Subcortical means that something is located beneath the outer layer of the brain, in the deeper parts. The word comes from Latin: "sub" means "under" and "cortex" refers to the outer layer of the brain, known as the cerebral cortex.
What does subcortical describe exactly?
In everyday medical practice, the word subcortical often appears in MRI or CT scan reports of the head. It always describes a location. Everything that is subcortical is not at the surface of the brain, but just beneath it. The cerebral cortex itself is only a few millimetres thick. Below it lie larger areas made up of what is called white matter. These areas are responsible for passing information between different parts of the brain.
Where in the brain is the subcortical area?
Directly beneath the cerebral cortex, the white matter of the brain begins. This is where many nerve fibres run, connecting different sections of the brain like data cables. Deeper still lie the basal ganglia and other important structures. Everything between the cortex and these deeper structures is described as subcortical. The opposite term is "cortical", which refers only to the cerebral cortex itself.
When does the term subcortical appear in reports?
In letters from doctors or radiology reports, you will often read about subcortical changes or findings. This can appear in the following contexts:
When describing small changes in the brain, for example as part of an imaging scan such as an MRI or CT.
In connection with certain conditions that tend to affect the regions beneath the cerebral cortex.
As a description of the location of lesions, meaning damage or changes that are not directly in the cortex but beneath it.
One example of this is what are known as subcortical white matter lesions. These are small changes in the white matter that can occur in many people, especially in older age. Subcortical glioses are also sometimes described. These are scar-like changes that can develop after small disruptions to blood flow.
Are there conditions that particularly affect subcortical areas?
The term itself only describes the location of a change in the brain. However, there are conditions that mainly affect subcortical regions. These include certain forms of dementia in which the white matter is damaged, or small changes in blood vessels that lead to reduced blood flow. Multiple sclerosis can also cause subcortical lesions. Whether a subcortical change needs treatment always depends on the full picture and the exact diagnosis.
What does subcortical mean for your own report?
If you read the word subcortical in a doctor's letter or scan report, it initially only tells you where a change or finding is located in the brain. It does not say anything about how serious or dangerous something is. Only when combined with further details, such as the size, number, type of change, and any possible symptoms, can a proper assessment be made. Subcortical changes are often age-related and have no medical significance. In other cases, they may point to an underlying condition that should be investigated further.
In summary: subcortical is a description of location
Subcortical always describes something that lies beneath the cerebral cortex. Whether it involves harmless age-related changes, reduced blood flow, or other processes depends on the overall findings.
