Unilateral Hemispheric Lesions Research Articles

The long-term outcomes in drug-resistant epilepsy patients who underwent subtotal hemispherotomy: A single-center retrospective cohort study

ObjectiveTo evaluate the long-term outcomes of subtotal hemispherotomy (SH) in treating drug-resistant epilepsy caused by unilateral hemispheric lesions and try to give the prognostic factors for these outcomes. MethodsWe retrospectively reviewed the clinical data of 19 patients who underwent SH in Sanbo Brain Hospital, Capital Medical University, Beijing, China, from May 2008 to April 2021. All clinical data and factors related to surgical and functional outcomes, including motor, neuropsychiatric, and language function, were collected and analyzed. ResultsThe surgical outcomes showed 13 (68 %) patients were seizure-free at the last follow-up (2–14 years, mean: 5.6±2.9). No changes were found in motor outcomes in 12 (63 %) patients; seven (37 %) patients had new permanent motor deficits (NPMD). Improvement in the full-scale intelligence quotient (FIQ) (p = 0.009) was observed. Univariate analysis found that patients who did not achieve seizure freedom had a significantly older age at surgery (p = 0.017) and acute post-operative seizures (APOS) (p = 0.046). Kaplan–Meier analysis also identified significant differences in seizure outcomes between the children and adult subgroups (p = 0.0017). Multivariate Cox analysis showed that older age at surgery (HR=1.055, p = 0.034) was associated with shorter time-to-seizure-recurrence. Resection of the central operculum and insula (OR= 80.433, p =0.031) and higher monthly seizure frequency (OR= 1.073, p = 0.040) were also poor prognostic factors for motor function outcomes. ConclusionSH is an effective treatment procedure in treating patients with drug-resistant epilepsy caused by hemispheric lesions with satisfied seizure outcomes, limited impairment of motor function, and preserving neuropsychiatric outcomes.

The Kinetics of Transtentorial Brain Herniation: Kernohan-Woltman Notch Phenomenon Revisited.

To critically review recent literature in understanding the pathological consequences of transtentorial brain herniation resulting from unilateral expanding supratentorial mass lesions. Modern neuroimaging assists in understanding the consequences of transtentorial brain herniation with the development of the Kernohan-Woltman notch phenomenon. MRI studies in post-operative patients undergoing craniotomy and removal of expanding unilateral hemispheric mass lesions (usually an extradural or subdural hematoma) have shown striking findings in the contralateral crus cerebri suggestive of damage as a result of impact against the free margin of the opposite tentorium as suggested by Kernohan and Woltman nearly a century back in autopsy studies. MR changes include T1 hypointensity, T2 and fluid-attenuated inversion recovery (FLAIR) hyperintensity, DW1 hyperintensity with restriction of diffusion, presence of hypointensity in GRE sequences and evidence of axonal damage in the corticospinal tracts in the cerebral peduncle in diffusion tensor imaging and MR tractography. The pathological basis of such changes may be variable or a combination of several pathological processes, which may all be related to the impact/compression of the contralateral crus with the tentorial margin. These include contusion, compression, demyelination, and perhaps most importantly microvascular damage including microbleeds. The role of uncal herniation is debatable. It appears that as a result of massive lateral shift in the supratentorial compartment, there is a transient forceful impact of the opposite cerebral peduncle against the rigid tentorial border to induce one or more of the abovementioned phenomena to explain the imaging findings. The limitation of these studies is that most of them have been done in the post-operative periods and surgical manipulations can surely alter anatomical relationships between intracranial structures. The exact sequence of events happening intracranially in the face of rapidly expanding supratentorial mass lesions is largely unknown. Even with rapid progress in neuroimaging, documentation of such changes during life are difficult, principally for logistic reasons. Consequently, the very truth of the much taught about phenomenon of uncal herniation and the resultant Kernohan-Woltman notch phenomenon and the false localizing sign of unilateral motor weakness and contralateral pupillary dilation have been questioned. Animal experimentation and autopsy studies have not contributed much in our understanding of the actual process happening intracranially in such an emergent situation. The midbrain undoubtedly is the key structure bearing the brunt of the effect of brain shift which is more lateral than downward in cases with unilateral expanding lesions. Structural changes in the cerebral peduncles have now been visualized with modern neuroimaging. These alterations may result from the interplay of one or more factors which include compression, contusion, demyelination, and perhaps most importantly microvascular ischemia and hemorrhage resulting from a forceful yet transient impact of the cerebral peduncle with the tough tentorial margin. The last mentioned hypothesis would be in conformity with Kernohan and Woltman's concept of elastic deformation of the midbrain. In the present article an attempt is made to provide a historical account of the changing concepts in relation to brain herniation as systematically and chronologically as possible, and then, critically review recent neuroimaging observations with a view to hypothesize on the sequence of events during transtentorial brain herniation.

