Epileptic features of patients with unilateral and bilateral schizencephaly

The extent of cortical maldevelopment might correlate with the severity of the clinical manifestation, such as cognitive delay or motor dysfunction. The objective of this study was to investigate the clinical features of epilepsy in patients with unilateral and bilateral schizencephaly. We studied 44 consecutive patients with schizencephaly diagnosed by magnetic resonance imaging (MRI). The epileptic features were analyzed in detail: frequency of epilepsy, median age at onset of epilepsy, semiology of seizures, characteristic features of electroencephalographic (EEG) abnormalities, epileptic syndromes, and antiepileptic drug treatment. We also verified the presence of motor disabilities. Data were analyzed according to the presence of unilateral or bilateral clefts and to the presence of open-lip versus closed-lip schizencephaly. We used the chi-square test and Fisher exact test for statistical analysis. Twenty-four patients had a unilateral cleft (group 1) and 20 patients had bilateral clefts (group 2). Ages ranged from 1 to 37 years (mean 10.6 years). Epilepsy was present in 15 (63%) patients in group 1 and in 11 (55%) patients of group 2; a history of status epilepticus occurred in 13% of group 1 and in 27% in group 2; and a history of clusters of seizures occurred in 40% of group 1 and in 45% of group 2. Eight (53%) patients in group 1 and 6 (54%) patients in group 2 were in monotherapy. Ten (67%) patients in group 1 and 7 (64%) patients in group 2 had seizures controlled with antiepileptic drugs. The frequency of EEG abnormalities was similar between groups (75% and 85%, groups 1 and 2, respectively). Statistical analysis showed no difference between the two groups in the variables mentioned above. However, motor disability was significantly more frequent and more severe in group 2. Regarding the type of schizencephaly (open lip versus closed lip), there was no difference in the frequency of patients with epilepsy, and severe motor deficit was more frequently found in bilateral and open-lip schizencephaly. The extent of the cortical maldevelopment in patients with schizencephaly does not correlate with the severity of the clinical and EEG features of epilepsy, unlike the cognitive and motor manifestations. In addition, the type of schizencephaly (open lip versus closed lip) does not correlate with the presence of epilepsy or seizure control, unlike motor deficit.     

False fMRI activation after motion correction

Motion correction of echo‐planar imaging (EPI) data used in functional MRI (fMRI) is an essential preprocessing step performed prior to statistical analysis. At ultra‐high resolution fMRI, current requirements regarding translational and rotational motion may no longer be acceptable. This prompts the need for a systematic investigation of the effects of motion correction procedures with in vivo fMRI data. Here we systematically evaluated the effect of retrospective motion correction with freely available fMRI analysis software packages (FSL, AFNI, and SPM) on activation maps using fMRI data acquired with prospective motion detection, to identify and quantify confounding effects of retrospective motion correction, and to evaluate its dependence on spatial resolution and motion correction algorithms. Brain activation maps were obtained for two different resolutions, an ultrahigh, that is, 0.65³ mm³, and a more widely used 2.0³ mm³ isotropic resolutions at 7 T. The EPI data were acquired using simultaneous non‐image‐based optical moiré phase tracking (MPT) of physical motion. The results showed that image‐based motion detection, performed by SPM8 software package, may be erroneous in high‐field fMRI data with partial brain coverage and can introduce spurious motion leading to false‐positive and false‐negative activation. Further analyses demonstrated that limited acquisition field of view has the dominant influence on the effect. Hum Brain Mapp 38:4497–4510, 2017. © 2017 Wiley Periodicals, Inc.     

Cortical reorganization after acute unilateral hearing loss traced by fMRI

Unilateral acoustic stimulation produces a functional MRI (fMRI)-blood-oxygenation-level-dependent (BOLD) response mainly in the contralateral auditory cortex. In unilateral deaf patients, the BOLD response is bilateral. We studied a subject with sudden hearing loss after cochlear nerve resection before and repeatedly after surgery. During normal bilateral hearing, contralateral cortical BOLD responses were found. Progressing compensatory reorganization with bilateral representation of unilateral stimulation was detected over a period of approximately 1 year.     

