What is a Stroke?
Stroke occurs when blood flow to the brain is severely disrupted. There are two main types of stroke: ischemic and hemorrhagic. Ischemic stroke occurs when a blockage, such as a blood clot, prevents blood from reaching a region of the brain. Ischemic stroke accounts for approximately 80% of all strokes [1]. Ischemic stroke can be a embolic or thrombotic stroke.
Hemorrhagic stroke occurs when a blood vessel in the brain is weakened to the point of rupture, which causes blood to flow into the surrounding tissue. This haemorrhaging of blood can damage or destroy the functioning of the neural tissue, leading to neurological complications.
Deprived of essential nutrients and oxygen, this restriction in blood flow leads to neuronal damage and death, leading to symptoms of stroke. Depending on the extent of damage and region impacted, such complications may be irreversible.
What is Basal Ganglia Stroke?
Basal ganglia stroke is a stroke that occurs in the basal ganglia, an essential region of the brain located just above the brainstem.
The basal ganglia is a key regulator of both basic and higher neurological functions, and thus basal ganglia strokes can severely disrupt physiological functioning.
The basal ganglia consist of many clusters of neurons, divided into different structures, namely the caudate nucleus, putamen, substantia nigra, globus pallidus, nucleus accumbens and subthalamic nucleus. Damage to these different structures may cause different symptoms.
Basal ganglia strokes may be haemorrhagic or ischemic, though it is more common for strokes in this region to be haemorrhagic [2].
Non-traumatic haemorrhagic stroke often occurs due to rupture of the small and delicate blood vessels which supply the basal ganglia.
Ischemic Basal Ganglia Stroke
Ischemic basal ganglia stroke is a stroke caused by a blood clot or narrowed arteries which restrict blood flow. Usually, in the basal ganglia, we see the middle cerebral artery being blocked and causing damage. This restriction causes the brain to lose access to oxygen and nutrients and results in stroke.
Haemorrhagic Basal Ganglia Stroke
On the other hand, haemorrhagic basal ganglia stroke occurs due to an artery rupture in the basal ganglia, which causes bleeding and result in stroke.
Haemorrhagic Basal Ganglia Stroke vs Basal Ganglia Haemorrhage
When we observe bleeding in the basal ganglia, which does not lead to stroke, we refer to it as the basal ganglia haemorrhage. Such bleeding can be due to various causes such as high blood pressure, trauma or blood vessel abnormalities.
The blood vessels in the basal ganglia region of the brain are small and vulnerable, therefore basal ganglia haemorrhage can be observed although it does not have to lead to stroke.
However, when the bleeding in the basal ganglia leads to a stroke, we refer to the stroke as a haemorrhagic basal ganglia stroke.
Left vs Right Basal Ganglia Stroke
The basal ganglia can be split in two groups - the left basal ganglia and the right basal ganglia. Stroke in left basal ganglia may produce different symptoms compared to stroke in right basal ganglia:
Symptoms of Basal Ganglia Stroke
Whether haemorrhagic or ischemic, basal ganglia stroke results in symptoms such as [3, 4]:
- Muscle weakness or paralysis
- Difficulty walking
- Difficulty maintaining balance
- Difficulty coordinating movements; clumsiness
- Difficulty speaking, difficulty swallowing
- Emotional dysregulation, confusion
- Tremors
- Personality changes
Some of these symptoms are universal across all strokes, however, basal ganglia stroke brings a unique set of symptoms due to its location. These are mainly abovementioned tremors, difficulty swallowing and difficulty maintaining balance,
Upon recognizing any of these symptoms, neurological attention should be sought immediately. If a neurologist suspects that a stroke may have occurred, they will likely order a CT or MRI scan to confirm the diagnosis.
These brain imaging techniques can reveal bleeding in the brain and help localize areas of damaged tissue [5]. Basal ganglia strokes, which are typically characterized by small lesions, may be better detected by MRI than CT [6].
Hyperkinetic Disorders Caused by Basal Ganglia Stroke
It has been hypothesised that the basal ganglia stroke can result in long-term complications.