Long term outcome of functional hemispherectomy for refractory epilepsy: Experience from a single center

BackgroundHemispherectomy has an established role as a treatment of last resort in patients with unilateral hemispheric lesions suffering from refractory epilepsy. MethodsSeven patients were evaluated at our Epilepsy Unit. We compared the seizure outcome at 6 months, 1, 2, 5 years post-surgery, as well as at end follow-up (mean 7.1 years) using Engel classification. Reduction of antiepileptic drugs (AEDs) was also assessed utilizing equal time frames. ResultsThe mean age of seizure onset was 5.4 years. Engel I was achieved in 5 patients at 6 months (71.4%). Engel at 1 year was predicted by the Engel at 6 months (p=0.013) with a similar number of patients being classified as Engel I outcome. Engel at 2 years was also predicted by Engel at 6 months and at 1 year (p=0.030). At end follow-up only 3 patients (42.9%) remained categorized as Engel I outcome. There was a trend toward a stability in Engel classification. All patients with developmental causes for their epilepsy experienced some deterioration of the surgical outcomes. Conversely, all patients with acquired causes were stable throughout follow-up. Seizure outcome at 6 months was worse in the patients who had post-op complications (p=0.044). Adult and pediatric populations did not differ significantly in any tested variable. ConclusionsHemispherectomy is a valuable resource for seizure control in properly selected patients. Engel patient's evolution could be predicted at 6 months interval. Hemispherectomy could be considered a useful attitude in difficult cases.

Long term outcome of functional hemispherectomy for refractory epilepsy: Experience from a single center.

Hemispherectomy has an established role as a treatment of last resort in patients with unilateral hemispheric lesions suffering from refractory epilepsy. Seven patients were evaluated at our Epilepsy Unit. We compared the seizure outcome at 6 months, 1, 2, 5 years post-surgery, as well as at end follow-up (mean 7.1 years) using Engel classification. Reduction of antiepileptic drugs (AEDs) was also assessed utilizing equal time frames. The mean age of seizure onset was 5.4 years. Engel I was achieved in 5 patients at 6 months (71.4%). Engel at 1 year was predicted by the Engel at 6 months (p=0.013) with a similar number of patients being classified as Engel I outcome. Engel at 2 years was also predicted by Engel at 6 months and at 1 year (p=0.030). At end follow-up only 3 patients (42.9%) remained categorized as Engel I outcome. There was a trend toward a stability in Engel classification. All patients with developmental causes for their epilepsy experienced some deterioration of the surgical outcomes. Conversely, all patients with acquired causes were stable throughout follow-up. Seizure outcome at 6 months was worse in the patients who had post-op complications (p=0.044). Adult and pediatric populations did not differ significantly in any tested variable. Hemispherectomy is a valuable resource for seizure control in properly selected patients. Engel patient's evolution could be predicted at 6 months interval. Hemispherectomy could be considered a useful attitude in difficult cases.

