Biomedical subjects

K Willmes

Publications and source records attributed to K Willmes.

At least 37 records · Page 2Linked to original sources

PubMed1999

Active and remitted schizophrenia: psychopathological and regional cerebral blood flow findings.

Single photon emission computed tomography with technetium-99m-d,l-hexamethylpropyleneamine oxime (99mTc-HMPAO) was used to assess regional cerebral blood flow (rCBF) during both florid and remitted stages of schizophrenia. Forty schizophrenic patients in an active phase of illness (diagnosis by DSM-III-R) were examined in two clinical states (ill vs. improved). At study entry, 24 patients were drug-naive, five were currently drug-free, and 11 were being treated with antipsychotic medication. Twenty medical patients who suffered from non-specific headaches but were free of neurological and psychiatric symptoms served as control subjects. At initial examination during the active phase of illness, cerebral perfusion patterns in the schizophrenic patients were characterized by both hypofrontality and hypotemporality. After remission, hypofrontality was no longer apparent in two of four frontal regions, and hypotemporality disappeared completely. As assessed with the Positive and Negative Syndrome Scale (PANSS), formal thought disorders, hallucinations, and ideas of grandiosity correlated with rCBF in the active phase of illness, but not after remission. In the remitted but not in the florid state, blunted affect, difficulties in abstract thinking, lack of spontaneity, and stereotyped thoughts correlated with rCBF. Correlations of five symptoms with rCBF changed significantly from first to second examination. The present study suggests that correlations between single psychotic symptoms and rCBF differ significantly in florid vs. remitted phases of schizophrenia.

Adult↗

PubMed1999

Functional anatomy of intrinsic alertness: evidence for a fronto-parietal-thalamic-brainstem network in the right hemisphere.

Alertness, the most basic intensity aspect of attention, probably is a prerequisite for the more complex and capacity demanding domains of attention selectivity. Behaviorally, intrinsic alertness represents the internal (cognitive) control of wakefulness and arousal; typical tasks to assess optimal levels of intrinsic alertness are simple reaction time measurements without preceding warning stimuli. Up until now only parts of the cerebral network subserving alertness have been revealed in animal, lesion, and functional imaging studies. Here, in a 15O-butanol PET activation study in 15 right-handed young healthy male volunteers for this basic attention function we found an extended right hemisphere network including frontal (anterior cingulate-dorsolateral cortical)-inferior parietal-thalamic (pulvinar and possibly the reticular nucleus) and brainstem (ponto-mesencephalic tegmentum, possibly involving the locus coeruleus) structures, when subjects waited for and rapidly responded to a centrally presented white dot by pressing a response key with the right-hand thumb.

Adult↗

PubMed1999

[Aspects of cerebral connnectivity in schizophrenia. A comparative CBF study on treated schizophrenics before and after medication].

INTRODUCTION: The hypothesis of prefrontal-temporolimbic disconnectivity, considered to be relevant to the pathogenesis of schizophrenia, has been tested in 29 drug-naive schizophrenic patients, comparing the active with the remitted state. METHOD: A pre-post-treatment design was applied to 29 drug-naive schizophrenic inpatients, 18 male, mean age 32 years, 11 female, mean age 32 years, mean duration of illness 29 months. Psychopathological symptoms were assessed using PANSS, regional cerebral blood (rCBF) was measured by HMPAO-SPECT. RCBF values were calculated for 21 regions of interest after normalization to cerebellum, and plotted by Euklidean diagrams using the ordinal, nonmetric, multidimensional scaling method. These diagrams represent similarity correlations visualized as spatial distances. High correlation levels as indicated by small Euklidean distances have been interpreted as functional connectivity. RESULTS: In active schizophrenia, functional disconnectivity was observed between prefrontal and temporal cortex. After remission, connectivity was improved between temporolimbic and frontal cortex. CONCLUSION: Comparing active with remitted schizophrenia, a frontotemporal disconnectivity appears. Temporolimbic as well as frontolimbic connections restitute parallel to psychopathological improvement.

Adolescent↗

PubMed1999

Determination of cognitive hemispheric lateralization by "functional" transcranial Doppler cross-validated by functional MRI.

