Basal ganglia haemorrhage
On CT head
Introduction
When it comes to CT head interpretation, recognising an intracerebral haemorrhage quickly and accurately is vital. In this case, we focus on a deep bleed in the basal ganglia.
You’ll learn how to spot key CT features like mass effect and intraventricular blood, and understand the typical causes of basal ganglia haemorrhage.
Case introduction
A male in his 50s presents to the Emergency Department with loss of consciousness. What does the CT scan show?
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Video explanation
Here is a video explanation of this case: click full screen in the bottom right corner to make it big. If you prefer though I go through this in the text explanation below.
Bright things on a non contrast CT head
Let’s take a closer look at this CT head scan: there’s something clearly abnormal on the left side of the brain. We perform most acute CT head scans without IV contrast as haemorrhage appears bright and we don’t want bright IV contrast to mask this.
What Normally Appears Bright on a CT Head?
Some structures naturally show up as bright (hyperdense) on CT scans:
- Bone – The skull vault, of course.
- Pineal Gland – Often calcifies with age.
- Choroid Plexus – Found in the ventricles, commonly calcified.
- Falx and Tentorium Cerebelli – Can show normal physiological calcification.
- Basal Ganglia – Calcification can be pathological but also can be seen with aging.
However if you can’t explain high density by calcification or a normal structure, you need to seriously consider haemorrhage.
Locating the bleed
While a tumour or underlying lesion could be a possibility, the most common cause in this location is high blood pressure (hypertension).
Chronic hypertension can cause tiny, weak-walled microaneurysms called Charcot-Bouchard aneurysms, which can rupture and cause bleeding. These tend to happen in specific locations, and the basal ganglia, especially the putamen, is one of the most common sites. Other typical locations include:
- Thalamus
- Pons
- Cerebellum
Now, looking at our patient’s scan, the bleed is clearly centered in the lentiform nucleus and more specifically, the putamen, which together with the globus pallidus makes up the lentiform nucleus.
The bleed is centred on the left lentiform nucleus and more specifically the putamen.
Cause of basal ganglia haemorrhage
While a tumour or underlying lesion could be a possibility, the most common cause in this location is high blood pressure (hypertension).
Chronic hypertension can cause tiny, weak-walled microaneurysms called Charcot–Bouchard aneurysms, which can rupture and cause bleeding. These tend to happen in specific locations, and the basal ganglia—especially the putamen—is one of the most common sites. Other typical locations include:
- Thalamus
- Pons
- Cerebellum
Other findings
A deep hemorrhage in the brain is never good news, but there are certain signs that make this case even more worrisome:
- Mass Effect – The bleed is pushing against nearby brain structures, increasing pressure in the skull. We can see the lateral ventricle has lost its normal shape in the picture below. Other signs of mass effect to look for include cerebellar tonsil herniation or uncal herniation although these are not present in this case.
- Blood in the Ventricles – Looking at the dependent (lowest) parts of the ventricles, we can see hyperdensity, meaning blood has leaked into the right lateral ventricle. This is always an important review area – blood within a dependent position of the ventricles can be the only abnormal finding on a scan so always worth checking.
Having intraventricular hemorrhage (blood in the ventricles) is linked to a worse prognosis and worsened patient outcomes.
There is mass effect: there is effacement of the left lateral ventricle caused by the haemorrhage.
Blood is seen within a dependent region of the right lateral ventricle: always a key review area.
KEY POINTS
Deep brain haemorrhage within the basal ganglia, thalamus, pons and cerebellum are highly suggestive of a hypertensive bleed.
Once you see this look for secondary signs such as mass effect and intraventricular haemorrhage.