Effect of lateralized lesions on ipsilateral and contralateral motor functioning

Abstract

The present study investigated the effect of lesions principally involving the left or right cerebral hemisphere upon measures of grip strength and finger tapping speed. The purpose was to determine whether ipsilateral and contralateral motor deficits were more frequently associated with lesions of the right or left cerebral hemispheres in patients with cerebral vascular, traumatic, or neoplastic damage. Groups of subjects with right hemisphere (n = 45) and left hemisphere (n = 45) damage were composed solely on the basis of detailed neurological records. Each group consisted of 15 subjects with vascular, traumatic, or neoplastic lesions. The results indicated that neither lesions of the left nor right cerebral hemisphere were pre-eminent in producing ipsilateral or contralateral motor deficits. The significant differences found were interpreted as reflecting the hand preference of the patients.     

American College of Surgeons: Southern California Chapter Neurosurgical Section

Abstract

The strategy for treating arteriovenous malformations (AVMs) has undergone changes and long-term follow-up results remain unclear. To compare the outcomes of different treatment strategies, we divided 112 patients with 113 AVMs into groups with hemorrhagic (n = 71, 62.8%) and nonhemorrhagic (n = 42, 37.2%) AVMs and subdivided these according to the period in which they were treated (before/after 1990). In the more recent period, treatment more frequently involved the use of the γ-knife and microembolization to the AVM as well as combination therapy. Long-term follow-up showed that the complication rate was lower and the Rankin scale better, in the more recently treated group. Based on our findings we suggest that AVMs should be treated aggressively using a multimodality strategy.     

Language lateralization in temporal lobe epilepsy: a comparison between fMRI and the Wada Test

PURPOSE: Recent studies have claimed that language functional magnetic resonance imaging (fMRI) can identify language lateralization in patients with temporal lobe epilepsy (TLE) and that fMRI-based findings are highly concordant with the conventional assessment procedure of speech dominance, the intracarotid amobarbital test (IAT). METHODS: To establish the power of language fMRI to detect language lateralization during presurgical assessment, we compared the findings of a semantic decision paradigm with the results of a standard IAT in 68 patients with chronic intractable right and left temporal lobe epilepsy (rTLE, n=28; lTLE, n=40) who consecutively underwent a presurgical evaluation program. The patient group also included 14 (20.6%) subjects with atypical (bilateral or right hemisphere) speech. Four raters used a visual analysis procedure to determine the laterality of speech-related activation individually for each patient. RESULTS: Overall congruence between fMRI-based laterality and the laterality quotient of the IAT was 89.3% in rTLE and 72.5% in lTLE patients. Concordance was best in rTLE patients with left speech. In lTLE patients, language fMRI identified atypical, right hemisphere speech dominance in every case, but missed left hemisphere speech dominance in 17.2%. Frontal activations had higher concordance with the IAT than did activations in temporoparietal or combined regions of interest (ROIs). Because of methodologic problems, recognition of bilateral speech was difficult. CONCLUSIONS: These data provide evidence that language fMRI as used in the present study has limited correlation with the IAT, especially in patients with lTLE and with mixed speech dominance. Further refinements regarding the paradigms and analysis procedures will be needed to improve the contribution of language fMRI for presurgical assessment.     

Predicting hemispheric dominance for language production in healthy individuals using support vector machine

We used a Support Vector Machine (SVM) classifier to assess hemispheric pattern of language dominance of 47 individuals categorized as non‐typical for language from their hemispheric functional laterality index (HFLI) measured on a sentence minus word‐list production fMRI‐BOLD contrast map. The SVM classifier was trained at discriminating between Dominant and Non‐Dominant hemispheric language production activation pattern on a group of 250 participants previously identified as Typicals (HFLI strongly leftward). Then, SVM was applied to each hemispheric language activation pattern of 47 non‐typical individuals. The results showed that at least one hemisphere (left or right) was found to be Dominant in every, except 3 individuals, indicating that the “dominant” type of functional organization is the most frequent in non‐typicals. Specifically, left hemisphere dominance was predicted in all non‐typical right‐handers (RH) and in 57.4% of non‐typical left‐handers (LH). When both hemisphere classifications were jointly considered, four types of brain patterns were observed. The most often predicted pattern (51%) was left‐dominant (Dominant left‐hemisphere and Non‐Dominant right‐hemisphere), followed by right‐dominant (23%, Dominant right‐hemisphere and Non‐Dominant left‐hemisphere) and co‐dominant (19%, 2 Dominant hemispheres) patterns. Co‐non‐dominant was rare (6%, 2 Non‐Dominant hemispheres), but was normal variants of hemispheric specialization. In RH, only left‐dominant (72%) and co‐dominant patterns were detected, while for LH, all types were found, although with different occurrences. Among the 10 LH with a strong rightward HFLI, 8 had a right‐dominant brain pattern. Whole‐brain analysis of the right‐dominant pattern group confirmed that it exhibited a functional organization strictly mirroring that of left‐dominant pattern group. Hum Brain Mapp 38:5871–5889, 2017. © 2017 Wiley Periodicals, Inc.     