BACKGROUND AND PURPOSE: Changes of blood flow velocity in the right and left middle cerebral artery (MCA) induced by cognitive demands are detectable by means of "functional" transcranial Doppler sonography (fTCD). Functional MRI (fMRI) is an alternative method for mapping brain activity. The purpose of this study was to determine whether fTCD can detect hemispheric lateralization and to cross-validate fTCD with fMRI. METHODS: Bilateral continuous MCA monitoring of 14 healthy, right-handed subjects with TCD was performed while the subjects underwent a visuospatial task, and the hemispheric blood flow velocity shift was calculated. Identical stimulus and response patterns were used in fMRI. Blood oxygenation level-dependent fMRI was performed with the use of a gradient-echo echo-planar sequence on a 1.5-T scanner. Statistical maps were computed on a voxel-by-voxel basis, hemispheric ratios for activated pixels were computed, and a group study was performed separately for the male and female subgroups. RESULTS: Statistical analyses (t test) showed a significantly higher mean peak blood flow velocity increase (P<0.05) of the right MCA (111.3+/-7.0%) compared with the left MCA (107.1+/-6.1%). fMRI demonstrated bilateral activation in the superior parietal lobulus (Brodmann area 7) with a right/left ratio of 1.95. Concordant differences between the female and male subgroups could be visualized with both methods. CONCLUSIONS: Both methods succeeded in discriminating a blood flow shift to the right hemisphere induced by a complex cognitive visuospatial task. fMRI cross-validates the findings of fTCD. Our study suggests that fTCD can investigate the close relationship between brain activity and blood flow and lateralize higher cognitive functions reliably.

Adult↗

PubMed1999

Success rate of radioiodine therapy in Graves' disease: the influence of thyrostatic medication.

There is controversy whether simultaneous thyrostatic medication influences the outcome of radioiodine (131I) therapy in Graves' disease by reducing the absorbed energy dose of 131I when delivering a standard dose. We therefore sought to ascertain whether the outcome of ablative 131I therapy is in any way affected by simultaneous thyrostasis (carbimazole) by aiming for a constant absorbed dose of 200-250 Gy. We prospectively studied 207 patients with Graves' disease (106 with and 101 without simultaneous carbimazole at the time of 131I therapy). All patients were reexamined 3, 6, and 12 months after 131I therapy. The 101 nonthyrostatic patients showed a highly significantly greater success rate (93%) than the 106 thyrostatic patients (49%). Stepwise logistic regression demonstrated that failure was related to the administration of carbimazole during 131I therapy (P < 0.00005) and the absorbed dose (P < 0.025), but was not related to free T3, free T4, TSH receptor antibodies, or thyroid volume. The success rate was 100% in 93 nonthyrostatic patients with absorbed doses of 200 Gy or more, but was only 12.5% (1 of 8) for absorbed doses less than 200 Gy. Correlation between success and absorbed dose was significantly higher for nonthyrostatic than for thyrostatic patients (r = 0.93 vs. r = 0.24). Sixteen patients who discontinued thyrostasis 1-3 days before 131I therapy showed 94% successes. Simultaneous thyrostasis is the decisive factor against a successful 131I therapy even if the significantly reduced 131I uptake/half-life values under thyrostasis are compensated with a higher delivered dose to ensure a comparable absorbed dose, possibly due to the additionally effective radioprotective properties of carbimazole. Therefore, if clinically feasible, we recommend discontinuing thyrostasis at least 1 day before beginning 131I therapy, because even in hyperthyroid nonthyrostatic patients the success rate was 100%.

Adult↗

PubMed1998

The Thai version of the German Aachen Aphasia Test (AAT): description of the test and performance in normal subjects.

The Aachen Aphasia Test (AAT), originally developed as a test for aphasia language disorders in Germany, consists of six spontaneous speech rating scales and five subtests: Token Test, Repetition, Written Language, Confronting Naming and Comprehension. The study aimed to describe the linguistic properties of the AAT Thai version and to investigate the test performances of the normal subjects. In this study some problems of linguistic changes in the construction of the Thai version were discussed. The results revealed that the normal subjects' performances on the test were independent of age, sex and education level. Therefore, the Thai version of AAT is applicable to the differential diagnosis of the communicative abilities of Thai aphasic patients.

