In simple terms, what actually causes cerebral palsy in the brain?

Cerebral palsy happens when the developing brain is injured, or develops atypically, during a specific window before, during, or shortly after birth, or occasionally in early childhood. The injury itself doesn't get worse over time; it's a one-time event whose physical effects then unfold as the child grows. Exactly which part of the brain was affected, and when, shapes which specific pattern of movement difficulty a child ends up with.

What is hypoxic-ischemic encephalopathy, and why can it look different in different babies?

Hypoxic-ischemic encephalopathy, or HIE, is brain injury caused by a period of reduced oxygen and blood flow, most often around the time of birth. Which part of the brain is affected depends heavily on the pattern of the oxygen shortage itself: a sudden, severe, short interruption tends to affect deeper brain structures involved in movement control, while a more prolonged, partial reduction tends to affect the outer, watershed regions of the brain instead. This is a major reason two children with HIE can end up with genuinely different patterns of cerebral palsy.

What is kernicterus, and how is it different from other causes of brain injury?

Kernicterus is brain damage caused by very high levels of bilirubin, a substance produced when red blood cells break down, crossing into the brain when severe newborn jaundice goes untreated. Unlike PVL or HIE, which tend to affect white matter or broader brain regions, kernicterus specifically damages the basal ganglia, a structure involved in controlling movement quality, which is why it tends to cause a distinctly different pattern of cerebral palsy involving involuntary, fluctuating movements.

Can cerebral palsy be caused by something that happened before birth even started?

Yes. Some cases result from the brain developing atypically during pregnancy itself, sometimes for reasons that are never fully identified, rather than an injury to an otherwise typically developing brain. A less common but real cause is a perinatal stroke, where a blood vessel in the developing brain becomes blocked, and certain infections during pregnancy can also affect how the fetal brain develops. Understanding which of these applies, where possible, can meaningfully change how future risk and specific therapy needs are thought through.

Does understanding the exact cause change how a child's cerebral palsy is treated?

Understanding the specific mechanism helps explain the particular pattern a child has, but treatment decisions are generally guided more by the resulting movement pattern itself than by the original cause. For children whose CP is primarily spastic, meaning it involves genuine muscle tightness, treatments aimed specifically at reducing that spasticity, from physiotherapy through to minimally invasive procedures such as SFDM available at CP Clinic, are what actually address the day to day physical impact, regardless of which specific brain mechanism originally caused it.

What Happens in the Brain to Cause Cerebral Palsy?

Causes & Prevention 14 min read

What Happens in the Brain to Cause Cerebral Palsy?

Q: What is periventricular leukomalacia, and why does it mostly affect premature babies?

Periventricular leukomalacia, or PVL, is damage to the brain's white matter, the tissue that carries signals between different brain regions, located near fluid-filled spaces called ventricles. In the final months of pregnancy, the blood vessels supplying this area and the cells responsible for building it are still maturing, which makes it especially vulnerable in babies born very early. This is exactly why PVL is far more common in premature infants than in babies born at full term.

“What actually happened in my child’s brain?” is one of the most common questions parents ask, and one of the least clearly answered anywhere. This article walks through it properly: when it can happen, where in the brain it happens, and why the same general cause can look completely different from one child to the next.

Written by CP Clinic Medical Team Tovmed Medical Center, Vinnytsia, Ukraine

Medically reviewed by Prof. Vigein Tovmasian PhD · Orthopedic Surgeon · Honorary Doctor of Ukraine

The basic idea, in one paragraph

Cerebral palsy happens when the developing brain is injured, or develops in an atypical way, during a specific window of time. That injury or difference is a one-time event. It doesn’t get worse on its own afterward. What changes over time is how its physical effects unfold as a child grows, not the underlying brain injury itself. Exactly which part of the brain was affected, and exactly when, shapes which specific pattern of movement difficulty a child ends up with.

The three windows when it can happen

Prenatal

During pregnancy

The brain can develop atypically, or be affected by an infection or other factor, before birth even begins.

Perinatal

During birth itself

The most well known window, covering complications during labour and delivery that reduce oxygen or blood flow.

Postnatal

In early childhood

Less common, but real: infections such as meningitis, or other injuries to the still-developing brain in the first years of life.

The specific mechanisms, explained plainly

🧵

Periventricular leukomalacia (PVL)

Mostly premature babies

Damage to the brain’s white matter, the tissue that carries signals between brain regions, located near fluid-filled spaces called ventricles. In the final months of pregnancy, the blood vessels and cells building this area are still maturing, making it especially fragile in babies born very early.

🫁

Hypoxic-ischemic encephalopathy (HIE)

Mostly term babies

Injury caused by a period of reduced oxygen and blood flow, most often around birth. A sudden, severe, brief interruption tends to affect deeper structures involved in movement control. A more gradual, partial reduction over a longer period tends to affect the outer regions of the brain instead, which is a major reason HIE doesn’t always produce the same pattern of CP.

🩸

Intraventricular hemorrhage (IVH)

Mostly premature babies

Bleeding into the fluid-filled spaces inside the brain. More severe bleeding carries a higher chance of lasting effects, and it’s often invisible from the outside, which is why premature babies are routinely screened for it with ultrasound.

