Selective Dorsal Rhizotomy (SDR) is a neurosurgical procedure developed to permanently address severe muscle spasticity, a form of continuous muscle tightness resulting from hyperactive reflex arcs within the spinal cord. The surgery works by targeting and interrupting the abnormal nerve signals that cause muscles, primarily in the lower limbs, to contract involuntarily and excessively. Spasticity occurs due to damage to the brain or spinal cord, leading to an over-responsive stretch reflex that makes movement difficult and often painful. SDR is a selective intervention designed to correct this imbalance by reducing overactivity and improving muscle tone and overall motor function.
Patient Selection and Eligibility Criteria
The primary patient population considered for SDR is children diagnosed with spastic diplegic cerebral palsy, where spasticity mainly affects both legs. Ideal candidates have generalized spasticity that significantly interferes with walking, balance, or daily care activities, rather than fixed contractures. The typical age range is between 3 and 8 years old, allowing for maximal benefit before severe orthopedic deformities develop. The child must also have the cognitive ability to cooperate with the intensive post-operative physical therapy program and possess adequate underlying muscle strength.
Pre-operative assessment includes a detailed neurological and orthopedic examination, often involving gait analysis. This analysis determines if movement difficulties stem from spasticity or other issues like fixed deformities. Patients with fixed joint contractures, significant scoliosis, or very poor motor control are generally not suitable candidates. The multidisciplinary team ensures the patient has the resources to translate spasticity reduction into meaningful functional improvement.
The Selective Dorsal Rhizotomy Procedure
The SDR procedure is performed under general anesthesia by a neurosurgeon specializing in pediatric spinal surgery. The surgeon makes a small incision in the lower back, typically over the lumbar and sacral spine. A small portion of the bony arch of the vertebrae (lamina) is removed in a laminectomy to expose the spinal cord and nerve roots.
The surgeon identifies the dorsal nerve roots, which carry sensory information, and meticulously separates them from the ventral nerve roots, which carry motor signals and must remain intact. The dorsal root is then divided into several smaller bundles called rootlets.
Each dorsal rootlet is tested using an electrical stimulating electrode while a specialist monitors muscle responses via electromyography (EMG). Rootlets that are excessively hyperactive, causing abnormal muscle contraction, are identified as contributing to spasticity. Only a select percentage (20% to 50%) of these abnormal rootlets are cut in the rhizotomy process.
This selective cutting permanently interrupts the hyperactive reflex arc, achieving a permanent reduction of spasticity. By preserving the normal rootlets and leaving the motor roots untouched, the procedure maintains adequate sensation and motor function while restoring a more normal balance of nerve activity.
Post-Operative Recovery and Rehabilitation
The immediate post-operative phase involves a hospital stay, typically lasting two to five days, focusing primarily on pain management. Patients may experience discomfort at the incision site and temporary sensory changes. While a noticeable reduction in spasticity is immediate, this often reveals an underlying muscle weakness that the spasticity had previously masked.
The success of SDR hinges on the rigorous, intensive physical therapy (PT) program that must follow the surgery. Rehabilitation begins within days of the operation and continues intensively for at least six to twelve months. Since the muscles are free from constant tension, patients must learn new movement patterns and build functional strength.
Rehabilitation focuses on strengthening the relaxed muscles, improving balance, and training a more typical walking pattern. Therapy sessions are often required five or more times per week. This sustained effort is necessary to convert the permanent reduction in muscle tone into long-term functional gains, such as improved walking and mobility.
Anticipated Results and Functional Gains
The most significant result of SDR is the permanent reduction or elimination of targeted muscle spasticity. This reduction is sustained over the patient’s lifetime, preventing spasticity-induced orthopedic deformities. Removing constant muscle tightness improves joint range of motion and makes daily care activities, like dressing and hygiene, easier.
In terms of gross motor function, many patients experience improved balance, increased walking speed, and a more efficient gait pattern. Functional gains depend highly on the patient’s pre-operative strength and adherence to the intensive physical therapy regimen. For children who were already walking, the surgery improves the quality of their gait; for others, it may allow transition to less restrictive assistive devices.
Temporary side effects, such as mild back pain or changes in bladder function, are possible immediately after surgery but typically resolve. A slight decrease in leg sensation can occur, but it is usually minor and not functionally limiting. The long-term benefit is a fundamental change in muscle tone that provides a stable foundation for better mobility and an enhanced quality of life.