Baclofen is a muscle relaxant medication used to treat spasticity and dystonia. Baclofen works at receptor sites (called GABA) in the spinal cord and the brain. It is commonly taken in a tablet form however its effectiveness is limited as side effects become common as dose is increased. By infusing the Baclofen directly into the area around the spinal cord (the intrathecal space) it goes right to where it is needed. A much lower dose can therefore be used with a much greater effect. In this way, side effects of the medication can be minimized.
What is intrathecal Baclofen therapy?
Intrathecal Baclofen therapy is the surgical implantation of a pump underneath the skin of the abdominal wall. A catheter tunnels under the skin and enters into the cerebrospinal fluid (CSF) around the spinal cord. Baclofen medication is then delivered as a continuous infusion from the pump into the CSF. As some children do not show any response to intrathecal Baclofen, a test dose is recommended prior to decision about surgical implantation. This allows us to assess the potential effectiveness of intrathecal Baclofen therapy for each individual child.
How the test-dose is administered
The most common way of performing a test dose is by lumbar puncture. A needle is placed through the skin on the back into the space between the spinal bones. The Baclofen medication is then instilled through the needle before the needle is removed. A lumbar puncture can be an uncomfortable procedure. To assist the child, pain relief, sedation or general anaesthesia may be given.
What to expect
A lumbar puncture test dose is performed in hospital as a day procedure. The child will need to be admitted in the early morning. If needed, the child will then be reviewed by the ITB team therapists for relevant assessments. The lumbar puncture will then be performed. This will be done in the Medical Day Unit, or in the operating theatres if general anaesthetic is required.
Morning medications, including oral Baclofen, should be given at usual times. If the child takes regular aspirin or blood thinning medication it is important to discuss this with the child’s doctor prior to the test dose being arranged.
Typically, the effects of intrathecal Baclofen take two to four hours to be seen. During this time, we recommend that the child lies flat in bed.
The ITB doctors and therapists will review the child at two and four hours after the test dose to see what changes have occurred. This will involve a musculoskeletal examination of all four limbs, moving the child from lying to sitting and observing various activities such as dressing. The ITB team may videotape these examinations so that comparison can be made to previous assessments.
Children are typically discharged home during the early afternoon. As the Baclofen may still be in the child’s system, this is a good opportunity for caregivers to try transfers and cares in the home environment.
Risks of lumbar puncture are rare. Occasionally, headache may be experienced following lumbar puncture. Extremely rare risks are spinal or epidural bleeding or trauma to the spinal nerve roots. Occasionally, we are unable to pass the lumbar puncture needle into the spinal fluid space. This usually occurs when the child has rotatory scoliosis. In these instances, the procedure will need to be aborted. If this occurs we repeat the lumbar puncture test dose at a later date using general anaesthesia (if not used during initial trial) and radiological guidance where deemed necessary.
Children may experience an adverse reaction to sedation, analgesia or general anaesthetic. Reactions may range from no effect to severe allergic reactions. Children may occasionally vomit or have a prolonged period of drowsiness.
The most common adverse event following administration of an intrathecal Baclofen test dose is loss of spasticity causing excessive floppiness. Less common side effects are vomiting, nausea, constipation, urinary retention, dizziness and low blood pressure. There are very rare reports of respiratory compromise and coma.
Queensland Paediatric Rehabilitation Service
Lady Cilento Children’s Hospital
Level 6, 501 Stanley Street, South Brisbane 4101
t: 07 3068 2950
t: 07 3068 1111 (general enquiries)
f: 07 3068 3909
In an emergency, always call 000.
If it’s not an emergency but you have any concerns, contact 13 Health (13 43 2584). Qualified staff will give you advice on who to talk to and how quickly you should do it. You can phone 24 hours a day, seven days a week.