cranial ultrasound - increased head circumference

[cmr1987]

My 6 month old baby has just had a cranial ultrasound due to a sudden increase in head circumference from the 50th to 95th percentile and the report states that there is a widening of the extra axial CSF spaces bilaterally and the 3rd and 4th ventricles whilst visible do not appear to be dilated, no mass identified, no evidence of haemorrhage, no evidence of hydrocephalus. My doctor has referred him to have a CT scan to exclude a subdural hygroma..... what does all this mean?? what are the extra axial CSF spaces and what is hygroma?

[Jannah G., RN]

Hello cmr1987,

Hope all is well!

There are tons of really good info online about subdural hygromas, even some pretty nifty pictures of the brain. A subdural hygroma is basically a collection of CSF (cerebrospinal fluid) in the subdural space. Very similar to hydrocephalus that you mentioned earlier, just in a different space. The subdural space in a "normal" brain is actually not a space at all. It is really just the seperation of 2 different parts of the brain. Picture it like this, you have 2 pieces of bread on top of each other, the space in between would be your subdural space. So, any collection of anything in that space is abnormal, because it is really just a "virtual" space.

The CT that your baby is going to have performed will give the Doctors a really good image of what is going on.

I wish you both much luck!