[Movement Disorders and Rehabilitation in Idiopathic Normal Pressure Hydrocephalus].

Movement disorders, particularly gait and balance disturbances can lead to falls and reduced daily activities in patients with idiopathic normal pressure hydrocephalus (iNPH). In this study, we investigate movement disorders from both the pathophysiological and kinematic perspectives in patients with iNPH. Additionally, we discuss essential factors that should be evaluated before and after cerebrospinal fluid tap tests and shunt surgeries and considerations for assessment of fall risk in patients with iNPH. Additionally, we describe the most recent findings on rehabilitation of iNPH patients.

Rehabilitation effects in idiopathic normal pressure hydrocephalus: a randomized controlled trial.

BACKGROUND: Gait-balance disturbances are core symptoms of idiopathic normal pressure hydrocephalus (iNPH). However, the rehabilitation effects of cerebrospinal fluid (CSF) shunting along with other treatment or no further treatment (natural course [NC]) for iNPH are unknown. OBJECTIVES: This study evaluated whether dynamic equilibrium gait training (DEGT) can improve gait-balance functions after CSF shunting of patients with iNPH compared to standard exercise (SE) and NC. Furthermore, it investigated the incidence of falls. METHODS: A total of 70 patients with iNPH who underwent CSF shunting were randomly assigned to 6 weeks of DEGT (n = 23), 6 weeks of SE (n = 23), or NC (n = 24). Evaluation was performed at baseline (preoperatively) and at 1 week, 7 weeks (postintervention), and 6 months postoperatively (follow-up). Outcomes were measured using the functional gait assessment (FGA), 10-m walk test, timed up-and-go test, life-space assessment (LSA), and fall incidence. RESULTS: A total of 65 participants completed the study. During the intention-to-treat analysis, the DEGT group demonstrated significant recovery of gait-balance functions according to only the FGA at postintervention and follow-up compared to the SE and NC groups; however, recovery of the SE group did not differ from that of the NC group. The DEGT group had a significantly lower fall incidence than the other groups at follow-up. Significantly better LSA results were observed for all groups at follow-up compared to baseline; however, no difference in LSA results were observed between groups. CONCLUSIONS: DEGT in addtion to CSF shunting can facilitate the recovery of gait-balance function and reduce the fall incidence of iNPH patients.

Dynamic gait stability in patients with idiopathic normal pressure hydrocephalus with high and low fall-risk.

BACKGROUND: This study aimed to investigate whether dynamic gait stability differs between idiopathic normal-pressure hydrocephalus with high- and low-fall-risk. METHODS: Participants comprised 40 idiopathic normal-pressure hydrocephalus patients and 23 healthy-controls. Idiopathic normal-pressure hydrocephalus patients were divided into those with high-fall-risk (n = 20) and low-fall-risk (n = 20) groups using the cut-off score of ≤14/30 for fall-risk on the Functional Gait Assessment. Dynamic stability during gait was assessed by three-dimensional motion analysis. Dynamic stability was defined as the ability to maintain an extrapolated center of mass within the base of support at heel contact, with the distance between the two defined as the margin of stability. Conscious motor control was assessed by the Movement-Specific Reinvestment Scale. FINDINGS: Anteroposterior and mediolateral margin of stabilities were significantly larger in both idiopathic normal-pressure hydrocephalus groups than in healthy-controls. The mediolateral margin of stability was significantly higher in the high-fall-risk group than in the low-fall-risk group; whereas, the anteroposterior margin of stability did not differ between idiopathic normal-pressure hydrocephalus groups. The Movement-Specific Reinvestment Scale was significantly higher in the high-fall-risk group than in the low-fall-risk group. INTERPRETATION: Idiopathic normal-pressure hydrocephalus patients with have high forward and lateral dynamic stability during gait regardless of their fall-risk. In particular, idiopathic normal-pressure hydrocephalus patients with high-fall-risk may consciously maintain lateral dynamic stability to a greater extent than those with low-fall-risk. These findings highlight a conscious motor control component in the pathological gait of idiopathic normal-pressure hydrocephalus, and provide clues for rehabilitation and fall prevention strategies in idiopathic normal-pressure hydrocephalus patients.

Mediolateral Postural Control during Gait in Parkinson's Disease.

