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A 9 year old girl is admitted to the paediatric intensive care unit (PICU) with a diagnosis of Guillain-Barré syndrome (GBS). She has global motor weakness with an MRC power grade 3 and does not require mechanical ventilation. She has dysautonomia and remains on the PICU for respiratory and invasive arterial monitoring. During her admission she develops severe leg and back pain. Regular paracetamol and non-steroidal anti-inflammatories are ineffective. Your educational supervisor asks you whether anticonvulsants would be an effective analgesic, or whether the tried and tested opiates would be the best option.
Structured clinical question
In patients experiencing pain complicating Guillain-Barré syndrome [patient], do anticonvulsants [intervention] provide better analgesia than opiates [comparison] and with fewer side effects [outcome]?
Search strategy and outcome
Guillain Barre (MeSH–explode) and pain (explode).
Thirteen hits: one relevant; 12 papers excluded because they did not address the problems of analgesia in GBS.
Guillain Barre (explode all fields) and pain (explode all fields).
Limit LA = English.
Twenty one hits: two relevant; 19 papers excluded (see above).
See table 3.
The apparent success of carbamazepine, an anticonvulsant with an unknown mode of action, in the treatment of pain associated with GBS was documented as long ago as 1970.3 Since then, anticonvulsants have been shown to be effective in neuropathic pain of differing origin.4 There have been only two trials conducted in a cohort of patients with GBS that have compared the use of anticonvulsants to placebo, with opiate rescue analgesia. The trials, using either gabapentin or carbamazepine, despite small numbers, have shown both a significant reduction in opiate requirements and in the subjective perception of pain, as assessed by pain scales. The advantages to reducing the opiate requirements are obvious. In both trials the sedation scores were significantly reduced in the groups receiving anticonvulsants at that time. Improved sedation scores can lead to improved respiratory function and less time weaning from mechanical ventilation. Side effects from the anticonvulsants were not apparent.
Can we draw the conclusions above given that the data reviewed were obtained from adult patients? We believe that the data are applicable in this case.
Guillain-Barré syndrome is a disease that commonly affects adults and older children but can affect children as young as infants. Pain pathways in older children are similar to those of adults and there is growing evidence that pain pathways are fully functional in the newborn.
In this age of evidence based medicine there are more adult data available than paediatric, possibly secondary to difficulties of ethics, recruitment, and consent. To ignore all adult data and reproduce randomised trials in children would be time consuming, expensive, and unethical, particularly in cases such as the one cited above where the underlying pathophysiology is very similar.
Our conclusions from studying the adult data led us to apply the findings to our paediatric practice. We do endorse the need for seeking out critically appraised “paediatric literature” where available, but to ignore all adult data is to do the child a disservice. We suggest that in circumstances similar to ours—where the pathophysiology of the disease is understood and similar to the mature state—adult data should be considered.
CLINICAL BOTTOM LINE
Guillain-Barré syndrome can be associated with pain in up to 55–80% of patients.5
This pain tends to be of two different types: musculoskeletal and neuropathic.
Anticonvulsants are at least as effective as opiates in treating the neuropathic pain in GBS. They have the additional advantages of reducing the opiate requirements and consequently lessening sedation scores and opiate related side effects.
S F McDouall, Department of Anaesthetics, Oxford Radcliffe Trust, Oxford, UK;
R C Tasker, Paediatric Intensive Care Unit, Addenbrooke’s Hospital, Cambridge, UK