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HYDRANENCEPHALY PORENCEPHALY |
Partial or subtotal defects in cerebral hemispheres due to ischemia, hemorrhage infection or tumor (1). Occurs between the second trimester and early post natal period.
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PORENCEPHALY |
- Single unilateral cavity within the cerebral hemisphere.
- May / may not communicate with the ventricles.
- Ultrasound.
- Cystic lesion that communicates with the ventricle.
- Dilatation of the ipsilateral ventricle.
- No mass effect (differentiates it from an arachnoid and interhemispheric cyst).
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HYDRANENCEPHALY |
- Massive bilateral lesions.
- Most of the cerebral hemispheres are a fluid filled CSF sac.
- Thought to be due to ICA occlusion (similar cerebral lesions have been produced in monkeys by ligating both carotid arteries (2).
- Several reports of in utero development of hydranencephaly resulting from intracranial hemorrhage (3,4).
ULTRASOUND |
- Normal size skull or macrocephaly. Skull normally formed.
- Fluid filled cranial cavity.
- No cerebral cortex (may have partial preservation of the occipital lobe).
- Falx intact and usually present.
- Midbrain and basal ganglia are normal.
- Thalami normal and never fused (3).
- Cerebellum intact with a normal tentorium cerebelli (3).
- Polyhydramnios.
- The earliest reported diagnosis was made at 12 weeks of gestation (4).
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No cerebral cortex; Falx intact and usually present |
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DIFFERENTIAL DIAGNOSIS |
- Massive hydrocephalus (all parts of the ventricular system dilated).
- Alobar holoprosencephaly (thalami fused and no falx present)
ASSOCIATED SYNDROMES |
- Familial hydranencephaly (AR).
- Trisomy 13.
- Fowler syndrome.
REFERENCES |
- Volpe JJ. Hypoxic-ischemic encephalopathy, neuropathology, and pathogenesis. In: Neurology of the newborn: Neuronal proliferation, migration, organization and myelination. Philadelphia, WB Saunders;1995:299-307.
- Myers RE. Brain pathology following fetal vascular occlusion: an experimental study. Invest Opthalmol 1969;8:41-50.
- Greene MF, Benacerraf B, Crawford JM. Hydranencephaly: Ultrasound appearance during in utero evolution. Radiology 1985;156:779-780.
- Lin YS, Chang FM, Liu CH. Antenatal detection of Hydranencephaly at 12 weeks menstrual age. J Clin Ultrasound 1992;20:62-64.
- Edmondson SR, Hallak M, Carpenter RJ et.al. Evolution of hydranencephaly following intracerebral hemorrhage. Obstet Gynecol 1992;79:870-871.