Crossed cerebellocerebral diaschisis in patients with cerebellar stroke

Cognitive impairment in essential tremor assessed by the cerebellar cognitive affective syndrome scale

Background

Essential tremor (ET) is a movement disorder characterized by cerebellar neurodegenerative changes. ET is also associated with non-motor symptoms including cognitive impairment. The neuropsychologic profile of a patient with ET could relate to cerebellar cognitive affective syndrome (CCAS).

Objective

This study aimed to assess the prevalence of cognitive impairment in patients with ET and identify whether the cognitive impairment in ET corresponds to a CCAS.

Methods

Cognitive functions were evaluated with the CCAS-Scale (CCAS-S) in 20 patients with ET and 20 controls matched for age, sex, and level of education. The results of the CCAS-S were compared between patients and controls. The underlying determinant of CCAS inpatients with ET was identified through the correlation between the results of the CCAS-S and age at onset of symptoms, disease duration, and the Essential Tremor Rating Assessment Scale (TETRAS).

Results

On a group level, ET patients performed significantly worse than matched controls. In total, 13 individuals with ET had a definite CCAS (CCAS-S failed items ≥ 3). ASO and TETRAS scores significantly correlated with CCAS-S performances in ET patients.

Conclusion

CCAS is highly prevalent in patients with ET which supports the cerebellar pathophysiology of associated cognitive impairment and supports a more systematic use of the CCAS-S to cognitively assessed patients with ET.

Dysfunctional cerebello-cerebral network associated with vocal emotion recognition impairments

Vocal emotion recognition, a key determinant to analyzing a speaker's emotional state, is known to be impaired following cerebellar dysfunctions. Nevertheless, its possible functional integration in the large-scale brain network subtending emotional prosody recognition has yet to be explored. We administered an emotional prosody recognition task to patients with right versus left-hemispheric cerebellar lesions and a group of matched controls. We explored the lesional correlates of vocal emotion recognition in patients through a network-based analysis by combining a neuropsychological approach for lesion mapping with normative brain connectome data. Results revealed impaired recognition among patients for neutral or negative prosody, with poorer sadness recognition performances by patients with right cerebellar lesion. Network-based lesion-symptom mapping revealed that sadness recognition performances were linked to a network connecting the cerebellum with left frontal, temporal, and parietal cortices. Moreover, when focusing solely on a subgroup of patients with right cerebellar damage, sadness recognition performances were associated with a more restricted network connecting the cerebellum to the left parietal lobe. As the left hemisphere is known to be crucial for the processing of short segmental information, these results suggest that a corticocerebellar network operates on a fine temporal scale during vocal emotion decoding.

Cerebellar cognitive affective syndrome after acute cerebellar stroke

Introduction

The cerebellum modulates both motor and cognitive behaviors, and a cerebellar cognitive affective syndrome (CCAS) was described after a cerebellar stroke in 1998. Yet, a CCAS is seldom sought for, due to a lack of practical screening scales. Therefore, we aimed at assessing both the prevalence of CCAS after cerebellar acute vascular lesion and the yield of the CCAS-Scale (CCAS-S) in an acute stroke setting.

Materials and methods

All patients admitted between January 2020 and January 2022 with acute onset of a cerebellar ischemic or haemorrhagic first stroke at the CUB-Hôpital Erasme and who could be evaluated by the CCAS-S within a week of symptom onset were included.

Results

Cerebellar acute vascular lesion occurred in 25/1,580 patients. All patients could complete the CCAS-S. A definite CCAS was evidenced in 21/25 patients. Patients failed 5.2 ± 2.12 items out of 8 and had a mean raw score of 68.2 ± 21.3 (normal values 82–120). Most failed items of the CCAS-S were related to verbal fluency, attention, and working memory.

Conclusion

A definite CCAS is present in almost all patients with acute cerebellar vascular lesions. CCAS is efficiently assessed by CCAS-S at bedside tests in acute stroke settings. The magnitude of CCAS likely reflects a cerebello-cortical diaschisis.

Delayed cerebral atrophy after cerebellar stroke: topographical relation and clinical impact

Remote dysconnectivity following cerebellar ischaemic stroke may have a negative impact on supratentorial brain tissue. Since the cerebellum is connected to the individual cerebral lobes via contralateral tracts, cerebellar lesion topography might determine the distribution of contralateral supratentorial brain tissue changes. We investigated (i) the occurrence of delayed cerebral atrophy after cerebellar ischaemic stroke and its relationship to infarct volume; (ii) whether cerebellar stroke topography determines supratentorial atrophy location; and (iii) how cortical atrophy after cerebellar stroke impacts clinical outcome. We performed longitudinal volumetric MRI analysis of patients with isolated cerebellar stroke from the Swiss Stroke Registry database. Stroke location and volume were determined at baseline MRI. Delayed cerebral atrophy was measured as supratentorial cortical volumetric change at follow-up, in contralateral target as compared to ipsilateral reference-areas. In patients with bilateral stroke, both hemispheres were analysed separately. We obtained maps of how cerebellar lesion topography, determines the probability of delayed atrophy per distinct cerebral lobe. Clinical performance was measured with the National Institutes of Health Stroke Scale and modified Rankin Scale. In 29 patients (age 58 ± 18; 9 females; median follow-up: 6.2 months), with 36 datasets (7 patients with bilateral cerebellar stroke), delayed cerebral atrophy occurred in 28 (78%) datasets. A multivariable generalized linear model for a Poisson distribution showed that infarct volume (milliliter) in bilateral stroke patients was positively associated with the number of atrophic target areas (Rate ratio = 1.08; P = 0.01). Lobe-specific cerebral atrophy related to distinct topographical cerebellar stroke patterns. By ordinal logistic regression (shift analysis), more atrophic areas predicted higher 3-month mRS scores in patients with low baseline scores (baseline score 3–5: Odds ratio = 1.34; P = 0.02; baseline score 0–2: OR = 0.71; P = 0.19). Our results indicate that (i) isolated cerebellar ischaemic stroke commonly results in delayed cerebral atrophy and stroke volume determines the severity of cerebral atrophy in patients with bilateral stroke; (ii) cerebellar stroke topography affects the location of delayed cerebral atrophy; and (iii) delayed cerebral atrophy negatively impacts clinical outcome.

