Neurology India Medknow Publications on behalf of the Neurological Society of India ISSN: 0028-3886 EISSN: 1998-4022 Vol. 51, Num. 3, 2003, pp. 427

Neurology India, Vol. 51, No. 3, July, 2003, pp. 427

Anticonvulsant-hypersensitivity syndrome in a child

Kumar S
Department of Neurological Sciences, Christian Medical College Hospital, Vellore, Tamilnadu - 632004

Correspondence Address:
Department of Neurological Sciences, Christian Medical College Hospital, Vellore, Tamilnadu - 632004
sk@cmcvellore.ac.in

Code Number: ni03146

Sir,
I read with interest the recent article by Goraya et al.[1] They have highlighted an important complication of anticonvulsants: carbamazepine- induced thrombocytopenia. However, I would like to make certain observations.

Firstly, the child was started on anticonvulsants (carbamazepine and later phenytoin) after a single episode of seizure. The recent guidelines suggest that anticonvulsants after a single episode of seizure do not prevent the future development of epilepsy and hence are not universally recommended in children.[2] This is especially important as all anticonvulsants produce undesirable adverse effects.

Secondly, this child was started on phenytoin after developing hypersensitivity to carbamazepine. However, it is well known that a patient with hypersensitivity to carbamazepine may also develop hypersensitivity to other aromatic anticonvulsants such as phenytoin and phenobarbitone and this cross-reactivity may be as high as 75%.[3] Therefore, in cases of anticonvulsant hypersensitivity syndrome (AHS), benzodiazepines, gabapentin and sodium valproate are safer options.[3],[4]

Finally, the authors make contradictory statements regarding the cause of carbamazepine-induced thrombocytopenia (CIT). They initially report that the bone marrow examination in their patient showed increased megakaryocytes, but later go on to say that CIT results from myelosuppression. However, the commonly accepted cause for CIT is an antibody-mediated destruction of platelets in the peripheral blood in the absence of bone marrow suppression. Anti-IgG carbamazepine-dependent platelet-reactive antibodies have been demonstrated in the peripheral blood.[5]

In conclusion, anticonvulsants are not routinely recommended for all children presenting with the first episode of unprovoked seizure. Phenytoin and phenobarbitone should be avoided in a patient with hypersensitivity to carbamazepine due to a high degree of cross-reactivity between them. Carbamazepine-induced thrombocytopenia results due to an immune-mediated peripheral destruction and not due to bone marrow suppression.

REFERENCES

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