If your baby seems to favor one hand, reaches for toys with only one arm, or moves one side of their body differently from the other, you may be seeing the earliest signs of hemiplegic cerebral palsy. What does this mean for your child? Will they walk? Can therapy help? Hemiplegia is one of the most common forms of CP, and one where early therapy can make a profound difference in your child’s hand function and independence.
What Is Hemiplegic Cerebral Palsy?
Hemiplegic cerebral palsy (also called spastic hemiplegia or unilateral CP) affects one side of the body. The arm is typically more involved than the leg. It accounts for approximately 25 to 40 percent of all spastic CP cases, making it one of the most common subtypes.
Because the brain controls movement on the opposite side of the body, a right-brain injury causes left-sided hemiplegia, and a left-brain injury causes right-sided hemiplegia. This crossed pattern is an important part of understanding how the brain injury maps to your child’s symptoms.
The good news: most children with hemiplegic CP walk independently, typically classified at GMFCS Level I or II. Most have typical intelligence. The primary functional challenge is usually reduced strength, coordination, and dexterity in the affected hand, which impacts daily tasks like grasping, writing, dressing, and eating.
Early Signs: How Hemiplegic CP Is First Noticed
Hemiplegic CP is often the first subtype parents notice on their own, because the asymmetry between the two sides of the body is visible during everyday interactions. The signs typically become apparent between 4 and 9 months of age:
- Early hand preference before 12 months: This is the single most distinctive early sign. Babies normally do not develop a preferred hand until 12 to 18 months. If your baby consistently reaches, grasps, or transfers objects with one hand while ignoring or fisting the other, this is not typical and should be evaluated.
- One hand stays fisted: The affected hand may remain clenched, often with the thumb tucked across the palm (cortical thumb), while the other hand opens and grasps freely.
- Asymmetric reaching: The baby reaches across midline with the unaffected arm rather than using the closer hand when a toy is placed on the affected side.
- Asymmetric kicking: One leg kicks vigorously while the other moves less frequently or with less force.
- Asymmetric crawling: The baby may drag one side of the body, scoot on their bottom, or develop an unusual crawling pattern that compensates for the weaker side.
- Walking with a limp: When walking begins, the child may walk on tiptoe on the affected side, keep the affected arm tucked close to the body in a flexed position, or have a noticeably asymmetric gait.
What Causes Hemiplegic CP?
Hemiplegic CP results from damage to one hemisphere of the brain. The most common causes include:
| Cause | Description | Timing |
|---|---|---|
| Perinatal arterial ischemic stroke (PAIS) | A blood clot blocks blood flow to part of one brain hemisphere, most commonly in the middle cerebral artery territory. This is the single most common cause of hemiplegic CP. | Around the time of birth |
| Focal HIE | Localized oxygen deprivation during delivery damages one hemisphere more than the other, creating an asymmetric injury pattern. | During labor and delivery |
| Unilateral PVL | Damage to the white matter on one side of the brain, particularly in premature infants. | Third trimester or perinatal |
| Intracranial hemorrhage | Bleeding in or around one side of the brain, which can result from traumatic delivery or prematurity. | During or shortly after birth |
| Middle cerebral artery infarction | A stroke specifically in the middle cerebral artery, which supplies the motor cortex controlling hand and arm movement. | Perinatal |
How Is Hemiplegic CP Treated?
Treatment for hemiplegic CP focuses on maximizing use of the affected hand, improving gait symmetry, and supporting independence in daily activities. The two therapies with the strongest evidence base are:
Constraint-Induced Movement Therapy (CIMT)
CIMT is the gold-standard therapy specifically designed for unilateral CP. It works by temporarily restraining the unaffected (stronger) hand with a cast, mitt, or sling, forcing the child to use the affected hand intensively. Treatment is typically delivered in concentrated blocks of 2 to 6 weeks, with several hours of structured practice per day.
A Cochrane systematic review confirmed that CIMT produces meaningful improvements in hand function, grip strength, and ability to perform two-handed tasks. The improvements are durable, persisting months after the therapy block ends. CIMT is most effective when started in early childhood, during the period of greatest brain plasticity.
Bimanual Intensive Therapy (BIT)
BIT focuses on training both hands to work together through structured two-handed activities. Rather than restraining the stronger hand, BIT teaches the child to use both hands in coordinated tasks like catching a ball, opening a container, or buttoning a shirt. Research shows BIT is equally effective as CIMT for improving bimanual coordination and may be preferred for children who resist the constraint or who need to improve two-handed skills specifically.
Perinatal stroke and oxygen deprivation during delivery are common causes of hemiplegic CP. If medical errors played a role, your family may have options.
Could My Child’s Hemiplegic CP Be the Result of a Birth Injury?
The brain injury that causes hemiplegic CP frequently occurs during labor and delivery. Perinatal stroke, the most common cause, may result from complications that were not identified or managed in time. Other cases involve focal oxygen deprivation or traumatic delivery that could have been avoided with appropriate care.
If your child experienced any of the following, a preventable birth injury may be responsible:
- Complicated or prolonged labor with signs of fetal distress
- Emergency resuscitation or low Apgar scores at birth
- NICU admission for seizures, encephalopathy, or abnormal neurological findings
- Forceps or vacuum delivery with complications
- Delayed C-section when fetal heart rate patterns indicated distress
- Failure to detect or treat maternal infection during labor
- HIE diagnosis (hypoxic-ischemic encephalopathy)
A thorough case review examines the complete medical record, including fetal monitoring strips, delivery notes, imaging results, and the neonatal course, to determine whether preventable errors contributed to your child’s brain injury and resulting hemiplegic CP.
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