Cerebellar dentate nucleus functional connectivity with cerebral cortex in Alzheimer's disease and memory: a seed-based approach

Alzheimer's disease (AD) is a chronic neurodegenerative disorder characterized by specific patterns of gray and white matter damage and cognitive/behavioral manifestations. The cerebellum has also been implicated in the pathophysiology of AD. Because the cerebellum is known to have strong functional connectivity (FC) with associative cerebral cortex regions, it is possible to hypothesize that it is incorporated into intrinsic FC networks relevant to cognitive manifestation of AD. In the present study, the cerebellar dentate nucleus, the largest cerebellar nucleus and the major output channel to the cerebral cortex, was chosen as the region of interest to test potential cerebellocerebral FC alterations and correlations with patients' memory impairment in a group of patients with AD. Compared to controls, patients with AD showed an increase in FC between the dentate nucleus and regions of the lateral temporal lobe. This study demonstrates that lower memory performances in AD may be related to altered FC within specific cerebellocortical functional modules, thus suggesting the cerebellar contribution to AD pathophysiology and typical memory dysfunctions.

Posterior Fossa Arachnoid Cyst in a Pediatric Population is Associated with Social Perception and Rest Cerebral Blood Flow Abnormalities

Posterior fossa arachnoid cysts (PFAC) may produce not only neurological symptoms but also other symptoms still poorly understood such as behavioral and learning deficits, awkwardness, and difficulties in social interaction. These subtle social impairments have not been formally described and their underlying brain mechanisms remain unknown. In the present case-control study, we aimed to empirically characterize social impairments in a pediatric population with PFAC using eye tracking. In addition, we investigated putative functional cortical abnormalities in these children using arterial spin labeling magnetic resonance imaging. Overall, 15 patients with PFAC (3f, age = 9.4 ± 4 years) and 43 typically developing volunteer children (16f, age = 9.3 ± 3.6 years) were enrolled in this study. Eye tracking was used to record gaze patterns during visualization of social interaction scenes. Viewing times to faces of characters and non-social background were analyzed. A voxel-wise whole-brain analysis was performed to investigate rest cerebral blood flow (CBF) abnormalities. Significantly reduced viewing time to faces was observed in patients compared with controls (p < 0.01). A ROC curve analysis revealed that 30% of PFAC patients presented viewing time to the face lower than the cutoff, while none of the controls did. The whole-brain analysis revealed a significant decrease in rest CBF in PFAC patients compared with controls bilaterally in the superior temporal gyrus and the temporoparietal junction (TPJ) (p < 0.05 FWE). These results suggest that early life PFAC may have an impact on functional activity of the temporal lobe, which could be associated with social perception deficits.

Altered resting-state brain activity in Parkinson's disease patients with freezing of gait

Freezing of gait (FOG) is a common and debilitating symptom in Parkinson's disease (PD). The current study investigated alterations of resting-state spontaneous brain activity in PD patients with FOG. A total of 29 patients with FOG, 28 patients without FOG and 31 controls were included. All subjects underwent resting-state functional MRI, and the amplitude of low-frequency fluctuation (ALFF) was calculated to measure the spontaneous brain activity. Between-group differences and correlations with FOG severity (both subjective and objective measures) were analyzed. Compared to those without FOG, patients with FOG showed increased ALFF in right anterior cingulate cortex (ACC) and left inferior parietal lobule (IPL), as well as decreased ALFF in right superior frontal gyrus (SFG), bilateral cerebellum and left thalamus. Correlation analyses demonstrated that ALFF within the right SFG, right ACC and bilateral pallidum were positively correlated with FOG; while ALFF within the thalamus, putamen, cerebellum and sensorimotor regions were negatively correlated. Our results indicate that FOG is associated with dysfunction within frontal-parietal regions, along with increased inhibitory outputs from basal ganglia. Additionally, altered activity of cerebellum implicates its role in the pathophysiology of FOG. These findings provide further insight into the underlying neural mechanisms of FOG in PD patients.

Cognitive impairment in cerebellar lesions: a logit model based on neuropsychological testing

Background

Damage to the cerebellum may lead to motor dysfunctions, but also to the neuropsychological deficits that comprise the Cerebellar Cognitive Affective Syndrome (CCAS). It can affect executive functions, attention, memory, visuospatial functions, language, and emotions. Our goal was to determine which neuropsychological tests could be effectively used to identify this syndrome during a short examination.

Methods

Twenty-five patients with an isolated cerebellar lesion and 25 matched healthy controls were examined using an extensive neuropsychological battery.

Results

Logistic regression models and sub-models were computed for individual tests, as well as for the full battery. The best results were produced by a model combining patient education level, the number of errors on the California Verbal Learning Test, and time on Prague Stroop Test (Dots).

Conclusions

Based on the results, we suggest that a condensed battery of neuropsychological tests can be used to detect CCAS. The tests are easy to administer and could be helpful in both research and clinical settings.

Electronic supplementary material

The online version of this article (doi:10.1186/s40673-017-0071-9) contains supplementary material, which is available to authorized users.

