Carbamazepine-Responsive Chorea in a Toddler with Semilobar Holoprosencephaly: Case Report.

Introduction: Holoprosencephaly (HPE) is a central nervous system malformation defined by incomplete separation of the prosencephalon in two hemispheres and determines a broad spectrum of clinical presentations based on extension of non-separation.

Case presentation: A 1 year and 8 months' old girl with semilobar HPE and 18p deletion syndrome was admitted to our hospital due to viral bronchiolitis. During hospitalization, she started generalized choreic movements, with face dyskinesia and without any identified aggravating factors. Haloperidol, clonazepam, and valproic acid did not achieve an attenuation of the movement disorder. Significant symptom relief was obtained with the use of trihexyphenidyl, with reduced amplitude and frequency of movements, but hyperthermia compromised its use. Control of chorea with no important side effects was only achieved after the introduction of carbamazepine.

Discussion: Despite significant morbidity, there are few cases described in the literature of chorea and movement disorders in HPE and no effective treatment strategies described. Carbamazepine is an antiepileptic drug that stabilizes voltage-gated sodium channels and is the most effective treatment for paroxysmal kinesigenic dyskinesia. Although it has been used successfully in the treatment of different movement disorders, few therapeutic trials have been reported. The mechanism by which carbamazepine alleviates chorea is still unknown but may be justified through the blocking of post-synaptic dopamine receptors and stimulation of cholinergic pathways.