Midbrain-hindbrain involvement in septo-optic dysplasia.
OBJECTIVE
Midbrain-hindbrain involvement in septo-optic dysplasia has not been well described, despite reported mutations of genes regulating brain stem patterning. We aimed to describe midbrain-hindbrain involvement in patients with septo-optic dysplasia and to identify possible clinical-neuroimaging correlations.


METHODS
Using MR imaging, we categorized 38 patients (21 males) based on the presence (group A, 21 patients) or absence (group B, 17 patients) of visible brain stem anomalies. We measured height and anteroposterior diameter of midbrain, pons, and medulla, anteroposterior midbrain/pons diameter (M/P ratio), vermian height, and tegmento-vermian angle, and compared the results with 114 healthy age-matched controls. Furthermore, patients were subdivided based on the type of midline anomalies. The associations between clinical and neuroradiological features were investigated. Post hoc tests were corrected according to Bonferroni adjustment (pB).


RESULTS
Patients with brain stem abnormalities had smaller anteroposterior pons diameter than controls (pB < .0001) and group B (pB = .012), higher M/P ratio than controls (pB < .0001) and group B (pB < .0001), and smaller anteroposterior medulla diameter (pB = .001), pontine height (pB = .00072), and vermian height (pB = .0009) than controls. Six of 21 patients in group A had thickened quadrigeminal plate, aqueductal stenosis, and hydrocephalus; 3 also had agenesis of the epithalamus. One patient had a short midbrain with long pons and large superior vermis. There was a statistically significant association between brain stem abnormalities and callosal dysgenesis (P = .011) and developmental delay (P = .035), respectively.


CONCLUSIONS
Midbrain-hindbrain abnormalities are a significant, albeit underrecognized, component of the septo-optic dysplasia spectrum, and are significantly associated with developmental delay in affected patients.
From the Neuroradiology Unit (M.S., A.R.) mariasavinaseverino@ospedale-gaslini.ge.it.
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Severino
Pediatric Department (A.E.M.A., N.D.I., M.M.).
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Allegri
Epidemiology and Biostatistics Unit (A.P.), Istituto Giannina Gaslini, Università di Genova, Genoa, Italy.
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Pistorio
Università di Genova (B.R.), Genoa, Italy.
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Roviglione
Pediatric Department (A.E.M.A., N.D.I., M.M.).
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Di Iorgi
Pediatric Department (A.E.M.A., N.D.I., M.M.).
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Maghnie
From the Neuroradiology Unit (M.S., A.R.).
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Rossi
D000015:Abnormalities, Multiple / Q000473:pathology; D000328:Adult; D002648:Child; D002658:Developmental Disabilities / Q000209:etiology*; D005260:Female; D006801:Humans; D008297:Male; D008636:Mesencephalon / Q000002:abnormalities*; D012249:Rhombencephalon / Q000002:abnormalities*; D025962:Septo-Optic Dysplasia / Q000473:pathology*; D055815:Young Adult