Hemispherectomy: Procedure, Benefits, Risks, Recovery and Alternatives

Hemispherectomy is one of the most radical yet effective neurosurgical treatments for severe, drug-resistant epilepsy, especially in children. The prospect of removing or disconnecting half of the brain naturally raises concerns and curiosity. However, for carefully selected patients, this procedure can dramatically improve quality of life. This article unpacks what hemispherectomy involves, its benefits and risks, how patients recover, and what alternatives exist.

Hemispherectomy: The Procedure

Hemispherectomy is a neurosurgical operation aimed at treating catastrophic epilepsy by either removing or functionally disconnecting one cerebral hemisphere. This surgery is typically reserved for patients whose seizures originate from one side of the brain, often due to conditions such as Rasmussen’s encephalitis, hemimegalencephaly, Sturge-Weber syndrome, or extensive stroke or trauma in childhood. Advances in surgical technique now allow for less invasive approaches, reducing complications and improving outcomes.

Type	Main Approach	Key Feature	Sources
Anatomical	Removal of entire hemisphere	High efficacy, higher risk	2 7 8
Functional	Disconnection, minimal removal	Less tissue removed, fewer late complications	2 4 17
Transsylvian Keyhole	Small craniotomy, intraventricular disconnection	Shorter surgery, less blood loss	1 4
Hemispherotomy	Subtotal anatomical, functional disconnection	Lower complication rates	3 5

Table 1: Hemispherectomy Procedure Types

Indications and Patient Selection

Hemispherectomy is generally offered to children (and rarely adults) with severe, medication-resistant epilepsy localized to one hemisphere, especially when associated with hemiparesis (weakness on one side) or developmental brain disorders. Typical conditions include:

• Rasmussen’s encephalitis
• Hemimegalencephaly
• Sturge-Weber syndrome
• Infantile hemiplegia
• Malformations of cortical development
• Severe post-stroke epilepsy in children 2 3 7

Candidates usually already have significant neurological deficits on the affected side, and the potential benefits of seizure freedom outweigh the risk of further loss of function.

Surgical Techniques

There are several main hemispherectomy techniques:

1. Anatomical Hemispherectomy

• Involves physically removing almost all of one cerebral hemisphere.
• Historically effective but associated with a high risk of late complications such as superficial cerebral hemosiderosis and hydrocephalus 8 9.

2. Functional Hemispherectomy

• Developed to minimize complications.
• Most of the hemisphere is disconnected rather than removed, reducing the risk of late bleeding while maintaining seizure control 2 4 8 17.
• Preserves some brain tissue, especially deep structures.

3. Hemispherotomy

• Modern evolution of functional hemispherectomy.
• Small craniotomy, disconnection of pathways rather than tissue removal.
• Techniques include lateral, vertical, and transsylvian approaches 1 4 5 17.
• The transsylvian keyhole approach offers even less invasive entry, reducing operative time and blood loss 1 4.

Procedure Steps

• Craniotomy: The skull is opened, typically with a small bone flap in modern techniques.
• Exposure and Disconnection: Brain areas responsible for seizure propagation are disconnected from the rest of the brain.
• Removal or Preservation: Depending on the technique, some brain tissue may be removed or left in place.
• Closure and Recovery: The bone flap is replaced, and the patient is brought to recovery.

Benefits and Effectiveness of Hemispherectomy

While hemispherectomy is a major intervention, its primary benefit is seizure freedom or significant seizure reduction in patients otherwise facing devastating epilepsy. This can translate to dramatic improvements in cognitive, behavioral, and psychosocial function, especially when surgery is performed early in life.

