patients with idiopathic parkinson &# 39 ; s disease and refractory gait disturbances under best individual subthalamic nucleus stimulation and dopaminergic medication are enrolled into an ongoing double - blind 2 × 2 crossover clinical trial . this trial consists of two arms . severity of the gait disturbance are assessed after 30 min (‘ short term ’) and a three week follow - up (‘ long term ’) of both ( i ) conventional stimulation of the stn area [ stnmono ] and ( ii ) combined stimulation of the stn area and the caudal stn / snr border zone [ stn + snr ]. up to date 11 out of planned 12 consecutive patients were randomised on blocks to the two treatment conditions in a 1 : 1 ratio and treatments will be crossed - over after three weeks of follow - up , respectively . moreover , a baseline assessment ‘ off dopaminergic medication ’ is performed in order to assess short - term effects and to assure optimal stimulation parameters of the conventional stn - dbs [ stnmono ]. a composite ‘ axial score ’ including the major clinical and anamnestic items on gait , posture and balance function from updrsii ( items 13 - 15 ) and updrs iii ( items 27 - 31 ) constitutes the primary outcome measure . idiopathic parkinson &# 39 ; s disease ( according to the “ british brain bank criteria ” including genetic forms and therapy with stn - dbs ( activa pulse generator ) gait disturbance refractory to best individual stndbs ( stnmono ) and dopaminergic therapy : composite ‘ axial score ’ in the best clinical [ medon / stnmono ] condition ≧ 12 clinical and image - guided or electrophysiological confirmation of ( i ) at least one of the two rostral contacts of the quadripolar electrode localized in the stn area . dopaminergic medication constant for at least four weeks prior to study enrolment implantation of the dbs electrodes at least 6 months before study enrolment participation in other clinical trials within the past three months and during enrolment in our study other severe pathological chronic condition that might confound treatment effects or interpretation of the data acute adverse effects from stimulation on contacts in the caudal stn / snr border zone the primary outcome measure is defined as the difference of the composite ‘ axial score ’ including the major updrs ii and iii items of gait , balance and posture after 30 min (‘ short term ’) or three weeks (‘ long term ’) of double - blind treatment with either ( i ) conventional [ stnmono ] or ( ii ) combined [ stn + snr - dbs ]. the secondary efficacy variables enable a differentiated assessment of specified axial symptoms , namely freezing of gait ( including provoking maneuvers ), gait velocity , clinical balance testing , neuropsychiatric symptoms , and non - motor symptoms . clinical testings at baseline were performed after overnight withdrawal of dopaminergic medication and after optimization of subthalamic stimulation . follow - up examinations were performed in the ‘ dopaminergic on state ’. of note , no follow - up examinations with a single active snr contact were conducted as this previously failed to control for segmental symptoms like tremor , bradykinesia and rigidity . the treatment effects of [ stnmono ] and [ stn + snr ] were assessed after 30 min (‘ short term ’) and after three weeks (‘ long term ’) of constant stimulation on either setting . in the ‘ long term ’ approach the order of the treatment conditions will be randomized and crossed after the first visit . the primary endpoint for the statistical evaluation of the therapy is the change in composite ‘ axial score ’. the ‘ axial score ’ is built by 8 items from the updrs ii and iii , all 5 - point rated . for the statistical evaluation the five rating points are represented by the numbers 0 to 4 , which represent increasing levels of pathology . the ‘ axial score ’ will be scored by the sum of the ratings across the 8 items ( range 0 to 32 ). as change in updrs scores is a common primary efficacy outcome measure in parkinson &# 39 ; s disease and only items of the original updrs are required for the definition of the primary endpoint the statistical evaluation methods should be based on the psychometric validation of the updrs and no own validation studies are necessary . the primary endpoint for the statistical evaluation will be the change in ‘ axial score ’ from baseline to visit 2 ( after 6 weeks ). for every patient two change - scores for the two phases in the cross - over were determined . by means of a paired t - test the null hypothesis of equality of the two therapies concerning the change in ‘ axial score ’ were tested . the decision for maintaining or rejecting the null hypothesis was made applying a two - sided test with a = 0 . 05 . the observed effects were described by use of means and effect sizes including the appropriate 95 % confidence intervals . the confirmatory statistical evaluation of the efficacy of the [ stn + snr - dbs ] in this trial will be restricted to the primary endpoint . only the rejection of the null hypothesis was interpreted as statistical evidence for the efficacy of [ stn + snr - dbs ]. as no comparable study is available at the moment , the inventors defined an improvement of 4 points on the primary outcome measure ‘ axial score ’ to be clinically relevant on hypokinetic gait disturbances and assumed a standard deviation of 4 . 0 ( effect size : 1 . 