Direct and Indirect Timing Functions in Unilateral Hemispheric Lesions.

Introduction:The neural substrates of temporal processing are not still fully known. The majority of interval timing studies have dealt with this subject in the context of “Explicit timing” (computing the time intervals explicitly). The hypothesis “Implicit timing” (implicitly using temporal processing to improve function) has also proposed. This lesion study addressed explicit and implicit timing paradigms simultaneously using identical experimental tasks.Methods:In this case-control study, 15 patients with Right Hemisphere Damage (RHD) and 15 patients with Left Hemisphere Damage (LHD) and 15 age-matched normal subjects were included. Participants performed a temporal reproduction task (assessing explicit timing) and a temporal prediction task (assessing implicit timing) in two sub- and supra-second intervals.Results:Our results showed that RHD can lead to significantly lower accuracy in the temporal reproduction task in sub-second (P=0.005) and supra-second (P=0.001) intervals, compared with the normal subjects. Also, LHD led to perturbation in temporal prediction task by an increase in reaction time (lower accuracy) in sub- (P=0.011) and supra-second (P=0.006) time intervals than the normal subjects.Conclusion:Overall, our findings suggested that there is a right hemispheric bias in the neural substrate of explicit timing, in both sub- and supra-second intervals. Furthermore, for the first time in a lesion study, we showed the evidence of left-hemispheric bias in neural substrates of implicit timing.

Outcomes after hemispherectomy in adult patients with intractable epilepsy: institutional experience and systematic review of the literature.

OBJECTIVE Hemispherectomy is a surgical technique that is established as a standard treatment in appropriately selected patients with drug-resistant epilepsy. It has proven to be successful in pediatric patients with unilateral hemispheric lesions but is underutilized in adults. This study retrospectively evaluated the clinical outcomes after hemispherectomy in adult patients with refractory epilepsy. METHODS This study examined 6 cases of hemispherectomy in adult patients at Barrow Neurological Institute. In addition, all case series of hemispherectomy in adult patients were identified through a literature review using MEDLINE and PubMed. Case series of patients older than 18 years were included; reports of patients without clear follow-up duration or method of validated seizure outcome quantification were excluded. Seizure outcome was based on the Engel classification. RESULTS A total of 90 cases of adult hemispherectomy were identified, including 6 newly added by Barrow Neurological Institute. Sixty-five patients underwent functional hemispherectomy; 25 patients had anatomical hemispherectomy. Length of follow-up ranged from 9 to 456 months. Seizure freedom was achieved in 80% of patients. The overall morbidity rate was low, with 9 patients (10%) having new or additional postoperative speech or language dysfunction, and 19 patients (21%) reporting some worsening of hemiparesis. No patients lost ambulatory or significant functional ability, and 2 patients had objective ambulatory improvement. Among the 41 patients who underwent additional formal neuropsychological testing postoperatively, overall stability or improvement was seen. CONCLUSIONS Hemispherectomy is a valuable surgical tool for properly selected adult patients with pre-existing hemiparesis and intractable epilepsy. In published cases, as well as in this series, the procedure has overall been well tolerated without significant morbidity, and the majority of patients have been rendered free of seizures.

Functional reorganization after hemispherectomy in humans and animal models: What can we learn about the brain's resilience to extensive unilateral lesions?