Perception of complex sounds: abnormal pattern of cortical activation in autism

OBJECTIVE: Bilateral temporal hypoperfusion at rest was recently described in autism. In normal adults, these regions are activated by listening to speech-like sounds. To investigate auditory cortical processing in autism, the authors performed a positron emission tomography activation study. METHOD: Regional cerebral blood flow was measured in five autistic adults and eight comparison subjects during rest and while listening to speech-like sounds. RESULTS: Similar to the comparison subjects, autistic patients showed a bilateral activation of the superior temporal gyrus. However, an abnormal pattern of hemispheric activation was observed in the autistic group. The volume of activation was larger on the right side in the autistic patients, whereas the reverse pattern was found in the comparison group. The direct comparison between the two groups showed that the right middle frontal gyrus exhibited significantly greater activation in the autistic group. Conversely, the left temporal areas exhibited less activation in autistic patients. CONCLUSIONS: These findings suggest that abnormal auditory cortical processing is implicated in the language impairments and the inadequate response to sounds typically seen in autism.     

Functional recovery after brain lesion--contralateral neuromodulation: an fMRI study

Behavioral recovery takes place even after permanent damage to the entire brain region normally controlling sensorimotor hind limb function in the rat. In our study, 2 weeks after full behavioral recovery from an experimental unilateral permanent brain damage, the topographic representation of the previous paretic hindlimb was investigated by fMRI. The analysis showed that during electrical stimulation of the previously paretic hindlimb, two normally inactive brain regions were now being activated. One region was the non-damaged contralateral sensori-motor cortex and the other region was located lateral to the lesion. These results suggest that behavioral recovery can be explained by functional reorganization and neuromodulation of the brain.     

首发精神分裂症听觉感觉门控异常的功能磁共振研究

目的 探讨首发精神分裂症患者听觉门控异常与脑功能异常激活之间的关系.方法 11例首发精神分裂症患者及11名年龄、性别、受教育程度相匹配的正常对照进行脑功能磁共振成像,实验采用多声音刺激和单声音刺激比较的范式,以多声音刺激减单声音刺激的对比探测感觉门控的脑激活效应.以SPM2处理脑影像数据,使用两样本t检验比较两组间听觉感觉门控脑功能激活的差异.结果 患者组的感觉门控脑激活在右侧海马(x ＝ 24,y ＝ -28,z ＝ -8,体素集合数＝ 16)、右侧丘脑(x ＝ 8,y ＝ -4,z ＝ 4,体素集合数＝ 22)低于正常对照组(t ＝ 3.57,P ＝ 0.001;t ＝ 3.38,P ＝ 0.001).结论 首发精神分裂症患者的听觉门控异常可能与海马、丘脑等脑区的功能激活异常有关.     

Unilateral closed-lip schizencephaly and epilepsy: a comparison with cases of unilateral polymicrogyria

We compared the electroclinical features and evolution of patients with two different types of abnormal cortical organization: unilateral closed-lip schizencephaly (SCHZ) and unilateral polymicrogyria (PMG). Between February 1990 and June 2002, 51 children with either unilateral PMG or closed-lip SCHZ were selected through neuroradiological analysis for investigation at our service. We evaluated the frequency of epilepsy, electroclinical features and evolution. The mean time of follow-up was 7 years (range 1-12 years). All patients underwent neurological examination, computed tomography scan and magnetic resonance imaging, serial electroencephalographic (EEG) recordings and neuropsychological assessment. Thirty-six of the 51 patients had unilateral PMG. All patients had hemiparesis with mild spasticity. Mental retardation was mild in 20 and moderate in 14. In two patients IQ was normal. Partial motor seizures were recorded in 28 patients, with secondary generalization in 20. The median age at onset of seizures was 2 years (range 4 months-7 years). Interictal EEGs showed unilateral spikes in all patients. In 21 patients epilepsy worsened between the ages of 4 and 8 (mean 5.6 years) with frequent atonic seizures, atypical absences, epileptic negative myoclonus and gait difficulties. EEGs showed continuous spike-wave activity or bilateral high-frequency spike discharges during slow-wave sleep. Frequent relapses of atonic and myoclonic seizures were seen in nine patients. At present, 16 patients are seizure-free. Fifteen patients with unilateral SCHZ were included in the study. Focal motor seizures were registered in seven cases, in three of them with secondary generalization. The median age at onset of epilepsy was 2.5 years (range 1-4 years). Interictal EEGs showed unilateral spikes in these seven cases. All patients except one presented mild spastic hemiparesis. Mental retardation was mild in ten children, moderate in two and IQ was normal in three. Although the underlying mechanisms leading to PMG and SCHZ are probably similar, the electroclinical phenomenon of secondary bilateral synchrony with frequent negative myoclonus was not present in our cases with unilateral closed-lip SCHZ.     