Benefit	Outcome Rate	Notes	Sources
Seizure Freedom	52–80% (long-term)	Higher in acquired/progressive	3 5 6 7
Major Seizure Reduction	80–96%	Includes rare/minor seizures	2 3 6 11
Cognitive Stability/Improvement	Most cases	Especially with early surgery	2 6 7 11
Behavioral Improvement	>90% (in those affected)	Marked in pre-op behavior issues	6 7

Table 2: Benefits and Effectiveness Overview

Seizure Outcomes

• Long-term seizure freedom rates range from roughly 52% to 80%, depending on the underlying brain condition and surgical technique 3 5 6 7.
• Children with acquired (e.g., stroke, trauma) or progressive etiologies (e.g., Rasmussen’s encephalitis) have the best outcomes, with seizure freedom rates up to 91–100% in some series 3 6 7.
• Even when complete seizure freedom is not achieved, most patients experience a substantial reduction in seizure frequency and severity.

Cognitive and Psychosocial Benefits

• Many children demonstrate cognitive stability or even improvement after surgery, as uncontrolled seizures and heavy medications can be more harmful to brain development than the surgery itself 2 6 7 11.
• Early surgery is associated with better developmental and psychosocial outcomes, allowing some children to participate in regular schooling and improved social interactions 2 6 7 11.
• Behavioral problems often improve, especially in those with severe preoperative issues 6 7.

Brain Plasticity

• Young children’s brains are capable of remarkable reorganization after hemispherectomy, sometimes shifting language and other functions to the remaining hemisphere, mitigating expected deficits 2 16.
• However, the degree of recovery varies and depends on individual factors and the underlying cause 14 16.

Risks and Side Effects of Hemispherectomy

Despite its benefits, hemispherectomy carries significant risks, both short-term and long-term. Advances in technique have reduced complications, but careful patient selection and management remain crucial.

Risk/Complication	Frequency/Severity	Notes	Sources
Hydrocephalus	13–18% (modern techniques)	May require shunt surgery	3 5 12
Infection	~6% (modern series)	Treatable, rarely fatal	5 13
Bleeding	Less common, still possible	Improved with less invasive approaches	1 13
Hemiplegia/Worsening Weakness	Variable	Most have preop weakness, may worsen	6 7 16
Cognitive/Language Deficits	Uncommon but possible	Especially if dominant hemisphere involved	6 14 16
Death	<2–7% (historic); ~2% (modern)	Decreased with newer methods	3 7 11

Table 3: Risks and Side Effects of Hemispherectomy

Common Complications

Hydrocephalus

• Abnormal accumulation of cerebrospinal fluid, sometimes requiring permanent shunt placement.
• Modern techniques and material choices have reduced its frequency 3 5 12.

Infection

• Surgical site or central nervous system infections occur in a minority of cases and are usually treatable 5 13.

Bleeding

• Excessive bleeding and need for blood transfusion are less common with keyhole and minimally invasive techniques 1 13.
• Delayed hemorrhagic complications (superficial cerebral hemosiderosis) were more common in older anatomical hemispherectomies 8 9 18.

Neurological Deficits

• Most patients already have significant weakness on one side before surgery; this may persist or rarely worsen post-operatively 6 7 16.
• Visual field deficits (hemianopia) and loss of fine motor function on the affected side are expected.
• In rare cases, especially if the dominant hemisphere is involved, language and cognitive deficits may be more pronounced 14 16.

Mortality

• Perioperative mortality has dropped significantly with advances in anesthesia, surgical technique, and postoperative care, now under 2% in most modern series 3 7 11.

Other Considerations

• Racial disparities and socioeconomic factors can affect access to surgery and outcomes, highlighting the need for equitable care 13.
• Some complications, like delayed hydrocephalus or craniosynostosis, may appear months or years later, requiring long-term follow-up 5 12.

Recovery and Aftercare of Hemispherectomy

Recovery from hemispherectomy is a journey that involves not just surgical healing, but also rehabilitation, family education, and long-term neurological care. Patients and families are supported by a multidisciplinary team throughout the process.

Phase	Focus Areas	Duration/Timeline	Sources
Immediate	Intensive monitoring, infection/bleed prevention	1–2 weeks (hospital)	5 11 13
Early Rehab	Physical, occupational, speech therapy	Weeks to months	6 11 16
Long-term	Seizure monitoring, cognitive/behavioral support	Years–lifetime	6 7 15
Functional Reorganization	Brain adapts, functions compensated	Months–years; variable	2 16

Table 4: Recovery and Aftercare Timeline

Immediate Postoperative Care

• Patients are closely monitored in the hospital for neurological stability, infection, bleeding, and hydrocephalus.
• Early complications are addressed promptly, with interventions such as antibiotics or shunt placement if needed 5 11 13.