Bilateral effects of unilateral cerebellar lesions as detected by voxel based morphometry and diffusion imaging

Over the last decades, the importance of cerebellar processing for cortical functions has been acknowledged and consensus was reached on the strict functional and structural cortico-cerebellar interrelations. From an anatomical point of view strictly contralateral interconnections link the cerebellum to the cerebral cortex mainly through the middle and superior cerebellar peduncle. Diffusion MRI (dMRI) based tractography has already been applied to address cortico-cerebellar-cortical loops in healthy subjects and to detect diffusivity alteration patterns in patients with neurodegenerative pathologies of the cerebellum. In the present study we used dMRI-based tractography to determine the degree and pattern of pathological changes of cerebellar white matter microstructure in patients with focal cerebellar lesions. Diffusion imaging and high-resolution volumes were obtained in patients with left cerebellar lesions and in normal controls. Middle cerebellar peduncles and superior cerebellar peduncles were reconstructed by multi fiber diffusion tractography. From each tract, measures of microscopic damage were assessed, and despite the presence of unilateral lesions, bilateral diffusivity differences in white matter tracts were found comparing patients with normal controls. Consistently, bilateral alterations were also evidenced in specific brain regions linked to the cerebellum and involved in higher-level functions. This could be in line with the evidence that in the presence of unilateral cerebellar lesions, different cognitive functions can be affected and they are not strictly linked to the side of the cerebellar lesion.

Neural substrates of motor and cognitive dysfunctions in SCA2 patients: A network based statistics analysis

Spinocerebellar ataxia type 2 (SCA2) is an autosomal dominant neurodegenerative disease characterized by a progressive cerebellar syndrome, which can be isolated or associated with extracerebellar signs. It has been shown that patients affected by SCA2 present also cognitive impairments and psychiatric symptoms.

The cerebellum is known to modulate cortical activity and to contribute to distinct functional networks related to higher-level functions beyond motor control. It is therefore conceivable that one or more networks, rather than isolated regions, may be dysfunctional in cerebellar degenerative diseases and that an abnormal connectivity within specific cerebello-cortical regions might explain the widespread deficits typically observed in patients.

In the present study, the network-based statistics (NBS) approach was used to assess differences in functional connectivity between specific cerebellar and cerebral “nodes” in SCA2 patients. Altered inter-nodal connectivity was found between more posterior regions in the cerebellum and regions in the cerebral cortex clearly related to cognition and emotion. Furthermore, more anterior cerebellar lobules showed altered inter-nodal connectivity with motor and somatosensory cerebral regions. The present data suggest that in SCA2 a cerebellar dysfunction affects long-distance cerebral regions and that the clinical symptoms may be specifically related with connectivity changes between motor and non-motor cerebello-cortical nodes.

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A cerebellar dysfunction affects long-distance cerebral regions in SCA2 patients.

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Connectivity changes affect sensorimotor and cognitive cerebello-cortical nodes.

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Cerebellar symptoms may be related to altered cerebello-cerebral connectivity.

Postural asymmetry correlated with lateralization of cerebellar perfusion in persons with chronic stroke: A role of crossed cerebellar diaschisis in left side

OBJECTIVE

Hemiplegia after stroke leads to impairment of the affected limbs and induces more weight on the non-paretic lower limb to form postural asymmetry. Studies of asymmetric cerebral functions have found similarly asymmetric functions in the cerebellum. Crossed cerebellar diaschisis (CCD) is defined as reduced blood flow and hypometabolism in the cerebellar hemisphere contralateral to supratentorial cerebral pathology. No study explored the relationship between posture (standing balance) and CCD in those persons yet. It was hypothesized that CCD would impair postural control and tend toward lateralization of cerebellar perfusion.

METHODS

To determine the relationship between postural asymmetry and CCD among patients with chronic stroke while testing in the upright position. Based on images from Tc-99m-ECD brain perfusion, 42 patients were retrospectively allocated into three groups: left CCD, right CCD and no CCD. The ability to maintain an upright stance as assessed by postural parameters was evaluated using a force platform.

RESULTS

The sway intensity differed significantly between the groups with left CCD and no CCD (p = 0.0052), as did the sway velocities (p = 0.0010). The association between the duration of stroke and sway intensity was highly significant (p < 0.0001). The interval from the stroke onset to the postural analysis was significantly associated with sway intensity and velocity.

CONCLUSIONS

This study indicates that the impairment of posture sway control was more severe in left CCD than the other CCD types. The results support a relationship between the postural asymmetry and lateralization of CCD in patients with chronic stroke.

Implied functional crossed cerebello-cerebral diaschisis and interhemispheric compensation during hand grasping more than 20 years after unilateral cerebellar injury in early childhood

BACKGROUND

Crossed cerebello-cerebral diaschisis (CCCD) conventionally refers to decreased resting cerebral activity caused by injury to the contralateral cerebellum. We investigated whether functional activation of a contralesional cerebral cortical region controlling a specific task is reduced during task performance in a patient with a unilateral cerebellar lesion. We also examined functional compensation by the corresponding ipsilesional cerebral cortex. It was hypothesized that dysfunction of the primary sensorimotor cortex (SM1) contralateral to the cerebellar lesion would be detected together with a compensatory increase in neural activity of the ipsilesional SM1. To test these possibilities, we conducted non-invasive functional neuroimaging techniques for bilateral SM1 during hand grasping, a task known to activate predominantly the SM1 contralateral to the grasping hand. Activity in SM1 during hand grasping was measured electrophysiologically by magnetoencephalography and hemodynamically by near-infrared spectroscopy in an adult with mild right hemiataxia associated with a large injury of the right cerebellum due to resection of a tumor in early childhood.

RESULTS

During left hand grasping, increased neural activity was detected predominantly in the right SM1, the typical developmental pattern. In contrast, neural activity increased in the bilateral SM1 with slight right-side dominance during right (ataxic) hand grasping.

