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ITB Test Dose

What is a test dose?

If a child fits the criteria and is a good candidate for intrathecal baclofen, the neurosurgery team will coordinate an admission to the Bristol Royal Hospital for Children for a test dose of baclofen under a general anaesthetic.

Prior to going to theatre, the physiotherapist will assess the child. This assessment will involve a repeat Modified Ashworth Score (MAS) to measure spasticity. They will also assess the child's range of movement whilst under general anaesthetic to get a true picture of any contractures or limited range of movement. This is important as these will not be improved with ITB and there should be considered for additional orthopaedic surgery. After these assessments, a lumbar (lower back) catheter is put in place in theatre by the neurosurgeon.

The child will return from theatre to the ward. Once they are awake, alert and not suffering from excessive nausea, vomiting or pain, a 50 microgram bolus of Baclofen will be administered by one of the Advanced Paediatric Nurse Practitioners to the lumbar catheter. Approximately 3-4 hours later the physiotherapist will repeat the spasticity assessment (MAS), and have a discussion with parents to determine the efficacy of ITB.

If the ITB test dose shows to be effective on the child's spasticity, it is counted as a positive test dose and the catheter can be removed. If it is negative (ineffective), the child can go on to have another bolus of a larger dose of 100 micrograms. This is done on the following day, when the effect of the first ITB dose has worn off. 3-4 hours after the larger dose has been given, the physiotherapist will reassess the spasticity levels. If the result is negative then it is deemed unsuccessful.

The child's lumbar catheter is removed once the effects of the ITB have disappeared and the child is stable. The child and family will be discharged from hospital with appropriate advice. This is usually the following day. If the dose is deemed to have a positive response and the parents are happy to go ahead, the child can proceed to the baclofen pump implant waiting list.