Selective Dorsal Rhizotomy (SDR) for Cerebral Palsy

Introduction

If your child has spastic cerebral palsy, you have probably been told that the tightness in their legs — the stiffness that makes walking, standing, or stretching difficult — comes from signals in the spinal cord that the brain can no longer fully control. Selective dorsal rhizotomy, usually shortened to SDR, is a neurosurgical operation designed to reduce that tightness at its source. It is one of the few treatments for cerebral palsy that aims to permanently lower spasticity rather than manage it day by day with medication or injections.

SDR is a major decision. It is irreversible, it requires a long period of intensive rehabilitation afterwards, and it is not suitable for every child with cerebral palsy. This article is written for parents and families who are already considering SDR for their child — perhaps because a paediatrician, neurologist, or physiotherapist has raised it, or because you have been researching options for managing spasticity. It walks through what SDR is, who is considered a good candidate, what the alternatives are, what the surgery and recovery involve, and what life tends to look like in the months and years afterwards.

What Is Selective Dorsal Rhizotomy?

Selective dorsal rhizotomy is a surgical procedure performed on the lower part of the spinal cord. The word “rhizotomy” means cutting nerve roots. “Dorsal” refers to the sensory nerve roots, which carry information from the muscles and skin back up to the spinal cord, as opposed to the motor nerve roots that carry movement signals out to the muscles. “Selective” means the surgeon does not cut all of the sensory rootlets — only the specific ones that are sending abnormal signals contributing to spasticity.

To understand why this works, it helps to know what spasticity is. In spastic cerebral palsy, the brain injury that occurred before, during, or shortly after birth disrupts the normal control the brain exerts over reflexes in the spinal cord. Without that control, a feedback loop forms: muscles send sensory signals up to the spinal cord, the cord sends amplified motor signals back, and the muscles tighten. This loop produces the stiff, hard-to-move muscles that families recognise as spasticity. By cutting a portion of the sensory rootlets that feed into this loop — the ones that intra-operative testing identifies as most abnormal — the surgeon reduces the amplification, and the muscles relax.

The result is a permanent reduction in spasticity in the muscles supplied by those nerve roots, which are the muscles of the legs, hips, and trunk. SDR does not cure cerebral palsy. The underlying brain injury is unchanged. What changes is the tone in the muscles, which then opens a window for the child to build strength, balance, and movement patterns through intensive physiotherapy.

Why Is SDR Performed?

SDR is performed to reduce spasticity in the legs of children with spastic cerebral palsy. Reducing spasticity is not an end in itself — the goal is to improve function. Depending on the child, that may mean walking with less effort, walking longer distances, walking with fewer assistive devices, sitting more comfortably, being easier to dress and position, or being able to stretch and care for the legs without pain.

Neurosurgical teams describe the goals of SDR along a spectrum:

• Functional gains in independent walkers. For children who already walk but with significant stiffness, crouch, or scissoring, SDR aims to make walking easier, more efficient, and more sustainable into adulthood.
• Improved mobility in children who walk with assistance. For children who use walkers or crutches, SDR may make assisted walking less tiring and reduce the energy cost of movement.
• Easier care and comfort in children with more severe involvement. For children who do not walk and are not expected to, SDR is sometimes performed with the goal of reducing painful spasticity, making positioning, hygiene, and stretching easier, and slowing the development of hip and joint problems. This is a different goal from functional walking gains and is decided case by case.

The decision to perform SDR rests on whether spasticity is the main barrier to a child’s function and comfort — as opposed to weakness, poor balance, dystonia (a different type of abnormal movement), or fixed contractures of the joints. Surgical teams assess this carefully before recommending SDR.

Who Is a Candidate?

SDR is not for every child with cerebral palsy. Decades of clinical experience have narrowed down the profile of children who tend to benefit most. The candidacy criteria used by experienced SDR centres are reasonably consistent worldwide, although they vary at the edges.

The classic candidate

The child for whom SDR is most commonly considered has:

• Spastic diplegia. This is the form of cerebral palsy in which both legs are predominantly affected, usually with the arms less involved or not involved.
• An identifiable cause typical of premature birth. Many candidates were born preterm and have a pattern of brain changes (called periventricular leukomalacia) seen on MRI.
• Pure spasticity, not mixed tone. The tightness is spastic in character, without significant dystonia, athetosis (writhing movements), or ataxia (coordination problems).
• Good underlying strength. When the surgeon or physiotherapist passively moves the legs and the spasticity is reduced, there is enough underlying muscle strength to produce useful movement.
• Good motivation and cognitive ability to engage in rehabilitation. The child should be able to participate in months of intensive physiotherapy after surgery.
• Family commitment to the rehabilitation programme. SDR without intensive rehabilitation does not produce its full benefit. Families must be prepared for the time, effort, and consistency this requires.