CONCLUSIONS

This study reported a case that implied functional CCCD and compensatory neural activity in the SM1 during performance of a simple hand motor task in an adult with unilateral cerebellar injury and mild hemiataxia 24 years prior to the study without rehabilitative interventions. This suggests that unilateral cerebellar injuries in early childhood may result in persistent functional abnormalities in the cerebrum into adulthood. Therapeutic treatments that target functional CCCD and interhemispheric compensation might be effective for treating ataxia due to unilateral cerebellar damage.

Storage of a naturally acquired conditioned response is impaired in patients with cerebellar degeneration

Previous findings suggested that the human cerebellum is involved in the acquisition but not the long-term storage of motor associations. The finding of preserved retention in cerebellar patients was fundamentally different from animal studies which show that both acquisition and retention depends on the integrity of the cerebellum. The present study investigated whether retention had been preserved because critical regions of the cerebellum were spared. Visual threat eye-blink responses, that is, the anticipatory closure of the eyes to visual threats, have previously been found to be naturally acquired conditioned responses. Because acquisition is known to take place in very early childhood, visual threat eye-blink responses can be used to test retention in patients with adult onset cerebellar disease. Visual threat eye-blink responses were tested in 19 adult patients with cerebellar degeneration, 27 adult patients with focal cerebellar lesions due to stroke, 24 age-matched control subjects, and 31 younger control subjects. High-resolution structural magnetic resonance images were acquired in patients to perform lesion–symptom mapping. Voxel-based morphometry was performed in patients with cerebellar degeneration, and voxel-based lesion–symptom mapping in patients with focal disease. Visual threat eye-blink responses were found to be significantly reduced in patients with cerebellar degeneration. Visual threat eye-blink responses were also reduced in patients with focal disease, but to a lesser extent. Visual threat eye-blink responses declined with age. In patients with cerebellar degeneration the degree of cerebellar atrophy was positively correlated with the reduction of conditioned responses. Voxel-based morphometry showed that two main regions within the superior and inferior parts of the posterior cerebellar cortex contributed to expression of visual threat eye-blink responses bilaterally. Involvement of the more inferior parts of the posterior lobe was further supported by voxel-based lesion symptom mapping in focal cerebellar patients. The present findings show that the human cerebellar cortex is involved in long-term storage of learned responses.

Cerebellar dysfunction may play an important role in vascular dementia

The cerebellum has traditionally been seen as a brain area limited to the coordination of voluntary movement, gait, posture, speech, and motor functions. There are increasing evidence, however, proving that the cerebellum is implicated in processes associated with the control of cognition, behavior, and psychiatric illness. Furthermore, the fact that the cerebellum is reciprocally connected to a broad range of limbic structures including the amygdale and hippocampus, as well as the cerebral cortex including the prefrontal areas, provides a strong neuroanatomical argument in favor of cerebellar involvement in cognition regulation. Studies have already found the fact that after stroke, the cerebellum suffered from reduction in metabolism and blood flow in the cerebellar hemisphere contralateral to a destructive cerebral lesion. The notion of crossed cerebellar diaschisis (CCD) may contribute to the explanation of the phenomenon. Consequently, theoretically, stroke in any part of the brain including frontal lobe and hippocampus, will affect cerebellar function and the later then results in vascular dementia (VD). More recently, a few clinical trials found that electrical stimulation of fastigial nucleus (FNS) in cerebellum could improve symptom of VD, though the relationship between cerebellum and VD is unclear. Taken together, there seems to be sufficient empirical ground to assume that the cerebellum plays a role in the regulation of VD. The hypotheses of cerebellar role in VD, which will be discussed in this paper, if confirmed, may lead to the formulation of new pathogenesis and new therapeutic approaches to VD.

Cerebellar injury in the premature infant is associated with impaired growth of specific cerebral regions

We have shown that cerebellar injury in the premature infant is followed by significant growth impairment of the contralateral cerebral hemisphere evident as early as term adjusted age. In this study, we hypothesize that this remote growth restriction is region specific in the cerebrum. In a prospectively enrolled cohort of 38 expreterm infants with isolated cerebellar injury by neonatal MRI, we performed follow-up volumetric MRI studies at a mean postnatal age of 35.5 +/- 13.8 mo. We measured volumes of cortical and subcortical gray matter, and cerebral white matter within eight parcellated regions for each cerebral hemisphere. Unilateral cerebellar injury (n = 24) was associated with significantly smaller volumes of cortical gray and cerebral white matter in the following regions of the contralateral (versus ipsilateral) cerebral hemisphere: dorsolateral prefrontal, premotor (PM), sensorimotor, and midtemporal regions (p < 0.001 for all except midtemporal cortical gray, p = 0.01), as well as subcortical gray matter in the PM region (p < 0.001). Conversely, in cases of bilateral cerebellar injury (n = 14), there was no significant interhemispheric difference in tissue volumes for any of the cerebral regions studied. These findings suggest that regional cerebral growth impairment results from interruption of cerebellocerebral connectivity and loss of neuronal activation critical for development.

Cerebellum of the premature infant: rapidly developing, vulnerable, clinically important

Brain abnormality in surviving premature infants is associated with an enormous amount of neurodevelopmental disability, manifested principally by cognitive, behavioral, attentional, and socialization deficits, most commonly with only relatively modest motor deficits. The most recognized contributing neuropathology is cerebral white matter injury. The thesis of this review is that acquired cerebellar abnormality is a relatively less recognized but likely important cause of neurodevelopmental disability in small premature infants. The cerebellar disease may be primarily destructive (eg, hemorrhage, infarction) or primarily underdevelopment. The latter appears to be especially common and relates to a particular vulnerability of the cerebellum of the small premature infant. Central to this vulnerability are the extraordinarily rapid and complex developmental events occurring in the cerebellum. The disturbance of development can be caused either by direct adverse effects on the cerebellum, especially the distinctive transient external granular layer, or by indirect remote trans-synaptic effects. This review describes the fascinating details of cerebellar development, with an emphasis on events in the premature period, the major types of cerebellar abnormality acquired during the premature period, their likely mechanisms of occurrence, and new insights into the relation of cerebellar disease in early life to subsequent cognitive/behavioral/attentional/socialization deficits.

