This 2-year-old female presents with developmental delay, and drags her right leg.
(QUIZ ANSWER) MOST LIKELY DIAGNOSIS IN THIS CASE:
Lissencephaly (type II).
Using the diagnostic web viewer, we have provided images that assist in telling our clinical story. Areas of significance are indicated below.
Signs of lissencephaly with alteration in the gray-white matter configuration is most conspicuous on the axial FLAIR and is seen in the left posterior-inferior parietal lobule with overlying pachygyria or lissencephalic under sulcation. Highlighted montage included. Additional sites with similar alteration or disorganization and gray-white matter transition zone is noted in the left frontal and left parietal region also accompanied by under sulcation. Additional areas of under sulcation are identified foci of pachygyria or possibly polymicrogyria right orbital frontal gyrus and left lateral occipital gyrus. Findings are also provided with arrows on accompanying montage.
A very shallow cleft is identified in the region of the left middle frontal gyrus and highlighted by triple arrows on the accompanying montage. The findings are compatible with a small focal closed-lip schizencephaly.
No signs of developmental venous anomaly are noted and parallel areas of high-signal intensity in the temporal region may represent N/2 phase ghosting or pulsation mismapping, so called periodic motion artifact.
Lissencephaly syndrome with multiple areas of under sulcation most likely pachygyria or less likely polymicrogyria. Findings consistent with cortical dysplasia with alterations in white matter distribution as a component of dysplasia. For educational interest, the areas of exaggerated hypointensity on the FLAIR sequence represent compact myelin that is exaggerated due to its increased compactness as well as its ectopic positioning.
ADDITIONAL EDUCATIONAL NOTES:
Lissencephaly may be associated with under- or overmigration. Lissos is Greek for “smooth brain”. The defect in neuronal migration occurs in the 12th to 24th week of gestation. Band heterotopias are caused by undermigration. Pebble cortex such as that associated with the Walker-Warburg Fukuyama muscular dystrophy is a form of overmigration. Lissencephaly may be divided into: (a) type I with a smoother, thicker cortex; or (b) type II with a pebbly cortex.
A characteristic of lissencephaly, besides migrational disturbance, is microcephaly. Another classification for lissencephaly is that of the classic (type I) and the cobblestone (type II). Remember that microcephaly plus abnormalities of sulcation and migration suggest lissencephaly syndromes.
Classic (or Type I) lissencephaly is associated with:
Lis I: lissencephaly due to platelet-activating factor acteylhydrolase (PAFAHB1) gene mutation. Subtypes include:
Lis XI: lissencephaly due to doublecortin (DCX) gene mutation.
Lissencephaly, type I, isolated without other known genetic defects.
Cobblestone (or Type II) lissencephaly is associated with:
Because of poor gyral and sulcal development, sylvian fissure narrowing, colpocephaly, flat qyri and a thick smooth cortex, lissencephalic brains may demonstrate the “figure of eight sign”.