Masanaka Takeda

Slowly progressive limb-kinetic apraxia with a decrease in unilateral cerebral blood flow.

We report two patients with slowly progressive motor disorders, whose principal manifestations were asymmetric limb‐kinetic apraxia and muscle rigidity. In both patients MRI revealed no responsible lesion, whereas single photon emission computed tomography (SPECT) showed a decrease in cerebral blood flow (CBF) in the unilateral hemisphere. One patient with mainly right‐sided apraxia had a decreased CBF in the left central region between the frontal and parietal cortices, and the other patient with left‐sided apraxia in the right parietal cortex. In agreement with asymmetric clinical symptoms, the regional CBF decrease in the unilateral cortical areas including the frontal and parietal cortices may suggest a degenerative disease, presumably diagnosed as having corticobasal degeneration.

Comparison of Brain Perfusion in Corticobasal Degeneration and Alzheimer’s Disease

To compare brain perfusion between corticobasal degeneration (CBD) and Alzheimer’s disease (AD), we measured regional cerebral blood flow (rCBF) semiquantitatively with single-photon emission computed tomography in 10 patients with CBD and 16 with AD. There was no significant difference in age or illness duration between the patients with CBD and AD. Mini-Mental State Examination scores were significantly lower in the AD patients than in the CBD patients. All CBD patients showed asymmetric akinetic-rigid syndrome and limb apraxia. Four CBD patients were demented, and 1 AD patient had parkinsonism. Compared with 12 age-matched control subjects, the average of the left and right rCBF values for the CBD patients was significantly reduced in the prefrontal, anterior cingulate (AC), medial premotor, sensorimotor (SM), posterior parietal (PP) and superior temporal (ST) cortices as well as in the basal ganglia (BG) and thalamus (Th), while the prefrontal, PP and ST cortices were significantly hypoperfused in the AD patients. In the CBD patients, rCBF was significantly less in the AC and SM cortices, and in the Th and BG, and significantly greater in the PP cortex than in the AD patients. Interhemispheric differences of rCBF in the inferior prefrontal and SM cortices were significantly greater in the CBD patients than the AD patients. It is concluded that rCBF comparison may aid in differentiating CBD from AD.

Focal cortical hypoperfusion in corticobasal degeneration demonstrated by three-dimensional surface display with123I-IMP: a possible cause of apraxia

To clarify cortical lesions responsible for apraxia in corticobasal degeneration (CBD), we reconstructed three-dimensional surface images from single-photon emission computed tomography (SPECT) data withN-isopropyl-p[I-123]-iodoamphetamine in two patients with CBD. Both had limb-kinetic apraxia (LKA) and one also had constructional apraxia (CA). Both showed asymmetrical cortical hypoperfusion in the perirolandic area. The patient with CA had unilateral hypoperfusion in the posterior parietal area. Thus, cortical hypoperfusion in the perirolandic area corresponded to LKA, and that in the posterior parietal area to CA.

Electrophysiological comparison between corticobasal degeneration and progressive supranuclear palsy

Multimodal evoked potentials were recorded in four patients with corticobasal degeneration (CBD), four patients with progressive supranuclear palsy (PSP) and 15 normal control subjects. CBD and PSP patients showed significant prolongation of the N200 and P300 latencies of auditory event-related potentials compared with controls. Patients with CBD showed significant prolongation of interpeak latencies between N13 and N20 of short-latency somatosensory evoked potentials compared with the controls and patients with PSP. The present results show that the two diseases have different electrophysiologic features.

Event-related potentials reveal memory deficits in Parkinson's disease.

To evaluate whether patients with Parkinsons disease (PD) exhibit deficits in memory tested indirectly, we measured event-related potentials (ERPs) in 23 patients with nondemented PD and 14 age-matched control subjects. The auditory N400 component was measured during an indirect repetition priming paradigm. Some words were repeated immediately after initial presentation (lag 0), while others were repeated after five intervening words (lag 5) or at lags 11-77. Subjects were required to push a button to the occasional nonwords (targets). The N400 amplitudes were quantified in latency window between 300 and 800 ms for the different conditions. The N400 amplitudes for the first presentation were significantly lower in PD patients than controls for both words and nonwords. The N400 in the control group was attenuated for lag 0, lag 5, and lags 11-77 repetitions, while the attenuation in PD patients was noted only for lag 0 repetition. The data suggest that memory assessed in this fashion is impaired in PD patients.