Lateral preferences and cerebral speech dominance

Four types of lateral preference (hand, foot, eye, ear) were measured in 73 patients, who underwent sodium Amytal speech testing. In 63 cases, speech was on the left side whereas in 10, speech was on the right. All of the patients with right hemisphere lesions had speech represented in the left hemisphere. Only a third of the patients with left hemisphere damage prior to the end of the first year of life continued to have speech on the left side. By contrast, 82% of those with left hemisphere damage after this sensitive period had speech exclusively mediated by the left hemisphere. In short, the occurrence of right hemisphere speech dominance without an early lesion to the left hemisphere is rare. The majority of patients with right-sided motor and sense organ preferences had speech represented in the left hemisphere, independent of location or age of onset of the damage. By contrast, in individuals with a clinical history of early left hemisphere injury, left-sided motor and sense organ preferences were linked to right hemisphere speech dominance. In those cases without evidence of early cerebral damage, most of the non-right-sided individuals had speech in the left hemisphere. However, the proportion of unilateral, left hemisphere speech representation in the right-handed and right-footed was higher than that observed in the left-handed and left-footed, even when those with early onset of damage were excluded from analysis. It was suggested that in the normal population, handedness and footedness are relevant factors in predicting cerebral speech dominance. Knowledge of eye and ear preference may be of little predictive value. Further, in a neurological population the overall congruency across the four patterns of lateral preference may provide useful information regarding cerebral speech dominance. A small group (5) of patients with bilateral representation of speech was also examined. Contrary to the experience at the Montreal Neurological Institute, most of these patients preferred the right limb and sense organ. Differences in investigative approach may account for the conflicting observations.     

Differential effects of early hemisphere damage on lexical comprehension and production

Abstract

The effects of early hemisphere damage on lexical development were investigated in 33 children with unilateral left (n = 21) or right (n = 12) hemisphere damage and 16 normal healthy controls. Single-word naming was assessed using the Expressive One-Word Picture Vocabulary Test (EOW) and lexical comprehension was assessed using the Peabody Picture Vocabulary Test-Revised (PPVT-R). Left lesion subjects (LL) performed comparable to controls in naming, but scored lower than controls on the PPVT-R. Right lesion subjects (RL) scored lower than controls and LL subjects on both the EOW and the PPVT-R. The unexpected superiority of LL in comparison to RL children on the EOW and the PPVT-R argues against a simple left hemisphere dominance for early lexical development. RL subjects' significant comprehension deficits failed to correlate with more general measures of verbal intelligence, supporting a specialized role of the right hemisphere in mediating the acquisition of word meaning.     

Cortical stimulation mapping and Wada results demonstrate a normal variant of right hemisphere language organization

Purpose: Exclusive right hemisphere language lateralization is rarely observed in the Wada angiography results of epilepsy surgery patients. Cortical stimulation mapping (CSM) is infrequently performed in such patients, as most undergo nondominant left hemisphere resections, which are presumed not to pose any risk to language. Early language reorganization is typically assumed in such individuals, taking left hemisphere epileptiform activity as confirmation of change resulting from a pathologic process. We present data from CSM and Wada studies demonstrating that right hemisphere language occurs in the absence of left hemisphere pathology, suggesting it can exist as a normal, but rare variant, in some individuals. Furthermore, these data confirm the Wada test findings of atypical dominance. Methods: Cortical stimulation mapping data were examined for all right hemisphere surgical patients with right hemisphere speech at our center between 1974 and 2006. Of 1,209 interpretable Wada procedures, 89 patients (7.4%) had exclusive right hemisphere speech, and 21 (1.7%) of these patients underwent surgery involving the right hemisphere. Language site location was determined by examining intraoperative photographs, and site distribution was statistically compared to published findings from left hemisphere language dominant patients. Key Findings: Language cortex was identified in the right hemisphere during CSM for all patients with available data. All sites could be classified in superior or middle temporal gyri, inferior parietal lobe, or inferior frontal gyrus, all of which were common zones where language was identified in the left hemisphere dominant comparison sample. Significance: Results suggest that the Wada procedure is a valid measure for identifying right hemisphere language processing without any false lateralization found in the patients mapped with CSM (i.e., a positive Wada is 100% sensitive for finding right hemisphere language sites), and that the distribution of language sites is consistent across right hemisphere and left hemisphere language dominant patients, supporting the theory that right hemisphere language can occur as a normal variant of language lateralization.     

