Recently, we’ve seen several individuals at our center who have Ehlers-Danlos syndrome (EDS), a known connective tissue disorder associated with, among other things, hyperelasticity. Although there are several types of EDS, that’s not the focus of today’s blog post.
People have been referred to us who have severe and chronic pain of uncertain etiology.
Although it’s been well documented that people with EDS do experience chronic pain of varying quality, other conditions, fatigue, and pain- and fatigue-related disability, overall this syndrome has been poorly understood.
Uncovering a New Link in EDS
we elected to carry out diagnostic 3-mm skin punch biopsies. This actually wound up confirming a diagnosis of small-fiber neuropathy in both patients, on the basis of the reduction of intraepidermal nerve fiber densities that were established.
We thought this was quite interesting, and so we went to “write it up.” Of course, we found we were not the only ones to have recently identified this.
the real purpose of this blog post is to highlight to others who might be seeing patients with EDS the presence of small-fiber neuropathy in these individuals.
Mounting Evidence in the Literature
Recent published evidence of this in the peer-reviewed literature is found in a 2016 case report by Pascarella and colleagues in Clinical Neurophysiology. The authors noted that chronic pain, fatigue, headache, and dysautonomia had been previously reported to be important symptoms in individuals with EDS.
The investigators found evidence for a non–length-dependent small-fiber neuropathic process. Findings consistent with intraepidermal nerve fiber density reduction were seen in the thigh, but not in the distal lower extremity.
In a second just-published study in the journal Neurology, Cazzato and colleagues reported on a series of patients with EDS who underwent clinical nerve physiologic assessment as well as skin biopsy assessment. In addition, their sensory symptoms were recorded to determine whether or not they had neuropathic features according to the Douleur Neuropathique 4 (DN4) [instrument], a very quick and very easy, relatively sensitive, and specific questionnaire that can be used to help identify whether a person’s pain is neuropathic or not.
Twenty adults in this study had typical hypermobility EDS, three had vascular EDS, and one had classic EDS. Upon evaluation, it was found that all but one patient had neuropathic pain complaints according to the DN4.
Pain intensity was moderate in eight patients and severe in 11 patients. Sural nerve conduction studies, which are used for large-fiber testing, were normal in all 24 patients. All patients showed a decrease in intraepidermal nerve fiber density consistent with the diagnosis of small-fiber neuropathy, regardless of the type of EDS they had.
In conclusion, this is fascinating, because here is a condition that many of us have seen without really understanding the underlying mechanism.
Of course, knowing that the diagnosis of small-fiber neuropathy is now reported in an increasing number of published studies, and simply observed in patients with EDS, doesn’t give us all the answers.
What it does tell us, though, is that this may have an impact on how we treat people. It certainly tells us that small-fiber neuropathy may be a common associated feature of EDS. It may explain many or at least some of the symptoms.