Adult↗

PubMed1997

Piracetam as an adjuvant to language therapy for aphasia: a randomized double-blind placebo-controlled pilot study.

OBJECTIVE: To determine whether piracetam 4.8 g/day together with intensive language therapy improved language function more than language therapy alone. DESIGN: Double-blind, placebo-controlled parallel group study. SETTING: Referral speech and language clinic of a university department of neurology. PATIENTS: Sixty-six inpatients with aphasia present between 4 weeks and 36 months. INTERVENTIONS: Intensive language therapy for 6 weeks in all patients. Thirty-two patients received piracetam 4.8 g daily and 34 patients received placebo. MAIN OUTCOME MEASURE: The Aachen Aphasia Test (AAT), a standardized procedure for evaluating the severity of aphasia, was performed at baseline and after 6 weeks' treatment. RESULTS: In 50 patients evaluated for efficacy, a trend toward improvement in the active group was observed in all subtests of the AAT. This trend was statistically significant for absolute differences in recovery of "written language" and "profile level." CONCLUSION: Piracetam appears to have a positive adjuvant effect on the recovery of aphasia in patients receiving intensive language therapy.

Adult↗

PubMed1997

Hemispheric asymmetry in the recognition of emotional attitude conveyed by facial expression, prosody and propositional speech.

In this study 27 patients with right hemisphere lesions, 25 patients with left hemisphere lesions and 26 normal control subjects were investigated for unimodal and simultaneous multimodal recognition of emotional attitude. All subjects were shown 330 videotaped items of 4 seconds duration, each of which was to be judged in terms of facial expression, emotional prosody and the emotional meaning of the underlying spoken sentence. In a preceding experiment comparable unimodal emotional stimuli were applied. The results suggest (a) right hemisphere superiority for recognition of emotions conveyed by facial and prosodic information, (b) a right hemisphere dominance for the recognition of fear and (c) no significant enhancement of right hemisphere superiority under multimodal presentation of emotional stimuli.

Adult↗

PubMed1997

Subjective experience in brain-injured patients and their close relatives: a European Brain Injury Questionnaire study.

Results are reported from an international project the aim of which has been to develop and validate a wide-ranging questionnaire suitable for administration to brain-injured patients and their relatives. A self-report questionnaire concerning subjective experience of cognitive, emotional and social difficulties (The European Brain Injury Questionnaire, EBIQ) was administered to a group of 905 brain-injured patients, and close relatives to these competed a parallel version of the questionnaire concerning the brain-injured person. The sample was drawn from seven European countries together with Brazil. The same questionnaire was also administered to a group of 203-non-brain-injured controls, similarly in self-report and relative-report versions. Scales relating to eight specific areas of functioning, together with a global scale, are derived from the questionnaire and their internal reliability was estimated in the present data. Analyses of the 63 items of the questionnaire showed consistently greater levels of problems for the brain-injured group, especially as indicated by relatives. This pattern was substantially replicated among the nine scales. The scales discriminated well between stroke patients and those who had suffered a traumatic brain injury. There was also a tendency for reported problems to be greater for patients who were surveyed later post-injury (> or = 19 months) rather than earlier. Comparison of sets of controls derived from two countries (France and Brazil) showed small but important differences. It is concluded that the questionnaire has an acceptable reliability and validity, but that it will be necessary to obtain culturally relevant non-brain-injured control data when employing it in different countries.

Adolescent↗

PubMed1995

Central nervous system lesions and cervical disc herniations in amateur divers.

Permanent neuropsychological changes such as memory disturbances and depression have been found in professional divers, even in those who have never had decompression sickness. The changes are probably the result of intravascular gas bubbles insufficient to cause acute symptoms. We examined amateur divers with long histories of self-contained underwater breathing apparatus diving by magnetic resonance imaging and compared them with normal controls. Hyperintense lesions of the subcortical cerebral white matter and degenerative changes of the cervical disks were significantly more common in the divers. 27 of 52 divers had a total of 86 focal hyperintensities versus 10 of 50 controls with 14 focal hyperintensities (p < 0.01). 32 divers had at least one degenerated intravertebral disc versus 9 controls (p < 0.0001). These results suggest that amateur divers are at risk of accumulating lesions in the central nervous system and in cartilage.

