Anatomical Hemispherectomy Research Articles

Concurrent anatomic hemispherectomy and thalamic arteriovenous malformation resection

Arteriovenous malformations (AVMs) may present with hemorrhage, neurologic deficits, or seizure. Recent studies have found that of patients with AVMs, approximately 33 % have seizures, and of those patients with seizures, approximately 75 % have generalized tonic–clonic (GTC) seizures [4, 5]. In a recent study, seizure occurrence was associated with male gender, age <65 years, AVM size greater than 3 cm, and temporal lobe locations [5]. Complete obliteration of AVMs was associated with freedom from disabling seizure [5]. AVMs can be treated through microsurgical resection, embolization, radiosurgery, or a combination of these modalities. Deep location, size, and location in eloquent cortex are three factors which may limit surgical resection as they increase surgical morbidity significantly [11]. The high morbidity of surgical treatment for thalamic AVMs renders them often treated by stereotactic radiosurgery (SRS). A recent study found angiographic obliteration in 55 % of patients undergoing stereotactic radiosurgery with a 13 % rate of permanent radiation-related neurologic deficit; outcome with radiosurgery was linked to age of patient, AVM volume, and AVM location [12]. For patients with intractable hemispheric seizures, hemispherectomy is a possible treatment. Surgeons may opt to perform an anatomical hemispherectomy or a functional hemispherectomy; however, both have proven to be effective treatments for patients with unilateral intractable epilepsy and a severely injured hemisphere. A recent longitudinal study demonstrated a 65 % seizure-free rate in patients undergoing either anatomic or functional hemispherectomy [7]. We present the first reported case of a patient with intractable epilepsy secondary to deepAVMhemorrhage in which anatomic hemispherectomy was used as a corridor to remove the AVM.

Hemispherectomy: A Viable Surgical Treatment for Adults with Intractable Epilepsy - A Report of 5 Cases (P01.069)

Objective: To evaluate the outcome after hemispherectomy in adult patients with refractory epilepsy, and increase awareness of hemispherectomy as a viable surgical option in this population. Background Hemispherectomy is a surgical technique that is often used in refractory epilepsies, and is well-known to be successful in the treatment of unilateral hemispheric lesions. Most case series, however, are in the pediatric population. Despite some reports of success in the adult population, this procedure is still underutilized, presumably because of concerns of significant postoperative neurological deficits due to lack of plasticity in the adult brain. Design/Methods: A retrospective chart review identified 5 patients. In four, seizures were due to perinatal stroke, and 1 had a presumed viral syndrome (not Rasmussen encephalitis). All patients had varying degrees of hemiparesis and visual field abnormalities, but were ambulatory at baseline. Four had functional hemispherectomy, and 1 had an anatomic hemispherectomy following a functional hemispherectomy. Three patients had right and 2 patients had left hemispheric lesions. Preoperative EEG, MRI, and neuropsychological testing were completed in all patients. Two patients had a pre-surgical PET scan, and one had functional MRI prior to surgery. Results: Postoperatively, 3 of the 5 patients are seizure free, with an average follow up of 15 months (range 3-34 months). One patient had a significant improvement in seizures (Engel class II) sustained at 1.5 years, and 1 patient had greater than 70% reduction, with resolution of disabling seizures (Engel I). Only one patient had post-operative complications, consisting of severe headaches. One patient complained of mild occasional orthostasis at 3 months post-operatively. None of the patients experienced any worsening in neurological status, and 2 patients reported improvement in motor and/or communicative function. Conclusions: Hemispherectomy can be a valuable surgical option without significant postoperative deficits in adult patients with hemispheric lesions causing intractable seizures. Disclosure: Dr. Schusse has nothing to disclose. Dr. Schusse has nothing to disclose. Dr. Drees has nothing to disclose.

