Sunday 27 November 2011

Unilateral hydrocephalus

A 5 yo male with delayed mile stones.

CT brain shows:
Marked dilatation of right lateral ventricle.
Left lateral ventricle, third ventricle, and fourth ventricles are normal in size.
There is no peri ventricular ooze of csf.
Adjacent brain parenchyma show normal attenuation. There is no adjacent parenchymal Gliosis.

Imging diagnosis: Unilateral hydrocephalus.

The left foramen of Monro points in the direction of the third ventricle and and incontinuity with third ventricle consistent with normal, unobstructed flow of CSF. Right foramen of Monro ending abruptly, show marked blunting, not pointing towards the third ventricle so the site of obstruction appears to be foramen of Monro and cause appears to be congenital. No obvious adjacent space occupying lesion.

Unilateral hydrocephalus (UH) is an uncommon type of hydrocephalus, often congenital.
In congenital hydrocephalus, vast majority of cases are bilateral, symmetric hydrocephalus with high rate of association with CNS and extra-CNS anomalies and a mortality rate up to 85%.
In contrast, unilateral hydrocephalus is less frequently associated with other anomalies, and if no other anomalies are present, the survival rate is 70%.
UL first described by Von Mohr (1842), usually due to obstruction at FM.
In congenital, cause is atretic, stenotic FM or occluded by a membrane. Can be seen in conjunction with corpus callosal anomalies.
In Acquired, etiologies for obstruction at FM include thalamic and intraventricular neoplasm, colloid cysts, tuberculoma, post tb ependymal adhesions, ventriculitis, vascular malformations, and non-specific inflammatory conditions.

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