Adult↗

PubMed1995

Sensorimotor learning in ideomotor apraxia.

Sensorimotor learning ability in patients with ideomotor apraxia was investigated, using as subjects, eight patients with ideomotor apraxia, 8 with aphasia without ideomotor apraxia, and 8 normal controls. The aphasia, apraxia, and normal control groups were matched for age, sex, and education. The aphasia and apraxia groups were chosen to control for lesion size and scores on Kimura's recurring figure test, the Token test, and intelligence. The mirror-aiming test was performed and the learning effect in terms of decreases in total time, the number of errors, and the times for errors were examined. There was no statistically significant difference between the learning effect of the apraxic group and that of the aphasic group for total time, the number of errors, and the times for errors; however, there were group differences on each trial for number of errors and the times for errors. These results suggest that patients with ideomotor apraxia have some difficulties in motor performance rather than disturbance of learning.

Aphasia↗

PubMed1994

Transcranial Doppler ultrasonic assessment of middle cerebral artery blood flow velocity changes during verbal and visuospatial cognitive tasks.

Hemisphere specific changes of blood flow velocity in the right and left middle cerebral artery (MCA) induced by cognitive demands of verbal and nonverbal tasks were examined by means of a newly developed technique of simultaneous bilateral transcranial ultrasonic Doppler sonography (TCD). Thirty-one right-handed healthy volunteers served as subjects. Identical stimulus and response procedures were used with all tasks to avoid possible differential effects of these conditions on blood flow velocity. Compared to the preceding resting phase, the increase in flow velocity induced by each of the verbal tasks (sentence completion, similar or contrasting word meaning, similarities) proved to be significantly higher in the left than in the right MCA. Among the non-verbal visuospatial tasks only the "identical pictures" (perceptual speed) task led to a complementary higher increase in right MCA blood flow velocity. No such asymmetry in blood flow acceleration was observed, however, with the tasks "figure assembly" and "cube comparison" which require visualization and mental rotation of figures. The findings underline the recently emerging uncertainty in neuropsychological research with regard to the functional specialization of the right hemisphere.

Adult↗

PubMed1993

The case of aphasia or neglect after striatocapsular infarction.

The occurrence of aphasia or neglect was related to anatomo-structural (CT/MRI), functional [regional cerebral blood flow (rCBF)] and pathogenetic features [duration of middle cerebral artery (MCA) occlusion and degree of cortical leptomeningeal anastomoses] in 57 cases (26 with and 31 without aphasia or neglect) with strictly subcortical infarcts of one defined type, i.e. striatocapsular infarcts. No distinct pattern of language disturbances was found. Aphasic syndromes did not differ in the amount of involvement of the putamen, pallidum, head of caudate nucleus and white matter. Patients with aphasia or neglect had larger infarcts than those without. However, there was no specific involvement of the basal ganglia, the internal capsule or the deep white matter in patients with aphasia or neglect. Patients with aphasia or neglect had a significantly longer duration of MCA occlusion and mostly poor leptomeningeal collaterals. The cortical rCBF was significantly decreased in the cortical MCA territory in the patients with aphasia or neglect only. The rCBF remained low at follow-up after 1 year and corresponded to focal cortical atrophy on MRI, although neglect had subsided completely in all patients and aphasia had improved considerably in almost 75% of the cases. Aphasia or neglect after striatocapsular infarcts are most likely due to selective neuronal loss of the cerebral cortex due to prolonged MCA occlusion and insufficient collateral blood flow. Individual differences in recovery from aphasia after striatocapsular infarction can be explained in terms of the number of surviving cortical neurons.

Adolescent↗

PubMed1993

To what extent can aphasic syndromes be localized?