Bilateral Rasmussen encephalitis

Rasmussen encephalitis (RE) is a rare, chronic, inflammatory neurological disorder that usually affects one hemisphere of the brain. RE is characterized by frequent and severe seizures, progressive neurological dysfunction, and unilateral brain atrophy. This article documents a case of RE with bilateral involvement occurring at the age of 2. The patient's seizures consisted of focal motor seizures (epilepsia partialis continua in the fingers on the right hand); tonic convulsions of the right arm and head turning to the right with impairment of consciousness; and secondarily generalized tonic–clonic seizures. Antiepileptic drugs did not effectively control the seizures. The pathology of the left frontoparietal lobe biopsy of the abnormal MRI signal showed typical neuronal loss, abundant lymphocytic infiltration into the perivascular space, and numerous microglial nodules. Bipolar electrocoagulation on functional cortexes, which failed to alter the course of the illness, was followed by high-dose prednisone (about 2weeks worth), without improvement. Both functional hemispherectomies and anatomical hemispherectomies failed to halt the course of the illness, and contralateral seizures developed and became apparent after the operation, suggesting bilateral RE.

Atypical Rasmussen’s encephalitis treated with temporal lobectomy

Rasmussen’s encephalitis is characterized by seizures, progressive neurological deterioration and chronic inflammation of the brain. It typically presents in childhood and requires anatomic or functional hemispherectomy for seizure control. Here, we report an adult woman who presented with new onset, medically refractory seizures that were not progressive. The patient underwent a right anterior temporal lobectomy. The pathologic samples were consistent with Rasmussen’s encephalitis. The patient remained seizure free until her last follow-up at 2 years. This is an example of unique adult onset Rasmussen’s encephalitis, suggesting that this encephalitis represents a wide spectrum of presentations rather than a specific disease.

Epilepsy surgery in children under 3 years

PurposeResective epilepsy surgery in early childhood has become an important treatment option for selected infants and children with epilepsy. We describe experience and clinical outcomes of children under 3 years undergoing epilepsy surgery at Great Ormond Street Hospital (GOSH). MethodsAll children under 36 months of age who had resective surgery for the purpose of treating epilepsy within the GOSH epilepsy surgery programme were ascertained using a departmental database. Aetiology, post-operative seizure frequency, pre and post-operative cognitive function, long-term complications and re-operation rates were analysed by retrospective examination of clinical records. ResultsForty-two children were included in our cohort with a median age at surgery of 20 months (range 3–36 months). Surgical procedures comprised 25 functional hemispherectomies, two anatomical hemispherectomies, four multilobar resections, seven lobar resections and four focal resections. 7/42 (17%, 95% CI 8–31%) children underwent re-operation. 20/42 (48%, 95% CI 33–62%) children achieved seizure freedom. 18/42 (43%, 95% CI 29–58) demonstrated an improvement in seizure frequency and no children had an increase in seizure frequency. Post-operative complications included subsequent shunt procedure in 5/25 (20%, 95% CI 9–39%) children undergoing hemispherectomy. There were no mortalities. In 23 children pre- and post-operative DQ or IQ was determinable allowing longitudinal comparison. Five children had a decrease in DQ/IQ >15 and two children had an increase DQ/IQ >15. DiscussionEpilepsy surgery in children under 3 years of age offers suitable candidates a good chance of significantly improved seizure outcome which compares with rates in older cohorts.

Surgery for catastrophic epilepsy in infants 6 months of age and younger

Few data are available concerning efficacy and safety of surgery for catastrophic epilepsy in the first 6 months of life. The authors retrospectively analyzed epilepsy surgeries in 15 infants ranging in age from 1.5 to 6 months (median 4 months) and weight from 4 to 10 kg (median 7 kg) who underwent anatomical (4 patients) or functional (7 patients) hemispherectomy, or frontal (1 patient), frontoparietal (2 patients), or parietooccipital (1 patient) resection for life-threatening catastrophic epilepsy due to malformation of cortical development. No patient died. Intraoperative complications included an acute ischemic infarction with hemiparesis in our youngest, smallest infant. The most frequent complication was blood loss requiring transfusion, which was encountered in every case. The estimated blood loss was 3-214% (median 63%) of the total blood volume. At maximum follow-up of 6-121 months (median 60 months), 46% were seizure free. Epilepsy surgery may be effective in young infants as it is in older children. However, intraoperative blood loss and risk of permanent postoperative neurological deficits present significant challenges.