Objectives: Balance in the mediolateral direction is usually maintained in patients with early-stage Parkinson's disease (PD), but not in moderate-stage PD as revealed by the Tandem Gait Test. Although mediolateral postural control in PD patients remains controversial, previous studies have shown that the Tandem Gait Test may predict the risk of future falls in patients with PD. This study aimed to clarify postural control differences among PD patients with and without mediolateral balance impairments (MLBI: mediolateral balance impairments, nMLBI: non-mediolateral balance impairments, respectively) and healthy controls (HCs). Methods: We recruited 40 PD patients and 20 HCs. According to the Tandem Gait Test score, PD patients were divided into MLBI and nMLBI groups. Primary outcome measures were the ambulatory movement trajectory amplitude of the center of mass and its coefficient of variation (CV) during gait. Results: Mediolateral movement trajectory amplitudes and CV were not significantly different between the nMLBI group and HCs, whereas the mediolateral movement trajectory amplitude in the MLBI group was significantly higher than that in the nMLBI group. Moreover, the CV of the mediolateral movement trajectory amplitude in the MLBI group was significantly lower than that in the nMLBI group. The mediolateral movement trajectory amplitude was significantly correlated with the fall score. Conclusions: The current results suggest that PD patients with mediolateral balance impairments showed mediolateral postural sway during gait compared with PD patients without mediolateral balance impairments. It is necessary to focus on the instabilities in the mediolateral direction to avoid falls in PD patients.

Corrigendum: Evaluation of the Effectiveness of the Tap Test by Combining the Use of Functional Gait Assessment and Global Rating of Change.

[This corrects the article DOI: 10.3389/fneur.2022.846429.].

Impact of Early Intervention for Idiopathic Normal Pressure Hydrocephalus on Long-Term Prognosis in Prodromal Phase.

Objectives: Because the progression of idiopathic normal pressure hydrocephalus (iNPH) is partially irreversible, we hypothesized that early intervention would markedly improve its prognosis. To test this hypothesis, we retrospectively investigated the long-term prognosis of patients with early intervention in the prodromal phase of iNPH. Methods: We defined the prodromal phase of iNPH as a 3m Timed Up and Go (TUG) of 13.5 s or less and a Mini-Mental State Examination (MMSE) of 24 or more. Of the 83 iNPH patients who underwent shunt surgery at Osaka Medical and Pharmaceutical University Hospital over 3 years from January 2015, 12 prodromal phase cases (73.3 ± 6.2 years, 10 males and 2 females) were included in the study. The iNPH grading scale (INPHGS), MMSE, Frontal Assessment Battery (FAB), intermittent gait disturbance (IGD), social participation status, and development of comorbidities were evaluated over 4 years. Results: Preoperative MMSE was 27.2 ± 1.5, FAB was 14.1 ± 1.8, TUG was 10.7 ± 1.4 s, and total iNPHGS was 2.8 ± 1.4. At 1, 2, 3, and 4 years postoperatively, total INPHGS improved to 0.8, 0.9, 1.5, and 1.7, respectively, and remained significantly better than preoperatively except at 4 years postoperatively. The MMSE improved slightly to 27.5 after 1 year and then declined by 0.35 per year. After 4 years, the mean MMSE was 26.1, and only one patient had an MMSE below 23. FAB improved to 15.2 after 1 year and then declined slowly at 0.85/year. Ten patients (83%) maintained a high capacity for social participation postoperatively. The preoperative tendency to fall and IGD in 9 (75%) and 8 (67%) patients, respectively, completely disappeared postoperatively, resulting in improved mobility. Shunt malfunction associated with four weight fluctuations and one catheter rupture caused temporary worsening of symptoms, which were recovered by valve re-setting and catheter revision, respectively. Conclusion: Early intervention in the prodromal phase of iNPH patients maintained good cognitive and mobility function and social participation ability in the long term. The maintenance of long-term cognitive function suggests its preventive effect on dementia. To realize early intervention for iNPH, it is desirable to establish an early diagnosis system for iNPH.

Dynamic stability during gait in idiopathic normal pressure hydrocephalus and Parkinson's disease.