Hemispherectomy (HS) is an effective surgical procedure aimed at managing otherwise intractable epilepsy in cases of diffuse unihemispheric pathologies. Neurological recovery in subjects treated with HS is not limited to seizure reduction, rather, sensory-motor and behavioral improvement is often observed. This outcome highlights the considerable capability of the brain to react to such an extensive lesion, by functionally reorganizing and rewiring the cerebral cortex, especially early in life. In this narrative review, we summarize the animal studies as well as the human neurophysiological and neuroimaging studies dealing with the reorganizational processes that occur after HS. These topics are of particular interest in understanding mechanisms of functional recovery after brain injury. HS offers the chance to investigate contralesional hemisphere activity in controlling ipsilateral limb movements, and the role of transcallosal interactions, before and after the surgical procedure. These post-injury neuroplastic phenomena actually differ from those observed after less extensive brain damage. Therefore, they illustrate how different lesions could lead the contralesional hemisphere to play the "good" or "bad" role in functional recovery. These issues may have clinical implications and could inform rehabilitation strategies aiming to improve functional recovery following unilateral hemispheric lesions. Future studies, involving large cohorts of hemispherectomized patients, will be necessary in order to obtain a greater understanding of how cerebral reorganization can contribute to residual sensorimotor, visual and auditory functions.

The effect of contextual auditory stimuli on virtual spatial navigation in patients with focal hemispheric lesions

ABSTRACTTopographical disorientation is a frequent deficit among patients suffering from brain injury. Spatial navigation can be explored in this population using virtual reality environments, even in the presence of motor or sensory disorders. Furthermore, the positive or negative impact of specific stimuli can be investigated. We studied how auditory stimuli influence the performance of brain-injured patients in a navigational task, using the Virtual Action Planning–Supermarket (VAP-S) with the addition of contextual (“sonar effect” and “name of product”) and non-contextual (“periodic randomised noises”) auditory stimuli. The study included 22 patients with a first unilateral hemispheric brain lesion and 17 healthy age-matched control subjects. After a software familiarisation, all subjects were tested without auditory stimuli, with a sonar effect or periodic random sounds in a random order, and with the stimulus “name of product”. Contextual auditory stimuli improved patient performance more than control group performance. Contextual stimuli benefited most patients with severe executive dysfunction or with severe unilateral neglect. These results indicate that contextual auditory stimuli are useful in the assessment of navigational abilities in brain-damaged patients and that they should be used in rehabilitation paradigms.

Apraxia in left-handers

In typical right-handed patients both apraxia and aphasia are caused by damage to the left hemisphere, which also controls the dominant right hand. In left-handed subjects the lateralities of language and of control of the dominant hand can dissociate. This permits disentangling the association of apraxia with aphasia from that with handedness. Pantomime of tool use, actual tool use and imitation of meaningless hand and finger postures were examined in 50 consecutive left-handed subjects with unilateral hemisphere lesions. There were three aphasic patients with pervasive apraxia caused by left-sided lesions. As the dominant hand is controlled by the right hemisphere, they constitute dissociations of apraxia from handedness. Conversely there were also three patients with pervasive apraxia caused by right brain lesions without aphasia. They constitute dissociations of apraxia from aphasia. Across the whole group of patients dissociations from handedness and from aphasia were observed for all manifestations of apraxia, but their frequency depended on the type of apraxia. Defective pantomime and defective tool use occurred rarely without aphasia, whereas defective imitation of hand, but not finger, postures was more frequent after right than left brain damage. The higher incidence of defective imitation of hand postures in right brain damage was mainly due to patients who had also hemi-neglect. This interaction alerts to the possibility that the association of right hemisphere damage with apraxia has to do with spatial aptitudes of the right hemisphere rather than with its control of the dominant left hand. Comparison with data from right-handed patients showed no differences between the severity of apraxia for imitation of hand or finger postures, but impairment on pantomime of tool use was milder in apraxic left-handers than in apraxic right-handers. This alleviation of the severity of apraxia corresponded with a similar alleviation of the severity of aphasia as manifested by a lower proportion of left-handed patients with global aphasia.

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.