Rehabilitation

• Physical therapy begins as soon as possible to optimize mobility and compensate for weakness.
• Occupational and speech therapy support independence and communication skills.
• Many children make remarkable gains, especially if surgery is performed early and rehabilitation is intensive 6 11 16.

Neurological and Cognitive Follow-Up

• Long-term seizure monitoring is essential, as a small risk of recurrence remains 3 5 6.
• Periodic cognitive and behavioral assessments gauge development and guide interventions.
• Some children can return to age-appropriate schooling and activities 6 7 11.

Family and Psychosocial Support

• Families receive education about expected changes, rehabilitation needs, and ongoing care.
• Psychological support helps children and families adjust to life after surgery.

Brain Plasticity and Adaptation

• The young brain’s ability to reorganize is critical. In some cases, language and other functions shift to the remaining hemisphere 2 16.
• Adaptation is highly individual; some children recover more function than others 14 16.

Alternatives of Hemispherectomy

While hemispherectomy is highly effective for select patients, it is not the only surgical option for refractory epilepsy. Less invasive alternatives may be appropriate for some, depending on the location and cause of seizures.

Alternative	Description	Suitability	Sources
Hemispherotomy	Disconnection, minimal tissue removal	Fewer complications, similar efficacy	3 5 17
Commissurotomy	Dividing corpus callosum	For generalized seizure spread	19 20
Resective Surgery	Focal removal of epileptic area	When epilepsy is not diffuse	2
Medical Management	Antiepileptic drugs	For less severe epilepsy	2 3
Palliative Procedures	Vagal nerve stimulation, ketogenic diet	When surgery is not possible	2

Table 5: Alternatives to Hemispherectomy

Hemispherotomy

• Modern alternative to anatomical hemispherectomy.
• Involves disconnecting the dysfunctional hemisphere rather than removing it, reducing surgical trauma and risk of late complications 3 5 17.
• Similar efficacy in seizure control, with a more favorable complication profile.

Commissurotomy (“Split-Brain” Surgery)

• Involves cutting the corpus callosum to prevent seizure spread between hemispheres.
• Used when seizures are generalized but not confined to one hemisphere 19 20.
• Less radical than hemispherectomy, but not as effective for catastrophic hemispheric epilepsy.

Focal Resection

• Removal of specific epileptogenic zones, preserving as much normal brain as possible.
• Best for patients whose seizures are localized and not hemispheric 2.

Non-Surgical and Palliative Options

• Continued medical management with antiepileptic drugs for those not suitable for surgery 2 3.
• Vagal nerve stimulation, ketogenic diet, or other palliative options for patients unsuitable for resection/disconnection.

Conclusion

Hemispherectomy is a life-changing operation for children and select adults with catastrophic, drug-resistant epilepsy limited to one hemisphere. While it is among the most drastic surgical treatments in neurology, careful patient selection, modern surgical techniques, and multidisciplinary care maximize its benefits and minimize risks.

Key Points:

• Procedure: Hemispherectomy involves removal or disconnection of one cerebral hemisphere, with several modern techniques available.
• Benefits: Offers seizure freedom or major reduction in 52–80% of cases, with associated cognitive and behavioral improvements.
• Risks: Includes hydrocephalus, infection, bleeding, and potential for worsened neurological deficits, though these are much reduced with new techniques.
• Recovery: Requires multidisciplinary rehabilitation, long-term follow-up, and family support; brain plasticity may allow significant recovery.
• Alternatives: Less invasive procedures like hemispherotomy and commissurotomy, as well as focal resection and palliative therapies, are appropriate for some patients.

Ultimately, hemispherectomy remains a powerful tool in the fight against devastating epilepsy, restoring hope and function to patients who otherwise have few options.