OBJECTIVES: To clarify a characteristic of dynamic stability during gait in idiopathic normal pressure hydrocephalus (iNPH) and Parkinson's disease (PD), and to explore the association between dynamic stability and disease severity in each disease. MATERIALS AND METHODS: The 5-m gait of 36 iNPH (precerebrospinal fluid drainage), 20 PD (medicated state), and 25 healthy controls (HC) were evaluated using three-dimensional motion analysis. Ambulatory dynamic stability was defined as the ability to maintain the extrapolated center of mass within the base of support at heel contact, with the distance between the two referred to as the margin of stability (MOS). RESULTS: Anteroposterior direction (AP) MOS was significantly larger in the iNPH and PD groups than in the HC group; no significant difference was found between the iNPH and PD groups. Mediolateral direction (ML) MOS was significantly larger in the iNPH and PD groups than in the HC group and significantly larger in the iNPH group than in the PD group. In the iNPH group, the disease severity was positively correlated with only ML MOS. In the PD group, the disease severity was positively correlated with the AP MOS and ML MOS. CONCLUSIONS: Dynamic stability in iNPH increases in AP and ML, and it may be associated with not only iNPH-associated gait disturbance but also with a voluntarily cautious gait strategy. Dynamic stability in PD only increased in AP, and this may be associated with PD symptoms. These findings will help physicians understand the difference in pathological gait including dynamic stability between patients with iNPH and PD.

Effectiveness of Long-Term Physiotherapy in Parkinson's Disease: A Systematic Review and Meta-Analysis.

BACKGROUND: Long-term physiotherapy is acknowledged to be crucial to manage motor symptoms for Parkinson's disease (PD) patients, but its effectiveness is not well understood. OBJECTIVE: This systematic review and meta-analysis aimed to assess the evidence regarding the effectiveness of long-term physiotherapy to improve motor symptoms and reduce antiparkinsonian medication dose in PD patients. METHODS: Pubmed, Cochrane, PEDro, and CINAHL were searched for randomized controlled trials before August 31, 2020 that investigated the effectiveness of physiotherapy for 6 months or longer on motor symptoms and levodopa-equivalent dose (LED) in PD patients with Hoehn and Yahr stage 1- 3. We performed random effects meta-analyses for long-term physiotherapy versus no/control intervention and estimated standard mean differences with 95% confidence intervals (CIs). Levels of evidence were rated by the Grading of Recommendation Assessment, Development and Evaluation approach. RESULTS: From 2,940 studies, 10 studies involving 663 PD patients were assessed. Long-term physiotherapy had favorable effects on motor symptoms in off medication state [- 0.65, 95% CI - 1.04 to - 0.26, p = 0.001] and LED [- 0.49, 95% CI - 0.89to - 0.09, p = 0.02]. Subgroup analyses demonstrated favorable effects on motor symptoms in off medication state by aerobic exercise [- 0.42, 95% CI - 0.64 to - 0.20, p < 0.001] and LED by multidisciplinary rehabilitation of primarily physiotherapy [- 1.00, 95% CI - 1.44 to - 0.56, p < 0.001]. Quality of evidence for aerobic exercise and multidisciplinary rehabilitation were low and very low. CONCLUSION: This review provided evidence that long-term physiotherapy has beneficial impact on motor symptoms and antiparkinsonian medication dose in PD patients and could motivate implementation of long-term physiotherapy.

Forward gait instability in patients with Parkinson's disease with freezing of gait.

Freezing of gait (FOG) appears to be associated with increased risk of forward falls in patients with Parkinson's disease (PD). This study aimed to experimentally validate forward gait instability in PD patients with FOG (PD + FOG). Eleven PD + FOG patients, 9 PD patients without FOG (PD - FOG), and 13 healthy controls participated. Self-selected paced gait was analyzed by a three-dimensional motion-capture analysis system. We assessed the distance between the center of mass and the base of support (COM-BOS distance) and the margin of stability (MOS), considering the position and velocity of the COM as gait stability parameters, spatiotemporal gait parameters and kinematic parameters. The anteroposterior COM-BOS distance was smaller in PD + FOG patients than in PD-FOG patients and controls. Anteroposterior MOS was larger in PD + FOG and PD - FOG patients than controls (p < 0.05). PD + FOG patients showed smaller anteroposterior MOS than PD - FOG patients, when adjusting for disease severity (p < 0.05). Only in the PD + FOG group, when adjusting for disease severity, step length was positively correlated with the anteroposterior COM-BOS distance (p < 0.05), and cadence was negatively correlated with the anteroposterior MOS (p < 0.05). These results indicated that PD patients with FOG have forward gait instability and suggested that such instability may be associated with reduced step length and increased cadence.

Perceived and actual changes in gait balance after CSF shunting in idiopathic normal pressure hydrocephalus.