Anatomic hemispherectomy for intractable epilepsy in a patient with unilateral schizencephaly

Schizencephaly is a rare congenital cortical brain malformation defined by unilateral or bilateral clefts of the cerebral hemispheres. These malformations are often associated with medically intractable epilepsy. Surgical solutions include lesionectomy, lobectomy, or hemispherectomy. The authors describe the case of an anatomic hemispherectomy for medically intractable epilepsy in an 8-year-old boy with a large schizencephalic cleft. Seven years prior to his epilepsy surgery, the patient underwent placement of a ventriculoperitoneal shunt for communicating hydrocephalus that resulted in severe left-to-right shift. Subsequently, medically refractory epilepsy developed and the patient underwent an anatomic hemispherectomy for seizure control. The preoperative brain shift remained after the surgery, although the patient tolerated the procedure well and was seizure free postoperatively. Anatomic hemispherectomy is a viable option for treating medically intractable epilepsy in a schizencephalic pediatric patient-even one with considerable brain shift.

Hémisphérotomie verticale parasagittale : technique opératoire

After the occurrence of long-term complications of hemispherectomy, various methods have been used to reduce them. The aim was to reduce the large dead space left inside the skull. We have developed an original hemispheric disconnection technique that can achieve the same results as anatomic hemispherectomy in epilepsy, with excellent short- and long term-reliability. The detailed technique is described.

Évaluation à long terme des déconnexions hémisphériques

Hemispheric disconnection has been largely proposed for patients with severe epilepsy associated with a congenital or acquired hemispheric cerebral pathology. The classical procedure of anatomical hemispherectomy was progressively abandoned by neurosurgeons in order to avoid postoperative complications since then hemispherotomy techniques have been developed. Globally, with hemispheric disconnection, the rate of patients becoming seizure-free has been between 50 and 80%. The factors affecting seizure control have not been completely elucidated, but several authors suggested that differences in etiology as well as the hemispheric disconnection technique used may partially explain this variability. The percentage of seizure-free patients is higher with hemispherotomy techniques and in the group of patients with Rasmussen encephalitis, Sturge-Weber syndrome, and vascular insults. Depending on overall long-term progression, there is an improvement compared to preoperative status even if children exhibit heterogenous abilities. The lowest scores are observed for motor skills but communication and socialization are relatively well-preserved and strongly related to the duration of epilepsy: the longer the duration, the lower the scores were. Neuropsychological outcome following hemispheric disconnection makes it possible to study the development of hemispheric specialization during infancy and to provide information on cognitive recovery. Cerebral reorganization has been proved to exist in motor and language recovery. Ipsilateral corticospinal pathways seem to be involved in the movement of hemiplegic limbs. Everyday language can be supported by both hemispheres, but there is an early hemispheric specialization of the left hemisphere according to metaphonologic abilities.

Impaired social cognition 30 years after hemispherectomy for intractable epilepsy: The importance of the right hemisphere in complex social functioning

Clinical research with individuals following hemispherectomy typically quantifies the success of surgical outcomes by focusing primarily on the achievement of seizure control and the preservation of general brain functions, such as movement, sensation, language, and memory. In addition to these outcomes, careful study of individuals following hemispherectomy also has the potential to contribute to our understanding of functional brain asymmetries involving other complex cognitive behaviors. In this study, we report preliminary evidence for the lateralization of social perception. We administered a series of neuropsychological tests that were developed to assess emotional recognition and the formation of social inferences and advanced social cognitive judgments, as they occur in everyday situations, to two adult participants who underwent complete anatomic left- or right-sided hemispherectomy. Our results show that despite a 30-year postsurgical period of recovery and consistent and high levels of family support and social engagement, distinct cognitive profiles are still evident between our right- and left-sided participants. In particular, participant S.M., who underwent an anatomic right hemispherectomy, showed the most severe impairments in identifying negative emotional expressions and conversational exchanges involving lies and sarcasm and in “mentalizing” the intent of others. In contrast, participant J.H., who underwent an anatomic left hemispherectomy was highly skilled interpersonally, despite evident language-related limitations, and showed only mild difficulties when asked to identify emotional expressions involving disgust and anger. These results suggest that the right hemisphere plays a particularly important role in social cognitive functioning and reasoning. Further examination of the extent of social perceptual difficulties prior to and following surgical intervention for epilepsy may guide the development of effective social skills training programs that can improve quality of life beyond seizure control.