Cutaneous Venous Malformations Related to KRIT1 Mutation: Case Report and Literature Review

Cavernous malformations (CMs) are vascular anomalies of the nervous system mostly located in the brain. Cerebral cavernous malformations can present sporadically or familial, as a consequence of an autosomal dominant condition, with incomplete penetrance and variable clinical expression. Occasionally, extraneural manifestations of CMs involving the skin have been described. We report the case of two siblings presenting in adulthood diffuse cutaneous vascular lesions associated with cerebral CMs that, after surgical excision and histopathologic analysis, resulted to cavernous haemangiomas. Genomic DNA was extracted from peripheral blood, and molecular evaluation of KRIT1 gene was performed. Although no signs of neurological impairment were reported, cerebral MRI revealed multiple images in both patients, suggestive of cavernous haemangiomas. The genetic study demonstrated a nonsense mutation (c.535C>T) in the KRIT1 (Krev-1/rap1 interaction trapped 1) gene. Few reports describe extraneural manifestations of Cavernous malformation syndrome (CMs) related to a KRIT1 mutation; these involve the skin and are associated with hyperkeratotic cutaneous capillary–venous malformation. CMs should be suspected in patients developing multiple nodular cutaneous venous lesions in adulthood.     

Hemispheric mechanisms of motor speech

Abstract

A perceptual rating scale was used to evaluate the articulatory impairment of patients with suprabulbar, vascular lesions of the right (RHD, 35 patients) or the left (LHD, 35 patients) hemisphere. Both groups were matched for age, time elapsed since onset, lesion volume and lesion location. The amount and type of motor speech impairment differed significantly, resulting in hemispheric profiles of articulation. Slurring and rate reduction were the prominent features of left hemisphere dysarthria and dysprosody of the right. Verbal apraxia was found in six patients of the LHD group. Intrahemispheric correlations between dysarthria, lesion volume, and several hemispheric variables (orofacial apraxia, aphasia severity and visuospatial functions) did not exceed the 0–6 level. Most lesions causing hemispheric dysarthria were located in the basal ganglia, the cortical sensorimotor and opercular region. The observed lesion distribution and speech patterns implicate distinct hemispheric mechanisms of motor speech: bilateral control is suggested for basic motor speech functions, whereas supramodal and spatio-temporal planning mechanisms are hemisphere specific. Perceptual dysarthria rating is a valuable clinical method to differentiate motor speech impairment.     

Interpretation of outcome on dichotic listening tests following stroke

Abstract

The historical basis for interpretation of the dichotic listening performance of aphasic patients is presented. Most studies agree with respect to outcome; aphasic patients as a group tend to have ear advantages (EAs) that are shifted to the left relative to non-brain-damaged listeners. Studies disagree as to whether this difference reflects a shift toward right hemisphere dominance for language processing or a “contralateral ear lesion effect.” Emphasis is placed on the most recent additions to the literature, including discussion of factors that affect the accuracy with which lesions can be localized. The conclusion reached is that variables other than dominance determine the direction of ear advantage for many aphasic listeners.     

Transcortical motor aphasia due to a right hemisphere lesion in a right-handed man

Abstract

A 67-year-old, right-handed male became aphasic following a right hemispheric infarction involving the frontal and parietal regions. The patient was evaluated by means of neurological, behavioural, and neuroradiological examinations. Behavioural investigations included Ianguage and nonverbal visuospatial and constructive evaluations. Language evaluation demonstrated transcortical motor aphasia and nonverbal tests showed left-sided visual neglect, left hemiakinesia, and constructional apraxia. Besides the information concerning crossed aphasia in a right-handed person, this case also supports the hypothesis that right-sided language representation does not affect right hemisphere dominance for visuospatial abilities.     

