After decades of studying patients with autonomic disorders the NYU Dysautonomia Center team has published an article in the top medical journal. The review provides a clear classification to help doctors make sense of it all.
Untangling the dysautonomias
Because the autonomic nervous system innervates all the organs of the body, patients can present with wide array of seemingly unrelated symptoms, which can be difficult to diagnose. When it comes to diagnosing patients with autonomic dysfunction, there is no single clinical test or scan that can provide a conclusive answer. Quite often, the first sign of a change in the function of our autonomic nervous system is unstable blood pressure.
Often sent the most perplexing cases, over the years staff at the Center have watched thousands of patients with dysautonomia be worked up and diagnosed at the clinic. They also follow patients with genetic diseases like familial dysautonomia, that lead to inborn errors in the autonomic nerve pathways. This made it possible to compile decades worth of data help outline a framework of diagnosing patients with autonomic dysfunction and unstable blood pressure. When faced with a possible case of dysautonomia, a clinician has to listen to the patient’s story, and pick up clues, and begin forming a diagnostic framework. Whether the nerves are functional or not seems to be a good place to start, explained Dr. Kaufmann.
Functional autonomic disorders make up for the vast majority of patients that visit an autonomic clinic, explained Dr. Alberto Palma, who combed through hundreds of studies to understand the prevalence of the different forms of dysautonomia. In these patients their autonomic nerves are present, connected, and working, but at times they may become over-active or suddenly turned off. The common faint and postural tachycardia syndrome are typical examples of functional autonomic disorders. Outside of the episodes, the autonomic nervous system works normally, and controls blood pressure in the expected narrow physiological range. If the autonomic nerves aren’t functioning its either due to injury, auto-immunity or toxin build up, and the symptoms are usually chronic. The autonomic nerves projecting to the blood vessels are critical for maintaining blood pressure when standing. When they are inactive, blood pressure drops each time a person stands up, which can lead to fainting or falls.
These autonomic nerves running to the blood vessels are known as small fibers because they are thin, which makes them a vulnerable cell type in several metabolic and neurological diseases. This is why overtime doctors managing patients diabetes see more cases with cardiovascular autonomic dysfunction in clinic, as the small fiber neuropathy progresses. It’s also why unstable blood pressure can occur in neurodegenerative diseases like Parkinson’s or multiple system atrophy.
A window of opportunity
The main network of nerves that precisely control blood pressure are known as the baroreflexes. This brainstem reflex operates through a series of sensors throughout the body that allow the brain to preserve blood supply to the vital organs at all times. Clinicians are expected to stay up to date on new information and the field of autonomic disorders has been moving quickly. It’s now possible to localize where exactly the baroreflex problem occurs based on the particular pattern of autonomic responses the patient has, explained Dr. Lucy Norcliffe-Kaufmann.
The New England Journal of Medicine has the highest impact factor in all medical journals. It offers a real opportunity to reach a wide audience of readers and to teach what we now know to fellow professionals outside the specific field of autonomic medicine. We have had several doctors reach out to tell us that they are now recognizing patients with baroreflex dysfunction in their clinics. Improving our diagnostic capabilities should allow us to pick up these diseases quickly and get patients on the path to treatment.
Link to the article here: https://www.ncbi.nlm.nih.gov/pubmed/31914243
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