Tethered spinal cord syndrome
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|Tethered spinal cord syndrome|
|Classification and external resources|
- Tight filum terminale
- Split cord malformations (diastematomyelia)
- Dermal sinus tracts
All forms involve the pulling of the spinal cord at the base of the spinal canal, literally a tethered cord. The spinal cord normally hangs loose in the canal, free to move up and down with growth, and with bending and stretching. A tethered cord, however, is held taut at the end, or some point in the spinal canal. In children, a tethered cord can force the spinal cord to stretch as they grow. In adults the spinal cord stretches in the course of normal activity, usually leading to progressive spinal cord damage if untreated. It is often associated with the closure of a spina bifida—though not always, depending on the form it takes. For example it can be congenital such as in tight filum terminale, or the result of injury later in life.
Signs and symptoms
In children, symptoms may include:
- Lesions, hairy patches, dimples, or fatty tumours on the lower back
- Foot and spinal deformities
- Weakness in the legs
- Low back pain
- Urinary irregularities (incontinence or retention)
Tethered spinal cord syndrome may go undiagnosed until adulthood, when sensory, motor, bowel, and bladder control issues emerge. This delayed presentation of symptoms relates to the degree of strain on the spinal cord over time. Tethered spinal cord syndrome appears to result from improper growth of the neural tube during fetal development, and is closely linked to spina bifida.
Tethering may also develop after spinal cord injury. Scar tissue can block the flow of fluids around the spinal cord. Fluid pressure may cause cysts to form in the spinal cord, a condition called syringomyelia. This can lead to additional loss of movement or feeling, or the onset of pain or autonomic nervous system symptoms.
In adults, onset of symptoms typically include:
- Severe pain (in the lower back and radiating into the legs, groin, and perineum)
- Bilateral muscle weakness and numbness
- Loss of feeling and movement in lower extremities
- Urinary irregularities (incontinence or retention)
- Bowel control issues
Neurological symptoms can include a mixed picture of upper and lower motor neuron findings, such as amyotrophy, hyperreflexia, and pathologic plantar response, occurring in the same limb. Profound sensory changes, such as loss of pain, temperature, and proprioceptive sensations, are common. Last, progressive symptoms of a neuropathic bladder are noted on over 70% of adult patients, versus only 20% to 30% of children. These symptoms include urinary frequency and urgency, feeling of incomplete voiding, poor voluntary control, and urge and stress incontinence. Chronic recurrent infections are common and occasionally lead to nephrolithiasis (kidney stones), renal failure, or renal transplantation. Female patients also give a history of ineffective labor and postpartum rectal prolapse, presumably due to an atonic pelvic floor.
Because neurological deficits are generally irreversible, early surgery is recommended when symptoms begin to worsen. In children, early surgery is recommended to prevent further neurological deterioration, including but not limited to chronic urinary incontinence. In adults, surgery to free (detether) the spinal cord can reduce the size and further development of cysts in the cord and may restore some function or alleviate other symptoms. Tethered cord syndrome is causally linked to Chiari Malformation and any affirmative diagnosis of TCS must be followed by screening for Chiari's several degrees. TCS may also be related to Ehlers-Danlos syndrome, or Klippel-Feil syndrome which should also be screened for upon a positive TCS diagnosis.
Other treatment is symptomatic and supportive. NSAIDs, opiates, synthetic opiates, Cox II inhibitors, off-label applications of tricyclic anti-depressants combined with anti-seizure compounds have yet to prove they are of value in treatment of this affliction's pain manifestations. There is anecdotal evidence that TENS units may benefit some patients.
Treatment may be needed in adults who, while previously asymptomatic, begin to experience pain, lower back degeneration, scoliosis, neck and upper back problems, incontinence, and bladder control issues. Surgery on adults with minimal symptoms is somewhat controversial, for example Columbia University Dept of Neurosurgery says "For the child that has reached adult height with minimal if any symptoms, some neurosurgeons would advocate careful observation only," however surgery for those who have symptoms is not controversial. If the only abnormality is a thickened, shortened filum, then a limited lumbo-sacral laminectomy with division of the filum may be sufficient to relieve the symptoms.
This syndrome was first noticed in the late 19th century. While information has been available for years, little widespread blind research has been done. More research has been called for, and doctors have conducted many studies with good results. There is a low morbidity rate, and no complications have been documented, other than those typical of any type of back surgery. The association of this condition with others has been noticed, and needs further research to understand the relations. Spinal compression and the resulting relief is a known issue with this disorder. Like with the early-onset form, this disease form is linked to the Arnold-Chiari malformation, in which the brain is pulled or lowers into the top of the spine.
The disorder progresses with age, but the aforementioned treatments can help prevent or sometimes relieve symptoms. With treatment, individuals with tethered spinal cord syndrome have a normal life expectancy. However, most neurological and motor impairments are irreversible.
Occult tight filum terminale
In this variation, the filum terminale (which joins the spinal cord to the backbone) thickens or hardens and causes downward pressure on the spinal cord. This can actually cause scoliosis as well as most of the other symptoms of the more typical tethered cord. This syndrome was first noticed and documented in the late 19th century.
- Tethered Spinal Cord, Columbia University Dept of Neurosurgery
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