Atypical hemispheric language dominance in left temporal lobe epilepsy as a result of the reorganization of language functions

Hemispheric language dominance, as determined by intracarotid short-acting barbiturate injections (Wada testing), was retrospectively evaluated in 44 right-handed patients with medically intractable left (n=26) or right (n=18) temporal lobe epilepsy (TLE). Atypical hemispheric language dominance (right or bilateral) was revealed in 13.6% of all patients investigated. A significantly higher rate of deviance from complete left hemisphere dominance was observed in left TLE (23.1%) than in right TLE (0%). Patient age at the time of seizure onset was proven a critical variable affecting atypical speech development in left TLE. The mean patient age at the time of seizure onset in left TLE patients with atypical language representation was 5.61 years, but was 13.13 years in patients with left hemisphere language dominance. Our results strongly support the influential impact of epileptiform activity spreading from the left temporal lobe structures on the reorganization of language functions in patients with early brain injury.     

Localisation des centres du langage par l'analyse quantifiée de l'EEG (versus test de Wada) dans l'épilepsie temporale chez le droitier

Spectral analysis of the EEG alpha rhythm was studied in nine temporal epileptic right-handed patients in order to predict localization of the speech area. We studied the variation of the spectral power of the alpha rhythm during an activation paradigm previously validated in normal right-handed subjects. Significant alpha power decreases in the left hemisphere during writing with the right hand (as compared to resting) and/or significant alpha power decreases in the right hemisphere during left-hand recognition and classification of cardboard objects (as compared to resting) were considered as consistent with left-hemisphere dominance for language. The results of EEG spectral analysis were compared with those of the Wada test. The left hemisphere was dominant for language according to the Wada test in eight subjects and the right hemisphere in one subject. Six patients had a significant alpha power reduction in the hemisphere concerned during lateralized cognitive tasks, consistent with language localization in the left hemisphere according to the Wada test. The three remaining patients had no significant EEG spectral power variations. A significant decrease of alpha power in the active hemisphere during cerebral activation seems statistically related to left-hemispheric dominance for language in right-handed subjects (hemispheric specialization). However, the localization of the speech area using this electrophysiological method does not appear clinically relevant for a case-by-case decision in individual patients.     

Shift-back of right into left hemisphere language dominance after control of epileptic seizures: evidence for epilepsy driven functional cerebral organization

Atypical, i.e. right hemisphere language dominance is frequently observed in early onset left hemisphere epilepsies. In left mesial temporal lobe epilepsy, where eloquent cortex is not directly involved, it is a matter of debate, to which degree atypical language dominance is driven not only by morphological lesions but also by epileptic dysfunction, and whether atypical dominance is hardwired or not. Taking this as the background this study evaluated the hypothesis that epilepsy driven atypical dominancy might be reversible when seizures are successfully controlled. This was evaluated in patients with left mesial temporal lobe epilepsy, who were atypically language dominant by means of language fMRI before surgery, and became seizure free after left selective amygdalo-hippocampectomy. Three out of 53 consecutive atypically dominant patients with chronic epilepsy fulfilled these criteria. Postoperative follow-up language fMRI indicated reversal of right into left dominance in one patient going along with unexpected losses in verbal memory performance. The two other patients experienced unchanged or even enhancement of the pre-existing dominance pattern, going along with consistent postoperative performance changes in cognition. The data thus provide supporting evidence that atypical language dominance can indeed be functionally driven and moreover that in at least some patients, right hemispheric language can shift-back to the left hemisphere when the driving factor, i.e. seizures, becomes successfully controlled. The results have clinical implications for outcome prediction after brain surgery in atypically dominant patients with epilepsy. However, further research in larger groups of atypically dominant patients is required to identify the conditions under which atypical dominance becomes hardwired and when not.     

Brain SPECT imaging in transcortical aphasias: the functional status of the left perisylvian language cortex*

Single photon emission computerized tomography (SPECT) with 99mTc-HMPAO was used to examine the functional status of the left perisylvian language cortex (PLC) in eight patients with transcortical aphasias (TAs) due to cerebrovascular accidents. According to the lesion location within the left hemisphere, the aphasic patients were divided into two groups: (a) patients with corticosubcortical lesions involving portions or the whole PLC (perisylvian group, n = 4); (b) patients with corticosubcortical lesions sparing the PLC (extraperisylvian group, n = 4). Results showed that, as expected, the perisylvian group had significant decrements in regional cerebral blood flow (rCBF) in structurally damaged regions of the left PLC, although some morphologically spared regions of the left PLC (Wernicke's area) also had perfusion defects in one patient. Among the extraperisylvian group, there was structural and functional damage to the posterior association areas, but two patients additionally had significant decrements of rCBF in morphologically spared regions of the PLC (Wernicke's area, sensorimotor cortex, Broca's area). These findings demonstrate not only that the left PLC may be structurally and functionally damaged among patients with TAs, but additionally suggest a major contribution of the right hemisphere in the mediation of residual language repetition.     

