Skull asymmetries bear no relation to the occurrence of apraxia. A clinical and CT-scan study in patients with unilateral brain damage

This study aimed at assessing whether there was a relation between presence or absence of apraxia following a parietal and/or frontal left hemisphere lesion and "typical" skull asymmetries, evidenced by CT scan (prevalence of the left over the right occipital length and width and of the right over the left frontal length and width). Skull asymmetries were measured in a sample of 160 brain-damaged patients and their prevalence was found to agree with those reported by the literature in normal subjects. A subgroup of 72 patients with lesions restricted to the parietal and/or frontal lobe were given a movement imitation test and diagnosed as apraxic, borderline or normal making reference to the performance of 150 control subjects. The incidence in these three groups of typical or atypical occipital and frontal asymmetries was assessed and found not to differ significantly. It is concluded that no consistent relation between hemisphere dominance for praxis and skull asymmetry can be asserted. The study also investigated the relation of idemotor apraxia to the locus of left hemisphere damage and confirmed that both the incidence and the severity of the disorder are much greater following parietal than frontal lesions.     

脑卒中后抑郁与部位的相关性研究

目的：探讨急性期脑卒中患者影像学改变在脑卒中后抑郁（PSD）患者中的相关性和临床意义,期望早期发现PSD患者并为及时干预提供帮助。方法：对329例急性脑卒中后1个月内患者采用系统的神经心理评估和MRI检查。所有患者均常规行汉密尔顿抑郁量表（HAMD）评分,根据头颅MRJ结果分析病变部位。结果：PSD的发病率以左侧半球脑卒中患者明显高于双侧和右侧半球脑卒中患者,且左侧额叶和基底节尤为突出。不同病灶数目组间比较,PSD的发生率以多灶患者明显高于单灶患者（P〈0．01）。结论：急性脑卒中后PSD与病变部位在左侧半球尤其是左侧额叶、颞叶和基底节区具有显著相关性。完全前循环梗死也是易患PSD的危险因素。     

Application of a new image analysis technique to study brain asymmetry in schizophrenia

The hypothesis that normal brain torque (i.e. rightward frontal and leftward occipital asymmetry) is anomalous in schizophrenia (Crow, 1997. Trends in Neuroscience, 20, 339-343) was tested by application of a novel image analysis technique on three-dimensional magnetic resonance images obtained in 26 adult patients with chronic schizophrenia (18 males, 8 females) and 24 controls (14 males, 10 females). Right and left cerebral hemisphere tissue was extracted via non-linear co-registration with a mask image, and maps were computed of inter-hemispheric differences in tissue volume in an array of columns of voxels orthogonal to the mid-plane (2D), and profiles of coronal slice volumes (1D). Furthermore, integration of two-dimensional column maps gave approximate lobar asymmetries, and occipital and frontal asymmetries were combined to give a volumetric measure of brain torque. Significant brain torque was revealed in male and female control and patient groups, and did not correlate with brain size. Frontal and occipital asymmetries were significantly correlated in all groups. Both frontal and occipital components of torque were significantly increased in males than females. Patients tended to have reduced torque, particularly the leftward occipital component. Furthermore, 3/26 patients (but no controls) had reversed torque (leftward frontal and rightward occipital asymmetry). Contrary to Crow's hypothesis, brain torque was not significantly reduced in patients with schizophrenia relative to controls, although reversal of torque was found in three cases. Future studies with larger sample sizes should consider sexual dimorphism and specific symptoms in relation to asymmetry.     

Comparison of mania and depression after brain injury: causal factors

Patients who developed secondary mania after brain injury (N = 17) had a significantly greater frequency of injury to right hemisphere areas connected with the limbic system than poststroke patients with major depression (N = 31), who had injury primarily in the left frontal cortex and basal ganglia. For patients without mood disturbance after brain injury (N = 28), the location of the lesion was not significant. Secondary mania patients also had a significantly greater frequency of family history of affective disorder than did the other two groups. These results suggest that an interaction between injury to certain areas of the right hemisphere and genetic factors or other neuropathological conditions produces secondary mania.     

