Progress in pathogenesis and therapy of Rasmussen's encephalitis

Rasmussen's encephalitis (RE) is a rare condition of unknown etiology that causes a severe chronically neurological disorder with mostly affecting children. The main clinical feature of RE includes frequent seizures with drug-resistant, unilateral hemispheric atrophy, and progressive neurological deficits. In this review, we summarized five pathogenesis on the basis of the current research including virus infection, antibody-mediated degeneration, cell-mediated immunity, microglia-induced degeneration, and genetic mutations. So far, no exact virus in RE brain tissue or definite antigen in humoral immune system was confirmed as the determined etiology. The importance of cytotoxic CD8⁺ T lymphocytes and activated microglial and the role of their immune mechanism in RE development are gradually emerging with the deep study. Genetic researches support the notion that the pathogenesis of RE is probably associated with single nucleotide polymorphisms on immune-related genes, which is driven by affecting inherent antiretroviral innate immunity. Recent advances in treatment suggest immunotherapy could partially slows down the progression of RE according to the histopathology and clinical presentation, which aimed at the initial damage to the brain by T cells and microglia in the early stage. However, the cerebral hemispherectomy is an effective means to controlling the intractable seizure, which is accompanied by neurological complications inevitably. So, the optimal timing for surgical intervention is still a challenge for RE patient. On the contrary, exploration on other aspects of pathogenesis such as dysfunction of adenosine system may offer a new therapeutic option for the treatment of RE in future.

Rasmussen's encephalitis: Early diagnostic criteria in children

Rasmussen's encephalitis (RE) is a rare chronic inflammatory brain disorder resulting in progressive neurodegeneration in one cerebral hemisphere. The inflammatory process is accompanied by progressive loss of function of the affected hemisphere, associated with drug-resistant partial epilepsy. The diagnosis is based on a range of clinical, electroencephalographic, radiological and biochemical arguments, without any specific formal marker, which makes the diagnosis of the disease complex, especially in its initial phase. Seizures are refractory to anti-seizures medication (ASM) and to classical immunomodulatory treatments. These treatments are also ineffective to stop the degenerative process. Only surgical treatment with hemispherotomy (surgical disconnection of a cerebral hemisphere) allows definitive cessation of seizures but this leads to definitive motor and cognitive deficits. The etiology of RE is not known, but there is strong evidence for an immunopathogenic mechanism involving T-cell mediated immunity. The emergence of biotherapies targeting against various cytokines offers potential therapeutic perspectives. This disease is currently a real challenge in terms of: (i) early diagnosis, before the constitution of marked hemispheric atrophy and the appearance of neurological and cognitive consequences; (ii) recognition of incomplete form; (iii) therapeutic management due to advances in the field of targeted treatment of inflammation; (iv) surgery and recovery possibilities.

Robotic thermocoagulative hemispherotomy: concept, feasibility, outcomes, and safety of a new "bloodless" technique

OBJECTIVE

The authors present a new "bloodless" technique for minimally invasive robotic thermocoagulative hemispherotomy (ROTCH). Such a method is being described in the literature for the first time.

METHODS

A robotic system was used to plan five sets of different trajectories: anterior disconnection, middle disconnection, posterior disconnection, corpus callosotomy, and temporal stem and amygdalar disconnection. A special technique, called the "X" technique, allowed planar disconnection. Registration was performed with surface landmarks (n = 5) and bone fiducials (n = 1). Coregistration with O-arm images was performed one or two times to confirm the trajectories (once for middle disconnection, and once for disconnection of the temporal stem and amygdala or body of the corpus callosum). Impedance measured before ablation allowed for minor adjustments. Radiofrequency ablation was performed at 75°C-80°C for 60 seconds. Surgical procedures were performed with multiple twist drills. After removal of the electrode, glue was used to prevent CSF leak, and a single stitch was applied. Follow-up CT and MRI were immediately performed.

