Olfactory nerve hypertrophy: a clue to the presence of ipsilateral megalencephaly

A boy aged 4 years presented with refractory focal seizures since 9 months of age. The seizures involved the left side of the body and consisted of clonic movements with frequent generalisation. MRI brain showed abnormal area with poor grey-white differentiation involving the right frontal lobe, especially the basifrontal region and the temporal lobe (figure 1A,B) suggesting the presence of a frontotemporal developmental malformation. Interestingly olfactory nerve hypertrophy was also noted on the same side (figure 1C,D). Video-electroencephalogram study demonstrated concurrence of the interictal (figure 2A) and ictal data (figure 2B) with the MRI defined abnormality. An 18-fluoro-2-deoxy-D-glucose positron emission tomography/CT of the brain showed severe right frontotemporal hypometabolism. The boy underwent a disconnection procedure …