Etiological mechanisms of post-stroke depression: a review

Abstract

Post-stroke depression (PSD) has become a prominent negative factor of stroke recovery. Different etiological mechanisms may be involved, and there forms two major hypotheses: biological hypothesis and psychological hypothesis. Biological hypothesis included four mechanisms: lesion location mechanism, neurotransmitters mechanism, inflammatory cytokines mechanism and gene polymorphism mechanism. As for lesion location, the specific location of a lesion (e.g., basal ganglia or left frontal lobe lesions) played an important role in the etiology of PSD. For neurotransmitters, decreased serotonin and norepinephrine in the brain were associated with PSD. In inflammatory cytokines, increased cytokines [including interleukin (IL) 1β, IL-18, tumor necrosis factor α] after stroke lead to depression. For gene polymorphism, there was significant association between serotonin transporter gene-linked promoter region short variant genotype and post-stroke major depression. Psychological hypothesis suggested that social and psychological stressors associated with stroke may be the primary cause of depression. Up to now, there is no definitive evidence to support or refute either a solely biological or solely psychosocial mechanism. It appears to be a kind of biopsychosocial multifactorial mental illness.     

Volumetric asymmetries in late-onset mood disorders: an attenuation of frontal asymmetry with depression severity

The purpose of the study was to examine global and regional volumetric asymmetries in patients with late-onset mood disorders and non-depressed control subjects. Our sample comprised 34 patients with late-onset major depression, 18 patients diagnosed with late-onset minor depression and 30 control subjects. All subjects were scanned using a 1.5 Tesla GE Scanner, and quantitative estimates of global and focal brain volumes were obtained. Control subjects and patients displayed significant right-left volumetric differences across several regions, with right-sided regions being larger than the left. In the frontal lobes, the asymmetry differed significantly in the three groups (P=0.02). It was most pronounced in the control group and decreased significantly in the minor and major depression groups. There was a significant trend (P=0.005) in the magnitude of frontal asymmetry across groups, with the frontal asymmetry decreasing with increasing severity of depression. Hemispheric and temporal asymmetries were comparable in all three groups. These data suggest that an attenuation of the 'normal' volumetric asymmetry in the frontal regions may provide a structural basis to late-onset mood disorders     

Structural and functional brain asymmetries in human situs inversus totalis.

OBJECTIVE: To determine whether individuals with situs inversus totalis (SI), a condition in which there is a mirror-image reversal of asymmetric visceral organs, have alterations in brain asymmetries. BACKGROUND: The human brain is asymmetric in structure and function. Although correlations between anatomic asymmetries and functional lateralization in human brain have been demonstrated, it has been difficult to further analyze them. Characterization of asymmetries of brain structure and function in SI might advance the understanding of these relationships. METHODS: Using anatomic and functional MRI techniques, we analyzed asymmetries in the brains of three individuals with SI. RESULTS: Two major anatomic asymmetries of the cerebral hemispheres, the frontal and occipital petalia, were reversed in individuals with SI. In contrast, SI subjects had left cerebral hemisphere language dominance on functional MRI analysis as well as strong right-handedness. CONCLUSION: These observations suggest that the developmental factors determining anatomic asymmetry of the cerebral petalia and viscera are distinct from those producing the functional lateralization of language.     

Post-stroke affective or apathetic depression and lesion location: left frontal lobe and bilateral basal ganglia

This study was designed to examine the correlation between damage to the basal ganglia or frontal lobe and depression status (both affective and apathetic dimensions) in 243 stroke patients. We assessed the affective dimension in post-stroke depression (PSD) using the Zung Self-rating Depression Scale (SDS) and the apathetic dimension in PSD using the apathy scale (AS). We classified basal ganglia or frontal lobe damage into four groups: no damage, damage to the left side only, damage to the right side only, and damage to both sides. Affective and/or apathetic PSD was found in 126 patients (51.9%). The severity of affective depression (SDS score) was associated with left frontal lobe (but not basal ganglia) damage, and that of apathetic depression (AS score) was related to damage to the bilateral basal ganglia (but not to the frontal lobe). The anatomical correlates of PSD differ depending on the PSD dimension (affective or apathetic) and may explain interstudy differences regarding the association between lesion location and type of PSD.     