Same or Opposite? Association of Head-movement Weakness With Limb Paresis in Stroke

The precise innervation of the sternocleidomastoids is uncertain. Of clinical interest is whether a unilateral hemispheric lesion leads to an ispilateral or contralateral sternocleidomastoid weakness. Sternocleidomastoid strength was assessed in 124 consecutive acute stroke patients during yaw, pitch, and roll head movements. This was correlated with limb paresis and neuroimaging findings. The incidence and the degree of sternocleidomastoid paresis were low (16.9%). In all cases, head rotation weakness away from the affected hemisphere was observed. Lateral tilt and vertical head rotations were unaffected. No weakness was detected in lesions that did not cause manifest limb paresis. Our data point to an ipsihemispheric sternocleidomastoid control. Sternocleidomastoid paresis in stroke is expected only with concomitant limb paresis and is always less severe. Head tilt is not affected probably due to sparing of ancillary neck-muscle function.

2171 EFFECT OF DOMINANT HEMISPHERIC STROKE ON DETRUSOR FUNCTION IN PATIENTS WITH LOWER URINARY TRACT SYMPTOMS

You have accessJournal of UrologyUrodynamics/Incontinence/Female Urology: Urodynamic Testing1 Apr 20112171 EFFECT OF DOMINANT HEMISPHERIC STROKE ON DETRUSOR FUNCTION IN PATIENTS WITH LOWER URINARY TRACT SYMPTOMS Tae Gu Kim, Koo Han Yoo, and Seung-kwon Choi Tae Gu KimTae Gu Kim Seoul, Korea, Republic of More articles by this author , Koo Han YooKoo Han Yoo Seoul, Korea, Republic of More articles by this author , and Seung-kwon ChoiSeung-kwon Choi Seoul, Korea, Republic of More articles by this author View All Author Informationhttps://doi.org/10.1016/j.juro.2011.02.2408AboutPDF ToolsAdd to favoritesDownload CitationsTrack CitationsPermissionsReprints ShareFacebookTwitterLinked InEmail INTRODUCTION AND OBJECTIVES To determine the effect of unilateral hemispheric lesion on voiding dysfunction by comparing urodynamic parameters in dominant, non-dominant and bilateral hemispheric stroke patients. METHODS We retrospectively reviewed the medical records of patients from a magnetic resonance imaging and urodynamic study. We identified 69 cases among 192 stroke patients who had undergone urodynamic study due to lower urinary tract symptoms from June 2003 to December 2008. RESULTS Among the analyzed variables in the urodynamic study, total bladder capacity, voided volume, postvoid residual urine volume, maximum flow rate, average flow rate, detrusor pressure at the maximum flow rate, and bladder compliance did not show statistically significant differences among dominant, non-dominant and bilateral hemispheric stroke patients groups (P > 0.05). The dominant hemispheric stroke group had detrusor overactivity in 64.2% of cases and detrusor underactivity in 35.8%; the non-dominant hemispheric stroke group had detrusor overactivity in 66.7% of cases and detrusor underactivity in 33.3%; and the bilateral stroke group had detrusor overactivity in 60.0% of cases and detrusor underactivity in 40.0% (P = 0.946). CONCLUSIONS Urodynamic findings cannot be characterized by the laterality of the unilateral hemispheric ischemic lesion. There are no significant differences in lower urinary tract symptoms between dominant, non-dominant and bilateral hemispheric ischemic stroke patients. © 2011 by American Urological Association Education and Research, Inc.FiguresReferencesRelatedDetails Volume 185Issue 4SApril 2011Page: e870 Peer Review Report Advertisement Copyright & Permissions© 2011 by American Urological Association Education and Research, Inc.MetricsAuthor Information Tae Gu Kim Seoul, Korea, Republic of More articles by this author Koo Han Yoo Seoul, Korea, Republic of More articles by this author Seung-kwon Choi Seoul, Korea, Republic of More articles by this author Expand All Advertisement Advertisement PDF downloadLoading ...

