Tethered Cord

Tethered cord syndrome (TCS) referred to a group of disorders related to malformations of the spinal cord. Various forms include filum terminale, lipomeningomyelocele, split cord, dermal sinus tracts, dermoid and occult tethered cord. All of these conditions involve the spinal cord becoming tethered which causes tension on the cord. This mostly occurs at the base of the spine but can occur along the spine. 

Usually, the cord is free-flowing, allowing it to adjust with movement and growth. When it becomes tethered movement and growth causes the cord to stretch leading to damage to the cord. This tension on the cord is what causes the symptoms of TCS. These can include foot and spinal deformities, weakness in the legs, abnormal gait, low back pain, scoliosis, urinary and/or bowel irregularities (incontinence, urgency, and/or retention). TCS is usually a childhood disorder but can go undiagnosed till adulthood. 

While usually associated with Spina Bifida the tethered cord has theoretically been considered the cause of some Chiari types by the tension of the cord pulling on the cerebellar tonsils causing a cerebellar tonsillar herniation. It is also believed to be able to cause Syringomyelia due to the scar tissue/inflammation on the cord. 

Traditional tethered cord can be found via MRI by looking at the lumbar region and the location of the conus. Finding the conus below the level of L2 is diagnostically significant for a tethered cord, However, some types are hidden (occult) and the cord terminates at the appropriate level bu the filum terminale is fatty or tight. Occult tethered cord (OTC)  type while still felt to be controversial is diagnosed clinically from tests like urodynamic testing and from symptoms. Thie OTC is found mainly in people with Ehlers-Danlos

 

Treatment ranges from conservative management of symptoms to surgery to untether the cord. This can range from simple surgery to snip the flium terminale or newer approaches like spine-shortening. When cases are associated with Spina Bifida treatment can be more complex. 

There is some discussion about tethered cord/Filum disease being the true cause of chiari, syringomyelia and/or craniocervical instability at Institut Chiari & Siringomielia & Escoliosis of Barcelona.

  

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Lumbar MRI
"Normal" Lumbar MRI of a person with Occult Tethered Cord