OBJECTIVES: We evaluated the perceived and actual changes in gait and balance function immediately after cerebrospinal fluid (CSF) shunting in patients with idiopathic normal pressure hydrocephalus (iNPH), including those with mild cases. MATERIALS AND METHODS: Ninety-nine iNPH patients were assessed using the timed Up and Go (TUG) and Functional Gait Assessment (FGA) before and 1-week after CSF shunting and their perceived changes were assessed on a Global Rate of Change (GRC) scale. Minimal clinically important differences (MCIDs) were calculated using a receiver operating characteristic (ROC) curve method using GRC scores. RESULTS: In all patients (n = 99), the TUG value postoperatively was significantly faster than the preoperative value (difference; 3.1 ± 4.6 s, p < 0.001), and the postoperative FGA score was significantly better than the preoperative score (difference; 3.8 ± 3.3 points, p < 0.001). In the TUG <15 s group (n = 51), the postoperative FGA score was significantly improved (difference; 3.3 ± 2.9 points, p < 0.001), whereas the TUG value was only slightly improved (difference; 0.6 ± 1.6 s, p = 0.008). The ROC curve MCIDs of GRC ≥2 points, which is the recommended level of improvement, were 1.7 s (16.5%) for the TUG and 4 points (20.0%) for the FGA in all patients (n = 99) and the TUG <15 s group (n = 51). CONCLUSIONS: FGA can be used to confirm treatment effects, including perceived and actual changes after CSF shunting, in patients with mild iNPH. Our results can help clinicians to determine the clinical significance of improvements in gait and balance function immediately after CSF shunting in individual patients with iNPH.

Associations among falls, gait variability, and balance function in idiopathic normal pressure hydrocephalus.

OBJECTIVES: The factors influencing falls in idiopathic normal pressure hydrocephalus (iNPH) remain unclear, although iNPH-associated gait and balance disturbances can lead to an increased risk of falls. This study aimed to investigate the associations among fall status, gait variability, balance function in iNPH, and to identify fall-related factors in iNPH. PATIENTS AND METHODS: Sixty-three patients with iNPH with a positive cerebrospinal fluid tap test result according to the iNPH diagnosis criteria participated in this prospective cross-sectional study. Patients were assessed using the 10-meter walk test (10MWT), the Functional Gait Assessment (FGA), the Berg Balance Scale (BBS), and the isometric quadriceps strength (QS). We also investigated each patient's history of falls in the past 6 months. Gait variability was measured using a triaxial accelerometer attached to the patient's torso at the L3 vertebra level during the 10MWT. RESULTS: Fall status correlated significantly with gait variability (measured as the coefficient of variation; CV) in step time and movement trajectory amplitude (i.e., center of mass movement) in the medial/lateral (ML) and vertical (VT) directions, with balance function as assessed by FGA and BBS scores. In contrast, QS was not correlated with fall status. The independent variables associated with the risk of falling were step time CV, FGA score, and age. CONCLUSION: The factors associated with the risk of falling in iNPH were aging and gait-balance instability, particularly temporal gait variability and dynamic balance dysfunction. Our results may enable physicians to identify the patients with iNPH who are at risk of falling and implement suitable prevention strategies.

Dynamic Balance Measurements Can Differentiate Patients Who Fall From Patients Who Do Not Fall in Patients With Idiopathic Normal Pressure Hydrocephalus.

OBJECTIVES: To investigate which clinical assessments are suitable for differentiating patients who fall from patients who do not fall in patients with idiopathic normal pressure hydrocephalus (iNPH). DESIGN: Prospective observational study. SETTING: Osaka Medical College Hospital. PARTICIPANTS: Patients with a cerebrospinal fluid tap test (TT) result meeting the diagnosis criteria for iNPH (N=68). INTERVENTIONS: Not applicable. MAIN OUTCOME MEASURES: Participants were assessed before the TT based on the following: timed Up and Go (TUG), 10-meter walk test (10MWT), Functional Gait Assessment (FGA), Berg Balance Scale (BBS), isometric quadriceps strength (QS), and a history of falls within the past 6 months. RESULTS: The full area under the curve (AUC) of the receiver operating characteristic curves and 95% confidence interval were found to be 0.651 (95% confidence interval, 0.503-0.775) for the TUG, 0.692 (95% confidence interval, 0.540-0.812) for the 10MWT, 0.869 (95% confidence interval, 0.761-0.933) for the FGA, and 0.796 (95% confidence interval, 0.663-0.886) for the BBS; except for QS, they all were identified as statistically significant predictive variables. In the TUG<20 seconds group (n=47), the FGA (AUC 0.849 [95% confidence interval, 0.698-0.932]) and BBS (AUC 0.734 [95% confidence interval, 0.550-0.862]) were found to be statistically significant predictive variables; however, the other assessments were not. In the TUG<15 seconds group (n=34), the FGA was found to be the only statistically significant predictive variable (AUC 0.842 [95% confidence interval, 0.640-0.942]), whereas the other assessments were not. The AUC of the FGA was statistically significantly greater than those of the other assessments. CONCLUSIONS: Our findings indicate that patients with iNPH who fall experience falls due to dynamic balance dysfunction during gait rather than lower limb muscle strength. The FGA may be more suitable than other assessments for differentiating patients who fall from patients who do not fall in patients with mild iNPH.

