Hemispherectomy In Childhood Research Articles

Saccade Profiles Across Tasks After Childhood Hemispherectomy

Saccade Profiles Across Tasks After Childhood Hemispherectomy

Differential functional reorganization of ventral and dorsal visual pathways following childhood hemispherectomy

Differential functional reorganization of ventral and dorsal visual pathways following childhood hemispherectomy

Differential functional reorganization of ventral and dorsal visual pathways following childhood hemispherectomy

Hemispherectomy is a surgical procedure in which an entire hemisphere of a patient’s brain is resected or functionally disconnected to manage seizures in individuals with drug-resistant epilepsy. Despite the extensive loss of both ventral and dorsal visual pathways in one hemisphere, pediatric patients who have undergone hemispherectomy show a remarkably high degree of perceptual function across many domains. In the current study, we sought to understand the extent to which functions of the ventral and dorsal visual pathways reorganize to the contralateral hemisphere following childhood hemispherectomy. To this end, we collected fMRI data from an equal number of left and right hemispherectomy patients who completed tasks that typically elicit lateralized responses from the ventral or the dorsal pathway, namely, word (left ventral), face (right ventral), tool (left dorsal), and global form (right dorsal) perception. Overall, there was greater evidence of functional reorganization in the ventral pathway than in the dorsal pathway. Importantly, because ventral and dorsal reorganization was tested within the very same patients, these results cannot be explained by idiosyncratic factors such as disease etiology, age at the time of surgery, or age at testing. These findings suggest that because the dorsal pathway may mature earlier, it may have a shorter developmental window of plasticity than the ventral pathway and, hence, be less malleable after perturbation.

5 Social perception and ability to evaluate sincerity of speech impacted by childhood hemispherectomy

Objective:Hemispherectomy (HE) is a surgical intervention to treat intractable epilepsy. It involves disconnecting or removing the right or left cerebral hemisphere, depending on the location of the pathological substrate or epileptogenic activity. HE impacts neural functions related to social cognition (Fournier et al., 2008). This study investigates the effects of childhood HE on social deception and sarcasm using the Thames Awareness of Social Inferences Task (TASIT; McDonald, Flanagan, & Rollins, 2010) to explore emotion identification and social inference appraisal as adults.Participants and Methods:Fifteen adults with hemispherectomy and 16 neurotypical controls completed the TASIT. All HE patients underwent hemispherectomy (right-HE = 10) during childhood (age of surgery = 3 months to 16 years) and had FSIQ > 70 at the time of study. HE and control groups were matched for age (HE M = 25.7, SD = 5.4; control M = 27.1, SD = 10.7) and education (HE M = 14.0, SD = 1.88; control M = 13.3, SD = 1.8). FSIQ was significantly lower in the HE group than control group (HE M= 90.8, SD = 9.4; control (M = 100.4, SD = 7.1). TASIT uses videotaped vignettes to assess aspects of social perception: emotion recognition (Part 1), social inference regarding sincerity, simple sarcasm, and paradoxical sarcasm (Part 2) and social inference regarding sincerity of speech (lie vs sarcasm) in the presence of additional text or visual cues (Part 3).Results:For Part 1, MANCOVA (covarying FSIQ) found no group difference in emotion identification. Analysis of data from Part 2 was conducted using repeated measures ANCOVA accounting for 2 groups x 3 conditions (sincere, simple sarcasm, and paradoxical sarcasm) and revealed only a significant overall group effect, F (1, 28) = 5.72, p = .024, np2 = .170. Likewise, analysis of Part 3 using repeated measures ANCOVA accounting for 2 groups x 2 cue types (visual, text) and 2 actor intentions (lie, sarcasm) revealed only a significant overall group effect, F (1,28) = 11.35, p = .002, np2 = .288, with no interaction of group by condition.Conclusions:HE patients exhibited no difficulty identifying basic emotional expressions. Performance was significantly impaired when additional social information was added to the context (i.e., detecting sarcasm or deception). HE patients begin to struggle with the complexity of new social information or how it changes the meaning of a conversation. Even simple sarcastic exchanges are difficult to interpret. When a visual or textual cue was introduced to reveal the true state of affairs, HE patients could not could integrate the information into their interpretations of the scenario. There are unique contributions of the left and right hemispheres to cognitive processes for complex social behavior, and absence of an entire hemisphere results in deficits in social language comprehension. Future research should investigate performance differences in left vs. right HE patients.

