Selective dorsal rhizotomy for spasticity in cerebral palsy

2.1 Indications and current treatments

2.1.1 Cerebral palsy encompasses different brain disorders originating during fetal development, birth or early childhood. It is associated with abnormalities of movement, balance and posture, language and vision. Lower limb spasticity affects 80% of people with cerebral palsy. This can impair walking and sitting, and can cause discomfort, cramps and spasms.

2.1.2 Current treatments include oral muscle relaxant medication, orthotic devices, physiotherapy, and repeated intramuscular injections of botulinum toxin. Surgical procedures include tendonotomy, tendon lengthening, peripheral neurotomy, osteotomy, electrical stimulation of the muscles or dorsal spinal cord, and continuous intrathecal baclofen infusion.

2.2 Outline of the procedure

2.2.1 The aim of selective dorsal rhizotomy is to achieve a long-term reduction in sensory input to the sensory–motor reflex arcs responsible for increased muscle tone, by dividing some of the lumbar sensory nerve roots.

2.2.2 With the patient under general anaesthesia, a laminectomy of one or more vertebrae is performed to expose the dural sac, which is opened to display the spinal conus with or without the cauda equina. Intraoperative neurophysiological assessment is commonly used to identify the sensory nerve rootlets judged to be most responsible for the excess motor tone. Selected sensory rootlets are divided, preserving some sensory supply and the motor roots responsible for voluntary movements.

2.2.3 Intensive physiotherapy and aftercare is usually given for several months after the procedure. Patients who were previously able to walk may have to learn different walking skills.

2.3 Efficacy

2.3.1 A non-randomised comparative study of 142 patients treated by the procedure (n = 71) or intrathecal baclofen pump (ITBP) (n = 71) reported improvements in Modified Ashworth Scale scores (measures muscle tone on a scale from 0 to 5; lower score indicates lower muscle tone) of −2.52 and −1.23 points respectively at 1-year follow-up (p < 0.0001).

2.3.2 A non-randomised comparative study of 108 patients treated by the procedure plus physiotherapy or physiotherapy alone reported mean improvements in Gross Motor Function Measure (GMFM) score (higher score indicates better gross motor functioning) from baseline of 87 to 92 and 89 to 91 respectively at 20-month follow-up (p < 0.05 for both groups from baseline).

2.3.3 The non-randomised comparative study of 142 patients treated by the procedure or ITBP reported that 94% and 96% of parents respectively were satisfied at 1-year follow-up (absolute figures not stated) (p = 0.71).

2.3.4 The Specialist Advisers listed key efficacy outcomes as reduction in lower limb spasticity, reduction in number of subsequent orthopaedic procedures, improved gross motor function, improved gait and walking, improved level of independence and quality of life.

2.4 Safety

2.4.1 Radiologically observed scoliosis was reported in 9% (5/58) of patients who had laminectomy and 1% (2/150) of patients who had laminoplasty in the case series of 208 patients at a mean follow-up of 4.2 years. The percentage of patients with scoliosis pre-operatively was not stated. Case series of 105, 98 and 30 patients reported scoliosis of 10° or more in 55% at 4.3 years, in 43% at 5.8 years, and scoliosis of less than 35° in 50% at 21.4 years respectively.

2.4.2 In a case series of 61 patients, 4 patients developed spondylolysis and grade-I spondylolisthesis between 3 and 5 years after the procedure.

2.4.3 Urinary retention due to decreased bladder tone and hyporeflexia was reported in 10% (20/208) of patients in the case series of 208 patients. This resolved spontaneously within 4 weeks in 18 patients but 2 patients had long term urinary incontinence because of atonic bladder.

2.4.4 The Specialist Advisers considered theoretical adverse events to include death, worsening motor function and/or paraplegia, wound infection, meningitis, cerebrospinal fluid leakage, dislocation of the hip(s), back pain, constipation, weakness, chronic pain, and late arachnoiditis and/or syringomyelia.

2.5 Other comments

2.5.1 The Committee noted that most of the evidence for this procedure relates to children aged 4–10 years. The Committee also noted that this procedure and patient selection for it are still evolving. Several commentators recommend limited laminectomy to reduce the risk of late spinal deformity, and others question the need for intraoperative neurophysiology.