Impact of a unilateral brain lesion on cortisol secretion and emotional state: anterior/posterior dissociation in humans

The main goal of this study was to evaluate whether a unilateral brain lesion in a human population is associated with a modification of the circadian cortisol secretion profile, and/or patient's emotional state. The second goal of this study was to assess whether there would be differences in both the pattern of cortisol secretion and emotional state in brain-damaged patients as a function of side of lesion, and localization (anterior vs posterior) of lesion. Eight patients with a left cortical lesion, six patients with a right cortical lesion, four patients with basal ganglia lesions (2 left and 2 right) and ten healthy volunteers were evaluated daily on measures of salivary cortisol levels and subjective feelings of joy and sadness at 0700, 1200, 1600 and 1900 hours over a 15-day period. Patients with cortical brain lesions presented higher cortisol levels and higher scores of sadness at the time of the morning peak (7:00 am), when compared to healthy volunteers and patients with basal ganglia lesions. Laterality of the lesion was not related to cortisol secretion, but frontal damage (anterior lesion) was associated with higher cortisol levels at the time of the morning peak (7:00 am) when compared to more posterior damage. There was no significant correlation between basal circulating levels of cortisol and emotional states in patients and healthy subjects. The results of this study suggest that hypothalamic-pituitary-adrenal (HPA) axis dysregulation is associated with unilateral injury particularly in frontal areas. These results, obtained in a human population, go along with recent animal studies reporting an implication of frontal regions in HPA activity.     

Cerebral hemisphere asymmetry in CT and functional recovery from hemiplegia

Cerebral hemispheric asymmetries were assessed in relation to motor and functional recovery in nine patients with stroke. All were globally aphasic, assuring similar location and extent of lesion. Initial motor and functional ability were appraised from medical records and compared with neurologic and functional outcome. Frontal and occipital hemispheric widths and lengths were determined from CT. Patients were classified into three groups on the basis of mean combined asymmetry for width (typical asymmetry, atypical asymmetry, and equal symmetry). Patients with the most atypical cerebral asymmetries showed greater recovery than patients in other groups. Two patients with atypical mean occipital asymmetry (width) fared best functionally, whereas the patient who showed the greatest motor recovery had the most atypical mean occipital asymmetry (width). Cerebral asymmetries may contribute to recovery after stroke.     

Schizophrenia: evidence of a subgroup with reversed cerebral asymmetry.

Normal right-handed individuals often show neuroanatomical asymmetries of the brain on computed tomography (CT), with wider right frontal and left occipital lobes. We examined the frequency of reversals of this normal asymmetry in a group of 57 right-handed, the schizophrenic patients. Compared to 80 normal right-handeders, the schizophrenics had an increased frequency of both frontal and occipital reversals. We then divided the patients on the basis of whether they had CT evidence suggestive of brain atrophy. Those without evidence of atropy had increased frontal and occipital reversals. Those with evidence of atrophy had no increase in reversals. This suggests that reversals of neuroanatomical asymmetry, and by implication abnormalities of lateralization, are relevant to a subgroup of schizophrenic patients with otherwise normal CT scans.     

Depression in patients with acute traumatic brain injury.

OBJECTIVE: This study was undertaken to examine patients with closed head injuries for the presence of depressive disorders. METHOD: A consecutive series of 66 patients with closed head injuries but no significant spinal cord or other organ system injury were examined by means of a semistructured psychiatric interview. The Hamilton Rating Scale for Depression as well as scales measuring impairment in activities of daily living, intellectual functioning, and social functioning were administered. The patients' CT scans were also examined. RESULTS: Seventeen patients had major depression and two had minor depression. The presence of left dorsolateral frontal lesions and/or left basal ganglia lesions and, to a lesser extent, parietal-occipital and right hemisphere lesions was associated with an increased probability of developing major depression. Compared to the nondepressed group, the group with major depression had a higher frequency of previous psychiatric disorder and showed evidence of poorer social functioning. CONCLUSIONS: Major depression occurs in about one-quarter of patients after traumatic brain injury. This is the same frequency as in other major disorders such as stroke. Major depression appears to be provoked by one or more factors that include poor premorbid social functioning and previous psychiatric disorder or injury to certain critical brain locations.     

Psychiatric profiles and patterns of cerebral blood flow in focal epilepsy: interactions between depression, obsessionality, and perfusion related to the laterality of the epilepsy.

