What is tethered cord syndrome?

What is Tethered Cord Syndrome?

Tethered cord syndrome is a stretch-induced spinal cord disorder where the spinal cord becomes abnormally attached to structures within the spinal column, causing impaired blood flow, diminished oxidative metabolism, and metabolic failure at the mitochondrial level, leading to progressive neurological dysfunction. 1

Pathophysiology

The condition results from physical stretching of the spinal cord that restricts its normal movement with spinal fluid pulsation 2. This mechanical tension causes:

• Compromised blood supply to the distal spinal cord 1
• Diminished oxidative metabolism and glucose utilization 1
• Metabolic failure at the mitochondrial respiratory chain level 1
• The severity and reversibility of these metabolic disturbances directly correlate with how severe and chronic the tethering has become 1

Anatomical Definition

The conus medullaris (end of the spinal cord) normally terminates at the L1-L2 disc space by 2 months after birth 3. A conus medullaris ending below the middle third of the L2 vertebra is considered tethered 3.

Clinical Presentations by Age Group

Infants

• Often completely asymptomatic, with the condition recognized only by associated cutaneous abnormalities on the lower back 1
• Urinary tract infections may be the predominant sign, though urinary retention occasionally occurs 4

Children (After Toilet Training)

• Secondary urinary incontinence, especially combined with fecal incontinence and/or constipation is the most common presentation 4
• Pain (dull, aching, sharp, lancinating, electrical, or dysesthetic in character) 3
• Sensorimotor disturbances of the lower limbs 1
• Progressive musculoskeletal deformities and scoliosis 1
• Urinary frequency, urgency, and nocturia 4
• Pain may be aggravated by spinal flexion/extension or by walking/running 3

Teenagers and Adults

• Pain radiating into the groin, genitals, and/or perianal region 1
• Sensory abnormalities 1
• Urinary and fecal urgency/incontinence 1
• Recurrent urinary tract infections 1
• Motor deficits (present in 63% of adult cases) 2
• Pain is the most common symptom in adults, affecting 81% of patients 2

Associated Clinical Features

Urologic Dysfunction (Critical Presenting Feature)

• Incontinence, frequency, and repeated urinary tract infections 4
• Imaging may show hydroureter/hydronephrosis with small, enlarged, or trabeculated bladder 4
• Urodynamic testing reveals either:
  • Lower motor neuron dysfunction: enlarged bladder capacity with detrusor underactivity and denervation of external urethral sphincter 4
  • Upper motor neuron dysfunction: small, thick-walled bladder with detrusor overactivity and detrusor-sphincter dyssynergia 4

Orthopedic Manifestations

• 75% or more of patients present with lower extremity neurologic and orthopedic abnormalities 4
• Progressive scoliosis is common 4
• Muscle atrophy becomes apparent with long-standing tethering 3
• Orthopedic deformities of feet and spine may develop 3
• Skin of leg and foot may become thin, shiny, and hairless due to autonomic changes 3

Associated Malformations

• Between 10% and 52% of children with anorectal malformations have associated dysraphic malformations 4
• Higher association with complex (43%) versus simple (11%) anorectal malformations 4

Diagnostic Evaluation

Imaging

• MRI of the lumbar spine is indicated in patients with lower limb upper motor neuron signs, presence of sacral dimple, or other symptoms suggestive of tethered cord 1
• Plain abdominal radiograph may reveal bony spinal abnormalities 4
• Renal ultrasonography may show hydronephrosis and/or increased bladder wall thickness 4

Urologic Assessment

• History taking for incontinence, frequency, and urinary tract infections 4
• Formal urodynamic testing to assess bladder response to retrograde filling 4
• Urodynamic evaluation before surgical correction provides baseline for postoperative comparison 4

Common Pitfalls

Progression is the key feature that suggests underlying dysraphic malformation with spinal cord tethering 4. Do not dismiss new-onset symptoms in previously asymptomatic patients, particularly:

• Secondary urinary incontinence after successful toilet training 4
• New-onset enuresis in older children 4
• Combination of urinary and fecal symptoms 4

Cutaneous midline skin lesions combined with urologic/gastrointestinal symptoms, leg pain, sensorimotor loss, orthopedic deformity, or gait disturbance strongly suggests underlying spinal cord tethering 4.

Treatment Outcomes

Surgical untethering (tethered cord release) is effective in arresting or improving neurologic symptoms, sensorimotor dysfunction, and urologic deterioration 4. However:

• Long-standing or severe orthopedic deformities are unlikely to improve and may require subsequent orthopedic intervention 4
• Pain relief is accomplished in almost all surgical cases, with 81% of patients reporting improvement 2
• Early operative intervention is associated with improved outcomes 5

Required Follow-up

• 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