Probing the neural plasticity of space- and object-based attentional processing in childhood hemispherectomy

Probing the neural plasticity of space- and object-based attentional processing in childhood hemispherectomy

With childhood hemispherectomy, one hemisphere can support—but is suboptimal for—word and face recognition

The right and left cerebral hemispheres are important for face and word recognition, respectively-a specialization that emerges over human development. The question is whether this bilateral distribution is necessary or whether a single hemisphere, be it left or right, can support both face and word recognition. Here, face and word recognition accuracy in patients (median age 16.7 y) with a single hemisphere following childhood hemispherectomy was compared against matched typical controls. In experiment 1, participants viewed stimuli in central vision. Across both face and word tasks, accuracy of both left and right hemispherectomy patients, while significantly lower than controls' accuracy, averaged above 80% and did not differ from each other. To compare patients' single hemisphere more directly to one hemisphere of controls, in experiment 2, participants viewed stimuli in one visual field to constrain initial processing chiefly to a single (contralateral) hemisphere. Whereas controls had higher word accuracy when words were presented to the right than to the left visual field, there was no field/hemispheric difference for faces. In contrast, left and right hemispherectomy patients, again, showed comparable performance to one another on both face and word recognition, albeit significantly lower than controls. Altogether, the findings indicate that a single developing hemisphere, either left or right, may be sufficiently plastic for comparable representation of faces and words. However, perhaps due to increased competition or "neural crowding," constraining cortical representations to one hemisphere may collectively hamper face and word recognition, relative to that observed in typical development with two hemispheres.

Mapping degeneration of the visual system in long-term follow-up after childhood hemispherectomy – A series of four cases

ObjectiveAlthough hemidisconnection surgery may eliminate or reduce seizure activity in patients with epilepsy, there are visual, cognitive and motor deficits which affect patients’ function post-operatively, with varying severity and according to pathology. Consequently, there is a need to map microstructural changes over long time periods and develop/apply methods that work with legacy data. MethodsIn this study, we applied the novel single shell 3-Tissue method to data from a cohort of 4 patients who were scanned 20-years following childhood hemidisconnection surgery and presented with variable clinical outcomes. We have successfully reconstructed tractography of the whole visual pathway from single shell diffusion data with reduced number of gradient directions. ResultsAll patients presented with degeneration of the visual system characterised by low fractional anisotropy and high mean diffusivity. There were no apparent microstructural differences between both optic nerves that could explain the different level of visual function across patients. However, we provide evidence suggesting an association between the level of visual function and DTI metrics within the remaining components of the visual system, particularly the optic tract, of the contralateral hemisphere post-surgery. SignificanceWe believe this study suggests that diffusion MRI can be used to monitor the integrity of the visual system following hemispherectomy and if extended to larger cohorts and a greater number of time-points, including pre-surgically, can provide a clearer picture of the natural history of visual system degeneration. This knowledge may in turn help to identify patients at greatest risk of poor visual outcomes that might benefit from rehabilitation therapies.

Language after childhood hemispherectomy: A systematic review.

To conduct a systematic review on language outcomes after left and right hemispherectomy in childhood, a surgical procedure that involves removing or disconnecting a cerebral hemisphere. We searched MEDLINE, Embase, and PsycInfo for articles published between January 1, 1988, and May 16, 2019. We included (1) all types of observational studies; (2) studies in which hemispherectomy was performed before age 18 years; and (3) studies with standardized scores measuring receptive vocabulary, expressive vocabulary, sentence comprehension, and/or sentence production. We calculated mean z scores after left and right hemispherectomy in the whole group and within etiology-specific subgroups. Our search identified 1,096 studies, of which 17 were eligible. The cohort added up to 205 individuals (62% left hemispherectomy) assessed 1 to 15 years after surgery. In the left surgery group, all language skills were impaired (z scores <-1.5) except sentence comprehension. In the right surgery group, language performance was in the borderline range (z scores ∼ -1.5). Children with cortical dysplasia showed the worst outcomes irrespective of surgery side (z scores <-2.5). Individuals with left vascular etiology and right-sided Rasmussen syndrome showed the best outcomes. Evidence based on the largest patient cohort to date (205 participants) suggests that the risk of language impairment after hemispherectomy is high, with few exceptions. Etiology plays a major role in postsurgical plasticity. We recommend specialist evaluation of language skills soon after surgery to identify intervention targets. Large-scale studies examining outcomes in consecutive cases are still needed.