RESULTS

The pathologies included Rasmussen's encephalitis (n = 2), hemispheric cortical dysplasia (n = 2), posttraumatic encephalomalacia (n = 1), and perinatal insult (n = 1). The mean ± SD (range) age was 6.7 ± 3.6 years (5 months to 10.2 years), and the right side was affected in 4 patients. The mean ± SD seizure frequency was 7.4 ± 5.6 seizures per day (1 patient had epilepsia partialis continua). The mean ± SD number of trajectories was 15.3 ± 2.5, and the mean ± SD number of lesions was 108 ± 25.8. The mean ± SD maximum numbers of trajectories and lesions required for middle disconnection were 7.1 ± 1.7 and 57.5 ± 18.4, respectively. All but 1 patient had class 1 outcomes according to the International League Against Epilepsy Outcome Scale at a mean ± SD (range) follow-up of 13.5 ± 1.6 (12-16) months; the remaining patient had a class 2 outcome. The estimated blood loss was < 5 ml for all patients. Complications included repeat surgery (after 2 weeks) for a "skip" area (n = 1) and a small temporal hematoma (n = 1), which resolved.

CONCLUSIONS

ROTCH seems to be a safe, feasible, and bloodless procedure, with a very low morbidity rate and promising outcomes.

Brain-responsive neurostimulation in adult-onset rasmussen's encephalitis

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Treatment of Rasmussen’s encephalitis in adults is limted.

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Hemispherotomy is rarely performed in adults due to high morbidity.

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Immunotherapy in Adult onset rasmussen’s is rarely efficacious alone to control seizures.

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RNS system could be a therapeutic option for Rasmussen’s encephalitis patients with drug-resistant epilepsy.

Epilepsy associated with Rasmussen’s encephalitis (RE) is highly resistant to standard therapy and continues to present a therapeutic challenge. While epilepsy surgery remains the most effective management for patients with drug-resistant focal epilepsy and RE, hemispherotomy may debilitating consequences on adult patients. Here we present the outcome of a 32-year-old woman with adult-onset Rasmussen’s, who was treated with brain-responsive neurostimulation (RNS) after failure of several immunotherapeutic and anti-seizure medications.

Neuroendocrinological characterization of three cases

PURPOSE

Rasmussen's encephalitis (RE) is a chronic neurological disorder characterized by inflammation of the cerebral cortex, mainly unilateral, that leads to drug-resistant epilepsy and progressive neurological impairment. Central Precocious Puberty (CPP) is uncommon, albeit increased in frequency in patients with neurological conditions and the physiopathological bases of these associations remains unclear in most cases. Epilepsy has been proposed to play a role, as well as the accumulation of substances produced as a result of metabolism or tissue degeneration in some neurodegenerative diseases. However, CPP has not been previously described in patients with RE.

METHODS

From a series of patients affected by RE followed-up at a referral center, an in-depth review of the characteristics of those who developed CCP was carried out.

RESULTS

Three cases were identified, representing a relative frequency of 21.4 % for CPP. They were girls, of Caucasian ethnicity, without family history of CPP or any image-identified abnormalities in the hypothalamic area. In two cases CPP manifested immediately before the onset of the epilepsy (prior to the diagnosis of RE) and in the other, after epilepsy onset but coinciding with a worsening of the seizures. A GnRH test with pubertal response confirmed CPP in the three cases.

CONCLUSION

The high proportion of CPP in patients affected by RE suggested a plausible relationship between these two entities. Various factors involved, including neuroinflammation, are hypothesized in the present study. However, further studies are needed to elucidate the pathophysiological bases, which could provide insight in the understanding of both entities.

Comparison through two clinical cases

BACKGROUND AND IMPORTANCE

Rasmussen's Encephalitis (RE) is a chronic and progressive childhood disease caused by an inflammatory disorder that affects a cerebral hemisphere. On the other hand, Gliomatosis Cerebri (GC) is a rare primary neoplastic glial process with a diffuse and infiltrative growth.

CLINICAL PRESENTATION

We present two clinical cases with a history of continuous focal epilepsy refractory to antiepileptic drugs. They share similar clinical and radiologic features, but a different histopathological diagnosis. A brain biopsy was needed to distinguish GC from a RE.

CONCLUSION

The debut of a drug-resistant epilepsy with focal seizures and an ipsilateral progressive hemiparesis suggests the diagnosis of RE. However, there are other entities such as GC, which, despite its rarity, should be considered in the differential diagnosis. So, in some cases, histological diagnosis is needed.