The effect of comprehensive physiotherapy-based rehabilitation on stooped posture in Parkinson's disease.

[Purpose] The effect of physiotherapy on stooped posture in Parkinson's disease patients remains to be clarified. Therefore, the purpose of this study was to investigate whether comprehensive physiotherapy-based rehabilitation can improve stooped posture in Parkinson's disease patients. [Participants and Methods] The participants were Parkinson's disease patients with stooped posture. Outpatients were assigned to the control group and inpatients to the postural rehabilitation group. The outcomes measured were trunk bending angle, lumbar lordosis, and thoracic kyphosis. Each group was assessed at baseline and 1 month later. [Results] Of 22 participants identified, 20 were included, with 10 participants in the postural rehabilitation group and 10 in the control group. The age in the postural rehabilitation group was significantly greater than that in the control group, while other parameters were comparable in both groups. After the month-long intervention, the trunk bending angle and lumbar lordosis were significantly improved in the postural rehabilitation group compared to the control group. [Conclusion] The results showed improvement in stooped posture in the postural rehabilitation group as compared to the control group. Furthermore, improvement of lumbar lordosis accompanied improvement of stooped posture. These findings suggest that comprehensive physiotherapy-based rehabilitation may improve stooped posture in Parkinson's disease patients.

Postural control before and after cerebrospinal fluid shunt surgery in idiopathic normal pressure hydrocephalus.

OBJECTIVES: This study aimed to confirm whether cerebrospinal fluid (CSF) shunting for idiopathic normal-pressure hydrocephalus (iNPH) improves postural instability, and to investigate the relationship between postural control and gait ability. PATIENTS AND METHODS: Twenty-three iNPH patients and 18 age-matched healthy controls (HC) were examined using the timed up and go (TUG) test and a force platform for calculating the center of pressure (COP) trajectory during voluntary multidirectional leaning and quiescent standing. We determined the patients' TUG values and COP trajectories before and after shunt surgery. RESULTS: Postural sway was greater in iNPH patients before shunt surgery and the TUG value was lower in iNPH patients before shunt surgery than in HC. Voluntary COP movements were significantly improved in iNPH patients at 1 week post-surgery, but no significant changes in quiescent standing were found between pre- and post-surgery. Significant correlations were found between the TUG value and voluntary COP movements in iNPH patients before and after surgery, but no significant correlations were observed between the TUG value and quiescent standing. CONCLUSION: Our results indicate that CSF shunting in iNPH patients may improve voluntary postural control and reduce the risk of falling. Impaired voluntary COP control in iNPH patients may reflect the underlying pathophysiological mechanisms of balance disturbance in iNPH.

The effect of CSF drainage on ambulatory center of mass movement in idiopathic normal pressure hydrocephalus.

BACKGROUND: Although gait and balance disturbances are core symptoms of idiopathic normal pressure hydrocephalus (iNPH), the ambulatory center of mass (COM) movements in patients with iNPH remain unclear. We aimed to clarify the ambulatory COM movements using an accelerometer on the patients' lower torsos and to investigate the changes in COM movement after cerebrospinal fluid tap tests (TT) and shunt surgeries (SS). METHODS: Twenty-three patients with iNPH and 18 age-matched healthy controls (HCs) were recruited. A triaxial accelerometer was fixed with a belt onto each participant's torso at the L3 vertebra level. We assessed each patient's 10-m gait before TT, 3 days after TT, and 1 week after SS. RESULTS: Compared to the HCs, the patients exhibited decreased gait velocities, increased step numbers, and increased step times. Their movement trajectory amplitudes (i.e., the COM movements) were increased in the medial/lateral direction and decreased in the vertical direction. They also exhibited greater variability (measured as coefficients of variation) in step time and movement trajectory amplitude in both the medial/lateral and vertical directions. The patients' gait parameters were significantly improved after TT and SS. SIGNIFICANCE: Our results suggest that iNPH-associated gait disturbances could cause abnormal ambulatory COM movements and that these disturbances are mitigated by TT and SS.

