eMedicine Specialties > Radiology > Pediatrics

Hydranencephaly: Imaging

Author: Andrew L Wagner, MD, Assistant Professor of Radiology, Instructional Faculty, University of Virginia School of Medicine; Director of Neuroradiology, Department of Radiology, Rockingham Memorial Hospital
Coauthor(s): Dennis Rohrer, MD, Consulting Staff, Department of Radiology, Rockingham Memorial Hospital
Contributor Information and Disclosures

Updated: Feb 18, 2008

Computed Tomography

Findings

In hydranencephaly, CT scanning demonstrates an absence of most of the supratentorial structures, with preservation of the falx, thalami, and various amounts of the occipital lobes and basal ganglia. Macrocrania or microcrania may be present, or the head circumference may be normal.

Degree of Confidence

Hydranencephaly and severe hydrocephalus may appear similar on CT scans because in both entities the falx is present and the thalami are unfused.16 The key to distinguishing hydrocephalus from hydranencephaly is the presence of a thin rim of residual cerebral cortical tissue in hydrocephalus that is not present in hydranencephaly. Thin sections and overlapped coronal reconstructions may be helpful in detecting this rim. In addition, the third ventricle, which is absent in hydranencephaly, is identifiable in hydrocephalus. The brainstem is seen in hydranencephaly and hydrocephalus.

False Positives/Negatives

No normal variants mimic hydranencephaly.

Magnetic Resonance Imaging

Findings

MRI findings are similar to CT scan findings, although the improved soft-tissue contrast achieved with MRI allows for more confident identification of the falx and any residual supratentorial brain tissue. If fetal ultrasonographic findings are equivocal, fetal MRI is useful for the accurate prenatal diagnosis of hydranencephaly.15,16

Degree of Confidence

See CT Scan.

Ultrasonography

Findings

Most cases of hydranencephaly can be detected with prenatal ultrasonography, although fetal MRI may be necessary to confirm the diagnosis.17 If ultrasonography is performed prior to the etiologic insult, the initial study may be normal. When fetal ultrasonography is performed early in gestation, hydrocephalus and alobar holoprosencephaly can be difficult to distinguish from hydranencephaly.

Hydranencephaly appears as a supratentorial fluid collection that replaces the cerebral hemispheres, with preserved, nonfused thalami and minimal (if any) preserved cerebral cortical tissue, usually in the occipital area.18 There is no uniform rim of preserved cerebral cortical tissue, as seen in fetal hydrocephalus.

In cases caused by a massive intracranial hemorrhage, blood may initially be visualized as an echogenic mass in the supratentorial tissue.9,10 On sequential scans, blood evolves into an anechoic fluid collection that replaces the frontal and parietal lobes. In the early stages of hydranencephaly, the brain may appear heterogeneous, with multiple, small cystic areas seen; this appearance may mistakenly be attributed to intracranial teratoma.

Degree of Confidence

Differentiating hydranencephaly from hydrocephalus and alobar holoprosencephaly in the prenatal period can be challenging. The presence of a falx and of unfused thalami, as well as the absence of fused cortical tissue, excludes the diagnosis of alobar holoprosencephaly. Differentiation from hydrocephalus is somewhat more difficult, because the rim of peripheral cerebral cortical tissue that is diagnostic of fetal hydrocephalus may be difficult or impossible to visualize with prenatal ultrasonography. In difficult cases, prenatal MRI can be used to establish the correct diagnosis.

Distinguishing between hydranencephaly and alobar holoprosencephaly can be difficult with fetal ultrasonography. These 2 entities should not be confused on high-resolution postnatal images or fetal MRIs. Alobar holoprosencephaly is characterized by the presence of a pancake-shaped mass of fused frontal lobe tissue, fusion of the thalami, and a large dorsal cyst. In hydranencephaly, there is no fusion of cerebral hemispheric tissue; indeed, little normal supratentorial tissue remains. The presence of a normal falx and the absence of thalamic fusion help to exclude holoprosencephaly.19

False Positives/Negatives

No normal variants mimic hydranencephaly.

More on Hydranencephaly

Overview: Hydranencephaly
Imaging: Hydranencephaly
Follow-up: Hydranencephaly
Multimedia: Hydranencephaly
References
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References

  1. Halsey JH Jr. Hydranencephaly. In: Vinken P, Bruyn G, Klawans H, eds. Handbook of Clinical Neurology. New York, NY: Elsevier; 1987:337-53.

  2. Witters I, Moerman P, Devriendt K, et al. Two siblings with early onset fetal akinesia deformation sequence and hydranencephaly: further evidence for autosomal recessive inheritance of hydranencephaly, fowler type. Am J Med Genet. Feb 15 2002;108(1):41-4. [Medline].

  3. Kubo S, Kishino T, Satake N. A neonatal case of hydranencephaly caused by atheromatous plaque obstruction of aortic arch: possible association with a congenital cytomegalovirus infection?. J Perinatol. Nov-Dec 1994;14(6):483-6. [Medline].

  4. Golkar M, Azadmanesh K, Khoshkholgh-Sima B, et al. Serodiagnosis of recently acquired Toxoplasma gondii infection in pregnant women using enzyme-linked immunosorbent assays with a recombinant dense granule GRA6 protein. Diagn Microbiol Infect Dis. Jan 30 2008;[Medline].

  5. Rais-Bahrami K, Naqvi M. Hydranencephaly and maternal cocaine use: a case report. Clin Pediatr (Phila). Dec 1990;29(12):729-30. [Medline].