Prognostic relevance of pathological sympathetic activation after acute thromboembolic stroke

OBJECTIVE: To evaluate the prognostic impact of early pathologic sympathetic activation after stroke. METHODS: The authors examined 112 consecutive patients (mean age, 69 years; 60 men) with their first brain infarction. A pathologic sympathetic activation was presumed if the initial norepinephrine level exceeds 300 pg/mL. In addition, involvement of the insular cortex, nighttime blood pressure changes, and several cardiovascular risk factors were determined. One-year outcome measures were mortality rate, cardiovascular and cerebrovascular events, and activities of daily living (Barthel index and Rankin score). RESULTS: Norepinephrine levels greater than 300 pg/mL, nighttime blood pressure increases, and insular involvement were associated with a lower Barthel index (p < 0.005) at the 1-year follow-up. By stepwise logistic regression analysis, insular infarction, serum norepinephrine concentration, right-sided infarction, and nighttime blood pressure increase were significant and independent predictors of an unfavorable functional outcome. Cox regression analysis showed a higher rate of cardiovascular and cerebrovascular events (hazard ratio, 2.9; 95% CI, 1.07; 6.83; p < 0.04) in patients with initially increased norepinephrine concentrations. CONCLUSIONS: The involvement of the insular cortex, the occurrence of a pathologic nighttime blood pressure increase, and an initially increased serum norepinephrine concentration are independent predictors of poor long-term outcome.     

Functional imaging in Parkinson's disease: activation studies with PET,fMRI and SPECT

Activation studies with positron emission tomography (PET) and functional magnetic resonance imaging (fMRI) represent a powerful tool to study the functional anatomy of Parkinson's disease (PD). Activation studies offer the opportunity to study regional cerebral function in man in vivo under different conditions with the analysis of task specific changes in regional cerebral blood flow (rCBF) with PET or in the blood oxygenation level dependent (BOLD) effect with fMRI. The combination of PET and deep brain stimulation is particularly attractive to study the effects of discrete perturbations at different target structures throughout the basal ganglia-thalamocortical circuitries. The use of rCBF PET and fMRI to study the pathophysiology of PD in the motor and sensory system and mechanisms of dopaminergic therapy as well as surgical interventions will be reviewed.     

Functional imaging in Parkinson's disease: activation studies with PET,fMRI and SPECT

Activation studies with positron emission tomography (PET) and functional magnetic resonance imaging (fMRI) represent a powerful tool to study the functional anatomy of Parkinson's disease (PD). Activation studies offer the opportunity to study regional cerebral function in man in vivo under different conditions with the analysis of task specific changes in regional cerebral blood flow (rCBF) with PET or in the blood oxygenation level dependent (BOLD) effect with fMRI. The combination of PET and deep brain stimulation is particularly attractive to study the effects of discrete perturbations at different target structures throughout the basal ganglia-thalamocortical circuitries. The use of rCBF PET and fMRI to study the pathophysiology of PD in the motor and sensory system and mechanisms of dopaminergic therapy as well as surgical interventions will be reviewed.

     

Regional pattern of metabolic activation is reflected in the sleep EEG after sleep deprivation combined with unilateral whisker stimulation in mice

Regional differences in EEG slow wave activity (SWA) during sleep after sleep deprivation (SD) may be a consequence of differential metabolic activation of cortical areas. We investigated the relationship between the regional EEG dynamics and 2-deoxyglucose (DG) uptake after SD in mice. Six hours' SD were combined with natural unilateral whisker stimulation in an enriched environment to selectively activate the barrel cortex and motor areas. As expected, an interhemispheric asymmetry of 2-DG uptake was found in the barrel cortex immediately after SD. To test whether sleep contributes to recovery of the asymmetry, the stimulation was followed by either undisturbed sleep or by an additional SD. The asymmetry vanished after recovery sleep but also after the additional period of wakefulness without stimulation. In addition, relative 2-DG uptake in the primary motor cortex and retrosplenial area was significantly higher immediately after the SD than after the additional sleep or wakefulness, whereas no other region differed between the groups. Whisker stimulation elicited a greater increase in EEG SWA during non rapid eye movement sleep in the stimulated hemisphere than in the control hemisphere; this increase lasted for 10 h. Within a hemisphere, the initial increase in SWA was higher in the frontal than in the parietal derivation. We conclude that the regional SWA differences during sleep are use-dependent and may be related to the regional pattern of metabolism during the previous waking episode. However, the regional metabolic recovery is not dependent on sleep, and is not directly reflected in changes in SWA during sleep.     

