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Year : 2003  |  Volume : 13  |  Issue : 3  |  Page : 295-296
Images - alobar holoprosencephaly

Department of Radiodiagnosis, J.L.N Hospital and Research Centre, Sector 9-Bhilai Nagar Durg, India

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Keywords: Holoprosencephaly, CT

How to cite this article:
Dwivedi M K, Pal R K, Prashant S, Singh K. Images - alobar holoprosencephaly. Indian J Radiol Imaging 2003;13:295-6

How to cite this URL:
Dwivedi M K, Pal R K, Prashant S, Singh K. Images - alobar holoprosencephaly. Indian J Radiol Imaging [serial online] 2003 [cited 2020 Nov 28];13:295-6. Available from:

   Introduction Top

Holoprosencephaly is a complex intracranial abnormality characterized by absent or incomplete cleavage of the Prosencephalon [1].

From a genetic point of view all holoprosencephalies have the same significance. Their frequency is estimated at 1 in 16,000 to 1 in 18,000 births [2].

Holoprosencephalies have a heterogenous cause; chromosomal aberration is found in about one half of the cases. Chromosome 13 is most frequently involved. Partial deletion of chromosome 13 as well as trisomy may coexist with Holoprosencephalies. [2]

Holoprosencephaly as, an autosomal dominant inheritance is rare but certainly exists. Recurrence risk after an isolated case of holoprosencephaly with normal chromosome is 5-6% [3].

During the fourth gestational week, the neural tube forms three primary brain vesicles: the prosencephalon, mesencephalon and rhombencephalon. During the fifth week the forebrain (Prosencephalon) further divides into secondary vesicles: the telencephalon and diencephalons. Partial division of the telencephalon into two cerebral hemisphere occurs by the end of the fifth fetal week. Complete or partial failure in division of the developing cerebrum (Prosencephalon) into hemispheres and lobes results in the Holoprosencephalies. [4]

Alobar form is rare malformation consisting of large Holospheric Brain. Alobar holoprosencephaly is characterized by nearly complete lack of ventricular and hemispheric cleavage. The Brain is basically an undifferentiated Holosphere with central monoventricle and fused thalami [4]. 17% cases of Holoprosencephaly are reported with no facial anomaly [5].

   Discussion Top

CT scan head shows completely unsegmented rim of brain that surrounds a largely undifferentiated central CSF filled cavity. There is no interhemispheric fissure, falx cerebri or corpus callosum. A large posterior mid line cyst is present with out occipital and temporal horn of lateral ventricle. Brain parenchyma shows Horseshoe or Boomerang configuration. Peripheral rim of cerebral cortex displaced rostrally. CT Head is all that needed for the diagnosis but differential diagnosis is massive Hydrocephalus and Hydrancephaly.

   References Top

1.Macahan PJ, Nyberg AD, Mack AL. Sonography of facial feature of alobar and semi lobar Holoprosencephaly. AJR, 1990:154:143-148.   Back to cited text no. 1    
2.Barness EG.Prosencephalon Growth Failures. Potter's Pathology of the Foetus And Infants.3rd Ed: Vol 2:Mosby: 1997:1056-1059.   Back to cited text no. 2    
3.Baraister M, Winter RM. Holoprosencephaly.Color atlas of Congenital Malformation Syndrome.Mosby: 1996:148.   Back to cited text no. 3    
4.Osborn AG. Disorders of Diverticulation and Cleavage, Sulcation and Cellular Migration. Diagnostic Neuroradiology.1st Ed: Vol 1:Mosby, 1994:37-39.   Back to cited text no. 4    
5.Dahnert WG, Radiology Review Manual. 3rd Ed: Williams &Wilkins, 1996:213-214.  Back to cited text no. 5    

Correspondence Address:
M K Dwivedi
Department of Radiodiagnosis, J.L.N Hospital and Research Centre, Sector 9-Bhilai Nagar Durg
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Source of Support: None, Conflict of Interest: None

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[Figure - 1], [Figure - 2]


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