Asymmetric changes in somatosensory evoked potentials correlate with limb apraxia in corticobasal degeneration

To clarify the underlying mechanism of limb apraxia in corticobasal degeneration (CBD), we investigated somatosensory evoked potentials in 5 patients with CBD, as compared with 12 age‐matched control subjects. All patients presented with asymmetric limb apraxia, particularly of limb‐kinetic type. N20 latencies were significantly prolonged following median nerve stimulation on the more apraxic side, but not on the less apraxic side. These results suggest that limb apraxia in CBD may, at least in part, be due to a disorder of somatosensory information processing involving the parietal cortex.

Multimodal evoked potentials in Alzheimer's disease and Binswanger's disease

Somatosensory evoked potentials (SEPs), brainstem auditory evoked potentials (BAEPs), visual evoked potentials (VEPs), and auditory event-related potentials (ERPs) were studied in 15 patients with Alzheimers disease (AD), eight patients with Binswangers disease (BD), and 15 normal subjects. Patients with BD showed significant prolongation of the interpeak latency between N13 and N20 (N13-N20) and N20-P40 of SEPs as compared with the normal controls, whereas patients with AD only demonstrated significant prolongation of N20-P40. The interpeak latency between waves I and V of BAEPs in patients with both AD and BD was significantly longer than that of controls. There were no significant differences in P100 latency of VEPs among these three groups. Both groups with dementia showed significant prolongation of N200 and P300 latencies of ERPs compared with normal controls. In addition, patients with AD showed significant prolongation of P200 latency. We conclude that these two dementing diseases have different electrophysiologic features that may be related to their underlying pathogenetic mechanisms. Furthermore, the measurement of multimodal evoked potentials may be helpful in the differential diagnosis of AD and BD.

Short-Latency Somatosensory and Brainstem Auditory Evoked Potentials in Patients with Parkinson's Disease

Short-latency somatosensory evoked potentials (SSEPs) and brainstem auditory evoked potentials (BAEPs) were recorded in 44 patients with Parkinsons disease (mean age 67.3 years) and 23 normal subjects (mean age 69.3 years). Patients with Parkinsons disease and normal subjects did not show any significant difference with regard to the interpeak latencies between N13 and N20 central conduction time (CCTs). Likewise, there were no significant differences in CCTs between patients with and without dementia. The interpeak latencies between waves I and V (I-V IPLs) in patients with Parkinsons disease were significantly longer than those of the normal subjects (p less than 0.05). In particular, patients with dementia revealed significant prolongation of I-V IPLs compared to patients without dementia and normal subjects (p less than 0.01, p less than 0.001) although no significant differences were observed between patients without dementia and normal subjects. These results show that auditory brainstem pathways are involved in Parkinsons disease patients with dementia.

Cerebral Blood Flow Correlates of Higher Brain Dysfunctions in Corticobasal Degeneration

To investigate clinicoanatomic correlations of higher brain dysfunctions in corticobasal degeneration, regional cere bral blood flow (rCBF) was semiquantitatively measured with single-photon emission computed tomography in 9 patients with corticobasal degeneration and 12 age-matched control subjects. The patients showed significant reduc tions of relative tracer uptake in widespread cortical areas, as well as the basal ganglia and thalamus. Interhemispheric difference of hypoperfusion was significant in the sensorimotor and posterior parietal cortices. Asymmetric limb apraxia and cortical sensory disturbance corresponded to either sensorimotor cortical or posterior parietal cortical hypoperfusion or both. Compared with the patients without dementia, those with dementia showed significant reductions of relative rCBF in the inferior prefrontal region in the more affected hemisphere. The unique correla tion of cortical signs with regional hypoperfusion may be useful in distinguishing between corticobasal degeneration and other neurodegenerative diseases. (J Geriatr Psychiatry Neurol 1999; 12:189-193).

Visual form agnosia in multiple sclerosis

We report a case of multiple sclerosis with visual form agnosia and callosal syndromes. Initially, the patients visual recognition of object form was severely disturbed at the perceptual stage, in association with left‐sided ideomotor apraxia and agraphia. Magnetic resonance imaging showed large white matter lesions in the bilateral frontal and occipital lobes, the latter extending to the occipitotemporal junction, and widespread corpus callosum lesions. Over the course of one year follow‐up, neuropsychological examinations indicated that the patients visual recognition defects occurred not only at the early substage of form perception, but also at the stage of reproducing the shape of objects from visual memory store. The present case suggests that neural connections between the striate cortex and occipitotemporal visual areas are crucial for both the perceptual and associative stages of visual object recognition.