The role of GMFCS level

Cerebral palsy severity is often described using the Gross Motor Function Classification System (GMFCS), a five-level scale where Level I is the most mobile and Level V the most dependent. Many SDR programmes focus on children at GMFCS Levels II and III — children who walk, sometimes with assistive devices, and for whom spasticity reduction is likely to produce meaningful functional improvement. Some centres also operate on selected children at GMFCS Levels IV and V, with the goal of comfort and ease of care rather than walking gains. GMFCS Level I children are sometimes considered if spasticity is clearly limiting them. Practice varies between centres.

Age considerations

SDR is most often performed between roughly 3 and 10 years of age. This range reflects several factors: the child needs to be old enough to participate in the assessment and rehabilitation, but young enough that the bones, joints, and walking patterns have not yet developed fixed deformities that surgery cannot help. Some teams perform SDR in older children and adolescents in selected cases, and a smaller number of adult patients have undergone SDR for long-standing spasticity. The earlier window is generally preferred because the benefits of reduced spasticity have more time to translate into developmental gains.

Who is not a good candidate

SDR is typically not recommended when:

• The dominant problem is dystonia or another movement disorder rather than spasticity
• There are fixed contractures or joint deformities that orthopaedic surgery, not rhizotomy, needs to address
• Underlying muscle strength is too low to support useful movement once spasticity is removed
• The child has significant scoliosis or spinal abnormalities that complicate the surgery
• The family cannot commit to the post-operative rehabilitation programme

The full candidacy decision is made by a multidisciplinary team that typically includes a paediatric neurosurgeon, a paediatric neurologist or developmental paediatrician, a physiotherapist experienced in cerebral palsy, and often an orthopaedic surgeon. The assessment usually involves a detailed examination, a gait analysis if the child walks, video recording, and review of imaging.

Alternatives to SDR

SDR is one of several approaches to managing spasticity in cerebral palsy. Most children will have already tried some of the following before SDR is considered, and many will continue some of them afterwards. Understanding the alternatives helps families weigh the SDR decision in context.

Oral medications

Medications such as baclofen, diazepam, and tizanidine can reduce spasticity throughout the body. They are widely used but often limited by side effects such as drowsiness, weakness, and reduced alertness, which can interfere with learning and function. Oral medications are typically a partial solution rather than a definitive one.

Botulinum toxin injections

Botulinum toxin (often known by the brand name Botox, among others) is injected directly into specific spastic muscles and reduces tone in those muscles for roughly three to six months. It is widely used in children with cerebral palsy, often in combination with physiotherapy and bracing. The effect is temporary and the injections must be repeated. Botulinum toxin is well-suited to targeting a few specific muscles and is often the first-line interventional approach when spasticity is focal rather than widespread.

Intrathecal baclofen pump

An intrathecal baclofen pump is a small device implanted under the skin of the abdomen, with a thin catheter that delivers liquid baclofen directly into the fluid around the spinal cord. Because the medication is delivered where it acts, much smaller doses are effective and the sedating side effects of oral baclofen are largely avoided. The pump must be refilled at regular intervals and replaced when the battery runs out, typically every several years. Intrathecal baclofen is reversible (the pump can be turned off or removed) and adjustable. It is often considered for children with more severe spasticity, including those with significant arm involvement or mixed tone, and for those in whom SDR is not suitable.

Orthopaedic surgery

When spasticity has produced fixed contractures, hip dislocation, scoliosis, or bony deformities, orthopaedic surgery is often needed. This can include tendon lengthening, muscle releases, bone rotational surgery, and hip reconstruction. Many children with cerebral palsy will need orthopaedic procedures at some point in their growth, whether or not they have SDR. SDR and orthopaedic surgery are not alternatives in the strict sense — they address different problems and are often combined in a child’s overall care plan.

Physiotherapy, occupational therapy, and orthotics

Underlying all of these options is ongoing therapy and bracing. No surgical or medical treatment for spasticity replaces the role of therapy in building strength, balance, coordination, and functional skills. Therapy continues before SDR, during the post-operative rehabilitation, and for years afterwards.

