human
***TASK*** the task is to summarize an input biomedical literature in six sentences 
    ***INPUT*** the input is a biomedical literature 
    ***OUTPUT*** the output is the summary of an input biomedical literature in six sentences 
    ***DOCUMENTATION*** 
    ***EXAMPLES*** 
    Input: OBJECT Difficulty with step initiation , called " start hesitation , " is related to gait bradykinesia and is an early hallmark of gait freezing in Parkinson disease ( PD ) . Authors of this study investigated the effects of deep brain stimulation ( DBS ) and levodopa on step initiation before and 6 months after DBS surgery in 29 patients with PD who were r and omized to either the bilateral subthalamic nucleus ( STN ) or globus pallidus internus ( GPi ) as the DBS site . METHODS The authors measured the amplitude and duration of anticipatory postural adjustments ( APAs ) , the feed-forward postural preparation that precedes the onset of voluntary step initiation , based on center-of-pressure displacements on a force plate . They also measured the length and velocity of the first step using a motion analysis system to study kinematics . Some of the patients ( 22 ) were from a large , multicenter , double-blind clinical trial , and all patients in the study ( 29 , PD-DBS group ) were r and omized to  DBS in either the bilateral STN ( 15 patients ) or bilateral GPi ( 14 patients ) . Differences in step initiation were investigated in 2 conditions before surgery ( off/on levodopa ) and in 4 conditions after surgery ( off/on levodopa combined with off/on DBS ) . Twenty-eight elderly healthy control volunteers ( CTRL group ) were also tested , and 9 control volunteers with PD who met the criteria for DBS ( PD-C group ) were tested at baseline and 6 months later . RESULTS Patients in the PD-DBS group had smaller amplitudes and longer duration s of APAs compared with those in the 28 healthy control volunteers in all conditions . Before surgery , APAs improved with levodopa . After surgery , the APAs were significantly worse than in the best-treatment state before surgery ( DOPA condition ) , and responsiveness to levodopa decreased . No differences in APAs were detected between the STN and GPi groups . A comparison with PD control volunteers who did not undergo DBS surgery confirmed that a deterioration in step preparation was not related to disease progression . Step length and velocity were smaller in the PD-DBS group than in controls in all conditions . Before surgery , levodopa improved the length and velocity of the first step . Both step length and velocity were unchanged in the best-treatment state before surgery ( DOPA condition ) as compared with after surgery ( DBS+DOPA ) , with only step velocity in the STN group getting worse after surgery . CONCLUSIONS Six months of DBS in the STN or GPi impaired anticipatory postural preparation for step initiation , the opposite effect as with levodopa . Deep brain stimulation disrupted postural preparation more than step execution , suggesting independent motor pathways for preparation and execution of gait . Although turning the stimulators on after surgery combined with levodopa benefited the postural preparation to step , a comparison of pre- and postsurgery conditions suggests that either the surgery itself or 6 months of continuous stimulation may lead to an alteration of circuits or plastic changes that impair step initiation BACKGROUND High frequency stimulation ( HFS ) of the subthalamic nucleus ( STN-DBS ) has been shown to have little impact on postural control and gait improvements in Parkinson 's disease ( PD ) . There is a lack of consensus and quantitative evidence to suggest that stimulating STN at a lower frequency ( LFS ) as compared to HFS will be superior in improving symptoms . OBJECTIVE /HYPOTHESIS To determine if postural control and gait characteristics of persons with PD improve at an LFS ( 60 Hz ) compared to HFS ( > 100 Hz ) . We hypothesized that persons with PD would perform better on postural control and gait measures at LFS . METHODS Nineteen participants with bilateral STN-DBS underwent UPDRS , static and dynamic postural control using gait initiation , and gait evaluations in three stimulation conditions ( baseline voltage stable across conditions : OFF , LFS of 60 Hz , and HFS of > 100 Hz ) . Additionally 10/19 participants were also stimulated at 30 Hz and 60 Hz and at higher voltages . A one-way ANOVA was performed to compare the conditions . RESULTS Total UPDRS-III score , step length and velocity during gait initiation , and gait speed significantly improved during 60 Hz and > 100 Hz conditions when compared to the OFF condition ( P < 0.05 ) . There were no significant differences between 60 Hz and > 100 Hz conditions . Using LFS at higher voltage showed no improvement over > 100 Hz condition . CONCLUSIONS The positive effects of both LFS and HFS on postural control and gait were similar and clinical changes were relatively small . LFS may not help improve postural control , and gait particularly for persons with PD who do not develop gait-related disorders after HFS OBJECTIVE To evaluate the effects of bilateral deep brain stimulation in the subthalamic nucleus for symptomatic relief of advanced idiopathic Parkinson 's disease .  