The cerebellum in emotion regulation: a repetitive transcranial magnetic stimulation study

Several lines of evidence suggest that the cerebellum may play a role in the regulation of emotion. The aim of this study was to investigate the hypothesis that inhibition of cerebellar function using slow repetitive transcranial magnetic stimulation (rTMS) would lead to increased negative mood as a result of impaired emotion regulation. In a randomized counterbalanced within-subjects design, 12 healthy young right-handed volunteers received 20 min of cerebellar, occipital, or sham 1 Hz rTMS on three separate days. Mood state inventories were acquired prior to and immediately after rTMS and after an emotion regulation task (ERT). In the ERT, participants were instructed to either look at aversive and neutral scenes, or to suppress the negative feelings experienced while watching aversive scenes during which the electroencephalogram (EEG) was recorded. Results showing no changes in baseline-corrected mood were observed immediately after rTMS. However, significant increases in baseline-corrected negative mood following the ERT were reported after cerebellar rTMS exclusively. No effects on the EEG during the ERT were observed. These findings provide support for the view that the cerebellum is implicated in the regulation of emotion and mood, and concur with evidence of cerebellar abnormalities observed in disorders associated with emotion dysregulation. In order to clarify the underlying biological mechanisms involved, more research is needed.

Theories of impaired consciousness in epilepsy

Although the precise mechanisms for control of consciousness are not fully understood, emerging data show that conscious information processing depends on the activation of certain networks in the brain and that the impairment of consciousness is related to abnormal activity in these systems. Epilepsy can lead to transient impairment of consciousness, providing a window into the mechanisms necessary for normal consciousness. Thus, despite differences in behavioral manifestations, cause, and electrophysiology, generalized tonic-clonic, absence, and partial seizures engage similar anatomical structures and pathways. We review prior concepts of impaired consciousness in epilepsy, focusing especially on temporal lobe complex partial seizures, which are a common and debilitating form of epileptic unconsciousness. We discuss a "network inhibition hypothesis" in which focal temporal lobe seizure activity disrupts normal cortical-subcortical interactions, leading to depressed neocortical function and impaired consciousness. This review of the major prior theories of impaired consciousness in epilepsy allows us to put more recent data into context and to reach a better understanding of the mechanisms important for normal consciousness.

Quantification of gray matter changes in the cerebral cortex after isolated cerebellar damage: a voxel-based morphometry study

There is growing evidence based on behavioral and functional imaging studies about the cerebellar involvement in the modulation of cognitive functions. However, it still remains to be clarified how the cerebellum interacts with brain regions sub-serving different cognitive domains. In this study we used magnetic resonance imaging (MRI) and voxel based morphometry (VBM) to investigate changes of cerebral gray matter (GM) density in 15 patients with a focal cerebellar damage (CD) compared to 15 healthy controls. T2-weighted scans and T1-weighted volumes were collected from each subject. With the exception of the cerebellar lesion, none of the patients showed any additional brain MRI abnormality. T1-volumes were analyzed by voxel-based morphometry. Consistent with their neuropsychological abnormalities, patients with right-CD compared to controls showed a reduction of GM density mainly involving the left frontal, parietal and temporal lobes. Conversely, patients with left-CD did not show any significant neuropsychological or cerebral GM abnormality. The present study indicates that specific GM changes may be detected in patients with isolated CD and cognitive dysfunction. We discuss the findings in terms of cerebellar influence on the neuronal networks involved in higher level functions of the association cortex.

Evaluation of language functions in acute cerebellar vascular diseases

BACKGROUND

The principal features of the cerebellar infarcts are ataxia, failure of coordination, gait instability, and articulation and eye movement disabilities. Language disabilities are also seen with cerebellar lesions, but there are difficulties in diagnosis. This study was planned to evaluate the effects of cerebellar lesions on language functions and the relation between these functions and lesion type, age, and education level.

METHODS

A total of 20 patients, 13 male (65%) and 7 female (35%), were included in this study. Twenty control subjects with similar demographic characteristics were also included. The mean age of the patient group was not statistically different.

RESULTS

Patients with vermal lesions had significantly higher performance than patients with paravermal lesions when evaluating the understanding of hearing and total aphasia score. Understanding of reading function was significantly better in the patients with small lesions compared with those with large lesions. When the aphasia parameters were compared between the patient and control groups, significant differences were found for all parameters, which reflected the language abilities understanding, naming, true-wrong questions, complex questions, comparing, repeating, and total aphasia score. Reading and writing functions were also significantly different between the patients and the control subjects.

CONCLUSION

We found that the cerebellum contributes in several language parameters. These functions show difference according to localization and lesion volume of cerebellar disease. Aphasia should be explored as an important parameter when evaluating the loss of function in patients with cerebellar lesions.

Altered soleus responses to magnetic stimulation in pure cerebellar ataxia

OBJECTIVE

Transcranial magnetic stimulation (TMS) over the leg motor area elicits a soleus primary response (SPR) and a soleus late response (SLR). We evaluated the influence of the cerebellofugal pathway on the SPR and SLR in patients with 'pure' cerebellar ataxia.