Diffusion Tensor Imaging of the Corticospinal Tract Following Cerebral Hemispherectomy

Following cerebral hemispherectomy, the corticospinal tract is believed to undergo reorganizational changes, which can induce enhanced function of the contralateral motor pathway and mediate partial recovery of motor function. The aim of this study was to use diffusion tensor imaging to investigate the effects of hemispherectomy on the corticospinal tract, with particular attention to the corticospinal tract contralateral to the resection. Diffusion tensor imaging would presumably detect microstructural abnormalities through quantitative measurements of the fiber tract integrity and orientation. Four patients with anatomic hemispherectomy and three patients with subtotal hemispherectomy were examined and compared with age-matched normal controls. Apparent diffusion coefficient and fractional anisotropy values were measured in regions along the corticospinal tract: internal capsule, cerebral peduncle, rostral pons, midpons, and caudal pons. None of the patients with anatomic hemispherectomy or subtotal hemispherectomy showed significant changes in either apparent diffusion coefficient or fractional anisotropy values in the corticospinal tract contralateral to the resected hemisphere, whereas increased apparent diffusion coefficient and decreased fractional anisotropy were observed in the ipsilateral rostral pons, midpons, and caudal pons of all patients with anatomic hemispherectomy, as well as in the ipsilateral cerebral peduncle of one patient with subtotal hemispherectomy. Increased apparent diffusion coefficient values were also noted in the ipsilateral internal capsule of the same patient. This study revealed no evidence of significant reinforcement of the contralateral corticospinal tract in patients with hemispherectomy, at least from diffusion tensor imaging measurements, but suggests that wallerian degeneration most likely occurs in the ipsilateral motor pathway.

Anatomical hemispherectomy

Anatomical hemispherectomy is frequently employed in the surgical management of pediatric patients with medically refractory epilepsy. In this chapter, we review the historical evolution of this surgical procedure, outline the indications and the criteria for selecting surgical candidates and describe the important pre-operative evaluation of the surgical candidates. We provide a detailed description of our surgical technique, anesthesiological considerations, and post-operative care plan. Ultimately we analyze the most common complications associated with this procedure. Anatomical hemispherectomy performed in carefully selected pediatric patients with medically intractable epilepsy can be a safe and efficacious surgical procedure.

Postoperative fever after hemispherectomy: The role of non-infectious factors

Postoperative fever is a usual source of concern among caregivers and patients' family given that it may reflect a wide range of complications. The objective of this paper was to outline the expected postoperative temperature variation after hemispherectomies, and to establish factors that affect this curve. From 1987 to 2003, 30 patients were hemispherectomized in our institution. Among them, 24 patients without clinical diagnosis of infection were selected for this study. Postoperative axillary temperature from each patient was recorded over 10 days. Data was initially analyzed for all 24 patients and, later, for subgroups by (1) surgical technique (functional hemispherectomy, anatomical hemispherectomy, and hemispherotomy) and (2) hemispheric volume of the causative pathology (groups with large, moderately atrophic, and severely atrophic hemispheres). There was a trend of temperature elevation (p=0.06) over the first 4 days in all patients where 14 subjects recorded values over 38.5 degrees C, and 3 over 39.0 degrees C. Temperature curves from subgroups undergoing different techniques presented no statistical differences. However, the group including causative pathologies with larger hemispheres had a higher temperature curve when compared to patients with severely atrophic hemispheres (p<0.05). Our findings support the view that fever is an predictable event after hemispherectomies and causative pathologies with larger hemispheres present higher postoperative temperatures.

Anatomical hemispherectomy for intractable seizures: excellent seizure control, low morbidity and no superficial cerebral haemosiderosis

This current study was performed to evaluate whether superficial cerebral haemosiderosis (SCH) is still a complication of modern day anatomical hemispherectomy. We report a 13-year institutional experience with anatomical hemispherectomy for intractable epilepsy. Seizure control at a mean follow-up interval of 7 years was 83%. Though one patient died post-operatively from a non-neurosurgical complication, mortality was otherwise zero and morbidity minimal. The much-described complication of SCH following anatomical hemispherectomy was non-existent. We explain the history of SCH as a complication of anatomical hemispherectomy, and the measures that are presently taken to prevent it. We suggest that the importance of SCH in modern epilepsy surgery is probably over-emphasised.