DESIGN Prospect i ve cohort study . SETTING Patients were assessed and received medical treatment at the Kingston Centre , Southern Health , Melbourne . Surgery took place at Melbourne Neuroscience Centre , The Royal Melbourne Hospital . Both are tertiary public institutions . SUBJECTS 14 patients with Parkinson 's disease with intact cognition and difficult to manage motor symptoms who were referred to Kingston Centre between 1996 and 2000 and were eligible for surgical intervention . INTERVENTIONS All patients were assessed both after 12 hours ' withdrawal from and while taking their levodopa medication on two occasions before surgery . Further assessment s were carried out one , three , six and 12 months after surgery . MAIN OUTCOME MEASURES The Unified Parkinson 's Disease Rating Scale motor exam and gait parameters , such as stride length and velocity , were compared at six months after surgery with neither stimulation nor medication , with stimulation only , with medication only , and with stimulation and medication . RESULTS Stimulators were explanted in one patient after intracranial haemorrhage and relocated to the thalamus in a second . Extraneous factors prevented two patients from attending at six-month follow-up . Motor performance improved significantly with stimulation alone in the 10 remaining patients . Further significant gains were seen with stimulation and medication combined , with an apparent reduction in side-effects such as dyskinesia . CONCLUSIONS Bilateral deep brain stimulation of the subthalamic nucleus significantly improves motor performance in advanced Parkinson 's disease , despite a rather high complication rate Postural instability is a sign of progression of Parkinson 's disease ( PD ) and often resistant to levodopa treatment . To explore the effect of bilateral deep brain stimulation ( DBS ) of the subthalamic nucleus ( STN ) on postural stability and gait , full body gait analyses were performed without medication , OFF and ON DBS in eight PD patients and 12 healthy age-matched controls . DBS setting was changed at least 3 hours before gait analysis . To describe asymmetry most and least affected sides ( MAS and LAS ) were rated with the Unified Parkinson 's Disease Rating Scale , motor part and quantitative gait analysis with the Vicon 612 gait analysis system . Stride length and gait velocity but not cadence improved ON DBS . The distances between the heel markers and center of mass ( COM ) were asymmetric and reduced OFF DBS . STN DBS  increased the distances significantly and reduced asymmetry . The improvement in heel to COM distance was larger on the MAS compared with the LAS . OFF DBS knee momentum asymmetry was inversed so that LAS was more impaired than MAS . ON DBS asymmetry improved . PD patients OFF  DBS place the heel too close to COM . The most affected body side has the most impaired swing and the result is a smaller knee moment on the opposite and least affected body side and an asymmetric gait pattern with disturbed balance OFF STN DBS . The asymmetry OFF DBS improved ON DBS . We suggest that DBS facilitates symmetric gait and thereby improves balance during gait Abstract .Subthalamic nucleus ( STN ) stimulation , a recent surgical approach to Parkinson ’s disease ( PD ) , has been shown to be effective in relieving motor symptoms . The present study carried out a full body gait analysis , during overground walking , on ten PD patients with bilaterally implanted STN stimulation devices .  Walking performance was analyzed on the same day , in four conditions ( Stim Off – Med Off , Stim On – Med Off , Stim Off – Med On , Stim On – Med On ) . The results showed that , on average , STN stimulation alone ( S+M− ) and l -dopa alone ( S-M+ ) , significantly increased gait speed , stride length and the lower limb joint Range of Motion ( ROM ) with respect to the basal condition ( S−M− ) ; also cadence was found to play a role in velocity increase , particularly when l -dopa was administered . Both treatments improved pelvis and trunk kinematics , and power production at the ankle and hip joints . The combination of the two treatments ( S+M+ ) produced an additional effect on gait speed , stride length , ROM of knee and ankle joints , pelvis obliquity and trunk inclination . Given the additive and synergistic effects , it can be