperactivity. After two months treatment with droxidopa (at 400 mg/day), attention and hyperactivity scales scores decreased to the normal range (Scores Part A: 3/6 and Part B: 4/12). Impulsiveness scores assessed by Barratt impulsiveness scales also improved (attentional scores 15 and 11, motor scores 19 and 9 and planning scores 20 and 9). This case report suggests that behavioral deficits might be reversed in patients with CIPA by norepinephrine replenishment therapy. Clinical studies to evaluate the usefulness of droxidopa to treat behavioral problems in CIPA patients are warranted

We previously reported that the norepinephrine transporter inhibitor, atomoxetine, improves upright blood pressure and pre-syncopal symptoms as measured by the orthostatic hypotension symptom assessment (OHSA) in patients with neurogenic orthostatic hypotension (nOH). The purpose of this study was to determine the predictors of the improvement in orthostatic symptoms with atomoxetine. Our sample size consisted of 101 autonomic failure patients with nOH who participated in clinical trials (NCT00223691, NCT1316666) conducted in two national referral centers for autonomic disorders (Vanderbilt Autonomic Dysfunction Center and NYU Langone Medical Center Dysautonomia Center). The analysis was performed in patients with symptomatic nOH defined as item-1 OHSA (lightheadedness) equal or more than four points. Seated blood pressure was measured in three occasions before and 60 min after receiving 18 mg of atomoxetine. Standing blood pressure at 1, 3, 5 and 10 min and OHSA questionnaire was collected before and after the atomoxetine dose. Multiple linear regression was used to test for overall linear relations between the dependent variable (OHSA score after atomoxetine) and independent variables (baseline OHSA score, age, diagnosis, baseline supine norepinephrine levels) and to assess the significance of these relations after adjustments for each covariate.
Result(s): 47 patients (47 %) met criteria for symptomatic nOH. The average age at the time of evaluation was 67 +/- 9 years, 47 % were males. 55 % were diagnosed as pure autonomic failure, 30 % as multiple system atrophy, 11 % as Parkinson disease and 4 % were patients with nOH of unknown etiology. Adjusted R2 for this model was 0.3, only supine norepinephrine levels (P = 0.047) accurately predicted orthostatic symptoms following atomoxetine after adjusting for baseline OHSA, age and specific diagnosis.
Conclusion(s): Supine baseline norepinephrine levels predict the improvement in symptoms produced by atomoxetine in patients with symptomatic nOH

Non-invasive observation of spatiotemporal activity of large neural populations distributed over entire brains is a longstanding goal of neuroscience. We developed a volumetric multispectral optoacoustic tomography platform for imaging neural activation deep in scattering brains. It can record 100 volumetric frames per second across scalable fields of view ranging between 50 and 1000 mm3 with respective spatial resolution of 35-200 mm. Experiments performed in immobilized and freely swimming larvae and in adult zebrafish brains expressing the genetically encoded calcium indicator GCaMP5G demonstrate, for the first time, the fundamental ability to directly track neural dynamics using optoacoustics while overcoming the longstanding penetration barrier of optical imaging in scattering brains. The newly developed platform thus offers unprecedented capabilities for functional whole-brain observations of fast calcium dynamics; in combination with optoacoustics' well-established capacity for resolving vascular hemodynamics, it could open new vistas in the study of neural activity and neurovascular coupling in health and disease.

Non-invasive fluorescence retinal imaging in small animals is an important requirement for an array of translational vision applications. The in vivo two-photon imaging of the mouse retina may enable the long-term investigation of the structure and function of healthy and diseased retinal tissue. However, to date, this has only been possible using relatively complex adaptive-optics systems. Here, the optical modeling of the murine eye and of the imaging system is used to achieve correction-free two-photon microscopy through the pupil of a mouse eye to yield high-quality, optically sectioned fundus images. By remotely scanning the focus using an electronically tunable lens, high-resolution three-dimensional fluorescein angiograms and cellular-scale images are acquired, thus introducing a correction-free baseline performance level for two-photon in vivo retinal imaging. Moreover, the system enables functional calcium imaging of repeated retinal responses to light stimulation using the genetically encoded indicator, GCaMP6s. These results and the simplicity of the new add-on optics are an important step toward several structural, functional, and multimodal imaging applications that will benefit from the tight optical sectioning and the use of near-infrared light.

The resolution of an imaging apparatus is ideally limited by the diffraction properties of the light passing through the system aperture, but in many practical cases, inhomogeneities in the light propagating medium or imperfections in the optics degrade the image resolution. Here we introduce a powerful and practical new approach for estimating the point spread function (PSF) of an imaging system on the basis of PSF Estimation from Projected Speckle Illumination (PEPSI). PEPSI uses the fact that the speckles' phase randomness cancels the effects of the aberrations in the illumination path, thereby providing an objective pattern for measuring the deformation of the imaging path. Using this approach, both wide-field-of-view and local-PSF estimation can be obtained by calibration-free, single-speckle-pattern projection. Finally, we demonstrate the feasibility of using PEPSI estimates for resolution improvement in iterative maximum likelihood deconvolution.