Hemispherectomy: a schematic review of the current techniques

Anatomical hemispherectomy has been used for the treatment of seizures since 1938. However, it was almost abandoned in the 1960s after reports of postoperative fatalities caused by hydrocephalus, hemosiderosis, and trivial head traumas. Despite serious complications, the remarkable improvement of patients encouraged authors to carry out modifications on anatomical hemispherectomy in order to lessen its morbidity while preserving its efficacy. The effort to improve the technique generated several original procedures. This paper reviews current techniques of hemispherectomy and proposes a classification scheme based on their surgical characteristics. Techniques of hemispherectomy were sorted into two major groups: (1) those that remove completely the cortex from the hemisphere and (2) those that associate partial cortical removal and disconnection. Group 1 was subdivided into two subgroups based on the integrity of the ventricular cavity and group 2 was subdivided into three subgroups depending on the amount and location of the corticectomy. Grouping similar techniques may allow a better understanding of the distinctive features of each one and creates the possibility of comparing data from different authors.

Factors of morbidity in hemispherectomies: Surgical technique×pathology

Objective The objective of this paper is to evaluate factors of surgical morbidity from different techniques of hemispherectomy with emphasis on causative pathology. Patients and methods Thirty patients underwent hemispherectomy in our institution from 1987 to 2003, two presented with Sturge–Weber Syndrome (SWS), sixteen with Rasmussen's Syndrome (RS), eight with established hemispheric lesions (EHL), and four with cortical development malformations (CDM). Six surgeons operated on three patients using anatomical hemispherectomies (AH), 11 patients using functional hemispherectomy (FH), and 16 patients employing hemispherotomy (HT). Surgical technique and causative pathology were studied independently as factors of morbidity in hemispherectomy. Results Overall mean surgical time was 11:50±3:20 h and increased proportionately in pathologies with larger hemispheres. Blood transfusion was particularly influenced by the approach adopted by our team of anesthesiologists, independently of technique or pathology. Pathology was the most important factor related to hydrocephalus as two out of four patients with CDM needed ventriculoperitoneal shunt whilst none with EHL or SWS. Four patients undergoing HT and one FH presented residual bridges connecting the hemispheres, three were reoperated and are seizure free. Two patients with CDM did not improve their seizures worthwhile with surgery and other two (one with RS and other with CDM) were waiting a second procedure due to incomplete inter-hemispheric disconnection. Five patients presented infection and one died after developing meningoencephalitis. Conclusion Hemispherectomies are procedures where pathology and surgical technique interact narrowly. Therefore, in order to study surgical morbidity or outcome, both pathology and technique have to be analyzed independently.

Distinct right frontal lobe activation in language processing following left hemisphere injury

Right hemisphere activation during functional imaging studies of language has frequently been reported following left hemisphere injury. Few studies have anatomically characterized the specific right hemisphere structures engaged. We used functional MRI (fMRI) with verbal fluency tasks in 12 right-handed patients with left temporal lobe epilepsy (LTLE) and 12 right-handed healthy controls to localize language-related activity in the right inferior frontal gyrus (RIFG). During the phonemic task, LTLE patients activated a significantly more posterior region of the right anterior insula/frontal operculum than healthy controls (P = 0.02). Activation of the left inferior frontal gyrus (LIFG) did not differ significantly between the two groups. This suggests that, following left hemisphere injury, language-related processing in the right hemisphere differs from that with a functionally normal left hemisphere. The localization of activation in the left and right inferior frontal gyri was determined with respect to the anatomical sub-regions pars opercularis (Pop), pars triangularis (Ptr) and pars orbitalis (Por). In the LIFG, both healthy controls (8 out of 12) and LTLE patients (9 out of 12) engaged primarily Pop during phonemic fluency. Activations in the RIFG, however, were located mostly in the anterior insula/frontal operculum in both healthy controls (8 out of 12) and LTLE patients (8 out of 12), albeit in distinct regions. Mapping the locations of peak voxels in relation to previously obtained cytoarchitectonic maps of Broca's area confirmed lack of homology between activation regions in the left and right IFG. Verbal fluency-related activation in the RIFG was not anatomically homologous to LIFG activation in either patients or controls. To test more directly whether RIFG activation shifts in a potentially adaptive manner after left hemisphere injury, fMRI studies were performed in a patient prior to and following anatomical left hemispherectomy for the treatment of Rasmussen's encephalitis. An increase in activation magnitude and posterior shift in location were found in the RIFG after hemispherectomy for both phonemic and semantic tasks. Together, these results suggest that left temporal lobe injury is associated with potentially adaptive changes in right inferior frontal lobe functions in processing related to expressive language.

