Christoph Hein-Kropp

Cerebellar involvement in verb generation: an fMRI study.

A possible role of the human cerebellum in the generation of verbs corresponding to presented nouns has been suggested. Previous functional brain imaging studies have compared generation of verbs with the reading of nouns as a measure of verb generation. In the present fMRI study involving healthy human subjects, the effects of speech articulation and motor imagery associated with verb production were investigated in greater detail. Generation of verbs to visually presented nouns was compared to a condition in which subjects read those same verbs that had been individually generated by each subject. Activation in lobule HVI/Crus I of the right cerebellar hemisphere was found as a measure of verb generation. In contrast, reading of verbs as a measure of speech articulation evoked cerebellar activations in both left and right paravermal lobule VI. These results suggest an involvement of the right lateral cerebellar hemisphere in linguistic functions during verb generation. Alternatively, effects of inner speech could also possibly explain the results.

Cerebellar mutism--report of four cases.

Abstract.The aim of the present study was to investigate the manifestations of mutism after surgery in children with cerebellar tumors. Speech impairment following cerebellar mutism in children was investigated based on standardized acoustic speech parameters and perceptual criteria. Mutistic and non–mutistic children after cerebellar surgery as well as orthopedic controls were tested pre–and postoperatively. Speech impairment was compared with the localization of cerebellar lesions (i. e. affected lobules and nuclei). Whereas both control groups showed no abnormalities in speech and behavior, the mutistic group could be divided into children with dysarthria in post mutistic phase and children with mainly behavioral disturbances. In the mutistic children involvement of dentate and fastigial nuclei tended to be more frequent and extended than in the nonmutistic cerebellar children.Cerebellar mutism is a complex phenomenon of at least two types. Dysarthric symptoms during resolution of mutism support the anarthria hypothesis, while mainly behavioral changes suggest an explanation independent from speech motor control.

Preserved verb generation in patients with cerebellar atrophy.

A role of the right cerebellar hemisphere has been suggested in linguistic functions. Nevertheless, studies of verb generation in cerebellar patients provide inconsistent results. The aim of the present study was to examine verb generation in a larger group of cerebellar patients with well-defined lesions. Ten subjects with degenerative cerebellar disorders and ten healthy matched controls participated. Subjects had to generate verbs to the blocked presentation of photographs of objects (i.e. four blocks of sixteen objects). As control condition, the objects had to be named. Furthermore, dysarthria was quantified by means of a sentence production and syllable repetition task. Volumetric analysis of individual 3D-MR scans was performed to quantify cerebellar atrophy. Cerebellar patients were slower in the sentence production and syllable repetition tasks, and cerebellar volume was decreased compared to controls. Despite cerebellar atrophy and dysarthria, the answers produced did not differ between patients and controls. In addition, both groups revealed the same amount of decrease in verbal reaction time over blocks (i.e. learning). The results suggest that the role of the cerebellum in verb generation is less pronounced than previously suggested.

Behavioral and affective changes in children and adolescents with chronic cerebellar lesions.

The aim of the present study was to investigate if clinically relevant affective or behavioral changes as described in adults in the cerebellar affective syndrome by Schmahmann and Sherman [The cerebellar cognitive affective syndrome, Brain 121 (1998) 561-579] are likely to occur as a long-term sequelae of cerebellar vermis lesions in children. Site and extent of the vermal lesion were defined on the basis of individual 3D-MRI scans and lesion data were correlated with behavioral and affective changes. Affect and behavior were assessed in children after cerebellar tumor surgery by means of experimenter ratings based on the description of the cerebellar affective syndrome and free ratings by the patients and their parents. Twelve children and adolescents with a former cerebellar astrocytoma surgery without subsequent radiation or chemotherapy participated. Detailed analysis of individual 3D-MR images revealed that lesions affected the vermis in nine children. Experimenter ratings according to Schmahmann revealed no relevant problems in patients. In five out of nine patients with vermal affection somewhat increased thoughtful, anxious or aggressive behavior was reported by patients and parents. In conclusion, minor behavioral and affective changes were present in a subset of children with chronic vermal lesions.

Cerebellar Agenesis: Clinical, Neuropsychological and MR Findings

Cases of cerebellar agenesis are rare. The degree of motor impairment is a matter of discussion. It has been claimed that normal motor function can be observed. Detailed descriptions of neurological findings, however, are lacking. Neuropsychological testing in cerebellar agenesis is of additional interest based on recent findings of impaired non-motor functions in cerebellar disease. The case of an elderly woman with cerebellar agenesis is presented. 3D-MR imaging was used to confirm the diagnosis. Neurological and neuropsychological examination was performed including video documentation (see the authors’ own website). To assess deficits of motor learning eyeblink conditioning was investigated. Neurological examination revealed mild to moderate signs of cerebellar dysarthria, upper and lower limb ataxia and ataxia of stance and gait. Motor learning was affected as shown by inability to acquire conditioned eyeblink responses. In addition, neuropsychological testing disclosed mild to moderate deficits in IQ, planning behavior, visuospatial abilities, memory and attention. Cerebellar ataxia, although clearly present, was less than one would expect in almost complete absence of the cerebellum. Neuropsychological deficits, on the other hand, appeared to be more marked than one would expect in cerebellar disease. No conclusion, however, could be drawn whether impaired cognitive development and neuropsychological test performance were directly related to lack of cerebellar function, or caused by impaired motor development and performance.

Incidence of Dysarthria in Children with Cerebellar Tumors: A Prospective Study.

