Ehlers- Danlos syndrome is a connective tissue disorder including joint hypermobility as well as other findings. It has 13 subtypes, most of which are associated with distinct gene mutations. However, one of the subtypes is characterized by joint hypermobility alone and in this isolated hypermobile type, although it behaves as if it were autosominal dominant, the gene(s) is unknown. Castori et al (2014) commented that "Although proposed by a panel of experts, clinical identity between JHS and EDS-HT is still a matter of debate due to unknown molecular basis." Similarly, Martin (2019) commented that "the plethora of unknowns in hEDS continue to challenge healthcare outcomes and care experiences". Or in other words, there is a lot to learn and perhaps we are dealing with another "committee disease" rather than a single entity. . Tinkle et al (2017) commented that "The hypermobile type of Ehlers-Danlos syndrome (hEDS) is likely the most common hereditary disorder of connective tissue." Of course, this assumes that underlying the hypermobile manifestations of hEDS, there is a "cause" such as a metabolic or genetic derangement..
Although there seems to be some controversy, we do think that that hyperflexibility is very prevalent in young dizzy women, and also that there are some useful associations with hyperflexibility. We think that when you identify a patient with hypermobility, it is reasonable to think about the associations, and also reasonable to see if they might fit into one of the genetic variants of EDS.
As of 2017, there was a complicated classification system for naming EDS variants including classical-like EDS, cardiac, vascular, hypermobile, arthrochalasia, dermatosparaxis, kyphoscoliotic, brittle cornea syndrome, spondylodysplastic, musculocontractural, myopathic, and peridontal. See reference "Criteria" below. The Forghani article (2019) provides the criteria in detail.
Classical EDS requires skin hyperextensibility and atrophic scarring as well as joint hypermobility, or several minor criteria.
Vascular EDS requires a family history, and a variety of vascular related complications. Again, minor criteria include joint hypermobility.
Hypermobile EDS requires skin hyperextensibility and atrophic scarring as well as joint hypermobility. The joint hypermobility goes under the acronym of GJH, generalized joint hypermobility, and is identified by the Beighton score. Joint hypermobility itself does not suffice for determination of a genetic syndrome.
Hypermobility is scored using the Beighten score (Beighton et al, 1998). Cutoffs vary by age.
5 elements, and 1 point for each side (so could have 9 points max);
Image is from https://www.physio-pedia.com/Beighton_score
Cutoffs vary with age, namely
This is because people get stiffer with age.
The literature about hypermoble variant of EHD largely suggests that the criteria are overly sensitive, and not very specific. One cannot reasonably call all persons who are very flexible "EDS", as this could mix together people with genetic hyperflexibility syndromes with people who just work a lot on flexibility (such as gymnists or dancers). Forghani (2018) commented that "Hypermobile Ehlers Danlos is the only subtype in these groups of syndromes with no known genetic cause(s). " So in other words, there is no genetic test for the purely hypermobile EHD.
Of all of these diagnostic maneuvers, the one that seems most useful is the ability to touch the thumb to the forearm. It is rare and people don't "work on this" in Yoga.
Possible new maneuver ?
We have observed that in some of these patients, one can create a temporary subclavian bruit by pressing forcefully just behind their clavicle where one would ordinarily listen for a subclavian bruit. We do not know how sensitive/specific this is however.
EHD is occasionally associated with several types of dizziness
- Chiari malformation
- Basilar impression (or invagination)
- CSF leak
- Migraine (Bendik et al, 2011)
- POTS (postural orthostatic tachycardia syndrome) (Chen et al, 2019)
- Cervical spine disorders -- accelerated disk disease
- Carotid dissections, aneurysms, vertebral artery dissections (more of a cause of stroke than dizziness). (Shalub et al, 2019)
- TMJ disorders (not a big cause of dizziness, but still a correlation) (e.g. Diep et al, 2016)
- Mast cell activation disorders -- i.e. allergic type reactions. (the connection between EHD and MCAD is currently controversial; Kohn and Chang, 2020; the connection between MCAD and dizziness is also unclear).
Practically, the association between generalized hypermobility , POTS and migraine seems to be the most prevalent.
Chen et al (2019) reported that an amazing 98% of the hypermobile (hEDS) patients that they surveyed reported orthostatic symptoms.
One would expect that there would be more PLF (perilymph fistula) as well, but so far we have not encountered a patient with PLF and hEHS.
According to Bendik et al (2011), migraine is found in 75% of persons with the joint hypermobility variant of EHD. Migraine is much more common than EHD, and this is more relevant to diagnosis of dizziness in EHD than diagnosing migraine.
Chung et al (2017) reported a single case of bilateral SCD. Being just a single case report, this association may not be valid. Going the other way, we have not noticed many hypermobile patients with SCD. So this is probably a "red herring".
Shalhub et al (2019) reported a higher incidence of aortic, arterial and dissections at a young age. Note that this is also the vascular variant of EHD, not the hEDS. To be included in this cohort, one basically needs the conditions Shalhub reported, so this is a somewhat circular observation. We have not encountered any patients in this situation among our dizzy cohort.
Many of these disorders are probably related to the fragility of collagen (Henderson et al, 2017).
Weir et al (2016) reported that hearing loss was "prevalent" in EDS, and found 32/142 to have some kind of hearing loss. These patients might not be the "hEHD" group alone from their study design. As a general observation, EHD is a diverse genetic disorder and one would expect that there would be genetic variants that include hearing loss. . The FKBP14 autosomal recessive variant of EHD has some hearing loss, in association with myopathy, scoliosis, and skin hypermobility. The hearing impairment is sensorineural (Bauman et al, 2012; Bursztejn et al, 2017; Giunta et al, 2018 and others). These patients seem to be just a small portion of the overall EHD genetic spectrum.
We have encountered several patients to date with dizziness, eventually traced to joint instability, presumed a variant of EHD. Two of these patients underwent a cervico-occiptal fusion for an unstable upper cervical spine. This is a heroic procedure where bolts are put into the skull and upper cervical vertebrae to keep the head stable on the upper spine.
We have also had several patients with POTS and hypermobility together, and many patients with migraine and hypermobility together (but migraine is common, and perhaps this is a chance association).
There is no medical treatment for EHD, of for that matter, generalized hypermobility, and all treatments are based on managing the complications. We think it is prudent for these patients to avoid activities that might cause joint dislocation. For example, "cracking" the neck in chiropractic settings.