Tethered Cord Syndrome (TCS) is a neurological disorder where tissue attachments limit the movement of the spinal cord within the bony spinal column. Normally, the spinal cord floats freely, but in TCS, an abnormal anchor holds the cord taut. This anchoring causes the spinal cord to stretch and sustain injury, particularly during growth or movement. The condition is progressive, meaning neurological damage can worsen over time without intervention.
Understanding the Spinal Anatomy of Tethered Cord
The spinal cord typically ends in the conus medullaris, which normally rests at or above the L1-L2 vertebral disk space in adults and older children. Below this point, the filum terminale, a thin, non-neural filament, extends down to the tailbone. In a healthy spine, the filum is flexible, allowing the spinal cord to glide freely within the spinal canal during movement and growth.
When TCS is present, the spinal cord is held under tension by an abnormal attachment, often a thickened or fatty filum terminale. This tension pulls the conus medullaris down to an abnormally low position, typically below the L2 level. The constant mechanical stretching impairs the blood supply to the lower spinal cord segment, leading to chronic ischemia and subsequent nerve tissue damage.
The condition is categorized into primary (congenital) and secondary (acquired) tethering. Primary tethering is present from birth, often due to developmental abnormalities like a tight filum terminale or a lipoma. Secondary tethering develops later in life, commonly resulting from scar tissue formation following prior spinal surgery or injury.
The inability of the spinal cord to move freely means that any lengthening of the spinal column, such as during a growth spurt or bending, places mechanical strain on the neural tissue. This chronic traction on the lower spinal nerves interferes with their function, causing progressive symptoms.
Recognizing the Clinical Signs and Symptoms
The manifestations of TCS vary significantly depending on the patient’s age, often becoming noticeable as the body grows. In infants and young children, a common presentation involves cutaneous stigmata, which are visible skin signs on the lower back. These can include:
- Patches of excessive hair growth
- Deep dimples
- Skin tags
- Fatty lumps (lipomas) over the spine
Early neurological signs in children frequently involve orthopedic issues, such as foot deformities, leg length discrepancies, or an abnormal gait. Bladder function is also commonly affected, presenting as difficulty with toilet training or sudden urinary incontinence. Young children rarely complain of back pain, making these other indicators important.
In adults and older adolescents, symptoms are dominated by pain and progressive neurological dysfunction. Patients often experience severe lower back and leg pain, which worsens with physical activity or prolonged standing. This pain may radiate down the legs, mimicking sciatica, and is often accompanied by muscle weakness, numbness, or sensory loss in the lower extremities.
A significant symptom in adults is the deterioration of bladder and bowel control, manifesting as urinary urgency, frequent urination, or difficulty completely emptying the bladder. These symptoms reflect the direct impact of cord tension on the nerves controlling pelvic organ function. Symptoms tend to worsen gradually over time due to the progressive nature of the condition.
Methods for Diagnosis and Confirmation
Diagnosis begins with a neurological examination to assess motor function, reflexes, and sensation in the lower body. The physician looks for cutaneous signs, foot deformities, and gait abnormalities that frequently accompany the disorder. A detailed review of bladder and bowel function is also included.
Imaging technology provides definitive confirmation of tethering. Magnetic Resonance Imaging (MRI) is the standard method used to visualize the spinal cord, its attachments, and surrounding structures. The MRI scan clearly shows the position of the conus medullaris; a termination point below the L2 level is a strong indicator of a tethered cord in adults and older children.
The scan also identifies the physical cause of the tethering, such as a thickened filum terminale, a lipoma, or scar tissue from previous surgery. In some cases, a specialized MRI protocol may be used to assess spinal cord mobility by scanning the patient in both prone and supine positions.
To objectively evaluate the neurological impact of tethering on the bladder, specialized urodynamic studies are often performed. These tests measure bladder capacity, pressure, and the coordination between the bladder muscle and sphincter, providing quantifiable data on nerve function. An abnormal urodynamic result, even with minimal urinary symptoms, can support the need for intervention.
Surgical and Monitoring Treatment Approaches
Treatment for symptomatic TCS is primarily surgical, aiming to release the abnormal tension on the spinal cord and prevent further neurological damage. This procedure, known as detethering surgery, is typically performed by a neurosurgeon using a microsurgical approach. The surgeon makes a small incision in the lower back to access the spinal cord and sever the tissue attachment, such as the tightened filum terminale or scar tissue.
Although the procedure is often successful in stabilizing or improving existing symptoms, the main purpose is to halt neurological deterioration. Pain relief is a consistently reported benefit following detethering, and stabilization of lower extremity function and bladder control are common outcomes.
For patients who are asymptomatic or have very mild symptoms, a non-surgical approach called watchful waiting may be recommended. This involves close, regular surveillance, including periodic neurological exams and imaging studies. This monitoring strategy is relevant for adults with stable, mild symptoms where surgical risks may outweigh the benefits of immediate intervention.
Once symptoms begin to progress, surgery is generally advised to avoid irreversible nerve damage. Post-operative care involves a brief period of restricted activity for healing. Long-term follow-up is necessary to monitor for retethering, which can occur, especially in growing children. Management often includes physical therapy to address any residual motor or gait issues.