How hemispherectomy affects the global functioning of a child (such as whether they walk, speak, and read) is known as functional outcomes. Unfortunately, functional outcomes are poorly addressed in published research papers.

Approximately 71% percent of children who have this procedure are seizure-free afterwards. In one small study, parents of 115 children who had hemispherectomy were interviewed about how their children were doing after surgery. These parents reported that:

  • 42% over the age of 6 had satisfactory reading skills;
  • 60% participated in mainstream schools with assistance;
  • 70% had satisfactory speaking skills;
  • 83% were able to walk independently;
  • 24% of adults who had the procedure in childhood are gainfully employed.


All children after surgery will have homonymous hemianopsia which is the permanent loss of the visual field opposite the removed hemisphere. This is more than a loss of peripheral vision – it is loss of half the visual field in each eye, including half the central (foveal) vision. Learn more


Because one temporal lobe is removed or disconnected, mild-to-severe listening impairments (known as central auditory processing disorder) can occur. This affects hearing and listening in various environments, especially loud environments or with multiple speakers. Learn more


Because the surgery removes or disconnects the upper motor neurons from one side of the brain that are responsible for intentional movement on the opposite side of the body, the child is left with hemiparesis – a significant weakness of the opposite side of the body. Existing connections to the motor neurons of the remaining part of the brain, however, make it possible for the child to recover some movement, including the ability to walk and use the affected hand as an assist or for some bimanual activities. Although fine motor of the hand will be impaired greatly, the child should be able to move their shoulder, upper arm, and sometimes wrist over time. Some finger movement, especially closing of the hands, can occur after appropriate interventions. 

The weakness is most significant in the days and weeks after surgery, with the opposite arm and leg often totally floppy (flaccid). This is known as hypotonia (decreased activity of spinal circuits because of sudden deprivation of input from the brain). After the hypotonic phase is over, some of the movements will return most at the shoulder and hips. Some children do not experience a hypotonic phase at all.

Hemiparesis is associated with clonus, spasticity, and contracture. Children should be monitored closely as spasticity almost always increases over time, and can eventually lead to permanent contracture of the muscles. Shortened, contracted muscles can pull out bones from their sockets and lead to hip dysplasia and subluxation, painful shoulder subluxation, and other issues which often require surgery.

Children with hemiparesis often have difficulties maintaining their balance due to weakness. Performing daily living tasks such as dressing, eating, grabbing objects, or using the bathroom may be difficult for some children. Most require the use of orthotic devices to keep the feet in proper alignment.

Hemiparesis is part of the upper motor neuron syndrome, which includes weakness of the opposite side of the body, decreased speed, accuracy, and dexterity of the hand, altered muscle tone, decreased endurance, and exaggerated deep tendon reflexes including spasticity and contracture. Surgery also causes some reduced dexterity, strength, and fine motor skills in the “unaffected” hand. This may later cause difficulty with writing, drawing, force production, and pressure sensitivity.


In approximately 95% of typically-developing children, speech and language is a function of the left hemisphere of the brain;  however, after left hemispherectomy surgery, approximately 44 – 76% of children have expressive and receptive language skills depending on the underlying condition which caused the seizures.  Some are even bilingual.

Expressive speech can be challenging after hemispherectomy.  Children who spoke prior to the surgery may take several years to fully return to baseline. Additionally, children who did not speak prior to hemispherectomy have been known to speak afterwards, even when surgery occurred as late as nine years old.

Because the surgery removes parts of the brain responsible for motor planning and intentional movement, many children after hemispherectomy are diagnosed with apraxia.  Apraxia is a motor speech disorder where the child has problems saying sounds, syllables, and words; the child knows what he/she wants to say, but the brain has difficulty the muscle movements necessary to say it.

Many children have challenges with articulation (making clear speech sounds) and prosody (patterns of stress and intonation) which may be caused by motor planning challenges or motor deficits related to hemiplegia, which can also affect the oral muscles used in speech.


Children after hemispherectomy have the potential to learn how to read, with many going to college and some receiving master’s degrees. Because each child is different, comprehensive educational assessments are required in school to understand each child’s strengths and weaknesses. Some children may require intensive reading instruction.

“children who have undergone hemispherectomy should be evaluated for language, literacy, and cognitive skills to account for foundational skill development in these domains that can impact reading acquisition and development. To effectively address the learning needs of this population, it is critical to have a comprehensive evaluation inclusive of psychoeducational skills.” From Literacy Related Skills In Among Children After Left Or Right Hemispherectomy

See also Comparing Reading After Left Hemispherectomy to Developmental Dyslexia.


Research shows that sensitivity to heat, cold, and pain will be impaired in the hand, forearm, and upper arm opposite the removed hemisphere, and will vary in severity from child to child. The reduced sensitivity is most significant in the hand. This puts children at risk of unknown broken bones after falls because their pain reaction is significantly reduced, or burns. Also, sensitivity to hot and cold is impaired in the arm on the same side of the removed hemisphere in the upper arm area.

Eating and Drinking

Approximately 26% of children will have difficulty eating and drinking right after surgery.  Very limited research shows that symptoms lasted a median of 19 days. Anecdotally, some children require a gastric tube to be placed for several years and sometimes months.


Except in cases of true anatomical hemispherectomy, the disconnected hemisphere will continue to seize. Research indicates that these disconnected seizures can cause headaches. Headaches can also be caused by the craniotomy and in 30% of individuals who have craniotomy, the headaches can be ongoing. Headaches are also a sign of hydrocephalus, which should be ruled out.