Atypical language lateralization in epilepsy patients

Purpose:   To investigate whether atypical language dominance in epilepsy patients is related to localization and type of lesions.
Methods:   Four hundred and forty-five epilepsy patients received bilateral Wada testing. Language was classified as left (L), right (R), bilateral-dependent (BD, speech arrest after left and right injections), or bilateral-independent (BI, no speech arrest after either injection). Groups were compared regarding handedness and magnetic resonance imaging (MRI) lesions. Lesions were classified as "early" (congenital), "late" neocortical (acquired after birth), and hippocampal sclerosis (HS).
Results:   Of all patients, 78% were L, 6% R, 7% BD, and 9% BI. Right-handers with left lesions did not differ from those without lesions. Left-handers with normal MRI did not differ from right-handers. Left-handers with early left lesions were most likely R (46%). Left-handers with late neocortical left lesions were most likely BD (37%); those with left HS were most likely BD (33%) or L (33%). In both latter groups, R language was rare (13% and 11%, respectively).
Discussion:   The data support the notion that R dominance may indicate development of functional language areas in the right hemisphere following an early insult. BD language may signal defective maintenance of right hemispheric language caused by a late left hemispheric insult at a time when left dominance has already started to develop. In contrast, BI language may represent a variant with functional language representation in both hemispheres.     

Characterization of the integrin alpha v beta3 in arteriovenous malformations and cavernous malformations

BACKGROUND: Alpha V beta 3 (alphavbeta3) is an integrin specifically expressed on the endothelial cells of central nervous system (CNS) neoplasms. However, no data exist on the expression of alphavbeta3 in vascular malformations of the CNS. In this study, we investigate the expression of alphavbeta3 in arteriovenous malformations (AVMs) and cavernous malformations (CMs). METHOD: Frozen samples of AVMs from 12 patients and CMs from 5 patients were obtained intraoperatively. Once the final pathology had been confirmed, immunohistochemistry was performed using an antibody to the integrin alphavbeta3. The alphavbeta3 expression pattern was graded according to the percentage of positively staining vessels. RESULTS: Ten of 12 AVMs demonstrated alphavbeta3 immunopositivity. Six of these 10 AVMs had moderate or strong staining. Most notably, 5 of the 6 moderate or strongly staining AVMs came from patients 22 years of age or younger. Four of these 6 AVMs had previously been embolized. None of the cavernous malformations demonstrated alphavbeta3 immunopositivity. DISCUSSION: alphavbeta3 may contribute to the formation of AVMs in younger patients. alphavbeta3 may also provide a potential therapeutic target. The lack of alphavbeta3 expression in cavernous malformations, despite their high vascular densities, suggests that the pathophysiology of their formation differs from that of AVMs.     

血管内栓塞术在神经外科的应用

作者对两年多来收治的106例脑、脊髓AVMs、动脉瘤和供血丰富的头、颈、颌面部肿瘤,采用不同的血管内栓塞技术和栓塞材料,进行了153例次的栓塞治疗,取得了满意的效果。治疗结果表明,不同的病变宜采用相应的栓塞技术,有利于提高血管内栓塞治疗成功率。     

Mouth asymmetry during speech of epileptic patients who have undergone carotid amytal testing

Asymmetry in the opening of the two sides of the mouth during speech has been suggested as an observable correlate of lateralization of cerebral speech motor control. For 24 epileptic patients who suffered speech disturbance only during left hemisphere carotid amytal anesthetization, 22 showed the expected greater opening of the right side of the mouth during a repetition task. However, all four of the patients who suffered speech disturbance following only right hemisphere anesthetization, and 8 of the 11 "bilateral speech" patients, also showed greater opening of the right side of the mouth. The speech dominant patients may, however, have genetic left speech dominance but a pathology-forced shift of some components of language to the right hemisphere. Basic mouth asymmetry, as measured here, may primarily reflect lateralization of a component of the motor/speech/language control system that may not be shifted by pathology in epileptic patients sustaining early brain insult. Relative change in mouth asymmetry as the speech task becomes more demanding may, however, be a more sensitive indicator or cerebral asymmetries for language in pathological cases.