The one thing that doesn't stretch: Tethered Cord Syndrome in EDS
EDS is all about laxity - except for this?! Let's talk about the tight filum in tethered cord syndrome
Neurological complications of the Ehlers-Danlos Syndromes (EDS) are underappreciated in the medical field, despite their prevalence. One of which is tethered cord syndrome (TCS). Tethered Cord Syndrome (TCS) is a condition in which the spinal cord’s movement is restricted. Normally, the spinal cord freely floats within the spinal canal in the cerebrospinal fluid, allowing for movement with changes in body position.
For anatomical context, the bottom end of the spinal cord, called the conus medullaris, is connected to the coccyx by a fibrous band called the filum terminal. The filum terminale plays important roles in embryonic development. In adults, it plays a role in providing stability to the spinal cord within the spinal canal. When the spinal cord is “tethered” in TCS, it is referring to the spinal cord’s restricted movement due to abnormal attachment or other pathological changes in the filum terminale.
Occult Tethered Cord Syndrome
TCS was originally recognized as a condition presenting as a infant or in early childhood, defined by the presence of a low lying conus (from the spinal cord being pulled down) or fatty/thickened filum on imaging. TCS is closely associated with Spina Bifida, occurring during development. However, there are people with symptoms consistent with tethered cord syndrome that do not have obvious abnormalities on imaging, referred to as occult tethered cord syndrome. These patients often present later in life and the ‘tethering’ is believed to be due to pathological changes in the filum terminale, leading to a ‘tight’ filum and tension on the spinal cord. Typically in the context of EDS, patients with TCS will have occult TCS.
Signs and Symptoms
Symptoms of TCS are due to stretching of the spinal cord and can include:
lower back pain
lower extremity pain and weakness
balance changes
sensory changes
bowel and bladder dysfunction
sexual dysfunction
gait changes
changes in reflexes
Symptoms can vary in severity, occur intermittently and in some cases, begin seemingly out of nowhere. Research has yet to understand the onset and progression of symptoms in occult TCS. Additionally, TCS is believe to worsen or even cause Chiari malformation in some cases, which should be considered in patients with EDS and Chiari.
Diagnosis of Tethered Cord Syndrome
In the case of occult TCS, it is important to rule out other conditions that can share similar symptoms. This may include an MRI of the spine to look for other possible causes. Neurosurgeons who treat TCS will look at symptom presentation, a detailed medical history and co-occuring conditions. Sometimes, additional testing will be ordered, such as urodynamic testing. New studies are investigating the utility of ultrasound and other tools for assessing spinal cord tension intraoperatively, however there are no diagnostic tools to directly assess cord tension that do not require surgery at this time.
Treatment Approaches
Not all tethered cord cases need surgery or will progress to needing surgery right away. The decision to have surgery is best discussed with an experienced neurosurgeon, and because this is a patient-provider decision to be made on a case by case basis, I am going to avoid going into too many details of surgerical approaches and outcomes.
As a general overview, surgical interventions can include several approaches, one of the most common being filum sectioning. While surgery does provide significant relief in most cases, re-tethering can sometimes occur. Some surgeons may use spinal column shortening as an alternative.
TCS and EDS
There has been a growing appreciation of occult tethered cord syndrome and its occurrence in people with Ehlers-Danlos Syndrome (EDS). When thinking about a condition that is largely associated with laxity and too much motion - the filum is doing the complete opposite. Studies have shown that EDS patients have pathological changes in the filum terminale (such as inflammation and reduced filum elasticity). It’s sparked a lot of interesting questions in my mind. Do EDS patients have tight filums from birth or does it develop over time? Does something happen to the filum in response to growing or even just to laxity of the spine? Is Is it possible that mast cells and co-morbid mast cell activation disease can lead to this response (ultimately scarring and stiffening)? Could some sort of trigger set off this “process”? Unfortunately - we don’t have those answers yet. But I’m looking forward to working on and collaborating on projects in this space!
Resources to learn more:
For those looking for resources to learn more, the Bobby Jones CSF does a lot of education, awareness and research in this space. I have linked some youtube videos below.
References:
Henderson FC, Sr., Austin C, Benzel E, Bolognese P, Ellenbogen R, Francomano CA, Ireton C, Klinge P, Koby M, Long D, Patel S, Singman EL, Voermans NC. Neurological and spinal manifestations of the Ehlers-Danlos syndromes. Am J Med Genet C Semin Med Genet. 2017;175(1):195-211. Epub 20170221. doi: 10.1002/ajmg.c.31549. PubMed PMID: 28220607.
Zingman A, Tuchman K, Henderson F Sr, Francomano CA. Patient-Reported Outcomes Following Sectioning of the Filum Terminale for Treatment of Tethered Cord Syndrome Associated With Ehlers-Danlos Syndrome. Cureus. 2022 May 2;14(5):e24679. doi: 10.7759/cureus.24679. PMID: 35663696; PMCID: PMC9160501.
Howells M, Hamby T, Honeycutt J, Donahue DJ. Detethering of MRI-Demonstrated Tethered Cord Syndrome. Pediatr Neurosurg. 2022;57(2):85-92. Epub 20220121. doi: 10.1159/000522135. PubMed PMID: 35066504..
Philippe De Vloo and Aida Georgeta Monea and Raf Sciot and Johannes Van Loon and Frank Van C. The Filum Terminale: A Cadaver Study of Anatomy, Histology, and Elastic Properties. World Neurosurgery. 2016;90:565-73.e1 , pmid = 26805693 , publisher = Elsevier. doi: 10.1016/J.WNEU.2015.12.103.
Klinge PM, Srivastava V, McElroy A, Leary OP, Ahmed Z, Donahue JE, Brinker T, De Vloo P, Gokaslan ZL. Diseased Filum Terminale as a Cause of Tethered Cord Syndrome in Ehlers-Danlos Syndrome: Histopathology, Biomechanics, Clinical Presentation, and Outcome of Filum Excision. World Neurosurgery. 2022;162:e492-e502. doi: https://doi.org/10.1016/j.wneu.2022.03.038.
Kerensky MJ, Paul A, Routkevitch D, Hersh AM, Kempski Leadingham KM, Davidar AD, Judy BF, Punnoose J, Williams A, Kumar A, Lehner K, Smith B, Son JK, Azadi JR, Shekhar H, Mercado-Shekhar KP, Thakor NV, Theodore N, Manbachi A. Tethered spinal cord tension assessed via ultrasound elastography in computational and intraoperative human studies. Commun Med (Lond). 2024 Jan 5;4(1):4. doi: 10.1038/s43856-023-00430-6. PMID: 38182729; PMCID: PMC10770351.
I have hEDS and had my TC surgery last year with Dr Patel. I’m so grateful for him and Jared. Thank you for all you’re doing!!