Visual Function 20 Years After Childhood Hemispherectomy for Intractable Epilepsy

To investigate visual function in adults post hemispherectomy in childhood. Noncomparative case series. All participants underwent visual acuity, binocular function, visual field, optical coherence tomography (OCT) of the retinal nerve fiber layer (RNFL), and monocular pattern reversal visually evoked potentials (prVEP). Six adults who had a hemispherectomy in childhood (median 21.5 years postoperative). Comparison was made of visual acuity, visual field height, global RNFL thickness, and prVEP amplitude evoked by full- and half-field stimulation. Comparison of the eye ipsilateral to the side of surgery to the contralateral eye was achieved employing paired t tests to the visual function measures. All participants had homonymous hemianopia. The residual seeing visual field was constricted in all cases when compared with normative data despite crossing the midline into the blind hemifield in 11 of 12 eyes. This observation was supported by prVEP to stimuli presented in the blind half field. The height of the visual field was smaller in the eye contralateral to the side of surgery compared with the ipsilateral side (P= .047). Visual acuity and RNFL thickness also showed greater diminution in the contralateral eye (P= .040 and P=.0004). Divergent strabismus was found in 4 participants with greater field loss. Adults post hemispherectomy in childhood may have better visual function in the eye ipsilateral to the side of the hemispherectomy compared with the contralateral eye. Possible mechanisms of the interocular difference are discussed. Though visual fields and prVEP responses demonstrate evidence of reorganization into the blind half field, they also reveal significant unexpected constriction of the functional field.

The spectrum of long-term cognitive and functional outcome after hemispherectomy in childhood.

To evaluate cognition, behavior, daily functioning and health-related quality of life (HrQoL) five years to more than a decade after hemispherectomy (HE) in childhood. This countrywide Dutch cohort study of 31 patients, who underwent HE between 1994 and 2009, included a semi-structured interview with parents, an assessment of cognition, and screening of behavioral problems and HrQoL. Twenty-two school-age children and young adults [median age 13.8 years (0.5 at epilepsy onset, 5.3 at HE)] were assessed with age-appropriate cognitive tests. IQ ranged from 45 to 82 (median 61). Despite performing below mean norm scores, these participants could learn and remember, sustain attention, inhibit irrelevant responses, read and write. Nine more children [median age 9.7 years (0.25 at epilepsy onset, 1.4 at HE)] were so mentally retarded that age-appropriate testing was impossible. This group was almost totally dependent on others in daily activities, had the highest proportion of pre-existing contralateral MRI-abnormalities and after HE the highest rates of seizure recurrence and behavioral problems. Parents in both groups rated HrQoL surprisingly positively (mean VAS-score 72.5), with a scarce low rating (40). All parents reported problems with respect to their children's self-care, daily activities and mobility. At least five years after HE, cognitive, behavioral and daily functioning encompasses a broad spectrum that varies from profound retardation and almost total dependence to low normal cognition and a reasonably independent existence. Pre-existing contralateral MRI abnormalities reflect a more generally affected brain with a limited ability to mediate development after HE.

Speech and oral motor profile after childhood hemispherectomy

Hemispherectomy (disconnection or removal of an entire cerebral hemisphere) is a rare surgical procedure used for the relief of drug-resistant epilepsy in children. After hemispherectomy, contralateral hemiplegia persists whereas gross expressive and receptive language functions can be remarkably spared. Motor speech deficits have rarely been examined systematically, thus limiting the accuracy of postoperative prognosis. We describe the speech profiles of hemispherectomized participants characterizing their intelligibility, articulation, phonological speech errors, dysarthric features, and execution and sequencing of orofacial speech and non-speech movements. Thirteen participants who had undergone hemispherectomy (six left, seven right; nine with congenital, four with acquired hemiplegia; operated between four months and 13 years) were investigated. Results showed that all participants were intelligible but showed a mild dysarthric profile characterized by neuromuscular asymmetry and reduced quality and coordination of movements, features that are characteristic of adult-onset unilateral upper motor neuron dysarthria, flaccid-ataxic variant. In addition, one left and four right hemispherectomy cases presented with impaired production of speech and non-speech sequences. No participant showed evidence of verbal or oral dyspraxia. It is concluded that mild dysarthria is persistent after left or right hemispherectomy, irrespective of age at onset of hemiplegia. These results indicate incomplete functional re-organization for the control of fine speech motor movements throughout childhood, and provide no evidence of hemispheric differences.

