Medscape: Small-Fiber Polyneuropathy May Underlie Dysautonomia in ME/CFS

September 7, 2020

Dr Charles Shepherd, Hon. Medical Adviser, ME Association.

I was at the IACFS/ME virtual research conference recently where these potentially important new research findings were reported.

They bring together evidence of nerve damage and autoimmunity – the latter is already well documented in ME/CFS.

However, this is a small study. So we need to see these findings can be replicated in larger studies carried out in other research centres.

The Autonomic Nervous System

This is the sort of biomedical research that the MEA Ramsay Research Fund is keen to pursue and we would welcome research grant applications for a UK study.

As most people with ME/CFS will be aware, dysautonomia, or dysfunction of the autonomic nervous system (ANS), is a core feature of ME/CFS.

The ANS comprises of a complex set of nerves that in very simple terms speed up or slow down the activity of the heart (where it controls pulse and blood pressure), the blood vessels (where it can cause cold hands and feet), the gut (where it plays a role in causing irritable bowel symptoms) and the bladder (where it can cause urinary symptoms).

In particular, it causes orthostatic intolerance – a core symptom of ME/CFS whereby pulse and blood pressure control is faulty. So people have difficulty in maintaining an upright posture because not enough blood is going to the brain when standing up – it pools lower down the body.

OI can also involve what is called postural hypotension (where blood pressure falls more severely when moving from lying/sitting to standing resulting in dizziness or feeling faint) and postural orthostatic tachycardia syndrome (where there is an excessive rise in pulse rate when moving from lying to standing).

More information

The ME Association has information leaflets covering:

We also discuss autonomic dysfunction and how the ANS can cause common symptoms in ME/CFS in a really good research summary from Charlotte Stephens.

Research into ANS dysfunction is summarised and referenced in the 2020 edition of the MEA Clinical and Research Guide.

This authoritative and popular guide can now be ordered via the website shop and will be sent to you in the post (or can be downloaded in Kindle format via Amazon).

Small-Fiber Polyneuropathy May Underlie Dysautonomia in ME/CFS


A significant proportion of patients with myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) and dysautonomia may have potentially treatable underlying autoimmune-associated small-fiber polyneuropathy (aaSFPN), pilot data suggest.

The findings, from a single-site study of 61 patients with ME/CFS, were presented August 21 at the virtual meeting of the International Association for Chronic Fatigue Syndrome/Myalgic Encephalomyelitis by Ryan Whelan, BS, a research assistant at Simmaron Research Institute, Incline Village, Nevada.

Recent evidence suggests an autoimmune etiology for some patients with ME/CFS, which is defined as experiencing for a period of at least 6 months profound, unexplained fatigue, postexertional malaise, and unrefreshing sleep, as well as cognitive dysfunction and/or orthostatic intolerance (OI).

OI is part of a spectrum of autonomic dysfunction commonly seen in ME/CFS patients, which may also include postural orthostatic tachycardia (POTS), peripheral temperature dysregulation and light sensitivity, neuropathic pain, and gastrointestinal complaints.

Many of these symptoms overlap those reported by patients with aaSFPN, a common but underdiagnosed neurodegenerative disorder characterized by the loss of peripheral autonomic nerve fibers, Whelan explained.

Findings from the current study show that in more than half of ME/CFS patients, levels of at least one autoantibody were elevated. A majority had comorbid POTS or OI, and over a third had biopsy-confirmed aaSFPN.

“Given the overlap of symptoms and common etiological basis, it may be important to identify ME/CFS patients who present with comorbid aaSFPN, as it has been shown that immune modulatory agents, including intravenous gamma globulin [IVIG], reduce the autonomic symptom burden in aaSFPN patients,”

Ryan Whelan, Simmaron Research Institute.

He noted that Anne Louise Oaklander, MD, a neurologist at Massachusetts General Hospital, Harvard Medical School, Boston, and colleagues previously linked aaSFPN with fibromyalgia.

In addition, they've found a connection between small-fiber dysfunction and postexertional malaise, which is a hallmark ME/CFS symptom.

Asked to comment on Whelan's presentation, IACFSME co-president Lily Chu, MD, told Medscape Medical News that the new findings are:

“valuable, because ME/CFS has always been looked upon as just subjective symptoms. When people have laboratory abnormalities, it can be due to a bunch of other causes, but…here's pathology, here's a biopsy of actual damage. It's not just a transient finding. You can actually see it…. It's a solid concrete piece of evidence vs something that can fluctuate.”

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