Temporal Discrimination of Sub- and Suprasecond Time Intervals: A Voxel-Based Lesion Mapping Analysis

We used voxel-based lesion-symptom mapping (VLSM) to determine which brain areas are necessary for discriminating time intervals above and below 1 s. VLSM compares behavioral scores of patients that have damage to a given voxel to those that do not on a voxel-by-voxel basis to determine which voxels are critical for the given behavior. Forty-seven subjects with unilateral hemispheric lesions performed a temporal discrimination task in which a standard stimulus was compared on each trial to a test stimulus. In different blocks of trials, standard stimuli were either 600 or 2000 ms. Behavioral measures included the point of subjective equality, a measure of accuracy, and the coefficient of variation, a measure of variability. Lesions of the right middle and inferior frontal gyri were associated with decrements in performance on both durations. In addition, lesions of the left temporal lobe and right precentral gyrus were associated exclusively with impaired performance for subsecond stimuli. In line with results from other studies, these data suggest that different circuits are necessary for timing intervals in these ranges, and that right frontal areas are particularly important to timing.

Effect of dominant hemispheric stroke on detrusor function in patients with lower urinary tract symptoms

To determine the effect of unilateral hemispheric lesion on voiding dysfunction by comparing urodynamic parameters in dominant, non-dominant and bilateral hemispheric stroke patients. We retrospectively reviewed the medical records of patients from a magnetic resonance imaging and urodynamic study. We identified 69 cases among 192 stroke patients who had undergone urodynamic study due to lower urinary tract symptoms from June 2003 to December 2008. Among the analyzed variables in the urodynamic study, total bladder capacity, voided volume, postvoid residual urine volume, maximum flow rate, average flow rate, detrusor pressure at the maximum flow rate, and bladder compliance did not show statistically significant differences among dominant, non-dominant and bilateral hemispheric stroke patients groups (P > 0.05). The dominant hemispheric stroke group had detrusor overactivity in 64.2% of cases and detrusor underactivity in 35.8%; the non-dominant hemispheric stroke group had detrusor overactivity in 66.7% of cases and detrusor underactivity in 33.3%; and the bilateral stroke group had detrusor overactivity in 60.0% of cases and detrusor underactivity in 40.0% (P = 0.946). Urodynamic findings cannot be characterized by the laterality of the unilateral hemispheric ischemic lesion. There are no significant differences in lower urinary tract symptoms between dominant, non-dominant and bilateral hemispheric ischemic stroke patients.

Course 449: Pediatrics: Pediatric Stroke Recovery

Objective: Pediatric stroke recovery is not as well understood as adult stroke. We reviewed the pediatric poststroke recovery patterns of motor, swallowing, speech, and sphincter functions. Design: Retrospective study by medical chart review. Prognostic factors were investigated based on the final achieved functional levels. Setting: Acute pediatric rehabilitation inpatient and outpatient units affiliated with a university hospital. Participants: 44 patients admitted to an acute pediatric inpatient rehabilitation unit with diagnosis of first-ever stroke. Interventions: The recovery pattern was analyzed in regard to muscle tone by modified Brunnstrom stage, skills for ambulation by gross motor functional classification system, and activities of daily living (ADLs) by degree of indepency, swallowing by feeding methods, speech by communication level, and sphincter control by degree of continence. Prognostic factors were investigated based on the final achieved functional levels. Main Outcome Measures: Same as intervention. Results: Recovery of swallowing function occurred earlier than other functions in the first 2 to 3 months poststroke. Less than half of the patients were able to use the affected arms and legs without assistive devices. 11 of 32 patients who initially had poor body control became ambulatory without assistive devices. A total of 18 of 44 patients could walk without assistive devices. Most patients re-entered their premorbid schools, but half of them needed learning support. Bilateral hemisphere lesions and flaccid muscle tone of the affected extremity following stroke had a less favorable prognosis than unilateral hemispheric lesions and nonflaccid hemiplegia at stroke onset in terms of ambulation and ADLs. Hemorrhagic strokes without surgical complications had a better prognosis than nonhemorrhagic strokes. Conclusions: Most of the functional recovery for pediatric stroke occurs in the first 2 to 3 months after stroke, but the quality of functional recovery was better in the pediatric population. The lesion size of the stroke was related to prognosis.