Language after hemispherectomy in childhood: Contributions from memory and intelligence

After hemispherectomy (removal or disconnection of an entire cerebral hemisphere) in childhood for treatment of intractable epilepsy, gross speech and language functions are often rescued. Whether more complex functions, such as syntactic processing, are selectively impaired, remains controversial. Here we present a cross-sectional study of expressive and receptive language functions in 30 patients who have undergone hemispherectomy (17 left, 13 right). The patients had developed epilepsy-induced pathology either during the pre/perinatal period (19 cases), or after a period of normal development (11 cases; onset range=20 months to 10 years). The patients were assessed at least 1 year post surgery on tests of receptive vocabulary, expressive and receptive grammar, instruction comprehension, and semantic association. Measures of verbal and nonverbal intelligence, short-term verbal memory, and working memory were also obtained. Principal component analysis revealed that two core components could be extracted from the five language measures, one reflecting receptive vocabulary abilities, and the other a composite of the other four measures. Regression analyses revealed that the best predictor of the composite language score was the short-term verbal memory score with some contribution from verbal intelligence, while the only predictor of receptive vocabulary was verbal intelligence. The results suggest that during childhood the lone left and right hemispheres have a similar potential for developing an adequate level of receptive vocabulary. However, congenital pathology affecting either hemisphere, and postnatal damage to the left hemisphere result in substantial language deficits that are reflected also in limitations in short-term verbal memory, and, to a lesser extent, in verbal intelligence.

Speaking with a single cerebral hemisphere: fMRI language organization after hemispherectomy in childhood

Speech-related fMRI activation was examined in six hemispherectomy patients (three left LX, three right RX, four with congenital and two with late-acquired hemiplegia) operated in childhood for the relief of drug-resistant epilepsy. Although the temporal and sensorimotor pattern of activation was similar to that found in neurologically intact control participants, activation in Broca’s area and its right homolog varied greatly. Involvement of pars triangularis and orbitalis was found in the three cases with best outcome (two RX, one LX), whereas pars opercularis alone was activated in the two remaining LX patients. The results suggest that distinct subregions of Broca’s area and their right homologs can subserve speech and language, and that this variability may determine functional outcome.

Visual functions without the occipital lobe or after cerebral hemispherectomy in infancy

This paper investigates whether and to what extent vision with awareness is still possible in the whole visual field after loss of the occipital lobe of one or both cerebral hemispheres or after hemispherectomy in childhood. The visual functions of four children who suffered from unilateral or bilateral loss of the occipital lobe or who had been hemispherectomized were examined. The results show that even after unilateral loss of the striate and prestriate cortex the extent of the visual field may still be in the normal range. The residual visual functions may be mediated by intact extrastriate areas such as V5 and LO of the damaged cerebral hemisphere. It is also shown that even after complete hemispherectomy in early life the visual field may have a normal extent and that conscious visual perception in the whole visual field may be preserved. In hemispherectomized children, the remaining cerebral hemisphere or neural structures in the midbrain, including the superior colliculi and the praetectum, may be able to mediate these visual functions.

Superficial Siderosis of the Central Nervous System

The clinical and necropsy findings are described in nine cases of superficial siderosis of the central nervous system. Four of these had undergone cerebral hemispherectomy in childhood. All four showed multiple haemorrhagic spots in the cavity membrane and the walls of the remaining lateral ventricle. Of the other cases, to had repeated ruptures of cerebral aneurysms; one showed a destructive lesion of the cerebellar vermis; one, a hydrocephalic child, showed evidence of repeated haemorrhage in the area of a malformed aqueduct; and the last, a baby, had bilateral subdural haematomata.

Superficial siderosis of the central nervous system. A report on nine cases with autopsy.

The clinical and necropsy findings are described in nine cases of superficial siderosis of the central nervous system. Four of these had undergone cerebral hemispherectomy in childhood. All four showed multiple haemorrhagic spots in the cavity membrane and the walls of the remaining lateral ventricle. Of the other cases, to had repeated ruptures of cerebral aneurysms; one showed a destructive lesion of the cerebellar vermis; one, a hydrocephalic child, showed evidence of repeated haemorrhage in the area of a malformed aqueduct; and the last, a baby, had bilateral subdural haematomata. From the histological similarities of these cases and previously reported ones, and from the reported findings in experimental animals, it is argued that the common cause of superficial siderosis is recurrent intraventricular or subarachnoid haemorrhage.