Proliferative hippocampal activity in a group of patients with Rasmussen's encephalitis: Neuronal, glial, and BDNF tissue expression correlations

Rasmussen's encephalitis (RE) is a rare and devastating unilateral inflammatory brain disease that causes severe and intractable partial epilepsy. It has been shown that epilepsy and subsequent inflammation have deleterious influence on hippocampal cell survival and neurogenesis, but this still has not been systematically explored in human tissue. In this study, we investigated the correlation between inflammation and epilepsy as well as the rates of hippocampal gliogenesis and neurogenesis in a pediatric group of six patients with RE and six control cases. The dentate gyrus (DG) samples were obtained from patients who underwent surgery for intractable RE. Sections were processed for immunohistochemistry using antibodies against sex determining region Y-box 2 (Sox2), nestin, human protein encoded by MKI67 gen (Ki67), and brain-derived neurotrophic factor (BDNF). There was an increase in the number of Ki67-positive granule cells in the DG of patients with RE in comparison with the autopsy control group, but no statistical difference for Sox2-positive cells was observed between these groups. Nestin immunolabeling was less intense in the RE group while BDNF expression was increased. Neurons that were BDNF-positive were found in DG from patients with RE but not in the control group. In patients with RE, few nestin-positive cells in DG were also positive for BDNF, unlike in controls which showed no colocalization for these two markers. These results suggest a proliferation activity in the DG subfield of patients with RE, and also future studies are necessary to address the role of new cells in the hippocampus of patients with RE.

Arterial spin labeling hyperperfusion in Rasmussen's encephalitis: Is it due to focal brain inflammation or a postictal phenomenon?

BACKGROUND AND PURPOSE

The study evaluated the utility of arterial spin labeling (ASL) perfusion imaging in Rasmussen's encephalitis (RE).

MATERIAL AND METHODS

The hospital electronic database was searched using the search words "encephalitis," "autoimmune encephalitis" and "Rasmussen's encephalitis" for the period of 1 Jan 2015 to 31 Jan 2017. Clinically diagnosed cases of RE for which epilepsy protocol magnetic resonance imaging (MRI) with perfusion imaging (ASL) performed on a 3T scanner were retrieved. The diagnosis of RE was based on Bien's criteria (Bien et al., 2005). We obtained patient's demographic details, clinical features, electrophysiological studies, and follow-up data from electronic hospital records.

RESULTS

We included nine patients with RE of whom seven patients showed increased perfusion, and two patients decreased perfusion. Among these patients, MRI changes of gyral hyperintensity without volume loss corresponded to regional ASL hyperperfusion in six patients and ASL hypoperfusion in one patient. Two patients who showed ASL hypoperfusion had corresponding atrophy on MRI. Eight patients of RE had epilepsia partialis continua (EPC) or daily seizures, and one patient was seizure-free post-surgery. Five patients showed a concordance of ASL hyperperfusion with clinical ictal onset zone. Among the seven patients with ASL hyperperfusion, the finding was concordant (complete or partial) with the electroencephalogram (EEG) ictal onset zone in six patients and with interictal epileptiform discharges (IED) in seven patients.

CONCLUSION

Increased perfusion in ASL of the involved brain parenchyma in RE is a common MRI finding and may be due to either active inflammation of the brain involved or a seizure-related finding.

Can head trauma trigger adult-onset Rasmussen's encephalitis?

Rasmussen's encephalitis (RE) is a rare unilateral inflammatory brain disorder that causes progressive neurocognitive deterioration and refractory epilepsy including epilepsia partialis continua (EPC). We describe a patient with a unique presentation, where right upper limb EPC due to RE began within 2weeks of a concussive left frontal head injury, in a 36-year-old female without other identifiable etiology, no prior neurological deficit nor suggestion of intracranial pathology or infection, and no preceding seizures. The diagnosis of RE followed extensive investigation, excluding confounding diagnoses, with supportive histopathology, and her EPC has proven refractory to treatment. In the absence of a satisfactory alternative etiology and exclusion of differential diagnoses, the most likely cause or precipitant of this patient's RE was head trauma.

Functional hemispherotomy in Rasmussen syndrome in the absence of classic MRI findings

A 7-year-old previously healthy girl presented with a left-sided focal seizure without impaired consciousness and subsequently developed epilepsia partialis continua. Initial MRI was normal, and the subsequent images only showed a focal T2/FLAIR hyperintense area without cortical atrophy. She was diagnosed with Rasmussen syndrome by pathology and promptly treated with functional hemispherotomy. Rasmussen syndrome is a rare progressive neurological disorder, the only definitive cure for which is hemispheric disconnection. The disease presents a management dilemma, especially early in disease course without characteristic neuroimaging features. A high index of suspicion, multidisciplinary approach, and clear timely communication with the family are critical.