OBJECTIVES: In a study of patients with focal epilepsy the hypothesis was explored that different measurements of psychopathology are related to specific distributions of cerebral perfusion. METHODS: Forty patients had SPECT performed with (99m)Tc-HMPAO. In addition, patients received a psychiatric evaluation with the following psychiatric questionnaires: the Beck depression inventory, the Leyton obsessionality inventory, the Bear-Fedio questionnaire, and the social stress and support interview. Patients were analysed in two groups according to the laterality of the epilepsy. Nine patients were excluded based on poor quality scans (n = 1), unlateralised epilepsy (n = 4), and left or ambidextrous handedness (n = 4). RESULTS: There were no overall differences between the left and right epilepsy groups on measures of psychopathology. Associations were found between scores on some of the rating scales and regional cerebral blood flow. Specifically, for patients with left sided epilepsy, higher scores on the Beck depression inventory were associated with lower contralateral temporal and bilateral frontal perfusion, and higher occipital perfusion. For patients with right sided epilepsy higher scores on the Leyton obsessionality inventory were associated with increased perfusion in ipsilateral temporal, thalamic, and basal ganglia regions and bilateral frontal regions. CONCLUSION: The results do not support the notion that lateralised epileptogenic lesions are associated with different levels of depression, obsessionality, or personality traits. They support the view that certain psychopathological symptom patterns are related to specific regional dysfunctions depending on the laterality of a hemispheric lesion.     

PET in generalized anxiety disorder

Positron emission tomography (PET) measurements of cerebral glucose use were made in 18 patients with generalized anxiety disorder (GAD) during a passive viewing task off medication, and an active vigilance viewing task before and after medication or placebo treatment. In the passive viewing task, patients with GAD were compared with 15 normal controls. A significant difference in pattern of absolute brain metabolism was found. Patients showed lower absolute metabolic rates in basal ganglia and white matter. Relative metabolism was increased in the left inferior area 17 in the occipital lobe, right posterior temporal lobe, and the right precentral frontal gyrus. Significant left-right asymmetry of the parahippocampal gyri was not found in patients with GAD. An active vigilance task resulted in activation of relative basal ganglia metabolism in patients. Benzodiazepine therapy resulted in decreases in absolute metabolic rates for cortical surface, limbic system, and basal ganglia and was not associated with normalization of patterns of glucose metabolism. Change in anxiety scores was significantly correlated with change in limbic system and basal ganglia for the placebo group. The normal-anxious difference in the basal ganglia and the change seen in this region after benzodiazepine treatment are suggestive of a role in anxiety for this structure.     

A volumetric study of MRI signal hyperintensities in late-life depression.

OBJECTIVE: An increase in white-matter lesions has been previously described in older subjects with depression. The authors investigated whether the regional location varied between depressed and normal subjects and determined the relationship of magnetic resonance (MR) signal hyperintensities to known clinical risk factors for vascular disease. METHODS: Authors used automated image-processing software to determine volumes of signal hyperintensities from MR brain scans of older people with depression (N=29; mean age: 76 years) and normal subjects of similar age (N=32). RESULTS: Overall, subjects with depression had a significantly greater frontal-lobe white-matter lesion volume than normal subjects (0.35% versus 0.22%). However, after excluding subjects with hypertension, diabetes, or ischemic heart disease (leaving 14 depressed and 15 normal subjects), we found even greater differences between groups, with a larger volume of MR signal hyperintensities in the frontal region of the depressed group, but no difference in the basal ganglia or parietal and occipital lobes. CONCLUSION: The results support the "vascular depression" hypothesis and suggest that those with depression but without traditional vascular risk factors may be much more susceptible to cerebrovascular disease than normal subjects. The mechanisms for this increased susceptibility remain to be determined.     

Frontostriatal deficits in unipolar major depression

Recent accounts of major depression have tended to focus on dysfunction of frontothalamic-striatal reentrant circuits as a possible source of the disorder. Evidence of frontostriatal involvement in unipolar major depression from lesion and neuropsychological studies, and functional and structural imaging studies is examined. The high incidence of depressive symptomatology following left frontal and basal ganglia lesions implicate these as possible sites of dysfunction. Neuropsychological evidence indicates similar deficits in patients with major depression, perhaps with dorsolateral prefrontal deficits most prominent. Structural imaging studies report frontal and basal ganglia (BG) abnormalities particularly in cases of late-age onset depression. Resting state functional imaging studies show deficits in dorsolateral, anterior cingulate (medial frontal), and BG structures. Activation imaging studies show less consistent evidence of dorsolateral deficit, while anterior cingulate deficit is more consistently demonstrated. Variability in findings across studies may reflect differences between subtypes of depression and differences in methodology. Possible involvement of the BG in the psychomotor retardation of depression is examined. It is concluded that, while there is evidence of frontostriatal deficit in major depression, the exact nature of such deficits is uncertain. Issues such as component vs. system dysfunction need to be addressed.     

