What is tethered cord?

What is Tethered Cord?

Tethered cord syndrome is a clinical condition caused by abnormal fixation of the spinal cord to surrounding tissues, resulting in physical stretching of the cord that leads to impaired blood flow, diminished oxidative metabolism, and metabolic failure at the mitochondrial level. 1, 2

Anatomic Definition

• Radiographically, a conus medullaris (CM) ending below the middle third of the L2 vertebra is considered tethered, though clinical correlation is required to determine if this causes symptomatic tethered cord syndrome. 1
• Normally, the CM ends at the L1-L2 disc space by 2 months after birth, with the lowest normal level being the middle third of L2. 1

Pathophysiology

The core mechanism involves chronic mechanical stretching of the spinal cord that produces a cascade of metabolic dysfunction:

• Physical stretching impairs blood flow to neural tissue 1, 2
• This leads to diminished oxidative metabolism and glucose utilization 1, 2
• Ultimately causes metabolic failure at the mitochondrial respiratory chain level 1, 2
• The severity and reversibility of these metabolic disturbances directly correlates with the severity and chronicity of the tethering 1, 2

Embryologic Origins

Most cases result from disorders of primary or secondary neurulation:

• Dysraphic malformations (like myelomeningocele, dermal sinus tracts) create persistent anatomic connections between neuroectoderm and cutaneous ectoderm 1
• This persistent connection prevents proper ascent of the conus medullaris during development 1
• The result is a "tethered" spinal cord that remains abnormally fixed 1

Clinical Manifestations by Age

Infants

• Commonly asymptomatic at presentation 1, 2
• Malformations often recognized only by associated cutaneous abnormalities (midline skin lesions, dimples, hairy patches) 1, 2
• Urinary tract infections may be the predominant early sign 1

Children

• Pain (back and/or leg pain that may be dull, sharp, lancinating, or dysesthetic; aggravated by spinal flexion/extension or activity) 1
• Motor dysfunction (muscle weakness, gait disturbances, difficulty running, inability to keep up with peers during athletics, muscle atrophy with thinning of calf muscles or "saber shins") 1
• Sensory disturbances of lower limbs (typically starting distally and progressing proximally; occasionally "suspended" sensory loss) 1
• Bladder/bowel dysfunction (secondary urinary incontinence, fecal incontinence, constipation, urinary tract infections, urgency, frequency, enuresis) 1
• Progressive orthopedic deformities (foot deformities, progressive scoliosis, exaggerated lumbosacral lordosis) 1

Teenagers and Adults

• Pain may radiate into groin, genitals, and/or perianal region 1, 2
• Urinary symptoms include urgency, urge incontinence, stress incontinence, new-onset enuresis, frequency, nocturia 1, 2
• Fecal soiling often accompanies urinary symptoms 1, 2

Associated Conditions

Up to 75% of patients with spinal dysraphism present with lower extremity neurologic and orthopedic abnormalities from tethering. 1

• Anorectal malformations: 10-52% of children with anorectal malformations have associated dysraphic malformations (higher with complex vs. simple malformations) 1
• Urologic dysfunction: Can manifest as hydroureter/hydronephrosis, bladder abnormalities, detrusor dysfunction 1
• Scoliosis: Common manifestation of tethering 1

Key Clinical Pitfall

Progression is the critical feature that distinguishes pathologic tethering from static findings. 1 A child who was previously ambulatory but develops worsening gait, new incontinence after toilet training, or progressive orthopedic deformities should raise immediate concern for symptomatic tethered cord syndrome requiring evaluation. 1