Neuronal autoantibodies in patients with Rasmussen's encephalitis

Rasmussen's encephalitis (RE) is a rare disease with unknown pathophysiology. To disclose whether anti-neuronal autoimmunity participates in the aetiology of RE, various neuronal autoantibodies (NAAbs) were investigated in sera of patients with RE and controls. The study included five patients who fulfilled the RE diagnostic criteria (clinical, EEG, and MRI findings) as the patient group, and 50 multiple sclerosis patients and 50 healthy subjects as the control groups. Sera were evaluated for various NAAbs by radioimmunoassay or cell-based assays. All sera were also screened for uncharacterized antibodies to neuronal cell surface or synapse antigens by indirect immunofluorescence using hippocampal cell cultures. The mean age at onset of seizures was 8.3±3.4 years (range: 4-13.5) and mean follow-up time was 11.2±5.4 years (range: 5-19). All patients had unihemispheric atrophy of the cerebral cortex and epilepsia partialis continua. Two of the patients had moderate cognitive impairment, while the others were severely affected, as shown by neuropsychological testing. NAAb positivity was not detected in any of the patients. Immune aetiology is thought to have a role in RE, but the responsible players have not yet been elucidated. Our extensive antibody screening in a small number of patients does not support the presence of antigen-specific anti-neuronal autoimmunity in RE pathophysiology.

Antibodies to AMPA receptors in Rasmussen's encephalitis

Rasmussen's encephalitis is a rare progressive childhood disorder characterized by frequent severe seizures, hemiparesis, encephalitis and mental deterioration, and associated with severe unilateral neuroinflammation. Autoantibodies, particularly to the GluA3 subtype of the alpha-amino-3-hydroxy-5-methyl-isoxazole-4-propinonic acid receptor (AMPAR) were reported in the 1990s but not always confirmed. To explore further, sera from 52 patients with Rasmussen's encephalitis were tested by cell-based assays for antibodies to AMPAR GluA1/2/3, N-methyl-d-aspartate (NMDA NR1/2b), γ-aminobutyric acid type A and B (GABAAR α1/γ2/β2 and GABABR b1/b2) receptors, for potassium channel complex proteins, and for binding to live cortical and hippocampal neuronal cultures. Two patients' sera (3.8%) bound to HEK cells co-transfected with the GluA2 and GluA3 subunits. One additional patient had a low level of VGKC-complex antibodies. These three, and seven additional, sera bound to hippocampal cultures. No other antibodies were detected. Thus, despite the rarity of GluA2/3 antibodies, 10 patients (19.2%) had evidence of antibodies to neuronal antigens. Whether these antibodies play a primary role in RE, or appear secondary to the neuro-inflammatory damage in this highly destructive disease, requires further study.

Good outcome in adult-onset Rasmussen's encephalitis syndrome: is recovery possible?

A healthy 29-year-old man suffered from adult-onset epilepsy, characterized by polymorphic progressive seizures resistant to AEDs, leading to unilateral cortical deficits and atrophy of the left hemisphere. The disorder satisfied the clinical, EEG, and imaging criteria for a diagnosis of Rasmussen's encephalitis. During the acute phase of the disease, intrathecal synthesis of specific anti-CMV IgG was identified. This case was characterized by a very mild course and remission of seizures following a treatment with high-dose intravenous polyvalent immunoglobulins containing a high anti-CMV titre. The patient remained symptomless for more than 15 years from clinical onset and more than eight years after the discontinuation of immunological therapy. In agreement with a recent report, this case confirms that adult-onset Rasmussen's encephalitis syndrome may occur with a very mild clinical picture and persistent remission. In this case, the specific index for intrathecal production of anti-CMV antibodies suggested possible CMV involvement, indicating specific immuno-therapy as a treatment choice.

Complex syntax in the isolated right hemisphere: Receptive grammatical abilities after cerebral hemispherectomy

OBJECTIVES

In this study, we explored the syntactic competence of the right hemisphere (RH) after left cerebral hemispherectomy, on the premise that it (syntactic competence) is known to be one of the most strongly left-lateralized language functions. As basic syntactic development for individuals in this subject pool has already been extensively explored, we focused instead on the investigation of complex syntactic constructions that are normally acquired later in childhood, i.e., between 7 and 9years of age.

METHODS

Grammatical competence in 10 participants who had undergone left cerebral hemispherectomy was compared to that of a group of normally developing children, with the two groups matched by the size of their vocabulary. The two tests we used for this research were created by the 1st language acquisition linguists and were designed to test sets of constructions categorized and differentiated by the order in which they are normally acquired and by the type of grammatical competence that they involve.

