HYDROCEPHALUS / VENTRICULOMEGALY

Ventriculomegaly
Congenital Hydrocephalus	Non-obstructive Ventriculomegaly

ULTRASOUND

Link to Ultrasound diagnosis of fetal hydrocephalus

CONGENITAL HYDROCEPHALUS

[more information]

• Unilateral (rare)
1. Obstruction of the Foramen of Monro (1).

– Functional obstruction:

o Ventricular tumors (e.g. tuberous sclerosis (2); Weaver syndrome (3)).

o Post- inflammatory gliosis.

– Congenital atresia of the foramen of Monro (4).

– Transient obstruction secondary to interventricular hemorrhage, brain dysplasia or atrophy (5,6).

2. Patent foramen of Monro associated with unilateral parenchymal disease or unbalanced intracranial compliance.
3. Transient unilateral ventriculomegaly (may be a normal variant).

Ultrasound diagnosis of unilateral hydrocephalus

Prognosis of unilateral and / or asymmetrical hydrocephalus

• Bilateral
1. Non communication (intraventricular obstruction)
• Aqueductal stenosis
• Dandy-Walker Malformation
• Obstruction at level of foramen of Monro (bilateral).
• Mass lesions
• Post-hemorrhagic (aqueduct of IV ventricle obstruction).
2. Communication (obstruction is extraventricular at the level of the subarachnoid space)
• Arnold-Chiari malformation
• Encephalocele
• Congenital absence of arachnoid granulations
• Leptomeningeal inflammation
• Lissencephaly
• Achondroplasia
• Subarachnoid hemorrhage

NON-OBSTRUCTIVE VENTRICULOMEGALY

• Normal intraventricular pressure
• Dilatation of the fetal lateral ventricles
• Choroid plexus papilloma
• Venous obstruction
• Vascular infarction due to antenatal occlusion.
• Fowler syndrome.

REFERENCES

1. Oi S, Matsumoto S. Pathophysiology of nonneoplastic obstruction of the foramen of Monro and progressive unilateral hydrocephalus. Neurosurgery 1985;17:891-896.
2. Mitra AG, Dickerson C. central nervous sysyem tumor with associated unilateral ventriculomegaly : unusual prenatal presentation of subsequently diagnosed tuberous sclerosis. J Ultrasound Med 2000;19:651-654.
3. Senat MV, Bernard JP, Schwarzler P et.al. Prenatal diagnosis and follow-up of 14 cases of unilateral ventriculomegaly. Ultrasound Obstet Gynecol 1999;14:327-332.
4. Mohanty A, Das BS, Kolluri VRS et.al. Neuro-endoscopic fenestration of occluded foramen of Monro causing unilateral hydrocephalus. Pediatr Neurosurg 1996;25:248-251.
5. Patten RM, Mack LA, Finberg HJ. Unilateral hydeocephalus: prenatal sonographic diagnosis. Am J Roentgenol 1991;156:359-363.
6. Anquist KW, Parnes S, Cargill Y et.al. An unexpected fetal outcome following a severe maternal motor vehicle accident. Obatet Gynecol 1994;84:656-659.