How SDR compares

The distinctive feature of SDR is that it produces a permanent reduction in spasticity in the legs without an implanted device and without ongoing medication. It is irreversible, which is both its main advantage and its main risk. Doctors and families consider SDR when spasticity is widespread enough that injections alone are insufficient, when permanent reduction is preferred to the ongoing management of a baclofen pump, and when the child’s overall profile fits the candidacy criteria.

Preparing for SDR

Preparation for SDR is unusually thorough because the surgical decision and the rehabilitation plan are tightly linked. Families typically spend weeks or months in preparation.

The multidisciplinary assessment

A formal SDR assessment usually involves:

• Detailed clinical examination of tone, strength, range of motion, reflexes, and joint position in every muscle group
• Gait analysis for children who walk — sometimes using video, sometimes using a computerised gait laboratory with sensors
• MRI of the brain and spine to confirm the cerebral palsy pattern, look for periventricular leukomalacia or other findings, and check the anatomy of the lumbar spine where surgery will be performed
• Hip and spine X-rays to identify any deformities that need attention before or alongside SDR
• Cognitive and motivational assessment, particularly the child’s ability to engage with rehabilitation
• Detailed conversation with the family about realistic expectations and the demands of post-operative rehabilitation

Setting expectations

One of the most important parts of preparation is honest discussion about what SDR will and will not do. SDR almost always reduces spasticity. Whether that translates into the specific functional gains a family hopes for — walking independently, walking without a walker, climbing stairs — depends on factors beyond spasticity, including underlying strength, balance, motivation, the quality of rehabilitation, and the child’s starting point. Experienced surgical teams discuss specific, individualised goals rather than promising particular outcomes.

Practical preparation

Families are usually asked to:

• Arrange for an extended stay at or near the hospital, since post-operative rehabilitation often takes place in-patient or as a daily intensive outpatient programme for several weeks
• Plan for time away from school for the child, with arrangements for catch-up
• Plan for a parent or carer to be present continuously during the early recovery period
• Prepare the home for limited mobility on return — ramps, ground-floor sleeping, accessible bathroom
• Continue pre-operative physiotherapy to optimise strength as much as possible going in

What Happens During SDR

SDR is performed under general anaesthesia and takes several hours. The child is positioned face-down on the operating table.

The surgical approach

The surgeon makes an incision in the lower back, over the lumbar spine. There are two main variations in technique:

• Single-level approach. The surgeon removes a small portion of bone at one level of the spine (commonly around L1) to expose the lower end of the spinal cord, where the nerve roots gather into a structure called the cauda equina (Latin for “horse’s tail”).
• Multi-level approach. The surgeon exposes the nerve roots over several spinal levels, identifying each pair of roots where they exit the spinal cord.

Both approaches are in current use at experienced SDR centres. The choice depends on the surgeon’s training and the specific anatomy. Outcomes are broadly similar.

Identifying the sensory rootlets

Once the nerve roots are exposed, the surgeon and a neurophysiologist work together. The sensory (dorsal) roots are separated from the motor (ventral) roots. Each sensory root is then divided into smaller bundles called rootlets — typically three to seven rootlets per root.

Intra-operative testing

This is the “selective” part of selective dorsal rhizotomy. Each rootlet is stimulated electrically while the neurophysiologist watches and records muscle responses in the legs. Rootlets that produce abnormal, spread-out, or sustained muscle responses — the electrical signature of the spastic feedback loop — are identified as the ones contributing most to spasticity. Rootlets that produce normal, contained responses are preserved.

Length of surgery

The first days after surgery

Children usually spend the first one to two days in a closely monitored setting. The back is sore and the child is kept lying flat for a period (typically one to several days, varying by centre) to protect the surgical site and reduce the risk of spinal fluid leakage. Pain is managed with medication, and the surgical team monitors for any complications.

One of the things families notice almost immediately is how floppy the legs feel. The spasticity that was present for years is, in many cases, dramatically reduced from the moment the child wakes up. This is striking but also a reminder of why rehabilitation matters — the child is now relying entirely on their underlying muscle strength, which is usually weaker than the spastic tone made it appear.

The early rehabilitation phase

Within the first week, physiotherapy begins. This typically starts with gentle range-of-motion work and progresses to sitting, standing with support, and stepping over the following weeks. The pace varies, but most children begin standing and taking some steps with support within two to four weeks of surgery.

