What is tethered cord syndrome?

What is Tethered Cord Syndrome

Tethered cord syndrome is a neurological disorder caused by abnormal physical stretching and fixation of the spinal cord to surrounding tissues, resulting in impaired blood flow, diminished oxidative metabolism, and metabolic failure at the mitochondrial level that produces progressive neurological deterioration. 1

Pathophysiology

The fundamental problem in tethered cord syndrome involves physical stretching of the spinal cord that impairs blood flow and causes diminished oxidative metabolism and glucose utilization, with metabolic failure occurring at the mitochondrial respiratory chain level. 1 The severity and reversibility of these metabolic disturbances directly correlate with both the severity and chronicity of the tethering—meaning earlier intervention offers better potential for recovery. 1

In the healthy spine, the spinal cord moves freely with spinal fluid pulsation in rostral and caudal directions, but when the cord becomes attached to lesions within the spinal column, excess strain causes the characteristic signs and symptoms. 2 The conus medullaris normally ends at the L1-L2 disc space by 2 months after birth, and a conus ending below the middle third of L2 is considered tethered. 3

Clinical Presentation by Age

Infants

• Often completely asymptomatic, with malformations recognized solely by associated cutaneous abnormalities (such as sacral dimples, hairy patches, or lipomas). 1
• Urinary tract infection is the predominant sign when symptomatic. 4
• Urinary retention occasionally occurs. 4

Children (Toilet-Trained to Adolescence)

• Secondary urinary incontinence, especially combined with fecal incontinence and/or constipation, is the most common presentation. 4
• Pain (back and/or leg pain that may be dull, aching, sharp, lancinating, electrical, or dysesthetic). 3
• Sensorimotor disturbances of the lower limbs. 1
• Progressive musculoskeletal deformities and scoliosis (occurring in up to 75% or more of patients). 4
• Urinary tract infections remain common. 4
• Urgency, urge incontinence, sudden or stress incontinence, new-onset enuresis, urinary frequency, and nocturia. 4

Teenagers and Adults

• Pain radiating into the groin, genitals, and/or perianal region. 1
• Sensory abnormalities. 1
• Urinary and fecal urgency/incontinence. 1
• Urinary tract infections. 1
• Motor deficits (present in 63% of adult patients in one large cohort). 2
• Pain is the most common symptom overall, occurring in 81% of adult patients. 2

Associated Conditions and Risk Factors

Congenital Malformations

• Myelomeningocele (the most common dysraphic malformation). 3
• Spinal lipomas and fatty infiltrations of the filum terminale. 3
• Lipomyelomeningocele. 5
• Meningoceles and atretic meningoceles. 3

Anorectal Malformations

Between 10% and 52% of children with anorectal malformations have associated dysraphic malformations, with higher association in complex (43%) compared to simple anorectal malformations (11%). 4

Syndromic Associations

TCS occurs in 11% of pediatric patients with KBG syndrome (caused by ANKRD11 gene variants), with an additional 24% being investigated for the condition. 6

Diagnostic Evaluation

Imaging

• MRI of the lumbar spine is indicated in patients with lower limb upper motor neuron signs, presence of a sacral dimple, or other symptoms suggestive of tethered cord syndrome. 1
• MRI provides better visualization of soft tissue, bone marrow, and spinal canal compared to other modalities. 3
• Plain abdominal radiograph may reveal bony abnormalities of the spine. 4

Urologic Assessment

Urologic function assessment is essential and should include: 1

• History focusing on incontinence, frequency, and repeated urinary tract infections. 4
• Renal ultrasonography to evaluate for hydroureter/hydronephrosis, and bladder abnormalities (small, enlarged, or trabeculated bladder). 4
• Formal urodynamic testing showing either:
  • Enlarged bladder capacity with detrusor underactivity and denervation in external urethral sphincter (lower motor neuron dysfunction), OR 4
  • Small, thick-walled bladder with detrusor overactivity and detrusor sphincter dyssynergia (upper motor neuron dysfunction). 4

A urodynamic evaluation before surgical correction provides baseline information about sacral spinal cord involvement for postoperative comparison. 4

Key Clinical Patterns

Red Flag Combinations

Urologic and/or gastrointestinal symptoms in a child with a cutaneous midline skin lesion OR with leg pain, sensorimotor loss, orthopedic deformity, or gait disturbance strongly suggests underlying spinal cord tethering. 4

Progression as a Warning Sign

Progression of symptoms is an important feature that suggests an underlying dysraphic malformation with spinal cord tethering and warrants urgent evaluation. 4 Long-standing untreated tethering results in progressive musculoskeletal deformities, scoliosis, muscle atrophy, and orthopedic deformities of the feet and spine. 3 The skin of the leg and foot may become thin, shiny, and hairless due to autonomic changes. 3

Treatment Considerations

Surgical untethering (detethering) is indicated in patients with progressive or new onset symptomatology. 7 Early operative intervention is associated with improved outcomes, with pain relief accomplished in almost all cases (81% of patients report pain improvement after detethering). 2, 7 Realistic surgical goals include relief of pain and stabilization of neurological function, though improvement in function is often seen. 7

Although tethered cord release is effective in arresting or improving neurologic symptoms, sensorimotor dysfunction, or urologic deterioration, long-standing or severe orthopedic deformities are unlikely to improve and may require subsequent orthopedic intervention. 4

Follow-Up Requirements

• Continued urologic assessment is necessary. 1
• Orthopedic follow-up is required for associated deformities. 1
• Physical, occupational, and speech therapies may be necessary to maximize function. 1