  6. Dominguez R, Aguirre Vila-Coro A, Slopis JM, et al. Brain and ocular abnormalities in infants with in utero exposure to cocaine and other street drugs. Am J Dis Child. Jun 1991;145(6):688-95. [Medline].

  7. Lubinsky MS, Adkins W, Kaveggia EG. Decreased maternal age with hydranencephaly. Am J Med Genet. Mar 31 1997;69(3):232-4. [Medline].

  8. Watts P, Kumar N, Ganesh A, et al. Chorioretinal dysplasia, hydranencephaly, and intracranial calcifications: pseudo-TORCH or a new syndrome?. Eye. Dec 14 2007;[Medline].

  9. Greene MF, Benacerraf B, Crawford JM. Hydranencephaly: US appearance during in utero evolution. Radiology. Sep 1985;156(3):779-80. [Medline]. [Full Text].

  10. Edmondson SR, Hallak M, Carpenter RJ Jr, et al. Evolution of hydranencephaly following intracerebral hemorrhage. Obstet Gynecol. May 1992;79(5 Pt 2):870-1. [Medline].

  11. To WW, Tang MH. The association between maternal smoking and fetal hydranencephaly. J Obstet Gynaecol Res. Feb 1999;25(1):39-42. [Medline].

  12. Bae JS, Jang MU, Park SS. Prolonged survival to adulthood of an individual with hydranencephaly. Clin Neurol Neurosurg. Jan 25 2008;[Medline].

  13. Werth R. Residual visual function after loss of both cerebral hemispheres in infancy. Invest Ophthalmol Vis Sci. Jul 2007;48(7):3098-106. [Medline].

  14. Deshmukh CT, Nadkarni UB, Nair K, et al. Hydranencephaly/multicystic encephalomalacia: association with congenital rubella infection. Indian Pediatr. Feb 1993;30(2):253-7. [Medline].

  15. Poe LB, Coleman L. MR of hydranencephaly. AJNR Am J Neuroradiol. Sep-Oct 1989;10(5 Suppl):S61. [Medline].

  16. Poe LB, Coleman LL, Mahmud F. Congenital central nervous system anomalies. Radiographics. Sep 1989;9(5):801-26. [Medline]. [Full Text].

  17. Lin YS, Chang FM, Liu CH. Antenatal detection of hydranencephaly at 12 weeks, menstrual age. J Clin Ultrasound. Jan 1992;20(1):62-4. [Medline].

  18. Wintour EM, Lewitt M, McFarlane A, et al. Experimental hydranencephaly in the ovine fetus. Acta Neuropathol (Berl). 1996;91(5):537-44. [Medline].

  19. Kim MS, Jeanty P, Turner C, et al. Three-dimensional sonographic evaluations of embryonic brain development. J Ultrasound Med. Jan 2008;27(1):119-24. [Medline].

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Further Reading

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Keywords

hydrocephalus, anencephaly, absent cerebral cortex, absent basal ganglia, Fowler-type hydranencephaly, macrocrania, microcrania, alobar holoprosencephaly

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Contributor Information and Disclosures

Author

Andrew L Wagner, MD, Assistant Professor of Radiology, Instructional Faculty, University of Virginia School of Medicine; Director of Neuroradiology, Department of Radiology, Rockingham Memorial Hospital
Andrew L Wagner, MD is a member of the following medical societies: American College of Radiology, American Roentgen Ray Society, American Society of Neuroradiology, and Radiological Society of North America
Disclosure: Nothing to disclose.

Coauthor(s)

Dennis Rohrer, MD, Consulting Staff, Department of Radiology, Rockingham Memorial Hospital
Dennis Rohrer, MD is a member of the following medical societies: American College of Radiology, Medical Society of Virginia, Radiological Society of North America, and Society of Nuclear Medicine
Disclosure: Nothing to disclose.

Medical Editor

Charles M Glasier, MD, Professor, Departments of Radiology and Pediatrics, University of Arkansas for Medical Sciences; Chief, Magnetic Resonance Imaging, Vice-Chief, Pediatric Radiology, Arkansas Children's Hospital
Charles M Glasier, MD is a member of the following medical societies: American College of Radiology, American Society of Neuroradiology, Radiological Society of North America, and Society for Pediatric Radiology
Disclosure: Nothing to disclose.

Pharmacy Editor

Bernard D Coombs, MB, ChB, PhD, Consulting Staff, Department of Specialist Rehabilitation Services, Hutt Valley District Health Board, New Zealand
Disclosure: Nothing to disclose.

Managing Editor

Marta Hernanz-Schulman, MD, FAAP, Professor, Radiology, Radiological Sciences, and Pediatrics, Director, Department of Pediatric Radiology, Radiologist-in-Chief, Director, Department of Diagnostic Imaging, Vanderbilt University Medical Center, Vanderbilt Children's Hospital
Marta Hernanz-Schulman, MD, FAAP is a member of the following medical societies: American Institute of Ultrasound in Medicine and American Roentgen Ray Society
Disclosure: Nothing to disclose.

CME Editor

Robert M Krasny, MD, Consulting Staff, Department of Radiology, The Angeles Clinic and Research Institute
Robert M Krasny, MD is a member of the following medical societies: American Roentgen Ray Society and Radiological Society of North America
Disclosure: Nothing to disclose.

Chief Editor

Lawrence M Davis, MD, Assistant Professor of Diagnostic Imaging (Clinical), Department of Diagnostic Imaging, Warren Alpert Medical School at Brown University
Lawrence M Davis, MD is a member of the following medical societies: American College of Radiology, American Roentgen Ray Society, American Society of Neuroradiology, Radiological Society of North America, and Rhode Island Medical Society
Disclosure: Nothing to disclose.

 
 
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