Motohiko Hara

Comparison of quantitative EEGs between Parkinson disease and age-adjusted normal controls.

Summary: Quantitative EEG (qEEG) findings in Parkinson disease (PD) have been reported in only five previous studies. In these studies, the sample size was small and the distribution of qEEG changes was not estimated. This is the first qEEG evaluation not only employing multiple logistic regression analysis but also estimating the distribution of qEEG changes. The subjects comprised 45 PD patients without remarkable dementia and 40 age-adjusted normal controls. The lack of ischemic lesions in all subjects was confirmed by MRI. Absolute power values were measured for four frequency bands from delta to beta. The electrodes were divided into six, viz. frontal pole, frontal, central, parietal, temporal, and occipital locations. We calculated the spectral ratio, i.e., the sum of the power values in the alpha and beta waves divided by the sum of the values in the slow waves. The dependent variable was either PD or normal control; the independent variables were the spectral ratios, age, sex, and Mini-Mental State Examination score. The significant predictive variables in PD were the spectral ratios at all electrode locations except for the frontal pole (frontal location: P = 0.025, other locations: P < 0.01). PD presented diffuse slowing in the qEEG when compared with age-adjusted normal controls.

Nested polymerase chain reaction for assessing the clinical course of tuberculous meningitis

The authors examined the usefulness of nested PCR (N-PCR) to detect Mycobacterium tuberculosis (MTB) DNA in CSF for assessing the clinical course of tuberculous meningitis (TBM). N-PCR successfully detected MTB DNA in all nine CSF samples from patients with suspected TBM. During anti-tuberculosis treatments, N-PCR results converted from positive to negative, correlating with the improvement of the patient’s clinical condition.

Effects of Intravenous L-Dopa on P300 and Regional Cerebral Blood Flow in Parkinsonism

The P300 and regional cerebral blood flow were measured before and after intravenous injection of L-dopa in 10 patients with idiopathic Parkinsons disease and 10 patients with vascular parkinsonism. The P300 was measured with an evoked potential recorder using an oddball paradigm and the regional cerebral blood flow was measured using the stable xenon computed tomography method. The P300 latency was significantly longer and the regional cerebral blood flow in the cerebral cortex and basal ganglia was significantly lower in the Parkinsons disease group and the vascular parkinsonism group than in the age-matched healthy control group. The intravenous injection of L-dopa improved these abnormalities significantly in the Parkinsons disease group but did not improve these abnormalities in the vascular parkinsonism group. Cognitive function is considered to be impaired in Parkinsons disease and vascular parkinsonism and L-dopa is considered to improve it in Parkinsons disease.

Executive dysfunction using behavioral assessment of the dysexecutive syndrome in Parkinson's disease†

The objective of this study was to evaluate the executive dysfunction (ExD) in Parkinsons disease (PD) using the Behavioral Assessment of the Dysexecutive Syndrome (BADS), which provides a wide‐range assessment of ExD. The BADS and the Unified Parkinsons Disease Rating Scale (UPDRS) were investigated in 63 nondemented PD patients who revealed scores of ≥24 points on the Mini‐Mental State Examination based on the DSM‐IV. Multiple logistic regression analysis was performed to evaluate the predisposing factors to ExD, which was defined as <70 points on the age‐controlled standardized score. The total score on the UPDRS was a significant independent predisposing factor to ExD. Among the various parts of the UPDRS, part II was the significant factor for ExD. The profile scores of all subtests on the BADS in patients with ExD were significantly lower than those of patients without ExD. All profile scores decreased with severity of PD, but the changes among these scores differed. ExD in nondemented PD predisposed to a greater severity of PD, particularly as regards the activity of daily living impairment. Nondemented PD revealed wide‐range components of ExD. All components of ExD were impaired with severity of PD, but the patterns of each component exhibited variety.

Effect of motion imagery to counter rest-induced suppression of F-wave as a measure of anterior horn cell excitability

OBJECTIVE To test if motor imagery prevents the rest-induced suppression of anterior horn cell excitability. METHODS Ten healthy subjects underwent two separate experiments, each consisting of stimulating the median nerve 100 times and recording F-waves from abductor pollicis brevis (APB) in three consecutive sessions: (1) after muscle exercise to standardize the baseline, (2) after immobilization of APB for 3h and (3) after muscle exercise to check recovery. We instructed the subject to volitionally relax APB in experiment 1 (relaxation task), and to periodically simulate thumb abduction without actual movement in experiment 2 (imagery task). RESULTS F-wave persistence and amplitude declined after relaxation task and recovered quickly after exercise, but changed little with imagery task. F-wave latencies showed no change when analyzed individually. The frequency distribution of collective F-waves recorded from all subjects remained the same after relaxation task, but showed a shift toward longer latencies after imagery task. CONCLUSIONS Mental imagery without overt motor output suffices to counter the effect of sustained volitional muscle relaxation, which would, otherwise, cause a reversible reduction in anterior horn cell excitability. SIGNIFICANCE This finding documents the importance of central drive for spinal excitability, which affects F-wave studies of a paretic muscle.

Effect of motor imagery and voluntary muscle contraction on the F wave.