hypothesized that the two treatments have different mechanisms of action . Our results confirm the findings of earlier studies that employed treadmill walking Deep brain stimulation ( DBS ) of the subthalamic nucleus ( STN ) is effective for the treatment of advanced Parkinson 's disease . Most studies have evaluated the effectiveness of DBS of the STN using clinical motor scores or simple timed tests of motor function . There have been few studies that quantitatively assessed the outcome of STN DBS using multiple testing paradigms . In the current study , 11 patients who had bilateral STN DBS  were quantitatively evaluated under four conditions using gait , postural control , and gait initiation . The four conditions included the medication on/stimulation on ( M_on/S_on ) , medication on/stimulation off ( M_on/S_off ) , medication off/stimulation on ( M_off/S_on ) , and medication off/stimulation off ( M_off/S_off ) conditions . DBS of the STN significantly increased walking speed with and without levodopa , but had no influence on the cadence . The addition of levodopa had a minimal additional effect on walking speed . The effect of STN DBS on gait initiation approached the significant level . The mean values of lateral body sway during quiet st and ing increased moderately with medication and /or DBS , but the changes were not statistically significant . Future studies need to determine whether or not there is a potential negative effect of STN DBS on the postural control Bilateral high-frequency stimulation of the internal globus pallidus ( GPi ) and the subthalamic nucleus ( STN ) both alleviate akinesia , rigidity , and tremor in idiopathic Parkinson 's disease . To test the specific effect of these procedures on gait , we used quantitative gait analysis in addition to relevant subscores of the Unified Parkinson 's Disease Rating Scale in a group of 10 patients with advanced Parkinson 's disease treated by GPi stimulation and eight patients treated by STN stimulation .  Patients were assessed before and 3 months after surgery . Thirty age-matched healthy subjects served as controls . The non-r and om selection allowed a descriptive but no direct statistical comparison of the respective procedure . Gait analysis showed significant stimulation-induced improvements of spatiotemporal gait and step parameters in both patient groups . Moreover , the effects on step length and cadence suggested a differential effect of both basal ganglia targets . Hence , the increase in gait velocity in the STN group was almost exclusively due to a significant increase in step length , while in the GPi group statistically non-significant increases in both step length and cadence contributed OBJECTIVE To investigate the predictive value of gait speed for community walking in Parkinson 's disease and to develop a multivariate prediction model for community walking . DESIGN Data from baseline assessment s in a r and omized clinical trial were used . SUBJECTS A total of 153 patients with Parkinson 's disease were included . METHODS  Community walking  was evaluated using the mobility domain of the Nottingham extended activities of daily living index ( NEAI ) . Patients who scored 3 points on item 1 ( " Did you walk around outside ? " ) and item 5 ( " Did you cross roads ? " ) were considered community walkers .  Gait speed was measured with the 6-m or 10-m timed walking test . Age , gender , marital status , disease duration , disease severity , motor impairment , balance , freezing of gait , fear of falling , previous falls , cognitive function , executive function , fatigue , anxiety and depression were investigated for their contribution to the multivariate model . RESULTS Seventy patients ( 46 % ) were classified as community walkers . A gait speed of 0.88 m/s correctly predicted 70 % of patients as community walkers . The multivariate model , including gait speed and fear of falling , correctly predicted 78 % of patients as community walkers . CONCLUSION Timed walking tests are valid measurements to predict community walking in Parkinson 's disease . However , evaluation of community walking should include an assessment of fear of falling Introduction : The ventrolateral ( VL ) nucleus of the thalamus is the commonly chosen target for deep brain stimulation ( DBS ) to alleviate tremor . However , it has a poor efficacy in alleviating proximal tremor and patients may develop tolerance to the action component of tremor . We performed bilateral stimulation of the caudal or motor part of the zona incerta nucleus ( cZI ) to determine its safety and efficacy in alleviating tremor . Methods : 5 patients with parkinsonian tremor and 13 with a range of tremors ( Holmes ( HT ) , cerebellar ( CT ) , essential ( ET ) , multiple sclerosis ( MS ) and 
    Output:
    
