A 2-month-old boy, second-born to healthy parents, was brought with left-sided clonic
jerks and asymmetric spasms in clusters for the past 10 days. His birth history was
uneventful. He cannot recognize his parents, does not follow objects, and does not
turn his head to sounds. On examination, his head circumference was 39 cm (Z-score of −0.26). He has multiple café au lait macules over the trunk and back ([Fig. 1A, B]), normal tone, and just elicitable deep tendon reflexes with no paucity of movements.
Electroencephalography revealed a hemi-hypsarrhythmia pattern ([Fig. 1C]). Neuroimaging was suggestive of right hemimegalencephaly ([Fig. 2]). He was started on vigabatrin and oral steroids (4 mg/kg/d). Whole exome sequencing
showed an autosomal dominant heterozygous pathogenic missense variant (c.3104T > G)
in exon 23 of the NF1 gene. On follow-up till 7 months of age, the spasms reduced to two per day. He had
partial neck control and cannot roll over, but can recognize his parents. The parents
were advised for hemispherotomy and the surgery was delayed due to the financial constraints.
Fig. 1 (A, B) Multiple café au lait macules over the trunk and back with extensive Mongolian spots.
(C) Electroencephalography (sensitivity: 15 mcv/mm; sweep: 30 mm/s) showing high-voltage
multifocal independent spike discharges over the right hemisphere.
Fig. 2 (A) Noncontrast computed tomography of the brain showing large right temporal and occipital
lobes with enlarged temporal horn, (B) fluid attenuated inversion recovery weighted image showing right hemimegalencephaly
in the right temporal lobe, and (C–F) T2-weighted images showing right hemimegalencephaly with associated white and gray
matter hyperintensities, heterogeneous right thalamoganglionic region, and corona
radiata.
Hemimegalencephaly is a hamartomatous overgrowth involving one cerebral hemisphere
that occurs due to congenital malformation of cortical development secondary to abnormal
cell proliferation and apoptosis.[1] It can occur in isolation or often associated with various neurocutaneous syndromes
such as organoid nevus syndrome, Proteus' syndrome, tuberous sclerosis, hypomelanosis
of Ito, McCune–Albright syndrome, CLOVES syndrome, Klippel–Trenaunay syndrome, and
rarely neurofibromatosis type 1.[1]
[2]
[3] The infants usually present with drug-resistant seizures and severe global development
delay. The recommended treatment is early hemispherotomy.[1]