Hemispherectomy for Catastrophic Epilepsy in Infants

To report our experience with hemispherectomy in the treatment of catastrophic epilepsy in children younger than 2 years. In a single-surgeon series, we performed a retrospective analysis of 18 patients with refractory epilepsy undergoing hemispherectomy (22 procedures). Three different surgical techniques were performed: anatomic hemispherectomy, functional hemispherectomy, and modified anatomic hemispherectomy. Pre- and postoperative evaluations included extensive video-EEG monitoring, magnetic resonance imaging, and positron emission tomography scanning. Seizure outcome was correlated with possible variables associated with persistent postoperative seizures. The Generalized Estimation Equation (GEE) and the Barnard's exact test were used as statistical methods. The follow-up was 12-74 months (mean, 34.8 months). Mean weight was 9.3 kg (6-12.3 kg). The population age was 3-22 months (mean, 11.7 months). Thirteen (66%) patients were seizure free, and four patients had >90% reduction of the seizure frequency and intensity. The overall complication rate was 16.7%. No deaths occurred. Twelve (54.5%) of 22 procedures resulted in incomplete disconnection, evidenced on postoperative images. Type of surgical procedure, diagnosis categories, persistence of insular cortex, and bilateral interictal epileptiform activity were not associated with persistent seizures after surgery. Incomplete disconnection was the only variable statistically associated with persistent seizures after surgery (p<0.05). Hemispherectomy for seizure control provides excellent and dramatic results with a satisfactory complication rate. Our results support the concept that early surgery should be indicated in highly selected patients with catastrophic epilepsy. Safety factors such as an expert team in the pediatric intensive care unit, neuroanesthesia, and a pediatric epilepsy surgeon familiar with the procedure are mandatory.

Hemispherotomy: description of surgical technique

Hemispherectomy constitutes an established surgical method in the management of patients with medically intractable epilepsy, secondary to severe unilateral hemisphere damage. The well-established association of the anatomical hemispherectomy initially described with severe complications such as late hydrocephalus has led to the development of less resective and more disconnecting procedures. All these technical variations of hemispherotomy carry less favorable outcomes compared with anatomic hemispherectomy, but significantly fewer complications. In our current communication, we outline the indications and the surgical technique of hemispherotomy and report our experience of the clinical application of this surgical procedure. In our clinical series, the 5-year follow-up shows that 66.6% of our patients (6 out of 9) had class I outcome according to Engel's classification system, 22.2% (2 out of 9) class II outcome, while 11.1% (1 out of 9) had class III outcome. No mortality occurred in the current series and operative blood loss was significantly lowered. Hemispherotomy represents a less efficacious technique compared with anatomic hemispherectomy, but is a safe and technically simple surgical alternative for the management of patients with medically intractable seizures.

Hemispherectomy procedures in children: haematological issues

In literature, excessive perioperative haemorrhage and related haemodynamic instability have been described as major risk factors in hemispherectomy. In this report we analyse the impact of neurosurgical operation on both the haematological and coagulative patterns of these children, especially focusing on younger patients. From 1993 to 2003, 18 consecutive children suffering from intractable epilepsia and treated by hemispherectomy were admitted to the Pediatric Intensive Care Unit (PICU) of Catholic University Medical School, Policlinico Gemelli, Rome. Eight children had an entire hemisphere removed (anatomical hemispherectomy), whereas the remaining 10 underwent disconnective procedures (functional hemispherectomy) or cerebral cortex ablations (e.g. hemicorticectomy). Eleven out of these 18 children underwent hemispherectomy because of hemimegalencephaly (HME): their mean age was 14.5 months (range 3-56 months); non-HME patients underwent surgery for epileptogenic lesions involving the cerebral hemisphere to a great extent or diffusely. Data have been compared with an historical cohort of 13 children operated on before 1992 at the same institution comparable for age, aetiology of epilepsy and the modalities of surgical operation. Blood losses and haemotransfusions showed a profound influence on the haematologic/coagulative status of the children operated upon. A strict correlation was demonstrated between estimated red cell volume (ERCV) loss and haemostatic impairment in this series. Recent surgical techniques appear to reduce blood losses and related haemocoagulative risks even in younger patients.