RESULTS

We found that both groups followed the same developmental sequence of syntactic development with five (50%) postsurgical participants (all with prenatal etiologies) reaching nearly mature command of sentence grammar. Seizures negatively impacted performance on all tests.

CONCLUSIONS

The isolated RH has the potential to support the complex grammatical categories that emerge relatively late in the normal acquisition of English by native speakers. Successful performance may be related to the timing of the initial insult and seizure control following hemispherectomy.

Young woman with a four-year history of epilepsy and progressive focal cortical atrophy - What is the diagnosis?

The pathogenesis of disease progression in drug-refractory epilepsy is poorly understood. We report the case of a young woman with a four-year history of epilepsy that progressed rapidly as evidenced by the development of progressive focal cortical atrophy. She underwent biopsy that showed perinatal ischemia and a prominent inflammatory response, including T-cell infiltration and microglial activation. There was no consensus reached on the final diagnosis although the hypothesis of dual pathology (adult variant of Rasmussen's encephalitis and perinatal stroke) was considered. The possible role of inflammation in the progression of epilepsy caused by a “static” lesion (perinatal stroke) is discussed.

Unilateral holohemispheric central nervous system lesions associated with medically refractory epilepsy in the pediatric population: a retrospective series of hemimegalencephaly and Rasmussen's encephalitis

OBJECT

Cortical malformations and inflammatory encephalopathy are among common etiologies for medically refractory epilepsy in children. On rare occasions, lesions can affect an entire cerebral hemisphere while sparing the other; the 2 processes that can manifest in this manner are hemimegalencephaly (HME) and Rasmussen's encephalitis (RE). Although the clinical course and radiological appearance between the 2 disorders are distinct, there is occasional overlapping pathology between RE and cortical migration disorders. One question that arises from these observations is whether RE and HME, diseases with holohemispheric involvement but apparently different etiologies, have any overlapping characteristics.

METHODS

The authors performed a retrospective review of all patients with presumed diagnosis of HME or RE who underwent hemispherectomy at University of California, San Francisco, and reviewed their clinical presentation, imaging, and pathology data.

RESULTS

The authors present the clinicopathological features of 14 pediatric patients with unilateral holohemispheric lesions associated with medically refractory epilepsy. Radiological and pathological assessment classified 7 of the patients as having hemimegalencephaly, while the other 7 were diagnosed as having RE. Four of the patients had unusual features suggestive of overlapping developmental and inflammatory (dual) pathology. All patients underwent hemispherectomies. Eight patients (57%) became seizure free (Engel Class I), 5 patients (36%) had rare seizures (Engel Class II), and 1 patient had significant seizure reduction (Engel Class III).

CONCLUSIONS

Based on this case series, HME and RE can be distinguished on the basis of their radiological and histological appearance, even though some cases may have overlapping features. Hemispherectomy was effective at eliminating seizures for both HME and RE.

Evolution of MRI changes in Rasmussen's encephalitis

PURPOSE

We studied the MRI findings in 16 patients with Rasmussen's encephalitis (RE), further analysed serial MRI changes in 11 of them and correlated it with clinical features.

METHODOLOGY

The diagnosis of RE was based on the European consensus statement (Brain, 128, 2005, 454). Details related to demographical, clinical, MRI observations were analysed.

RESULTS

Forty MRIs of brain of 16 patients were reviewed. Eleven patients had undergone serial brain MRIs ranging from two to five occasions. All the patients had unihemispheric focal cortical atrophy, predominantly in the perisylvian region (n = 13). Other features were white matter signal changes (n = 14), and ipsilateral caudate (n = 6) and putamen (n = 4) atrophy. Signal alterations in putamen and caudate were noted in four each. In all the 11 patients with serial MRI, there was progression of cerebral atrophy and a trend towards increase in MRI staging. The MRI signal changes remained same in five patients, resolved in three patients, differential change in two patients and increased in one patient. Diffusion-weighted imaging showed facilitated diffusion (n = 5), and MR spectroscopy showed reduced N-acetyl-aspartate and elevated lactate (n = 2).

CONCLUSIONS

Pattern recognition of MRI findings and the changes in serial MRI might serve as a surrogate marker of disease viz. unihemispheric progressive focal cortical atrophy and signal changes predominantly in the perisylvian distribution and caudate followed by putamen involvement. This might assist in understanding and monitoring of the disease progression.