Postural instability differences between idiopathic normal pressure hydrocephalus and Parkinson's disease.

OBJECTIVES: We investigated the differences in postural control disability between idiopathic normal pressure hydrocephalus (iNPH) and Parkinson's disease (PD). PATIENTS AND METHODS: Twenty-seven iNPH patients, 20 PD patients, and 20 healthy controls (HCs) were examined using the Timed Up and Go test (TUG) and a force platform for recording the center of pressure (COP) trajectory during quiescent standing and voluntary multidirectional leaning (forward, backward, right, and left for 10 s each). RESULTS: In the leaning task, postural control in PD patients was impaired during forward and backward leaning, whereas postural control in iNPH patients was impaired in all directions. In particular, postural control during right and left leaning was significantly worse in iNPH patients than in PD patients. No significant difference was observed between iNPH and PD patients in TUG and postural sway during quiescent standing. CONCLUSION: Our results showed that the characteristics of impaired voluntary COP control in iNPH and PD patients might reflect pathophysiological differences in postural instability for each disease. In particular, postural instability during right and left leaning in iNPH patients may be responsible for wider steps and a higher risk of falling.

Time and direction preparation of the long latency stretch reflex.

This study investigated time and direction preparation of motor response to force load while intending to maintain the finger at the initial neutral position. Force load extending or flexing the index finger was given while healthy humans intended to maintain the index finger at the initial neutral position. Electromyographic activity was recorded from the first dorsal interosseous muscle. A precue with or without advanced information regarding the direction of the forthcoming force load was given 1000ms before force load. Trials without the precue were inserted between the precued trials. A long latency stretch reflex was elicited by force load regardless of its direction, indicating that the long latency stretch reflex is elicited not only by muscle stretch afferents, but also by direction-insensitive sensations. Time preparation of motor response to either direction of force load enhanced the long latency stretch reflex, indicating that time preparation is not mediated by afferent discharge of muscle stretch. Direction preparation enhanced the long latency stretch reflex and increased corticospinal excitability 0-20ms after force load when force load was given in the direction stretching the muscle. These enhancements must be induced by preset of the afferent pathway mediating segmental stretch reflex.

The effect of tonic contraction of the finger muscle on the motor cortical representation of the contracting adjacent muscle.

This study examined the effect of tonic contraction of the finger muscle on the motor cortical representation of the contracting adjacent muscle. A representation map of the motor evoked potential (MEP) in the first dorsal interosseous (FDI) and abductor digiti minimi (ADM) muscles was obtained with the subject at rest or during tonic contraction of the ADM muscle while the FDI muscle was tonically contracted. The center of gravity (COG) of the MEP map in the FDI muscle shifted medially during contraction of the ADM muscle. Motor cortical excitability in the motor cortical representation of the FDI muscle that did not overlap with the motor cortical representation of the ADM muscle was suppressed, but motor cortical excitability in the motor cortical representation of the FDI muscle overlapping with the motor cortical representation of the ADM muscle was not suppressed during contraction of the ADM muscle. The motor cortical representation of the FDI muscle not overlapping with the motor cortical representation of the ADM muscle was located lateral to that of the FDI muscle that did overlap with the motor cortical representation of the ADM muscle. Medial shift of the COG of the motor cortical representation of the contracting finger muscle induced by tonic contraction of the adjacent finger muscle must be due to suppression of motor cortical excitability in the lateral part of the representation, which is not shared by the adjacent representation.

Asymmetry of anticipatory postural adjustment during gait initiation.

The purpose of this study was to investigate the asymmetry of anticipatory postural adjustment (APA) during gait initiation and to determine whether the process of choosing the initial swing leg affects APA during gait initiation. The participants initiated gait with the leg indicated by a start tone or initiated gait with the leg spontaneously chosen. The dependent variables of APA were not significantly different among the condition of initiating gait with the preferred leg indicated by the start tone, the condition of initiating gait with the non-preferred leg indicated by the start tone, and the condition of initiating gait with the leg spontaneously chosen. These findings fail to support the view that the process of choosing the initial swing leg affects APA during gait initiation. The lateral displacement of the center of pressure in the period in which shifting the center of pressure to the initial swing phase before initiating gait with the left leg indicated by the external cue was significantly larger than that when initiating gait with the right leg indicated by the external cue, and significantly larger than that when initiating gait with the leg spontaneously chosen. Weight shift to the initial swing side during APA during gait initiation was found to be asymmetrical when choosing the leg in response to an external cue.