Microcephaly

What is Microcephaly:

Microcephaly is a clinical finding which is characterized by the measurement of head circumference (HC) less than 3 Standard deviations below the mean for age and gender.

The above statement is the generally accepted definition of microcephaly.

There does not exist a uniform definition for microcephaly. Some medical reference books refer to this condition as less than 2 S.D below the mean and some times even less than 4 S.D is considered.  

Microcephaly is a neurodevelopmental disorder. Unlike other defects , this condition is most often not a primary malformation. Instead , the underlying cause can vary widely, ranging from chromosmal or genetic abnormalites to environmental factors.

MRI of an individual with Normal brain( left)  Vs  a patient with Microcephaly ( right)
source: wikimedia commons

Classification:

Microcephaly has many different types of classification. The most common methods followed are- 

1. Based on the time of onset

2. Based on associated malformations

No particular classification is complete and most of the times many other factors are also considered in determining the reason for microcephaly. I have not gone in-depth with the classification (in this post) because it becomes too complicated to chart it out.

Click on the image to see a bigger picture

Click on the image to see a bigger picture

Do you have any other information to add to this post? If so, please comment below.