In a study looking at acute stroke patients, patients showed symptoms of various hyperkinetic movement disorders. [7]
These included:
- hemichorea-hemiballism - involuntary, irregular jerky movements of the limb on one side of the body
- asterixis - involuntary flapping movements
- limb shaking and dystonia - involuntary muscle contraction and abnormal posture.
These disorders are also commonly observed in neurodegenerative disorders involving the basal ganglia such as Parkinson’s disease.
Treatment for Basal Ganglia Stroke
When treating stroke, time is of the essence: the more quickly a person receives medical attention, the better their chances are for recovery.
In the case of ischemic stroke, treatment may involve medications that dissolve blood clots to allow restoration of normal blood flow [5].
However, basal ganglia strokes more often involve haemorrhage of small blood vessels rather than arterial blockages. Depending on the severity of haemorrhaging, a physician may opt for surgery or a more conservative approach to treatment [8].
Surgical treatments include: burr-hole aspiration [8], in which a small hole is drilled into the skull and a catheter is inserted to drain out the excess blood; and craniotomy with hematoma removal [8], wherein a surgeon creates a temporary flap in the skull and uses suction and irrigation to remove the pooled blood [9].
More conservative treatments include blood pressure medication and antiepileptic drugs [8].
Once the patient has been stabilized and the stroke has been mitigated, physical therapy and rehabilitation are often necessary for ongoing recovery of neurological function [5].
Causes of Basal Ganglia Stroke
There is no singular cause of stroke; rather, there are various sources of risk that may place an individual at greater risk.
Hypertenstion
A major risk factor for basal ganglia stroke is chronic hypertension, which puts strain on the blood vessels and causes them to become rigid and inflexible over time [10].
However, hypertension is neither necessary nor sufficient to cause deep brain hemorrhage and combines with other environmental and genetic risk factors to produce basal ganglia stroke.
Lifestyle
Modifiable risk factors for stroke include smoking, alcohol consumption, sedentary lifestyle, hypertension (high blood pressure), hypercholesterolemia (high cholesterol), excess weight, and diabetes mellitus [10].
These risk factors can elevate one’s risk of stroke by putting stress on the circulatory system and damaging the vasculature.
Head injury
While rare, ischemic basal ganglia strokes have also been observed. For example, ischemia in the basal ganglia has been reported due to traumatic head injury [11]. In such cases, there may be haemorrhagic injury to other regions of the brain, which cuts off subsequent blood flow to the basal ganglia [11].
Traumatic head injury can also cause damage to cerebral arteries, which provokes blood clotting and impairs blood flow, thereby contributing to basal ganglia ischemia and stroke [11].
Genetics
There is evidence that some gene variants may influence the risk of stroke (for example, TSPAN2, which is involved in vascular development; NOTCH3 mutations, which can contribute to small vessel disease; and variants of ABO blood group proteins, which can increase risk of thrombosis) [10].
The Demographics of Stroke
Notwithstanding the role of genetics, the risk of stroke is also heavily contingent upon demographic, lifestyle, and environmental factors. Demographically, stroke occurs more often amongst older adults, particularly those over age 55 [10].
Stroke is also more common in women than men [10], a statistic which, in part, may be influenced by the correlation between blood clotting and birth control/hormonal medications.
The risk of stroke is also significantly higher amongst Black populations compared to White and Hispanic populations [10]; this disparity likely emerges from a combination of biological and socioeconomic factors.
How To Prevent Basal Ganglia Stroke?
While age, sex, and ethnicity cannot be modified, lifestyle changes and judicious medication management can help reduce the likelihood of stroke in those at risk.
Avoiding smoking, alcohol, and recreational drug use plays a protective role in safeguarding against stroke.
Additionally, incorporating physical activity into one’s daily routine is beneficial for overall cardiac health and stroke prevention. For individuals with hypertension, hypercholesterolemia, and diabetes, a combination of mindful eating and medication can help diminish the cardiac complications associated with these diseases.
Overall, activities and behaviours which promote the maintenance of cardiac health and general well-being are effective and actionable tools in limiting the risk of stroke.