Cerebral palsy

It’s pretty well-established that your brain’s really important. It’s like, if your body was a computer, your brain’s the mainframe. It controls everything, whether you’re aware of it or not. Cerebral palsy means “brain condition causing paralysis”; so essentially, cerebral palsy refers to damage to the brain that causes loss of muscle control, like for example if the cerebellum was damaged, patients might have issues with fine motor skills like writing or typing.

That being said, though, cerebral palsy’s a broad umbrella term to basically cover a wide variety of issues, since ultimately the muscles affected and severity depends on which part of the mainframe’s been affected, right? Cerebral palsy is considered a neurodevelopmental condition, meaning that something happens to an area of the brain during its initial development, which is an extremely sensitive period. If that area doesn’t develop right, then it can’t carry out whatever function it’s supposed to control.

But what’s this vague “something” that can happen, though? Well, it’s “something” because there’s such a wide variety of causes. The majority of cerebral palsy cases are thought to happen before birth, or prenatally, which typically means the underlying cause is really hard to pin down. Exposure to radiation or infection during fetal development can cause cerebral palsy. Hypoxia to the developing fetus been linked as well, in this case the developing brain doesn’t get enough oxygen, potentially from problems like the placenta not being able to supply enough oxygen and nutrients. Cerebral palsy doesn’t have to happen prenatally, though, and some postnatal causes are things like head trauma, or again an infection or a period of oxygen deprivation. Although most cases are likely due to some trauma or injury, a very small proportion of cases are due to a genetic mutation. Even though the brain damage or injury or abnormality is permanent, one super important point to remember about cerebral palsy is that it doesn’t get worse over time, and for that reason it’s considered a non-progressive condition.

Cerebral palsy is classified by the type of muscle movements that result from the brain injury and how that affects what activities the patient can perform. The first type is called spastic cerebral palsy, which accounts for about 70% of cases, and this is characterized by having really tight or stiff muscles, which can make patients’ movements seem jerky. This tightness results from a lesion in an upper motor neuron. So with a lesion, which just means some kind of abnormality, the ability of some of these neurons to receive GABA might be impaired. GABA’s the main inhibitory neurotransmitter, so if nerve impulses can’t be inhibited, which is a double negative, then those nerves are basically over-excited, leading to hypertonia, which is an abnormal increase in muscle activity, basically like if the muscles were constantly contracting. This is why some people with spastic cerebral palsy have a scissor gait. Think about how hard it’d be to walk when your adductor muscles were always partly contracted which causes your knees and thighs to constantly touch. Similarly, sometimes patients have a “toe-walk”, because their calf muscles are always contracted, which pulls the achilles tendon up and causes someone to go up on their toes.

A second type of cerebral palsy is Athetoid or dyskinetic cerebral palsy, and this one involves damage or injury to the basal ganglia. The basal ganglia is this structure here which essentially helps us initiate and prevent certain movements. If the basal ganglia becomes damaged, patients can lose the ability to prevent movements, and therefore they can have involuntary movements, meaning out of their control. So dyskinetic cerebral palsy is characterized by dystonia and/or chorea—dystonia is random, slow, and uncontrolled movements in the limbs and trunk. Chorea is random “dance-like” movements, since the small uncontrolled movements seem to move from muscle to muscle.

Finally there’s ataxic cerebral palsy. Taxis refers to an order or arrangement, so ataxic essentially means without order, which is in reference to patients with this type being shaky or uncoordinated, and this is caused by damage to the cerebellum, which helps with coordination and fine or precise movements. These patients often have clumsy or unstable movements and poor balance when doing things like walking or picking something up.