MAGNETOENCEPHALOGRAPHIC STUDY OF POSTERIOR TIBIAL NERVE STIMULATION IN PATIENTS WITH INTRACRANIAL LESIONS AROUND THE CENTRAL SULCUS

To study interhemispheric differences of somatosensory evoked field (SEF) characteristics and the spatial distribution of equivalent current dipole sources in patients with unilateral hemispheric lesions around the central sulcus region. In 17 patients with perirolandic lesions, averaged somatosensory responses after posterior tibial nerve stimulation at the ankle were recorded with magnetoencephalography. Dipole source solutions in the affected (AH) and unaffected (UH) hemispheres were analyzed and compared for latency, equivalent current dipole strength, root mean square, and spatial distribution in relation to clinical findings. Three main SEF components, P45m, N60m, and P75m, were identified in the hemisphere contralateral to the stimulated nerve. Dipole strength for the P45m component was significantly higher in the AH compared with the UH. SEF characteristics in the AH and UH showed no significant differences with respect to component latency or dipole strength of the N60m and P75m components. Interdipole location asymmetries exceeded 1.0 cm in 71% of the patients. Comparison of the posterior tibial nerve evoked responses (P45m and N60m) in patients with motor deficits and patients without deficits showed that these responses are enlarged in the AH when perirolandic lesions are present. Patients with motor deficits also showed an increased response for P45m in the UH. The results of posterior tibial nerve SEFs suggest spatial and functional changes in the somatosensory network as a result of perirolandic lesions with a possible relationship with clinical symptoms. The results can provide further basis for the evaluation of cortical changes in the presence of perirolandic lesions.

Our Experience with Pediatric Epilepsy Surgery Focusing on Corpus Callosotomy and Hemispherotomy

In pediatric patients with intractable epilepsy, surgical intervention should be considered in terms of seizure control and prevention of neuronal deterioration. We present our experience with pediatric epilepsy surgery, focusing on corpus callosotomy and hemispherotomy. A total of 257 pediatric patients underwent epilepsy surgeries during the last decade in our clinic. The two most common surgical procedures were corpus callosotomy and hemispherotomy. The surgical outcomes of the patients undergoing these operations were analyzed with regard to seizure outcomes and surgical complications. Corpus callosotomy proved to be extremely effective in controlling drop attacks, especially when the callosum was totally sectioned. Postoperative improvement of psychomotor function also was noticeable in >70% of the cases. In patients who underwent hemispherotomy, the etiology of unilateral hemispheric lesions was closely related to surgical results, with cases of hemimegalencephaly having the worst seizure outcome and most frequent surgical complications. Incomplete section of the callosum, one of the most important causes of residual seizures, was found in three cases. In pediatric epilepsy surgery, corpus callosotomy is very effective in abolishing drop attacks and improving postoperative psychomotor function. For hemispherotomy, cases of hemimegalencephaly had the worst seizure control and surgical complications. Incomplete section of the corpus callosum should be carefully evaluated as a cause of surgical failure.

The Nonmalformed Hemisphere Is Secondarily Impaired in Young Children with Hemimegalencephaly: A Pre‐ and Postsurgery Study with SPECT and EEG