Functional relevance of ipsilateral motor activation in congenital hemiparesis as tested by fMRI-navigated TMS

Many, but not all patients with congenital hemiparesis (i.e., hemiparesis due to a pre-, peri- or neonatally acquired brain lesion) control their paretic hands via ipsilateral cortico-spinal projections from the contra-lesional hemisphere (CON-H). Patients who still control their paretic hands via preserved crossed cortico-spinal projections from the damaged hemisphere nevertheless show increased fMRI activation during paretic hand movements in the CON-H. We used fMRI-navigated rTMS induced functional lesions over the primary motor cortex (M1) hand area, the dorsal premotor cortex (dPMC) and the superior parietal lobe (SPL) of the CON-H in four of these patients to investigate whether this increased ipsilateral activation during finger movements of the paretic hand contributes to movement performance. Functional lesions of the dPMC and M1 but not SPL of the CON-H induced decreased temporal preciseness of finger sequences. The present results argue for a possible role of dPMC and M1 of the CON-H on complex motor behavior even in those patients with congenital hemiparesis who control their paretic hands via crossed cortico-spinal projections from the damaged hemisphere.     

Two adult cases of unilateral schizencephaly manifesting as minor neurological signs--importance of radiographic CT assessment]

We report two adult cases of unilateral schizencephaly manifesting as minor neurological signs. Case 1 was a 52-year-old female with an attack of partial seizure. CT demonstrated a closed cleft in the left frontal lobe. MRI revealed that the cleft was covered with gray matter, and was extending to the ventricular wall. Her epileptic seizure was successfully controlled by medication. Case 2 was a 58-year-old female with a history of mild right hemiparesis from her birth. CT demonstrated a closed cleft in the left peri-Rolandic area. MRI revealed a cortical infolding which extended to the lateral ventricle, and complication with polymicrogyria. Two patients were diagnosed as having normal intelligence, and unilateral schizencephalies with closed-lip. There has appeared to be more reports in the recent literature dealing with unilateral schizencephaly with mildly neurologic dysfunction. It is sufficiently capable of making such a diagnosis for schizencephaly by initial CT evaluation of a detailed radiographic assessment, in which characteristic findings with focal enlargement of cortical sulci or appearance of cortical infolding extending to deep white matter will be detected, though MRI is considered to be useful for a more detailed neuroanatomical evaluation.     

Monocular pattern discrimination learning after unilateral lesions of anteromedial cortex in rat

Monocularly patched rats were trained on a series of visual tilt discriminations ordered from simple to difficult to measure the angular difference threshold of each eye. Preoperatively there was no difference between discrimination performance for either eye. Unilateral lesions of anteromedial cortex did not alter the monocular angular difference threshold. However, there was a reduction in discrimination performance for all angular difference comparisons. Animals showed a visual neglect for stimuli in the field contralateral to the lesion. The neglect was independent of the eye used for the discrimination.     

Functional magnetic resonance imaging evidence for task-specific activation of developmentally abnormal visual association cortex

Functional magnetic resonance imaging was performed on a 36-year-old woman with muscular dystrophy, intractable epilepsy, and bilateral temporo-occipital lissencephaly. We observed islands of task-specific activation in lissencephalic cortex homologous to visual association regions activated in normal subjects on the same visual confrontation naming task. This result suggests lissencephalic cortex may develop specific functional connections with other brain regions.     

Reduced parietal activation in cervical dystonia after parietal TMS interleaved with fMRI

Objective

Clinically normal hand movement with altered cerebral activation patterns in cervical dystonia (CD) may imply cerebral adaptation. Since impaired sensorimotor integration appears to play a role in dystonia, left superior parietal cortex modulation with repetitive transcranial magnetic stimulation (TMS) was employed to further challenge adaptation mechanisms reflected by changes in cerebral activation.

Methods

Seven CD patients and ten healthy controls were scanned on a 3T magnetic resonance imaging (MRI) scanner with 1 Hz inhibitory interleaved TMS. They executed and imagined right wrist flexion/extension movements. Each task was preceded by a 10-s period with or without TMS.

Results

The activations of both tasks after TMS in controls showed a similar pattern as found in CD without TMS, i.e. activation increases in bilateral prefrontal and posterior parietal regions during both tasks and decreases in right anterior parietal cortex during imagery (P < 0.001). the activations of both tasks after TMS in CD were weaker but with a similar trend in activation changes. Only in the right angular gyrus, TMS significantly failed to induce an activation increase in CD as was seen in the controls (P < 0.001).

Conclusion

The similarity between TMS effects on the distribution of cerebral activations in controls and the pattern seen in CD may support the concept that CD make use of compensatory circuitry enabling clinically normal hand movement. The fact that a similar but weaker TMS effect occurred in CD could suggest that the capacity of compensation is reduced. Particularly for the right angular gyrus, this reduction was statistically significant.