🟡

Kernicterus

Severe untreated jaundice

Brain damage from very high bilirubin levels, which specifically targets the basal ganglia, a structure that controls movement quality rather than strength. This is exactly why kernicterus tends to produce involuntary, fluctuating movement patterns rather than the constant muscle tightness seen with PVL or HIE.

🧬

Brain malformation

During pregnancy

Sometimes the brain develops in an atypical way during pregnancy itself, rather than being injured after developing normally. The exact reason isn’t always identifiable, even with thorough investigation.

🧠

Perinatal stroke

Less common, real cause

A blood vessel supplying part of the developing brain becomes blocked, cutting off blood flow to that specific area, similar in concept to a stroke in an adult but occurring around the time of birth.

🦠

Infection

Prenatal or postnatal

Certain infections during pregnancy can affect how the fetal brain develops. After birth, infections such as meningitis can injure a still-developing brain directly during early childhood.

Why the same cause can look different in different children

The key insight tying this all together

The pattern of cerebral palsy a child has isn’t random. It follows directly from which brain area was affected and how mature that area was at the time. This is why prematurity so often leads to a specific pattern (spastic diplegia, legs affected more than arms, from white matter damage near the ventricles), why kernicterus produces a genuinely different pattern (involuntary movement, from basal ganglia damage), and why two children with what sounds like “the same cause” on paper can still end up with meaningfully different physical presentations. Location and timing, not just the cause’s name, are what actually determine the outcome.

What this means for you

Many of these mechanisms happen despite excellent prenatal and delivery care, and several, particularly brain malformations with no identifiable cause, aren’t preventable with today’s medical knowledge at all. Understanding what actually happened, in plain, specific terms rather than vague or frightening language, often helps parents process this more than any reassurance alone ever could. Knowing the mechanism doesn’t change what happened, but it can change how you carry it.

Does the cause change the treatment?

Understanding the mechanism explains why your child has the specific pattern they do. Treatment decisions, though, are generally guided more by that resulting pattern itself than by the original cause.

For spastic-pattern CP specifically

When the resulting pattern is primarily spastic, meaning genuine muscle tightness rather than involuntary movement, treatments aimed directly at reducing that spasticity are what address the day to day physical impact. Minimally invasive procedures such as SFDM (Selective Fibrotomy of Damaged Muscles), available at CP Clinic from age 2, are designed specifically for this, regardless of which original brain mechanism, PVL, HIE, or another cause, produced the spasticity in the first place.

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Frequently asked questions

In simple terms, what causes cerebral palsy in the brain?

Injury to, or atypical development of, the brain during a specific window before, during, or shortly after birth, occasionally in early childhood. The injury itself is a one-time event; it doesn’t worsen over time, though its physical effects unfold as a child grows.

What is periventricular leukomalacia, and why does it mostly affect premature babies?

Damage to white matter near the brain’s ventricles. This area’s blood vessels and cells are still maturing in the final months of pregnancy, making it especially vulnerable in babies born very early, which is why PVL is far more common in premature infants.

What is HIE, and why does it look different in different babies?

Brain injury from reduced oxygen and blood flow, usually around birth. A sudden severe interruption affects deeper movement-control structures, while a prolonged partial reduction affects outer brain regions instead, which is why two children with HIE can end up with different CP patterns.

What is kernicterus, and how does it differ from other causes?

Brain damage from very high bilirubin levels from untreated severe jaundice, specifically targeting the basal ganglia rather than white matter or broader regions. This is why it tends to cause involuntary, fluctuating movement rather than constant muscle tightness.

Can CP be caused by something before birth even started?

Yes. Some cases result from atypical brain development during pregnancy itself, sometimes with no identifiable reason. Perinatal stroke (a blocked blood vessel) and certain infections during pregnancy are other real, if less common, causes.

Does understanding the cause change treatment?

It explains the specific pattern a child has, but treatment is generally guided more by the resulting movement pattern than the original cause. For spastic-pattern CP, treatments targeting spasticity directly, including SFDM at CP Clinic from age 2, address the physical impact regardless of the original mechanism.

References

“Cerebral Palsy and the Relationship to Prematurity.” Springer Nature. Springer ↗
“Exploring the neurological impact of prematurity: Shared mechanisms in periventricular leukomalacia (PVL), intraventricular hemorrhage (IVH), and hydrocephalus.” ScienceDirect. ScienceDirect ↗
“A Practical Approach to Neonatal Jaundice.” American Family Physician. AAFP ↗
“Cerebral palsy: causes, pathways, and the role of genetic variants.” American Journal of Obstetrics and Gynecology, ScienceDirect. ScienceDirect ↗
“Perinatal stroke: mechanisms, management, and outcomes of early cerebrovascular brain injury.” The Lancet Child & Adolescent Health.

Medical disclaimer: This article is for informational purposes. Understanding your own child’s specific cause and pattern should come from a direct clinical assessment and their existing medical records, reviewed with a qualified specialist.