METHODS

SPRs and SLRs were recorded from 11 healthy subjects and 9 patients with 'pure' cerebellar cortical degeneration; 5 with spinocerebellar ataxia type 6 (SCA6), and 4 with late cortical cerebellar ataxia (LCCA). In addition, three patients with localized cerebellar lesions were tested.

RESULTS

The SPR latency was significantly longer in patients than in controls, but primary responses in the tibialis anterior muscle were normal. The frequency of abnormal SLR was 38.9% in the supine position and 83.3% in the standing position. Two out of three patients with localized cerebellar lesions also showed abnormal SLR.

CONCLUSIONS

Altered SPRs in patients may result from a dysfunction of the primary motor cortex caused by crossed cerebello-cerebral diaschisis. In addition, our results suggest that 'pure' cerebellar degeneration involves the mechanism responsible for evoking SLR which is related to the control of posture.

SIGNIFICANCE

SLR can be a useful neurophysiological parameter for evaluating cerebellofugal function.

Posterior fossa syndrome after a vermian stroke: a new case and review of the literature

The posterior fossa syndrome (PFS) is a well-known clinical consequence of posterior fossa surgery that has only been reported in a limited number of cases with a nontumoral etiology. It consists of transient cerebellar mutism, behavioral abnormalities and personality changes. We describe a 12-year-old child who developed transient cerebellar mutism associated with behavioral and emotional symptoms following rupture of a vermis arteriovenous malformation (AVM). Following the stroke, the girl experienced a 24-hour symptom-free interval. After that, she became mute and her emotional state was characterized by severe anxiety, irritability and withdrawal. After 3 days, mutism resolved and dysarthria became apparent. Two weeks after stroke, the AVM was surgically removed and the postoperative course was uneventful. This case is the first reported in which the PFS occurred after focal nonsurgically induced cerebellar damage.

The cerebellum's involvement in the judgment of spatial orientation: a functional magnetic resonance imaging study

A functional magnetic resonance imaging (fMRI) study was conducted to integrate the clinical observations of the impaired judgment of spatial orientation of cerebellar patients with recent theoretical discoveries about the role of the cerebellum in cognitive functions. Ten normal healthy male right-handed Chinese postgraduates consented to participate in this study. The experimental task employed was a modified version of Benton's Judgment of Line Orientation Test, administered in a blocked fMRI study. The findings indicated activation of the cerebellar regions, the Hemisphere Lobules IV, VI and Crus I, while the subjects were performing the experimental task of the judgment of the orientation of lines. Furthermore, cortical regions were activated, including the bilateral precuneus (BA 7), the extrastriate regions (BA 19), and the bilateral prefrontal regions (BA 9, 10, 44, 46). The imaging data confirmed that the activity of the cerebellum is associated with judging spatial orientation. The theoretical and clinical implications of the findings are discussed.

Triple stimulation technique in patients with spinocerebellar ataxia type 6

OBJECTIVE

To establish further evidence that SCA6 may not be a pure cerebellar syndrome.

METHODS

Seven patients with genetically confirmed SCA6 and 9 age-matched normal controls were studied. Recordings of the CMAP were obtained from the right first dorsal interosseus muscle. Transcranial magnetic stimulation of the left motor cortex was applied to the contralateral scalp with a plane figure-of-8 coil. Conventional transcranial magnetic stimulation (TMS), central motor conduction time (CMCT) by F-wave method and the triple stimulation technique (TST) amplitude ratio (TST test/TST control) were investigated.

RESULTS

The mean resting motor threshold and mean CMCT did not show significant differences between normal controls and patients, but the mean TST amplitude ratio was significantly smaller in patients than in controls.

CONCLUSIONS

An abnormal TST represents upper motor neuron loss, central axon lesions or conduction blocks, or inexcitability in response to TMS. The lack of pathological changes in the corticospinal tract of patients with SCA6 indicates that this abnormality may be caused by crossed cerebellar diaschisis, or a functional disorder in the brain resulting from CACNA1A mutations.

SIGNIFICANCE

TST is a useful method for quantifying corticospinal tract dysfunction.

Impaired trophic interactions between the cerebellum and the cerebrum among preterm infants

BACKGROUND

Advanced neuroimaging techniques have brought increasing recognition of cerebellar injury among premature infants. The developmental relationship between early brain injury and effects on the cerebrum and cerebellum remains unclear.

OBJECTIVES

To examine whether cerebral parenchymal brain lesions among preterm infants are associated with subsequent decreases in cerebellar volume and, conversely, whether primary cerebellar injury is associated with decreased cerebral brain volumes, with advanced, 3-dimensional, volumetric MRI at term gestational age equivalent.

METHODS

Total cerebellar volumes and cerebellar gray and myelinated white matter volumes were determined through manual outlining for 74 preterm infants with unilateral periventricular hemorrhagic infarction (14 infants), bilateral diffuse periventricular leukomalacia (20 infants), cerebellar hemorrhage (10 infants), or normal term gestational age equivalent MRI findings (30 infants). Total brain and right/left cerebral and cerebellar hemispheric volumes were calculated.

RESULTS

Unilateral cerebral brain injury was associated with significantly decreased volume of the contralateral cerebellar hemisphere. Conversely, unilateral primary cerebellar injury was associated with a contralateral decrease in supratentorial brain volume. Cerebellar gray matter and myelinated white matter volumes were reduced significantly not only among preterm infants with primary cerebellar hemorrhage but also among infants with cerebral parenchymal brain injury.

CONCLUSIONS

These data suggest strongly that both reduction in contralateral cerebellar volume with unilateral cerebral parenchymal injury and reduction in total cerebellar volume with bilateral cerebral lesions are related to trophic transsynaptic effects. Early-life cerebellar injury may contribute importantly to the high rates of cognitive, behavioral, and motor deficits reported for premature infants.

