Tethered Cord Syndrome (TCS) is a neurological disorder where the spinal cord’s normal movement is restricted within the spinal canal. This restriction is caused by abnormal tissue attachments, typically involving the filum terminale, a delicate fibrous thread extending from the bottom of the spinal cord. While often associated with childhood congenital conditions, TCS frequently goes undiagnosed until adulthood. The later presentation in adults is due to cumulative mechanical strain reaching a threshold of tension, leading to progressive neurological decline.
The Anatomy of Tethering in Adults
TCS arises when the spinal cord’s lowermost point, the conus medullaris, is held fast by an inelastic structure, preventing free movement with the spine. This fixation is most commonly caused by a tight or thickened filum terminale. In a normal adult, the conus medullaris rests at or above the L1-L2 vertebral level, but in TCS, it is often positioned abnormally low.
The condition can be classified as primary (congenital), present from birth but causing symptoms later, or acquired. Acquired tethering results from scar tissue following prior spinal surgery, trauma, or infection. Everyday movements cause chronic traction on the spinal cord anchored at its base.
This constant stretching causes physical damage through reduced blood flow, known as ischemia, to the lower spinal cord. This chronic tension impairs the oxidative metabolism necessary for proper nerve function. Over time, this metabolic dysfunction leads to the progressive damage that manifests as adult-onset symptoms.
Specific Neurological and Pain Symptoms
Symptoms experienced by adults with TCS are generally progressive and often vague, mimicking other common spinal conditions. Pain is a frequent complaint, typically manifesting as persistent low back discomfort that worsens with activity or specific postures. Patients often report pain aggravation when bending forward, sitting upright with crossed legs, or carrying a weight at waist level, sometimes called the “3-B sign.”
The discomfort often radiates down the legs, hips, or into the genital and perineal areas, mimicking radiculopathy. This pain is accompanied by specific neurological deficits in the lower extremities. Patients may experience numbness, tingling, or progressive weakness that can lead to muscle atrophy and difficulty with gait. These sensory and motor changes can be patchy and do not always follow a standard dermatomal pattern.
Bladder and bowel dysfunction is a concerning set of symptoms that can indicate TCS. Patients frequently report urinary urgency, increased frequency, incontinence, or a sensation of incomplete bladder emptying. Bowel control issues, such as constipation, may also occur.
Some adults may exhibit subtle skin manifestations in the lumbosacral area, known as dermal stigmata. These can include a tuft of hair, a deep dimple, or a subcutaneous lipoma (fatty growth). Progressive foot deformities, such as high arches or curled toes, and the development of scoliosis can also be part of the clinical picture.
Confirming the Diagnosis
The diagnostic process begins with a detailed physical and neurological examination, focusing on pain, motor, and bladder symptoms. Since symptoms are often nonspecific, advanced imaging is necessary to confirm the diagnosis and rule out other causes of back and leg pain. Magnetic Resonance Imaging (MRI) is the imaging modality of choice for evaluating suspected TCS in adults.
The MRI allows clinicians to visualize the position of the conus medullaris within the spinal canal. A definitive sign of tethering is a conus medullaris that terminates below the lower border of the L2 vertebral body. Imaging also identifies structural abnormalities, such as a thickened filum terminale, which is considered abnormal if its diameter exceeds 2 millimeters.
The MRI also helps detect associated lesions like spinal lipomas, tumors, or syringomyelia. Specialized functional tests are used to quantify the extent of nerve damage. Urodynamic studies objectively assess the severity of bladder dysfunction. Nerve conduction studies, such as Electromyography (EMG), may also evaluate nerve and muscle damage in the lower extremities.
Surgical and Non-Surgical Management
Treatment is determined by the severity of symptoms and the presence of progressive neurological deficits. For patients with mild or stable symptoms, careful observation is the initial course of action. Non-surgical management focuses on supportive care and symptom relief, including pain management protocols and physical therapy to address muscle weakness and gait issues.
Bladder management protocols are often instituted to mitigate urinary symptoms. These non-surgical approaches treat the symptoms but do not address the underlying physical tension on the spinal cord.
Surgical intervention, known as detethering, is the primary treatment for symptomatic adults, aimed at releasing tension on the spinal cord. The goal is to restore normal mobility, often involving a limited laminectomy to access the affected area. If the filum terminale is the sole cause, the surgeon performs a sectioning of the filum, cutting the inelastic tether.
While surgery often stabilizes the condition or improves symptoms like pain and bladder function, long-standing neurological deficits may not fully reverse. Post-surgery, there is a risk of recurrence, known as re-tethering, due to the formation of new scar tissue, necessitating long-term follow-up. The prognosis is variable, with many patients experiencing stabilization or improvement in pain and motor functions.