This 24-month-old reports with developmental delay and drags her right leg. Look at the first four images without arrows, and see what you come up with for a diagnosis. Then, take a look at the next four duplicate images with arrows indicating key findings.
Q1 – The diagnosis of lissencephaly (type II) may be associated with which of the following:
(a) Reduction in normal sulcation
(b) Band heterotopia
(c) Neuronal migration disturbance
(d) – (a) and (c)
(e) – (b) and (c)
Q2 (Advanced) – Which syndrome is NOT associated with lissencephaly:
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:
- Type I isolated
- Miller-Dieker syndrome
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:
- Walker-Warburg syndrome or HARD +/- E syndrome
- Fukuyama syndrome
- Muscle-eye-brain disease (MEB)
ProScan Pearl: 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”.
A1 – (d) Reduction in normal sulcation and Neuronal migration disturbance
A2 (Advanced) – (b) Cobb’s syndrome is associated with spine and soft tissue paraspinous AVM.
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1. Pilz et al. Syndromes with lissencephaly. J Mod Genetics, 1996: 33 (4), 319-323.