agent
***TASK*** the task is to summarize an input biomedical literature in six sentences 
    ***INPUT*** the input is a biomedical literature 
    ***OUTPUT*** the output is the summary of an input biomedical literature in six sentences 
    ***DOCUMENTATION*** 
    ***EXAMPLES*** 
    Input: OBJECT Difficulty with step initiation , called " start hesitation , " is related to gait bradykinesia and is an early hallmark of gait freezing in Parkinson disease ( PD ) . Authors of this study investigated the effects of deep brain stimulation ( DBS ) and levodopa on step initiation before and 6 months after DBS surgery in 29 patients with PD who were r and omized to either the bilateral subthalamic nucleus ( STN ) or globus pallidus internus ( GPi ) as the DBS site . METHODS The authors measured the amplitude and duration of anticipatory postural adjustments ( APAs ) , the feed-forward postural preparation that precedes the onset of voluntary step initiation , based on center-of-pressure displacements on a force plate . They also measured the length and velocity of the first step using a motion analysis system to study kinematics . Some of the patients ( 22 ) were from a large , multicenter , double-blind clinical trial , and all patients in the study ( 29 , PD-DBS group ) were r and omized to  DBS in either the bilateral STN ( 15 patients ) or bilateral GPi ( 14 patients ) . Differences in step initiation were investigated in 2 conditions before surgery ( off/on levodopa ) and in 4 conditions after surgery ( off/on levodopa combined with off/on DBS ) . Twenty-eight elderly healthy control volunteers ( CTRL group ) were also tested , and 9 control volunteers with PD who met the criteria for DBS ( PD-C group ) were tested at baseline and 6 months later . RESULTS Patients in the PD-DBS group had smaller amplitudes and longer duration s of APAs compared with those in the 28 healthy control volunteers in all conditions . Before surgery , APAs improved with levodopa . After surgery , the APAs were significantly worse than in the best-treatment state before surgery ( DOPA condition ) , and responsiveness to levodopa decreased . No differences in APAs were detected between the STN and GPi groups . A comparison with PD control volunteers who did not undergo DBS surgery confirmed that a deterioration in step preparation was not related to disease progression . Step length and velocity were smaller in the PD-DBS group than in controls in all conditions . Before surgery , levodopa improved the length and velocity of the first step . Both step length and velocity were unchanged in the best-treatment state before surgery ( DOPA condition ) as compared with after surgery ( DBS+DOPA ) , with only step velocity in the STN group getting worse after surgery . CONCLUSIONS Six months of DBS in the STN or GPi impaired anticipatory postural preparation for step initiation , the opposite effect as with levodopa . Deep brain stimulation disrupted postural preparation more than step execution , suggesting independent motor pathways for preparation and execution of gait . Although turning the stimulators on after surgery combined with levodopa benefited the postural preparation to step , a comparison of pre- and postsurgery conditions suggests that either the surgery itself or 6 months of continuous stimulation may lead to an alteration of circuits or plastic changes that impair step initiation BACKGROUND High frequency stimulation ( HFS ) of the subthalamic nucleus ( STN-DBS ) has been shown to have little impact on postural control and gait improvements in Parkinson 's disease ( PD ) . There is a lack of consensus and quantitative evidence to suggest that stimulating STN at a lower frequency ( LFS ) as compared to HFS will be superior in improving symptoms . OBJECTIVE /HYPOTHESIS To determine if postural control and gait characteristics of persons with PD improve at an LFS ( 60 Hz ) compared to HFS ( > 100 Hz ) . We hypothesized that persons with PD would perform better on postural control and gait measures at LFS . METHODS Nineteen participants with bilateral STN-DBS underwent UPDRS , static and dynamic postural control using gait initiation , and gait evaluations in three stimulation conditions ( baseline voltage stable across conditions : OFF , LFS of 60 Hz , and HFS of > 100 Hz ) . Additionally 10/19 participants were also stimulated at 30 Hz and 60 Hz and at higher voltages . A one-way ANOVA was performed to compare the conditions . RESULTS Total UPDRS-III score , step length and velocity during gait initiation , and gait speed significantly improved during 60 Hz and > 100 Hz conditions when compared to the OFF condition ( P < 0.05 ) . There were no significant differences between 60 Hz and > 100 Hz conditions . Using LFS at higher voltage showed no improvement over > 100 Hz condition . CONCLUSIONS The positive effects of both LFS and HFS on postural control and gait were similar and clinical changes were relatively small . LFS may not help improve postural control , and gait particularly for persons with PD who do not develop gait-related disorders after HFS OBJECTIVE To evaluate the effects of bilateral deep brain stimulation in the subthalamic nucleus for symptomatic relief of advanced idiopathic Parkinson 's disease .  