To study separately the functional value of each cerebral hemisphere in hemimegalencephaly (HME). HME is a unique model of unilateral hemispheric lesion, but one suspects that the non-HME hemisphere also could be functionally impaired because the postsurgery outcome is less favorable than expected. We performed simultaneous prolonged EEG and 133-xenon SPECT (single-photon emission computed tomography); we measured the absolute values of cerebral blood flow (CBF) in both hemispheres and compared them with the normal values previously acquired. Thirteen patients (aged 5-38 months) underwent 31 examinations, 20 before surgery (hemispherotomy) and 11 after. In the HME hemisphere, we confirmed the presurgical mixture of increased and decreased CBF due to intermittent ictal discharges. After surgery, CBF was decreased in most cases. In the non-HME hemisphere, presurgery CBF was abnormal in 60% of the patients, increased and related mostly to diffuse interictal spikes on the same side, whereas normal CBF cases had focal spikes. After surgery, CBF was normal in 82% of cases, corresponding to an EEG without diffuse spikes. In the six patients longitudinally studied, CBF dramatically decreased after surgery in the HME hemisphere, whereas in the non-HME hemisphere, CBF was mostly normal very early (three fourths before 2 months), increased as soon as 3 months, and normalized only after hemispherotomy, the more rapidly the child was operated on, the earlier it was. This study shows that the function of the nonmalformed hemisphere is impaired as soon as the first months of the course of HME but can be restored after surgery. Our data support the recommendations to operate on the children as early as possible.

Predicting Long-term Functional Outcome of Stroke Using Multivariate Analysis

The purpose of the present study was to investigate long-term prognosis of patients with stroke and to identify predictive factors for functional outcome. Subjects were consecutively hospitalized 1,056 patients with stroke due to unilateral hemispheric lesions at the Department of Neurology, Kitasato University Hospital from 1986 to 1997. One hundred and eighty-three patients died during hospital stay. The remaining 873 surviving patients were followed for 5 years after onset of stroke. Locomotive function (mobility status) of surviving patients was assessed by questionnaires mailed at 2 years and at 5 years after stroke. Outcome of locomotive function was classified into the following 5 categories: normal, walk alone, walk with device, using wheelchair, and bedridden. The following factors were tested by means of multiple regression analysis: age, sex, level of consciousness, location and size of lesion, history of previous stroke and 2 major risk factors for stroke (hypertension and diabetes mellitus). The results of multivariate analysis revealed that in patients with intracerebral hemorrhage, although level of consciousness on admission was the strongest predictor at discharge, locomotive function at discharge was the most important predictor at 2 years and at 5 years after stroke. Moreover, age was more strongly related to functional outcome than level of consciousness at 2 years and at 5 years after stroke. This trend was also found in patients with cerebral infarction. Multivariate analysis revealed that a linear combination of these predictors accounted for about 50% of the variance in the estimate of functional outcome at 2 years and at 5 years after stroke. The results of the present study suggest that the long-term outcome of stroke patients is more deeply influenced by unidentified factors which may not be present during the hospital stay.

Unilateral hemispheric lesions disrupt parallel processing within the contralateral intact hemisphere: an auditory fMRI study

Evidence from activation studies suggests that sound recognition and localization are processed in two distinct cortical networks that are each present in both hemispheres. Sound recognition and/or localization may, however, be disrupted by purely unilateral damage, suggesting that processing within one hemisphere may not be sufficient or may be disturbed by the contralateral lesion. Sound recognition and localization were investigated psychophysically and using fMRI in patients with unilateral right hemisphere lesions. Two patients had a combined deficit in sound recognition and sound localization, two a selective deficit in sound localization, one a selective deficit in sound recognition, and two normal performance in both tasks. The overall level of activation in the intact left hemisphere of the patients was smaller than in normal control subjects, irrespective of whether the patient's performance in the psychophysical tasks was impaired. Despite this overall decrease in activation strength, patients with normal performance still exhibited activation patterns similar to those of the control subjects in the recognition and localization tasks, indicating that the specialized brain networks subserving sound recognition and sound localization in normal subjects were also activated in the patients with normal performance, albeit to an altogether lesser degree. In patients with deficient performance, on the other hand, the activation patterns during the sound recognition and localization tasks were severely reduced, comprising fewer and partly atypical activation foci compared to the normal subjects. This indicates that impaired psychophysical performance correlates with a breakdown of parallel processing within specialized networks in the contralesional hemisphere.