The basal ganglia are a collection of gray matter (nuclei) in the brain.
These nuclei lie around the thalamus and they are interconnected. They can be seen as one regulation system that controls movements (planning and programming movements – how large or rapid must the movement be) as well as reward and motivation (cognition concerning motor activity). Movement is made easier, smoother.
They take care of smooth movements such as:
• Swinging the arms while walking.
• Crude movements of fascial expressions with emotions.
• Movements of limbs in swimming.
• Regulate posture.
The basal ganglia are:
• Nucleus caudatus.
• Globus pallidus.
• Substantia nigra.
• Subthalamus nucleus.
They are part of the extra-pyramidal circuit.
We must consider dysfunctions of these ganglia in the following cases:
• Jerky movements (chorea). As for example certain torticollis, adult onset sometimes.
• Writhing (worm-like movements, twisting) movements (athetosis).
• Rhythmic movements (tremors). As for example in Parkinson disease (resting tremor and bradykinesia), Huntington disease.
• General disturbance of muscle tone.
• Tics (as in for example Tourette).
• ADHD (problem lies in the frontal cortex and basal ganglia).
• OCD (obsessive compulsive disease).
• General hypertonicity of the muscular system, rigidity.
• Prolonged reaction time.
• Shuffling gait.
• Posture in flexion (statue like appearance).
The aetiopathogenesis of these nuclei is:
• Mainly idiopathic.
• Degeneration of dopaminergic neurons (because of age).
• Viral encephalitis.
• Cerebral arteriosclerosis.
• Rheumatic fever.
• Sometimes birth injury.
The blood supply of the basal ganglia is provided via three arteries:
• Anterior choroidal artery.
• Middle cerebral artery.
• Anterior cerebral artery.
All part of the carotid system.
Normal function of the brain's control centers is dependent upon adequate supply of oxygen and nutrients through a dense network of blood vessels.
The rate of the cerebral blood flow in the adult is typically 750 milliliters per minute, representing 15% of the cardiac output. The arteries deliver oxygenated blood, glucose and other nutrients to the brain, and the veins carry deoxygenated blood back to the heart, removing carbon dioxide, lactic acid, and other metabolic products.
• Theoretically it is possible that when we aim for a better circulation of the brain and a better O2-CO2 relation in the blood, this could benefit the functioning of the basal ganglia.
• However, there is no proof and the probability that this could work is very low.
• Even when we can’t help these patients, it is important that we can refer when we encounter these phenomena.
Luc Peeters, MSc.Ost.