Impaired neurovascular coupling by transhemispheric diaschisis in rat cerebral cortex

In acute brain disorders, elimination of the excitatory output from an injured brain region reduces activity in connecting brain regions remote from the lesion site (i.e., diaschisis). The authors examined the effect of functional ablation of the left cerebral cortex by cortical spreading depression (CSD) or topical application of tetrodotoxin on single cell spiking activity, baseline CBF, and neurovascular coupling in the right rat sensory cortex. CSD or tetrodotoxin in left cortex reduced the right cortical spontaneous spike rate by 36% and 45%, respectively. Baseline CBF in the right cortex was unaffected by a left-sided CSD, but decreased by 12% for left cortical application of tetrodotoxin. This suggested dissociation between spontaneous spiking activity and basal CBF. Left in-fraorbital nerve stimulation evoked local field potentials in right cerebral cortex that were reduced in amplitude by 19% for left CSD and by 23% for left tetrodotoxin application. The corresponding declines in the evoked CBF responses were 42% for CSD and 23% for tetrodotoxin. Vascular reactivity to adenosine remained unchanged in right cortex. Thus, transhemispheric diaschisis produced a pronounced decrease in the spontaneous spike rate accompanied by no reduction or a small reduction in basal CBF, and an attenuation in amplitudes of evoked synaptic responses and corresponding rises in CBF. The findings suggest that disturbed neurovascular coupling may contribute to the disturbance in brain function in acute transhemispheric diaschisis.

Crossed Cerebellar Diaschisis in Patients With Cortical Infarction

BACKGROUND AND PURPOSE

Crossed cerebellar diaschisis (CCD) refers to reduced metabolism and blood flow in the cerebellar hemisphere contralateral to a cerebral lesion. Many cortical areas have been reported to cause CCD without consideration of confounding factors. We performed single-photon emission computed tomography (SPECT) in patients with cortical infarction to identify regions independently related to CCD, controlling for possible confounding effects.

METHODS

Patients with unilateral cortical infarction (n=113; 75 male, 38 female; mean+/-SD age, 66+/-13 years) underwent SPECT of the brain with N-isopropyl-p-[(123)I]iodoamphetamine ((123)I-IMP). Regional cerebral blood flow was measured autoradiographically. Asymmetry indices (AIs) were calculated on the basis of ratios representing symmetrical regional cerebral blood flow in the cerebellum and 16 cerebral regions. CCD was defined as AI for cerebellum >0.1. AIs for 16 cortical regions were considered for both dichotomous and continuous variables for analysis of CCD occurrence by means of backward logistic regression.

RESULTS

For dichotomized variables, hypoperfusion of postcentral (odds ratio [OR]=7.607; 95% CI, 2.299 to 25.174) and supramarginal (OR=3.916; 95% CI, 1.394 to 11.003) regions independently influenced CCD. For continuous variables, hypoperfusion of postcentral (OR=1.044; 95% CI, 1.019 to 1.068) and supramarginal (OR=1.021; 95% CI, 1.001 to 1.041) regions (and, as a negative factor, medial occipital regions; OR=0.942; 95% CI, 0.895 to 0.991) independently influenced CCD.

CONCLUSIONS

Many cortical areas apparently do not contribute to CCD. Correspondence of CCD between dichotomized and continuous analyses suggests that location of a lesion, not severity, is the main determinant of CCD.

Enhanced intracortical inhibition in cerebellar patients

OBJECTIVE

The aim of the study was to examine intracortical excitability in cerebellar patients.

METHODS

Short-latency intracortical inhibition (SICI), long-latency intracortical inhibition (LICI) and intracortical facilitation (ICF) to paired transcranial magnetic stimulation (TMS) were investigated in 8 patients with 'pure' cerebellar syndromes and in 14 age-matched normal controls. The conditioning stimulus for short-latency intracortical inhibition and intracortical facilitation was set at 70% of the resting motor threshold (RMT) and preceded the test stimulus (110-120% of the resting motor threshold) by interstimulus intervals (ISIs) of 1-30 ms. For the long-latency intracortical inhibition determinations, the conditioning stimulus was set at 120% of the resting motor threshold and preceded the test stimulus (also 120% of the resting motor threshold) by interstimulus intervals of 30-500 ms.

RESULTS

No statistically significant differences were found between patients and controls as regards either short-latency intracortical inhibition or intracortical facilitation. A significant prevalence of long-latency intracortical inhibition was present in cerebellar patients at interstimulus intervals of 200-500 ms (conditioned MEP amplitude=29-41% of test MEP) as compared to controls (71-96% of test MEP). The amplitude of conditioned MEPs was persistently less than 45% of the test MEP in six patients, who were studied at interstimulus intervals up to 1000 ms.

CONCLUSIONS

Long-latency intracortical inhibition was prevalent and abnormally longer-lasting in patients. Tonic hyperactivation of a subpopulation of GABAergic interneurons in the motor cortex of patients may be the mechanism responsible for this abnormality. Our findings seem to be specific to cerebellar diseases and are the opposite of those found in movement disorders such as dystonia and Parkinson's disease. These data suggest that the cerebellum and the basal ganglia may have opposite influences in tuning the excitability of the motor cortex.

Abnormal cutaneomotor integration in patients with cerebellar syndromes: a transcranial magnetic stimulation study

OBJECTIVE

To examine the sensorimotor interactions in cerebellar patients.

METHODS

We investigated the effects of electrical stimulation of the second (D2) and fifth (D5) fingers on the amplitude of motor evoked potentials (MEPs) in response to transcranial magnetic stimulation and transcranial electrical stimulation (TES) in the relaxed right abductor digiti minimi muscles of 7 patients with cerebellar syndromes and of 14 age-matched controls. The digital stimulation was set at 3 times the sensory threshold and preceded brain stimulation at interstimulus intervals (ISIs) ranging from 10 to 100 ms.

