EHLERS-DANLOS
AUSTRALIA

Tethered Cord (TC) is a group of spinal conditions where the spinal cord becomes "stuck". This can occur anywhere along the spine, but most commonly occurs in the lumbar region. The spinal cord normally hangs loosely in the canal allowing it to move as we bend and stretch and especially as we grow taller. When the cord becomes stuck the cord gets stretched with movement causing damage to the cord. 

 

This can occur in patients with birth defects such as myelomeningocele or lipomyelomeningocele. It can also occur due to a tight filum terminale, split cord, diastematomyelia, dermal sinus tract, fatty filum.  Secondary tethering can occur after spinal surgeries. Some feel it is related to Chiari and the cause of brainstem herniation and is frequently seen in Craniocervical Instability. It can also be the cause of Syringomyelia. 

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TC can be diagnosed via MRI. The most common lumbar cord tethering MRI findings show the conus below the level of L2-3 in the spine. Urodynamics testing is a common test to show urological dysfunction/neurogenic bladder which is common in children and especially adults. 

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Symptoms

• Back Pain

• Weakness, numbness and problems in the legs

• Tremors or spasms in the leg muscles

• Changes in the feet (higher arches or curled toes)

• Urinary Irregularities

• Loss of bladder and/or bowel control 

• Scoliosis

• Abnormal gait/walking

• Recurrent bladder infections

• fatty mass, dimple, birthmarks, a tuft of hair or anorectal malformations

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This is commonly a paediatric disorder but can go undiagnosed into adulthood. Adult-onset symptoms include:

• Severe pain (in the lower back, radiating into the legs, groin, and perineum

• Muscle weakness and numbness (either bilateral or unilateral)

• Loss of feeling and movement in lower extremities

• Urinary Irregularities (incontinence or retention)

• Bowel Control issues

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Surgery is required in some cases where symptoms are severe to "release" the cord to try and avoid last nerve damage of loss of function. The most common surgery is untethered cord where stuck. Some newer types of surgery are becoming more common including Spinal Shortening (for recurrent tethered cord). This surgery shortens the spinal column to release tension off the cord.

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Occult Tethered Cord (OTC) in some cases (especially its seems in patients with EDS) tethered cord can occur but not sure up on the MRI. This is called "occult" type. This is where clinical diagnosis is required in the absence of radiological evidence. Position urodynamics is a strong indicator with symptoms of occult type tethered cord. 

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The link with EDS is still being investigated, but there is great interest. Some researchers like Dr Petra Klinge have published some interesting  research in 2022:

Diseased Filum Terminale as a Cause of Tethered Cord Syndrome in Ehlers-Danlos Syndrome: Histopathology, Biomechanics, Clinical Presentation, and Outcome of Filum Excision

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In this article it was state the spinal cord can also be considered tethered when the filum terminale (the fibrous tissue at the base of the spine which stabilises the cord) thickens (fatty filum) and/or becomes inelastic. This stops the spinal cord from being able to move freely as we move and grow causing the cord to be stretched and damaged. This type is usually associated with Ehlers-Danlos Syndrome.

 

Frequency and co-occurrence of comorbidities in the Ehlers-Danlos syndromes by Isabell Brock et al. 2021

Recent reports have suggested up to 40% of EDS patients display Tethered Cord Syndrome. Mostly Occult type tethered cord (occult meaning hidden) is the one mainly associated with EDS.