This early phase usually takes place in an in-patient rehabilitation setting or as a daily intensive outpatient programme. Sessions are typically several hours a day, focused on:

• Rebuilding strength in the hip, thigh, and core muscles
• Relearning movement patterns without the spasticity that had been there since birth
• Improving balance and trunk control
• Working on transfers, standing, and walking with appropriate assistance

The first six to twelve months

Intensive rehabilitation typically continues for at least six to twelve months after SDR. The early intensive period (often the first three months) is followed by ongoing physiotherapy at home, in the community, or at school. Most children continue to make functional gains throughout the first year and often beyond, as muscles strengthen and movement patterns refine.

The intensity of this period cannot be overstated. Families often describe it as a second job. The trajectory of a child’s gains after SDR is closely tied to the consistency of rehabilitation during this window.

The role of orthotics and bracing

Ankle-foot orthoses (AFOs) and other braces are usually continued or adjusted after SDR. As tone changes, bracing prescriptions are often updated.

Beyond the first year

Functional gains continue to develop over years. Children typically remain under regular review by a paediatric rehabilitation team and a physiotherapist. As the child grows, new orthopaedic needs may arise, and some children go on to have orthopaedic surgery in adolescence even after a successful SDR.

Risks and Complications

SDR is a major operation on the spinal cord, and although serious complications are uncommon at experienced centres, families should understand the risks before consenting.

Short-term surgical risks

• Bleeding and infection at the surgical site — uncommon but possible after any spinal surgery
• Spinal fluid leak from the membrane that surrounds the spinal cord — usually managed with bed rest or, occasionally, a further procedure
• Anaesthesia-related complications — risks similar to those of other major paediatric surgery
• Pain and muscle spasms in the first days after surgery, usually managed with medication

Sensory and bladder changes

Because SDR cuts sensory nerve fibres, some children experience temporary changes in skin sensation in the legs — tingling, numbness, or hypersensitivity — in the early weeks. These usually settle. Temporary changes in bladder or bowel function can occur but are uncommon when surgery is performed by experienced teams using intra-operative monitoring.

Weakness

SDR removes the spasticity that, in some children, was providing a degree of postural support. Once spasticity is reduced, the underlying muscle weakness becomes visible. This is expected and is the reason intensive strengthening rehabilitation is essential. Without rehabilitation, weakness rather than spasticity becomes the limiting factor.

Long-term concerns

• Spinal deformity. There has historically been concern about whether SDR contributes to scoliosis or other spinal problems later in life, particularly with multi-level approaches. Modern single-level techniques aim to minimise this. Long-term follow-up by orthopaedic and rehabilitation teams is part of standard care.
• Continued need for orthopaedic surgery. SDR does not eliminate the chance of future orthopaedic procedures. Some children still need tendon lengthening, hip surgery, or other interventions as they grow.
• Recurrence of spasticity. True recurrence of the original spasticity is uncommon, but some children develop residual tightness, often related to growth, that may need further management with botulinum toxin, oral medications, or orthopaedic surgery.

The irreversibility point

The most important thing for families to understand is that SDR cannot be undone. Once sensory rootlets are cut, they are cut. This is why patient selection is so careful, and why families are encouraged to take the time they need before deciding.

Life After SDR

The first year after SDR is intense, but for most children and families, the longer-term picture is one of gradual, sustained gain. Published clinical experience consistently shows that most children with appropriate candidacy maintain a substantial reduction in spasticity for many years and often into adulthood. Functional gains — walking ability, ease of care, posture, comfort — vary more than the spasticity reduction itself, because function depends on many factors beyond tone.

What changes

• Tone. Spasticity in the legs is reduced, often dramatically, and the reduction is durable.
• Movement quality. Walking, sitting, and transfers become smoother as rehabilitation progresses, particularly for children who started at GMFCS Levels II and III.
• Comfort. Painful spasms and tightness usually decrease.
• Ease of care. For children with more severe involvement, dressing, positioning, and hygiene typically become easier for the family.
• Energy cost of movement. Many children report and demonstrate less fatigue with daily activities.

What does not change

• The underlying brain injury
• Any cognitive, speech, vision, or seizure issues associated with cerebral palsy
• Dystonia, athetosis, or ataxia if present alongside spasticity
• The need for ongoing therapy, monitoring, and sometimes further surgery as the child grows

School and daily life

Most children return to school within a few months of surgery, sometimes initially on a part-time basis. Physiotherapy continues alongside school for at least the first year. Families often work with the child’s school to coordinate physical activity, adapted physical education, and any needed accessibility supports.

Adolescence and adulthood

Children who have had SDR are followed into adolescence and adulthood by paediatric rehabilitation services and, later, adult services. Growth spurts can bring changes in tightness and joint alignment that need attention. Many young adults who had SDR in childhood describe sustained benefits decades later, particularly in walking endurance and comfort.

