Bilateral posterior periventricular nodular heterotopia: a recognizable cortical malformation with a spectrum of associated brain abnormalities.
OBJECTIVE
Bilateral posterior PNH is a distinctive complex malformation with imaging features distinguishing it from classic bilateral PNH associated with FLNA mutations. The purpose of this study was to define the imaging features of posterior bilateral periventricular nodular heterotopia and to determine whether associated brain malformations suggest specific subcategories.


METHODS
We identified a cohort of 50 patients (31 females; mean age, 13 years) with bilateral posterior PNH and systematically reviewed and documented associated MR imaging abnormalities. Patients were negative for mutations of FLNA.


RESULTS
Nodules were often noncontiguous (n = 28) and asymmetric (n = 31). All except 1 patient showed associated developmental brain abnormalities involving a spectrum of posterior structures. A range of posterior fossa abnormalities affected the cerebellum, including cerebellar malformations and posterior fossa cysts (n = 38). Corpus callosum abnormalities (n = 40) ranged from mild dysplasia to agenesis. Posterior white matter volume was decreased (n = 22), and colpocephaly was frequent (n = 26). Most (n = 40) had associated cortical abnormalities ranging from minor to major (polymicrogyria), typically located in the cortex overlying the PNH. Abnormal Sylvian fissure morphology was common (n = 27), and hippocampal abnormalities were frequent (n = 37). Four family cases were identified-2 with concordant malformation patterns and 2 with discordant malformation patterns.


CONCLUSIONS
The associations of bilateral posterior PNH encompass a range of abnormalities involving brain structures inferior to the Sylvian fissures. We were unable to identify specific subgroups and therefore conceptualize bilateral posterior PNH as a continuum of infrasylvian malformations involving the posterior cerebral and hindbrain structures.
Florey Neurosciences Institute, Melbourne, Australia.
S A
SA
Mandelstam
R J
RJ
Leventer
A
A
Sandow
G
G
McGillivray
M
M
van Kogelenberg
R
R
Guerrini
S
S
Robertson
S F
SF
Berkovic
G D
GD
Jackson
I E
IE
Scheffer
D000293:Adolescent; D000328:Adult; D000368:Aged; D001927:Brain Diseases / Q000473:pathology*; D002540:Cerebral Cortex / Q000002:abnormalities; D002648:Child; D002675:Child, Preschool; D015331:Cohort Studies; D003285:Contractile Proteins / Q000235:genetics; D003337:Corpus Callosum / Q000473:pathology; D005260:Female; D005315:Fetal Diseases / Q000235:genetics / Q000473:pathology; D064448:Filamins; D006624:Hippocampus / Q000002:abnormalities; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D020547:Lateral Ventricles / Q000002:abnormalities* / Q000473:pathology; D008279:Magnetic Resonance Imaging; D008297:Male; D054220:Malformations of Cortical Development / Q000473:pathology*; D008840:Microfilament Proteins / Q000235:genetics; D008875:Middle Aged; D054091:Periventricular Nodular Heterotopia / Q000235:genetics / Q000473:pathology*; D011247:Pregnancy; D012249:Rhombencephalon / Q000002:abnormalities; D035781:Siblings; D014430:Twins, Monozygotic; D055815:Young Adult
D003285:Contractile Proteins; D064448:Filamins; D008840:Microfilament Proteins