We tested the validity of instructing patients to minimally contract the muscle to facilitate F‐wave recording in clinical practice. In 12 healthy subjects, F waves were recorded from the first dorsal interosseous muscle at rest, during motor imagery, and at up to 30% of the maximal voluntary contraction (MVC). F‐wave persistence increased significantly from 32.5 ± 11.9% (mean ± SD) at rest to 58.3 ± 15.2% during motor imagery and 90.0 ± 8.7% during 3% MVC. It then remained the same during stepwise changes to and from 30% MVC before decreasing significantly from 80.8 ± 18.5% during 3% MVC to 48.7 ± 23.8% during motor imagery and 27.0 ± 16.0% at rest. The trial average of F‐wave amplitude showed a similar pattern of facilitation. Motor imagery enhances F‐wave persistence and amplitude, which further increase with a slight muscle contraction and show no additional change with a stronger effort. Muscle Nerve, 2010

Effect of volitional relaxation and motor imagery on F wave and MEP: do these tasks affect excitability of the spinal or cortical motor neurons?

OBJECTIVE To test if simple motor imagery, like thumb abduction, preferentially influences the excitability of the spinal or cortical motoneurons. METHODS Ten healthy subjects underwent two separate experiments, each consisting of recording F waves and MEPs from abductor pollicis brevis (APB) in three consecutive sessions: (1) baseline, (2) after immobilizing APB for 3 h, and (3) after brief muscle exercise. During the immobilization, the subjects were instructed to volitionally relax APB in experiment 1 (relaxation task), and mentally simulate thumb abduction without actual movement in experiment 2 (imagery task). RESULTS Relaxation task suppressed both MEPs and F waves. Motor imagery reduced this suppression, restoring F waves nearly completely (94%) and MEPs only partially (77%). Hence, the rest-induced decline of MEPs in part results from cortical modulation. In contrast, statistical analysis revealed no differences in imagery-induced recovery of motoneuron excitabilities whether assessed by F wave or MEP. Thus, increased excitability of spinal motoneurons responsible for F-wave changes also accounts for recovery of MEPs. CONCLUSIONS Volitional relaxation depresses the spinal and cortical motoneurons, whereas mental simulation counters rest-induced suppression primarily by restoring spinal excitability. SIGNIFICANCE The present findings help elucidate physiologic mechanisms underlying motor imagery.

Motor imagery facilitates the spinal motor neurons without hemispheric asymmetry.

Purpose: To determine possible hemispheric differences of motor imagery in facilitating the anterior horn cells. Methods: We conducted a side-to-side comparison of motor imagery to counter rest-induced suppression of spinal motor neurons in 10 right-handed healthy adults using the F wave as a measure of excitability. Studies consisted of sequential recording of F waves from the abductor pollicis brevis with 100 supramaximal stimuli applied to the median nerve on three consecutive sessions: (1) after standardized hand exercise to establish the baseline; (2) after immobilizing abductor pollicis brevis bilaterally for 3 hours, with one side assigned to relaxation task and the other side to motor imagery task; and (3) after standardized hand exercise to assess a recovery. The same sequence was repeated, switching the side of relaxation and motor imagery tasks. Results: F-wave persistence and average amplitude showed a significant decrease (P < 0.01) from baseline after relaxation task, recovering quickly after exercise, but no change (P > 0.05) after motor imagery task. The results showed no significant differences (P > 0.05) between dominant and nondominant hands. Conclusion: Motor imagery facilitates the spinal motor neurons without hemispheric asymmetry.

Regional Cerebral Blood Flow in Lacunar Infarction

Ten cases of lacunar infarction, 10 cases of nonlacunar cerebral thrombosis, and 8 healthy controls who did not have risk factors of cerebrovascular diseases were studied. Subcortical cystic infarctions with a diameter of less than 1.5 cm were classified as lacunar infarction and the other cerebral thrombosis were classified as nonlacunar cerebral thrombosis. Cerebral blood flow examination by Xenon computed tomography (CT) method was performed within 14 days after the onset of stroke. Stable Xenon was inhaled for 3 minutes and CT scan was taken once before the inhalation, 3 times during the inhalation, and 5 times in the washout phase. Regional blood flows in the infarcted area, around the infarcted area, and in the cerebral cortex and the cerebral white matter where the influence of the infarction was considered to be little were measured before and after intravenous injection of 17 mg/kg acetazolamide. In the lacunar infarction, the blood flow in the cerebral cortex where the influence of the infarction was considered to be little was decreased and the cerebrovascular dilatory reserve capacity in the cerebral cortex and the cerebral white matter was decreased. Arteriolosclerosis is considered to be the basic cause of lacunar infarction.

P300 and cerebral blood flow before and after TRH in olivopontocerebellar atrophy

Ten cases of olivopontocerebellar atrophy (OPCA) (mean age 56 +/- 9 years) and 8 healthy controls (mean age 58 +/- 9 years) were studied. The P300 was measured with a Synax 1100 evoked potential recorder and the regional cerebral blood flow was measured using the stable xenon computed tomography method. The P300 latency was significantly longer in the OPCA group than in the healthy control group. The P300 latency after the intravenous infusion of thyrotropin releasing hormone (TRH) in the OPCA group was significantly shorter than that before the intravenous infusion of TRH. The blood flows in all the measured areas (the cerebellar cortex, the cerebellar white matter, the brainstem, the thalamus, the basal ganglia, the frontal lobe cortex and the frontal lobe white matter) were significantly lower in the OPCA group than in the healthy control group. The blood flows in the cerebellar cortex and in the frontal lobe cortex after the intravenous infusion of TRH were significantly higher than those before the intravenous infusion of TRH. The prolongation of P300 latency in the OPCA group suggests that subclinical disturbance in recognition function is present in OPCA and may be related to the blood flow decrease outside the cerebellum.