SDR in Adults

Although SDR is overwhelmingly a paediatric procedure, a smaller number of adults with long-standing spastic cerebral palsy have undergone SDR. Adult candidacy is more selective: fixed contractures, established walking patterns, and the lower potential for nervous-system adaptation in adults make outcomes less predictable. Some adults do report meaningful reductions in spasticity and improvements in comfort and mobility. Adult SDR is a specialist decision and is offered at relatively few centres.

Choosing a Surgical Team

SDR is a specialist procedure performed at centres with dedicated paediatric neurosurgery, paediatric neurophysiology, and intensive paediatric rehabilitation. When families are evaluating where to have surgery, things that surgical teams and patient organisations commonly suggest looking at include:

• Whether the centre performs SDR regularly, with a clearly experienced paediatric neurosurgeon
• Whether intra-operative neurophysiological monitoring is standard practice
• Whether the centre has an established paediatric rehabilitation programme, ideally on the same site, with experience in post-SDR recovery
• Whether the assessment process is multidisciplinary, with neurology, neurosurgery, physiotherapy, and orthopaedics involved in candidacy decisions
• How the centre communicates expected outcomes — honest, individualised goal-setting rather than generic promises
• Whether long-term follow-up is part of the care pathway

Frequently Asked Questions

Will SDR allow my child to walk?

This is the most common question and the one most difficult to answer in general terms. SDR reduces spasticity. Whether that reduction translates into independent walking depends on the child’s starting point, underlying strength, balance, and how they respond to rehabilitation. Children who are already walking with assistance often gain walking independence or efficiency. Children who are not walking before surgery sometimes do walk afterwards, but this is not the typical goal for children who are significantly affected. Honest individualised goal-setting with the surgical team is essential.

Is SDR permanent?

Yes. The cut nerve rootlets do not grow back. The reduction in spasticity is durable, and clinical experience shows it is maintained for many years and often into adulthood.

Can SDR be combined with orthopaedic surgery?

Yes. Many children eventually need orthopaedic procedures — for tendon lengthening, hip alignment, or scoliosis — alongside or after SDR. Some centres plan SDR and orthopaedic surgery in a coordinated sequence. SDR is best done before fixed bony deformities develop, where possible.

How long is my child in hospital?

The acute hospital stay after surgery is typically one to two weeks, depending on the centre. This is often followed by several weeks of in-patient or daily intensive rehabilitation. Families should plan for several weeks away from home in total, with the exact length discussed with the surgical team.

Will my child still need physiotherapy after SDR?

Yes — and intensively. The first six to twelve months involve far more physiotherapy than most children had before surgery. Ongoing therapy continues for years. SDR works best when paired with consistent rehabilitation.

What if my child also has dystonia?

SDR is designed for spasticity, not dystonia. If dystonia is significant, SDR is usually not the right procedure, and other options — including intrathecal baclofen and, in selected cases, deep brain stimulation — are considered. Some children have a mix of tone, and the dominant pattern matters to the decision.

Is there an age limit?

SDR is most often performed between roughly 3 and 10 years of age, though older children, adolescents, and selected adults are sometimes operated on. The reasoning is biological (development and bone alignment) rather than a hard rule.

Will my child still need a wheelchair or walker?

It depends on starting function. Some children move from walker to crutches, or from crutches to independent walking. Others continue to use the same assistive devices but with less effort. For children with more severe involvement, the goal is usually comfort and ease of care rather than changes in mobility devices.

What is the difference between SDR and a baclofen pump?

SDR is a one-time surgery that permanently reduces spasticity in the legs by cutting selected sensory nerve rootlets. An intrathecal baclofen pump is an implanted, adjustable, reversible device that delivers anti-spasticity medication directly to the spinal cord. SDR is often preferred for children with spastic diplegia and good strength. A baclofen pump is often considered for children with more widespread spasticity, mixed tone, or when irreversibility is a concern. The two are sometimes complementary at different points in a child’s care.

Conclusion

Selective dorsal rhizotomy is one of the most significant surgical decisions a family can make for a child with spastic cerebral palsy. It offers something few other treatments offer: a permanent reduction in spasticity, achieved in a single operation, with the potential to change how a child moves and feels for the rest of their life. It also asks a lot — careful selection, a major operation on the spinal cord, and many months of intensive rehabilitation. The right decision is the one made carefully, with a multidisciplinary team that knows your child, with realistic and individualised goals, and with the time and support to think it through fully.