Modern views on the representation of function in the cortex make it difficult to maintain the notion that specific subtypes of aphasia are associated with specific centres within the language area. We have conducted a retrospective study on 221 aphasic patients with one contiguous vascular lesion in the territory of the middle cerebral artery. The localization of CT lesions was established within a standardized grid model. Aphasiological data were based on one or more examinations with the Aachen Aphasia Test. Both sets of data were processed in a data- and methodbase system. No unequivocal association between type of aphasia and localization of lesion was found. In a smaller study, participation of basal ganglia and in particular of the head of the caudate nucleus in lesions producing aphasia was not confirmed. Concepts of the localization of a lesion in aphasia must account for changes in patterns of aphasic symptoms in the presence of a stable lesion and for the impact of the neurological condition that has produced the lesion.

Adult↗

PubMed1992

[The Aachen Aphasia Bedside Test--criteria for validity of psychologic tests].

The Aachen Aphasia Bedside Test (AABT) has been developed in order to examine aphasic patients within the first 4 to 6 weeks after onset of illness. The psychometric properties of the AABT were established by repeated examination of 82 acute stroke patients, ratings by 20 raters on the basis of 10 videotapes, repeated examination of 28 chronic aphasics three times with an interval of 2 days, and parallel examination of 47 chronic aphasic patients with the AABT and the Aachen Aphasia Test (AAT), administered on the same day. Objectivity, reliability and validity of the AABT were highly rated, indicating its usefulness in acute stroke cases. Data on the 82 acute stroke patients showed that an initial prognosis can be made as early as the fourth day after the stroke.

Adult↗

PubMed1992

[Topography of early cortical median nerve somatosensory evoked potentials: results for routine use of the method].

The results from a topographic analysis of the early median nerve SEPs allowed to design a method for recording and analysing the SEPs in the routine laboratory. The detailed analysis of the topography of 50 normal subjects revealed: 1. An inter- and intraindividual variability of the location of the maximal amplitudes, 2. A significantly longer latency of the cortical potentials after left side stimulation, 3. A significantly higher amplitude of N20 after left side stimulation and 4. A significantly higher amplitude of the later potentials P25 and N30 after right side stimulation. It was shown that a 4-channel recording from the neck at C7 with a Fz-reference as well as from stimulus contralateral F3, CP3 and P3 or F4, CP4 and P4 with an stimulus contralateral earlobe reference provides all necessary parameters in comparison to an 20-channel recording. The definition of normal values has to take into account these results. Absolute maximum values were taken instead of the standard deviation because all amplitude values were proven to be not distributed normally. In 7 out of 30 MCA-stroke patients pathological SEP amplitudes were obtained using the 4-channel montage, whereas the 1-channel recording from CP3 and CP4 with a Fz-reference revealed normal amplitudes.

Adult↗

PubMed1991

Interrater agreement for CT scans of patients with lacunar infarcts and leuko-araiosis.

A total of 74 CT scans from patients with lacunar syndromes were presented to 10 raters, most of them experienced in neuroradiology. The attributes to be judged were: lacunar infarcts (yes/no), leuko-araiosis (decreased density of the cerebral white matter) (yes/no), cortical atrophy (yes/no), and normal (yes/no). The chance corrected kappa coefficients were 0.641 for decreased density, 0.445 for lacunar infarcts and 0.206 for cortical atrophy. Taking into consideration the attribute cortical atrophy, the kappa coefficient for the attribute normal was 0.330, and without taking cortical atrophy into consideration, it was 0.523. Studies of lacunar infarcts and of leuko-araiosis should be based on clear definitions in order to guarantee a minimum level of interrater agreement.

Atrophy↗

PubMed1991

[A test for the detection of speech and language disorders in the acute phase after stroke. Development and clinical application].

No standardized assessment of aphasic symptoms for stroke patients in the acute phase has as yet been published in the German language. Current test batteries such as the AAT are too time-consuming and cannot be performed on severely impaired patients. A short test for the examination of aphasic and dysarthric symptoms has been developed which contains 7 subtests in three main areas: spontaneous speech, comprehension and planning of movements, speech and language abilities. Since abilities in acute cases may only be functionally impaired and often only detectable after stimulation, standardized stimulation is applied in most of the subtests. In this way it is possible to test acute stroke patients for aphasic and dysarthric symptoms. The course of recovery in a typical case is described.

Aged↗