Difference Between Acrania and Anencephaly

The key difference between acrania and anencephaly is the presence and absence of brain tissue. Acrania is a congenital disorder where the brain tissue is present while anencephaly is a congenital disorder where the brain tissue is absent.

Congenital disorders arise due to neural defects that take place during pregnancy. They give rise to a high degree of mortality. Acrania and Anencephaly are two such congenital disorders seen in infants. Infants with acrania and anencephaly have brain disorders; thus, they face problems with recognition, memory and intelligence.

CONTENTS

1. Overview and Key Difference
2. What is Acrania 
3. What is Anencephaly
4. Similarities Between Acrania and Anencephaly
5. Side by Side Comparison – Acrania vs Anencephaly in Tabular Form
6. Summary

What is Acrania?

Acrania is a condition where the human fetus completely or partially lacks the flat bones of the cranial vault. Here, though the cerebral hemisphere development takes place, its development is abnormal. Furthermore, the fetus may possess a normal facial bone and a cervical column but will lack the fetal skull. Moreover, it shows reduced brain volume.

Further, this congenital disorder takes place at the 12^th week of gestation (pregnancy). Genetics and chromosomal aberrations play an important role in the onset of the condition. Detection of acrania primarily takes place through an ultrasound image investigation. The disease risk is high if there are previously affected siblings.

What is Anencephaly?

Anencephaly refers to the incomplete development of the brain, skull and the scalp. A neural tube defect takes place during embryonic development. They occur during the third and fourth weeks of pregnancy. During anencephaly, the neural tube does not close properly. It results in the incomplete development of the brain.

Anencephaly is a genetic disorder. It is a multifactorial condition where multiple genes and environmental factors are involved in the onset. It may also occur due to a chromosomal aberration (trisomy 18).

Infants with anencephaly possess the following features in the newborn.

• Absence of the front part of the brain (forebrain)
• Absence of the cerebral hemispheres and the cerebellum
• Exposure of the brain tissue with the absence of the skull
• Impaired consciousness
• High mortality rate

What are the Similarities Between Acrania and Anencephaly?

• Acrania and anencephaly are congenital disorders.
• Both take place during the period of pregnancy.
• They occur due to genetic disorders and chromosomal aberrations.
• Both cause defects in recognition, intelligence and memory.

What is the Difference Between Acrania and Anencephaly?

The key difference between acrania and anencephaly is the presence or absence of the brain tissue. In acrania, the brain tissue is present while in anencephaly, the brain tissue is absent. Moreover, the period of gestation also differs in acrania and anencephaly. However, the symptoms of both conditions are similar and are fatal in nature.

The below infographic summarizes the difference between acrania and anencephaly.

Summary – Acrania vs Anencephaly

Acrania and anencephaly are congenital disorders. They arise due to birth defects of the neural canal. Therefore, the symptoms of these conditions can only be identified using ultrasonography. The primary difference between acrania and anencephaly is based on brain tissue. The brain tissue is visible in acrania while brain tissue is absent in anencephaly. It is important that the diagnosis takes place fast. However, infants with these disorders have a low survival rate.

Reference:

1. “Anencephaly.” NORD (National Organization for Rare Disorders), Available here.
2. Tae-Hee , Kwon, et al. “Acrania: Review of 13 Cases.” Sonography& Ultrasound Resources, Available here.

Image Courtesy:

1. “Acrania” By Dr.sachin23 – Own work (CC BY-SA 3.0) via Commons Wikimedia
2. “Anencephaly-web” By Centers for Disease Control and Prevention, National Center on Birth Defects and Developmental Disabilities (Public Domain) via Commons Wikimedia