Rasmussen's encephalitis presenting as focal cortical dysplasia

Rasmussen's encephalitis is a rare syndrome characterized by intractable seizures, often associated with epilepsia partialis continua and symptoms of progressive hemispheric dysfunction. Seizures are usually the hallmark of presentation, but antiepileptic drug treatment fails in most patients and is ineffective against epilepsia partialis continua, which often requires surgical intervention. Co-occurrence of focal cortical dysplasia has only rarely been described and may have implications regarding pathophysiology and management. We describe a rare case of dual pathology of Rasmussen's encephalitis presenting as a focal cortical dysplasia (FCD) and discuss the literature on this topic.

Childhood-onset nonprogressive chronic encephalitis

PURPOSE

The purpose of this study was to describe a series of patients with pathologically proven chronic encephalitis who had a nonprogressive course during a long follow-up, suggestive of a "benign" variant of Rasmussen's encephalitis (RE).

METHODS

Four patients who were referred to our Comprehensive Epilepsy Program at London Health Science Centre in London, Ontario, were diagnosed with chronic encephalitis on a pathological basis after epilepsy surgery to treat their partial-onset seizures.

RESULTS

None of our four cases followed the typical course of RE despite their childhood-onset seizures between ages 2 and 12years. One was preceded by a mild head trauma and fever at onset. None had epilepsia partialis continua (EPC). Their long-term follow-up revealed a nonprogressive form of the syndrome with respect to the neurological examination, EEG, MRI, and neuropsychological findings.

CONCLUSION

These cases extend the spectrum of childhood-onset intractable epilepsy with chronic encephalitis to include nonprogressive variants of RE. The absence of EPC may be a prognostic indicator of a nonprogressive course.

Current management and surgical outcomes of medically intractable epilepsy

Epilepsy is one of the most common neurologic disorders in the world. While anti-epileptic drugs (AEDs) are the mainstay of treatment in most cases, as many as one-third of patients will have a refractory form of disease indicating the need for a neurosurgical evaluation. Ever since the first half of the twentieth century, surgery has been a major treatment option for epilepsy, but the last 10-15 years in particular has seen several major advances. As shown in relatively recent studies, resection is more effective for medically intractable epilepsy (MIE) than AED treatment alone, which is why most clinicians now endorse a neurosurgical consultation after approximately two failed regimens of AEDs, ultimately leading to decreased healthcare costs and increased quality of life. Temporal lobe epilepsy (TLE) is the most common form of MIE and comprises about 80% of epilepsy surgeries with the majority of patients gaining complete seizure-freedom. As the number of procedures and different approaches continues to grow, temporal lobectomy remains consistently focused on resection of mesial structures such as the amygdala, hippocampus, and parahippocampal gyrus while preserving as much of the neocortex as possible resulting in optimum seizure control with minimal neurological deficits. MIE originating outside the temporal lobe is also effectively treated with resection. Though not as successful as TLE surgery because of their frequent proximity to eloquent brain structures and more diffuse pathology, epileptogenic foci located extratemporally also benefit from resection. Favorable seizure outcome in each of these procedures has heavily relied on pre-operative imaging, especially since the massive surge in MRI technology just over 20 years ago. However, in the absence of visible lesions on MRI, recent improvements in secondary imaging modalities such as fluorodeoxyglucose positron emission computed tomography (FDG-PET) and single-photon emission computed tomography (SPECT) have lead to progressively better long-term seizure outcomes by increasing the neurosurgeon's visualization of supposed non-lesional foci. Additionally, being historically viewed as a drastic surgical intervention for MIE, hemispherectomy has been extensively used quite successfully for diffuse epilepsies often found in pediatric patients. Although total anatomic hemispherectomy is not utilized as commonly today, it has given rise to current disconnective techniques such as hemispherotomy. Therefore, severe forms of hemispheric developmental epilepsy can now be surgically treated while substantially decreasing the amount of potential long-term complications resulting from cavitation of the brain following anatomical hemispherectomy. Despite the rapid pace at which we are gaining further knowledge about epilepsy and its surgical treatment, there remains a sizeable underutilization of such procedures. By reviewing the recent literature on resective treatment of MIE, we provide a recent up-date on epilepsy surgery while focusing on historical perspectives, techniques, prognostic indicators, outcomes, and complications associated with several different types of procedures.