Depression in secondary epilepsy: relation to lesion laterality.

Patients with epilepsy often have depressive disorders. This association may be particularly prominent in secondary epilepsy from a left hemisphere lesion. Among 1611 outpatients with epilepsy 272 patients were identified whose seizures originated from a structural brain lesion other than mesial temporal sclerosis. Sustained depressive disorders had occurred in 25 (9%) of these patients with secondary epilepsy. The depressed patients were compared with the remaining patients without depression with regard to location of lesion laterality and seizure variables. The only group difference was unilateral left hemisphere lesions in 58% of the patients with depression compared with only 21% of the non-depressed patients (chi 2 = 10.4, p = 0.006). This finding supports the idea of a relation of depression with epileptogenic lesions in the left hemisphere.     

Age-associated sex and asymmetry differentiation in hemispheric and lobar cortical ribbon complexity across adulthood: A UK Biobank imaging study

Cortical morphology changes with ageing and age-related neurodegenerative diseases. Previous studies suggest that the age effect is more pronounced in the frontal lobe. However, our knowledge of structural complexity changes in male and female brains is still limited. We measured cortical ribbon complexity through fractal dimension (FD) analysis at the hemisphere and lobe level in 7010 individuals from the UK Biobank imaging cohort to study age-related sex differences (3332 males, age ranged 45–79 years). FD decreases significantly with age and sexual dimorphism exists. With correction for brain size, females showed higher complexity in the left hemisphere and left and right parietal lobes whereas males showed higher complexity in the right temporal and left and right occipital lobes. A nonlinear age effect was observed in the left and right frontal, and right temporal lobes. Differential patterns of age effects were observed in both sexes with relatively more age-affected regions in males. Significantly higher rightward asymmetries at hemisphere, frontal, parietal, and occipital lobe level and higher leftward asymmetry in temporal lobe were observed. There was no age-by-sex-by asymmetry interaction in any region. When controlling for brain size, the leftward hemispheric, and temporal lobe asymmetry decreased with age. Males had significantly lower asymmetry between hemispheres and higher asymmetry in the parietal and occipital lobes than females. This work provides distinct patterns of age-related sex and asymmetry differences that can aid in the future development of sex-specific models of the normal brain to ascribe cognitive functional significance of these patterns in ageing.     

抑郁症患者局部脑血流的研究

目的：了解抑郁症患者局部脑血流灌注的特点：方法：应用单光子发射计算机断层扫描对20例抑郁症患者及18例正常对照者局部脑血流灌注进行对比分析。结果：抑郁症组双侧基底核、双侧额叶、左颞叶及左枕叶局部血流低灌注；抑郁症组与对照组左右大脑半球局部血流灌注无显著性差异：结论：抑郁症患者局部脑血流存在低灌注，但未发现局部脑血流低灌注有侧化现象。     

Language organization in patients with early and late left-hemisphere lesion: a PET study.

Functional neuroimaging studies have shown enhanced right-hemisphere language activations in adults with left-hemisphere damage. We hypothesized that this effect would be stronger in patients with lesion occurring early in development. Using [15O]-water PET, we studied eight normal adults and 23 patients with unilateral left lesion during rest, listening to sentences, and sentence repetition. Thirteen patients had lesions with early onset (< 5 years) and ten had lesions with late onset (> 20 years). For listening to sentences, frontotemporal blood flow increases were significantly stronger in the left than in the right hemisphere in normal adults. This normal asymmetry was reduced in patients with late lesion and reversed in those with early lesion. For sentence repetition, analogous group differences were significant for the basal ganglia, but failed to reach significance for the (pre)motor and insular regions. We conclude that left lesion leads to alterations in the asymmetry of language activations (in and beyond the perisylvian areas). In addition, rightward shifts of language activation tend to be stronger as a consequence of early (as compared to late) lesion. Finally, postlesional reorganization appears to reflect a coexistence of 'additive' and 'subtractive' effects, i.e., activation in some regions that are not normally involved in language processing and lack of activation in other (undamaged) regions that are normally activated by language tasks.