The test-dose to ascertain
whether the patient will respond and benefit from a pump
implant to deliver ITB has been likened to the analogy
of a “light switch”. A simple injection of
ITB is given to simply see whether there is a response
or not, in the same way as flicking a light switch, the
room is flooded with light or it is not. The implantation
of the programmable SynchroMed II pump using the same analogy
is the “dimmer switch”. The medical team is
able to determine exactly how much ITB to deliver to best
manage the spasticity, i.e. how
much light to flood the room with.
The test-dose always happens in a
hospital environment allowing the medical team to fully
care and assess the patient; this procedure may involve
a short in-patient stay.
There are many ways that the
test-dose is performed unique to the ITB centre and may include
repeated single injections through
a needle directly into the intrathecal space or the surgical
implant of a catheter through which injections can be made.
Whatever the method, only one injection can be made per day
of a determined dose to see if there is a response or not.
If there is no response to the first injection dose then
repeated injections of higher doses can be made during the
following days until a response or no-response is seen.
the test-dose the child may experience brief symptoms of
the following side-effects:
Overly loose muscles
Nausea and vomiting
You should not be worried
about these side-effects if they should occur, nor should
you think that this is what is to be expected if the pump
is implanted. Since the pump is fully programmable it allows
the medical team to slowly and accurately titrate the ITB
dosage to manage the spasticity whilst avoiding these side-effects.
The peak maximum effect of
a single dose is around 4 hours after the injection and it
is at this time when the critical evaluation assessments
are made to determine the effect on the child's spasticity.
Once a positive effect is seen on
the spasticity a thorough discussion between the patient,
parent and medical team will determine whether ITB Therapy
is the right option to proceed to pump implantation.