RESULTS

D5 stimulation produced significant MEP inhibition in normal subjects at ISIs of 20-50 ms, while D2 stimulation resulted in a non-significant inhibitory trend with the same intervals. In contrast, digital stimulation had no effect on MEP amplitude in cerebellar patients. A significant difference was found between patients and controls at ISIs of 20-50 ms with D5 stimulation. The difference in amplitude of MEPs conditioned by D5 and D2 stimulation was statistically significant between patients and controls at ISIs of 30 and 50 ms. TES conditioning induced MEP inhibition only at ISIs <40 ms.

CONCLUSIONS

Digital stimulation would appear to modulate motor system excitability less effectively in cerebellar patients. MEP inhibition by cutaneous afferences is reduced in response to stimulation of contiguous, as well as non-contiguous fingers. The difference between the conditioning effects of the two fingers is also decreased, and therefore the somatotopic distribution of cutaneomotor inhibition is absent in patients. These abnormalities may contribute to the genesis of cerebellar motor symptoms and their time course suggests involvement of subcortical and cortical sites.

Optimal hematocrit based on regional cerebral blood flow in hemodialysis patients with diabetic nephropathy

BACKGROUND

The optimal hematocrit (Hctopt) in hemodialysis (HD) patients has yet to be determined based on the etiology and complications of their endstage renal disease (ESRD). To investigate this problem, we compared regional cerebral oxygen supply (rCOS) in diabetic (DM group) and non-diabetic HD patients (non-DM group) with data from subjects without renal disease or DM (control group)

METHODS

Regional cerebral blood flow (rCBF) was measured with single-photon emission computed tomography (SPECT) by the N-isopropyl-p-[(123)I]-iodoamphetamine ((123)I-IMP)-autoradiographic (ARG) method, and both the O2 content (O2CT) of arterial blood and hematocrit (Hct) were evaluated. Using the regression lines of rCBF vs Hct and O2CT vs Hct, we established a convex curve between rCOS and Hct. The peak of the curve indicates the maximum rCOS (rCOSmax) and Hctopt for rCOSmax

RESULTS

The rCBF in both the DM and non-DM groups was lower than that of the control group at the same Hct level, and the DM group had the lowest values. The rCOSmax values in the DM and non-DM groups were nearly equal, but both were lower than in controls. The Hctopt in the DM group was lower than that in the non-DM group by 6.3%±3.3%

CONCLUSIONS

Although the difference in Hctopt values in the DM and non-DM groups was 6.3%, the rCOSmax values in both groups were nearly equal. This suggests that differences in the Hctopt may depend on complications or causes of ESRD. The optimal Hct in the DM group was 22.6%±1.9%, and that for the non-DM group was 29.0%±1.8%

The role of subcortical structures in human epilepsy

Like normal cerebral function, epileptic seizures involve widespread network interactions between cortical and subcortical structures. Although the cortex is often emphasized as the site of seizure origin, accumulating evidence points to a crucial role for subcortical structures in behavioral manifestations, propagation, and, in some cases, initiation of epileptic seizures. Extensive previous studies have shown the importance of subcortical structures in animal seizure models, but corresponding human studies have been relatively few. We review the existing evidence supporting the importance of the thalamus, basal ganglia, hypothalamus, cerebellum, and brain stem in human epilepsy. We also propose a "network inhibition hypothesis" through which focal cortical seizures disrupt function in subcortical structures (such as the medial diencephalon and pontomesencephalic reticular formation), leading secondarily to widespread inhibition of nonseizing cortical regions, which may in turn be responsible for behavioral manifestations such as loss of consciousness during complex partial seizures.

Frontal and parieto-temporal cortical ablations and diaschisis-like effects on auditory neurocognitive potentials evocable from apparently intact ipsilateral association areas in humans: five case reports

The aim of this study was to investigate the effects of disruption on the warning auditory S1-elicited ERP and CNV complexes recordable on the site and on remote ipsilateral apparently normal anatomo-functionally interconnected brain regions. These effects in some cases showed aspects of a probable diaschisis-like phenomenon, due to resections of extensive frontal association cortex or of primary and secondary sensory parieto-temporal areas damaged by differing pathological processes. Using a standard CNV paradigm, 21/19 EEG electrodes connected with three different references, and scalp-topographic bidimensional mapping analysis, the S1 auditory binaural/monaural clicks N1a,b,c, P2, N2, P3 and CNV waves were recorded in 10 normal subjects and 11 patients. Nine of the latter had been submitted to unilateral frontal dorsolateral cortex ablation, one to bihemispheric dorsomedial cortex ablation, and one to unilateral ablation of sensory parieto-temporal cortex and underlying white matter, verified through CT/MRI examinations. No true S1ERP/CNV components were recordable over the ablated cortical areas, whereas normal ERP/CNV complexes were observable on the intact hemispheres. In five patients, four of whom with frontocortical ablations, the S1 ERP/CNV complexes appeared severely diminished or disrupted, in two cases in a slow, partially-reversible manner, also in the neuroradiologically normal ipsilateral functionally-connected post-rolandic sensory and association areas. Similar deactivation of some ERP components was observed in reverse on the unilateral dorsolateral frontocortical region in the fifth patient with parieto-temporal cortex ablation. Even when they are partially reversible, these ipsilateral remote ERP changes in apparently intact brain regions, due to ablations of functionally-interconnected cortical formations, probably reflect cortical deactivation or simply dysfacilitation deriving from functional unilateral diaschisis. If these changes are instead irreversible they may probably be interpreted as transneuronal degeneration phenomena, though they are not at present easy to document either neuroradiologically or electroclinically.