The present study investigated dysarthric symptoms in children with cerebellar tumors. Ten children with cerebellar tumors and 10 orthopedic control children were tested prior and one week after surgery. Clinical dysarthric symptoms were quantified in spontaneous speech. Syllable durations were analyzed in syllable repetition and sentence production tasks. Localization of the cerebellar lesions were defined after manual transfer from individual 2D-MR images onto 3D images of a spatially normalized healthy brain. Cerebellar children showed few and mild clinical signs of dysarthria. No difference was present in the sentence production task compared to controls. In five cerebellar children, syllables were prolonged in the syllable repetition task after surgery. Syllable duration normalized in an additional four-week session in all but one case. The MR-analysis showed that superior paravermal cerebellar areas likely involved in dysarthria in adults (paravermal lobules HVI, Crus I) were not significantly affected. In children, speech impairments appear to be rare after cerebellar surgery because tumors most commonly affect posterior-inferior and medial parts of the cerebellum while critical cerebellar regions are likely spared. The results suggest a similar localization of speech functions in the cerebellum in children and adults.

Verb generation in children and adolescents with acute cerebellar lesions

The aim of the present study was to examine verb generation in a larger group of children and adolescents with acute focal lesions of the cerebellum. Nine children and adolescents with cerebellar tumours participated. Subjects were tested a few days after tumour surgery. For comparison, a subgroup was tested also 1 or 2 days before surgery. None of the children had received radiation or chemotherapy at or before the time of testing. Eleven age- and education-matched control subjects participated. Subjects had to generate verbs to blocked presentations of photographs of objects. As control condition, the objects had to be named. Furthermore, dysarthria was quantified by means of a sentence production and syllable repetition task. Detailed analysis of individual 3D-MR images revealed that lesions affected cerebellar hemispheres in all children and adolescents. The right cerebellar hemisphere was affected in four and the left hemisphere in five subjects. In the present study, naming and verb generation accuracy were preserved in the majority of subjects with cerebellar lesions. No significant signs of learning deficits were observed, as reduction of reaction times over blocks was not different compared to controls. There was a trend of children and adolescents with right-hemispheric lesions to perform worse compared to controls. In this group, however, significant signs of dysarthria were present. In sum, no significant signs of disordered verb generation were observed in children and adolescents with acute cerebellar lesions. Findings suggest that the role of the cerebellum in verb generation may be less pronounced than previously suggested. Findings need to be confirmed in a larger group of subjects with acute focal lesions.

Megalographia in Children with Cerebellar Lesions and in Children with Attention-Deficit/Hyperactivity Disorder

Structural changes of the cerebellum have been reported in attention-deficit/hyperactivity disorder (ADHD) in several studies. The cerebellum is a structure essential for motor coordination and motor learning. Beside behavioral deficits, children with ADHD often show slight motor abnormalities. In the present study, handwriting was examined in both children with ADHD and children with cerebellar lesions. By writing the same sentence several times, letter height increased in the ADHD and cerebellar groups but not in controls. Comparable disorders of handwriting in cerebellar and ADHD children support previous studies, which suggest a contribution of cerebellar dysfunction to motor abnormalities in ADHD. However, an involvement of non-cerebellar dysfunctions in ADHD cannot be excluded.

Cerebellar agenesis II: Motor and language functions

In a former study of a patient with cerebellar agenesis (HK) mild motor deficits, problems in delay eyeblink conditioning and mild to moderate deficits in IQ, planning behavior, visuospatial abilities, visual memory, and attention were found. The present study reports additional findings in the same patient. In the motor domain, impairments in fine motor manipulations, trace eyeblink conditioning and motor imagination in a functional magnetic resonance (fMRI) study were found. Based on fMRI findings; however, cortical areas involved in a tapping task did not significantly differ from a healthy control group. In the cognitive domain, deficits in speech comprehension as well as verbal learning and declarative memory were present. No significant affective symptoms were observed. Although problems in executive, visuospatial and language tasks are in agreement with the so-called cerebellar cognitive affective syndrome—other possibilities remain. Non-motor impairments in HK might also be a consequence of lacking motor abilities in development and motor deficits may interfere with the performance of parts of the cognitive tasks. In addition, lack of promotion and learning opportunities in childhood may contribute and mental retardation based on extracerebellar dysfunction cannot be excluded. We would like to thank HK for her time and effort, B. Brol and S. Sturm for conducting the conditioning experiment, B. Müller for providing the MLS, and H.G. Elles for his help in setting up the fMRI-experiment. The study was supported by a grant of the Deutsche Forschungsgemeinschaft (DFG Ti 239/5-1, DFG Ti 239/5-2).

Aphasia, neglect and extinction are no prominent clinical signs in children and adolescents with acute surgical cerebellar lesions

The aim of the present study was to examine if clinically significant signs of aphasia, neglect or extinction, which have a well-known cerebral lateralization, are present in children and adolescents with acute focal lesions following tumour surgery in the cerebellum. Eight children and adolescents with cerebellar tumours were tested within days after tumour surgery. None of the children had received radiation or chemotherapy at the time of testing. Eleven age- and education-matched control subjects with major orthopedic surgery participated. High-resolution magnetic resonance images showed lesions of the right cerebellar hemisphere in three and of the left hemisphere in five children. Standard aphasia tests revealed no statistically significant difference comparing children with right- and left-sided lesions and controls. Mild signs of language disturbance, however, were present in single subjects with right-sided cerebellar lesions. Neglect and extinction tasks revealed minor abnormalities, which lacked consistent lateralization and were best explained by more unspecific attentional deficits and motor disorders in acute post-surgical stage. Acute right-sided cerebellar lesions can be followed by mild signs of language disturbances in single subjects. Clinically significant signs of neglect and extinction, however, are not observed in children and adolescents with acute surgical cerebellar lesions.