DESIGN Prospect i ve cohort study . SETTING Patients were assessed and received medical treatment at the Kingston Centre , Southern Health , Melbourne . Surgery took place at Melbourne Neuroscience Centre , The Royal Melbourne Hospital . Both are tertiary public institutions . SUBJECTS 14 patients with Parkinson 's disease with intact cognition and difficult to manage motor symptoms who were referred to Kingston Centre between 1996 and 2000 and were eligible for surgical intervention . INTERVENTIONS All patients were assessed both after 12 hours ' withdrawal from and while taking their levodopa medication on two occasions before surgery . Further assessment s were carried out one , three , six and 12 months after surgery . MAIN OUTCOME MEASURES The Unified Parkinson 's Disease Rating Scale motor exam and gait parameters , such as stride length and velocity , were compared at six months after surgery with neither stimulation nor medication , with stimulation only , with medication only , and with stimulation and medication . RESULTS Stimulators were explanted in one patient after intracranial haemorrhage and relocated to the thalamus in a second . Extraneous factors prevented two patients from attending at six-month follow-up . Motor performance improved significantly with stimulation alone in the 10 remaining patients . Further significant gains were seen with stimulation and medication combined , with an apparent reduction in side-effects such as dyskinesia . CONCLUSIONS Bilateral deep brain stimulation of the subthalamic nucleus significantly improves motor performance in advanced Parkinson 's disease , despite a rather high complication rate Postural instability is a sign of progression of Parkinson 's disease ( PD ) and often resistant to levodopa treatment . To explore the effect of bilateral deep brain stimulation ( DBS ) of the subthalamic nucleus ( STN ) on postural stability and gait , full body gait analyses were performed without medication , OFF and ON DBS in eight PD patients and 12 healthy age-matched controls . DBS setting was changed at least 3 hours before gait analysis . To describe asymmetry most and least affected sides ( MAS and LAS ) were rated with the Unified Parkinson 's Disease Rating Scale , motor part and quantitative gait analysis with the Vicon 612 gait analysis system . Stride length and gait velocity but not cadence improved ON DBS . The distances between the heel markers and center of mass ( COM ) were asymmetric and reduced OFF DBS . STN DBS  increased the distances significantly and reduced asymmetry . The improvement in heel to COM distance was larger on the MAS compared with the LAS . OFF DBS knee momentum asymmetry was inversed so that LAS was more impaired than MAS . ON DBS asymmetry improved . PD patients OFF  DBS place the heel too close to COM . The most affected body side has the most impaired swing and the result is a smaller knee moment on the opposite and least affected body side and an asymmetric gait pattern with disturbed balance OFF STN DBS . The asymmetry OFF DBS improved ON DBS . We suggest that DBS facilitates symmetric gait and thereby improves balance during gait Abstract .Subthalamic nucleus ( STN ) stimulation , a recent surgical approach to Parkinson ’s disease ( PD ) , has been shown to be effective in relieving motor symptoms . The present study carried out a full body gait analysis , during overground walking , on ten PD patients with bilaterally implanted STN stimulation devices .  Walking performance was analyzed on the same day , in four conditions ( Stim Off – Med Off , Stim On – Med Off , Stim Off – Med On , Stim On – Med On ) . The results showed that , on average , STN stimulation alone ( S+M− ) and l -dopa alone ( S-M+ ) , significantly increased gait speed , stride length and the lower limb joint Range of Motion ( ROM ) with respect to the basal condition ( S−M− ) ; also cadence was found to play a role in velocity increase , particularly when l -dopa was administered . Both treatments improved pelvis and trunk kinematics , and power production at the ankle and hip joints . The combination of the two treatments ( S+M+ ) produced an additional effect on gait speed , stride length , ROM of knee and ankle joints , pelvis obliquity and trunk inclination . Given the additive and synergistic effects , it can be