The roles of electroencephalography and neuroimaging in children with holoprosencephaly.

We analyze the respective roles of neuro-imaging and EEG in the assessment of 11 children with holoprosencephaly and epilepsy. Seizures were present in seven patients (64%); six were treated with antiepileptic drugs; five had intractable epilepsy. Two of the patients with intractable epilepsy became seizure-free under polytherapy. Fourteen EEG recordings were performed in eight patients. The abnormal EEG findings included slow waves, focal epileptiform discharges, slow spike-and-wave complexes, hypsarrhythmia, frontal fast activity, fronto-occipital gradients of amplitudes (posterior amplitude attenuation), lack of photic driving, periodic discharges, and extremely large amplitudes. A fronto-occipital gradient was found only in alobar and semilobar holoprosencephaly (HPE), while hypsarrhythmia only in lobar HPE. Lack of photic driving was found only in alobar HPE. All EEGs showed diffuse slow waves, and all patients had severe developmental delay. The Deep Gray Score(DGS) in neuroimaging studies, thought to predict clinical outcome, was irrelevant given the presence and intractability of the epilepsies. Patients with higher DGS, nonetheless, tended to have higher mortality rate. In conclusion, EEG evaluation provides additional functional information to neuroimaging studies in the assessment of neurological outcome in patients with HPE. With a more mature and well-formed cerebrum, as found in the lobar and semilobar types, the possibility of hypsarrhythmia and photic driving increased, while that of fronto-occipital gradients decreased.