Spasticity, dystonia and tone management: SAQ

This child presents a classic tone-management decision in spastic diplegic cerebral palsy. The adductor and calf spasticity are limiting both function (scissoring and tip-toe gait) and care (nappy changing), so the tone is a legitimate treatment target. The goal-directed principle, the GMFCS level of two, the good selective motor control and the minimal dystonia together point toward focal botulinum toxin type A first, with selective dorsal rhizotomy as a definitive option to discuss with the family using the randomised-trial evidence. [1]

Question 1 (10 marks)

Outline how you would assess this child's tone, set the treatment goals with the family, and choose the first-line tone therapy for her adductor and calf spasticity. [1]

I would start with the goal-directed principle: tone is treated only when it limits function, comfort, care or participation, and for this child the adductor spasticity limits care and hygiene while the calf spasticity limits gait function, so both are legitimate targets. I would set SMART goals with the family using Goal Attainment Scaling, naming the concrete outcomes they want, such as easier nappy changing, a heel strike in gait, and a longer walking distance. [2]

My assessment would separate the spastic from the dystonic phenotype, because the therapy follows the phenotype. I would use the Modified Tardieu Scale, comparing the angle of catch at a fast velocity with the passive range at a slow velocity, to confirm that the tone is dynamic spasticity that a toxin can soften rather than a fixed contracture that needs surgery. I would grade the tone, test the deep tendon reflexes and clonus, and document the selective motor control, which is the best predictor of walking and of rhizotomy benefit. I would state her GMFCS level of two, which frames the functional goal and the modality, and I would examine the hips for pain and limited abduction and review her surveillance hip radiograph, because the spastic hip subluxes silently and the migration percentage must be below the thirty percent at-risk threshold. [1][3]

My first-line therapy for her focal adductor and calf spasticity is focal botulinum toxin type A, layered on the non-pharmacological foundation of a daily stretching and positioning program, an ankle-foot orthosis for the equinus, and serial casting if the range remains limited after injection. I would inject the overactive muscles individually, and I would counsel the family that the onset is two to seven days, the peak is around four weeks and the wear-off is at twelve to sixteen weeks, with the next cycle no sooner than twelve weeks to avoid neutralising antibodies. I would book a reassessment at four to six weeks with Goal Attainment Scaling and the Tardieu angle to show whether the injection met the goals. [1][5]

Question 2 (10 marks)

Discuss the role of selective dorsal rhizotomy in this child, the evidence that supports it, and the family counselling you would provide. [6]

Selective dorsal rhizotomy is the definitive operation for the ambulant spastic diplegic child, and this girl is a strong candidate because she is at GMFCS two, has good selective motor control, has minimal dystonia, has no major orthopaedic deformity on current imaging, and has a motivated family. The surgeon identifies the dorsal sensory rootlets from L2 to S1 and cuts a proportion of them, often around twenty-five to sixty-seven percent, to remove the afferent input that drives the spasticity in the legs. The aim is a durable reduction in leg spasticity and a reduced need for later orthopaedic surgery, not a new GMFCS level. [6]

The evidence is the cleanest in paediatric tone care. The McLaughlin meta-analysis of three randomised controlled trials showed that selective dorsal rhizotomy with therapy outperformed therapy alone for spastic diplegia in the younger child, and the Tedroff systematic review of the long-term effects confirms a durable reduction in spasticity and in later orthopaedic surgery. I would be honest that loss of spasticity is not the same as a gain in function, that the operation unmasks underlying weakness, and that the family must commit to months of intensive postoperative physiotherapy and strengthening or the child can lose ground. [6][7]

My counselling would set the expectation clearly. The operation buys a durable reduction in spasticity and reduces the later orthopaedic burden, and it is supported by randomised-trial evidence, but the gain depends on the postoperative rehabilitation and the child's own motor potential. I would explain the small risks, including transient leg weakness and very rare bowel and bladder disturbance from rootlet section, and the need for a period of reduced mobility after surgery. I would contrast selective dorsal rhizotomy with intrathecal baclofen, which suits the severe generalised GMFCS four and five child rather than the ambulant diplegic child, and I would emphasise that the decision is made jointly with the paediatric rehabilitation service, the neurosurgeon, the orthopaedic surgeon and the family, with the shared goal of preserving and improving her walking. [6][8]