hypothesized that the two treatments have different mechanisms of action . Our results confirm the findings of earlier studies that employed treadmill walking Deep brain stimulation ( DBS ) of the subthalamic nucleus ( STN ) is effective for the treatment of advanced Parkinson 's disease . Most studies have evaluated the effectiveness of DBS of the STN using clinical motor scores or simple timed tests of motor function . There have been few studies that quantitatively assessed the outcome of STN DBS using multiple testing paradigms . In the current study , 11 patients who had bilateral STN DBS  were quantitatively evaluated under four conditions using gait , postural control , and gait initiation . The four conditions included the medication on/stimulation on ( M_on/S_on ) , medication on/stimulation off ( M_on/S_off ) , medication off/stimulation on ( M_off/S_on ) , and medication off/stimulation off ( M_off/S_off ) conditions . DBS of the STN significantly increased walking speed with and without levodopa , but had no influence on the cadence . The addition of levodopa had a minimal additional effect on walking speed . The effect of STN DBS on gait initiation approached the significant level . The mean values of lateral body sway during quiet st and ing increased moderately with medication and /or DBS , but the changes were not statistically significant . Future studies need to determine whether or not there is a potential negative effect of STN DBS on the postural control Bilateral high-frequency stimulation of the internal globus pallidus ( GPi ) and the subthalamic nucleus ( STN ) both alleviate akinesia , rigidity , and tremor in idiopathic Parkinson 's disease . To test the specific effect of these procedures on gait , we used quantitative gait analysis in addition to relevant subscores of the Unified Parkinson 's Disease Rating Scale in a group of 10 patients with advanced Parkinson 's disease treated by GPi stimulation and eight patients treated by STN stimulation .  Patients were assessed before and 3 months after surgery . Thirty age-matched healthy subjects served as controls . The non-r and om selection allowed a descriptive but no direct statistical comparison of the respective procedure . Gait analysis showed significant stimulation-induced improvements of spatiotemporal gait and step parameters in both patient groups . Moreover , the effects on step length and cadence suggested a differential effect of both basal ganglia targets . Hence , the increase in gait velocity in the STN group was almost exclusively due to a significant increase in step length , while in the GPi group statistically non-significant increases in both step length and cadence contributed OBJECTIVE To investigate the predictive value of gait speed for community walking in Parkinson 's disease and to develop a multivariate prediction model for community walking . DESIGN Data from baseline assessment s in a r and omized clinical trial were used . SUBJECTS A total of 153 patients with Parkinson 's disease were included . METHODS  Community walking  was evaluated using the mobility domain of the Nottingham extended activities of daily living index ( NEAI ) . Patients who scored 3 points on item 1 ( " Did you walk around outside ? " ) and item 5 ( " Did you cross roads ? " ) were considered community walkers .  Gait speed was measured with the 6-m or 10-m timed walking test . Age , gender , marital status , disease duration , disease severity , motor impairment , balance , freezing of gait , fear of falling , previous falls , cognitive function , executive function , fatigue , anxiety and depression were investigated for their contribution to the multivariate model . RESULTS Seventy patients ( 46 % ) were classified as community walkers . A gait speed of 0.88 m/s correctly predicted 70 % of patients as community walkers . The multivariate model , including gait speed and fear of falling , correctly predicted 78 % of patients as community walkers . CONCLUSION Timed walking tests are valid measurements to predict community walking in Parkinson 's disease . However , evaluation of community walking should include an assessment of fear of falling Introduction : The ventrolateral ( VL ) nucleus of the thalamus is the commonly chosen target for deep brain stimulation ( DBS ) to alleviate tremor . However , it has a poor efficacy in alleviating proximal tremor and patients may develop tolerance to the action component of tremor . We performed bilateral stimulation of the caudal or motor part of the zona incerta nucleus ( cZI ) to determine its safety and efficacy in alleviating tremor . Methods : 5 patients with parkinsonian tremor and 13 with a range of tremors ( Holmes ( HT ) , cerebellar ( CT ) , essential ( ET ) , multiple sclerosis ( MS ) and 
    Output:
    