0 ). a sample size of 10 will have 80 % power to detect a difference in means of 4 . 0 ( e . g . first condition mean : 16 . 0 and a second condition mean of 12 . 0 ), using a paired t - test with a 0 . 05 two - sided significance level ( sample size estimated using nquery advisor 7 . 0 ). to adjust for a maximum of two dropouts a total of n = 12 patients were included in the study . as all secondary endpoints are based on validated scores , the inventors assumed that parametric statistical methods can be used for the analysis . the secondary endpoints were compared and statistically assessed for descriptive purposes and not in a confirmatory sense . the aim is explorative data analysis , not hypothesis testing or generation of evidence for efficacy . because of the explorative character of this part of the analysis , no a priori statistical analysis plan exists . if adequate , changes of scores over time were analysed with paired t - tests or appropriate statistical methods ( eg . repeated measurements anova ). if a categorization of scores should be adequate ( eg . classification in success vs . failure according to score - cut - offs ) the inventors used adequate analysis methods for categorical variables ( e . g . mcnemar test ). in addition , appropriate statistical methods of explorative data analysis including graphical methods and descriptive statistics were used . berg balance scale ( bbs ): test which evaluates postural stability and balance , by assessing the performance of functional tasks ; total score = 56 , low scores meaning higher imbalance or increase of postural instability . freezing of gait questionnaire ( fog - q ): form to assess freezing of gait in daily living ; score 0 - 24 , higher score meaning more severe freezing of gait . freezing of gait assessment course : clinical instrument to rate freezing of gait ( range from 0 to 36 points , higher score meaning more freezing and gait disorder ). capsit - pd : core assessment program for surgical interventional therapies in parkinson &# 39 ; s disease . electrode localization and treatment optimization of subthalamic stimulation is mandatory prior to study enrolment . based on the current knowledge for optimized dbs programming ( i ) gait disturbances emerge and progress in the first years after introduction of subthalamic stimulation , ( ii ) a further increase of the stimulation amplitudes may even aggravate the gait disturbance , and ( iii ) the stimulation intensity of the lower extremity with longer step length should be reduced compared to the worse affected side — this was previously demonstrated to ameliorate gait symmetry with beneficial effects to gait disturbances , presumably freezing of gait . these actions have been taken before considering combined [ stn + snr ] stimulation , however , even if applied a substantial proportion of patients continues to exhibit refractory gait disturbances . after written informed consent and screening for inclusion criteria , patients have been examined in the baseline condition ‘ off dopaminergic medications ’ in order to assure optimization of the best individual stimulation parameters of the conventional stn stimulation [ stnmono ] and to determine the short - term effects of either stimulation setting . the localization of the electrodes for both the [ stn + snr ] and the [ stnmono ] treatment is schematically illustrated in fig1 a . to support the assumption that the point of the electrode ( the deepest contact ) is localized in the caudal border zone of stn and snr the inventors combined preoperative and postoperative mri recordings with a reference brain and defined the coordinates of this electrode point to localize the stn and snr stimulation contacts ; cf . fig1 b . the [ stn + snr ] condition consisted of the [ stnmono ] parameters and additional simultaneous stimulation with interleaving pulses on a distal contact with best individual amplitude , 60 μs pulse width , and 125 hz frequency were introduced depending on individual thresholds for side effects from current spreading . in the baseline examination a randomized clinical evaluation of the treatment conditions [ stimoff ], [ stnmono ], and [ stn + snr ] in terms of short term effects were performed . after the baseline examination , patients were randomized to either [ stnmono ] or [ stn + snr ] treatment and scheduled at 30 min (‘ short term ’) or three weeks (‘ long term ’) of constant stimulation ( visit 1 ). after this first endpoint assessment ‘ long term ’ treatment was crossed - over and patients were re - scheduled after further three weeks of constant stimulation for the second endpoint assessment ( visit 2 ). the follow - up period in the ‘ long term ’ treatment is — due to the current clinical evidence — sufficiently long to control adequately for carry - over effects since the endpoint assessment in the follow - up period were scheduled only after three weeks of constant stimulation on either setting . stn - dbs in pd generally evokes clinical effects within short time intervals ranging from several seconds to few hours and presents completely reversible in the same time range . preliminary observations in three parkinson patients ( pd3 , pd4 , pd6 ) after a three - week follow - up are demonstrated in the following table 1 : note that pd3 and pd4 had predominant freezing phenomena and hypokinetic gait disturbance , whereas pd6 presented with imbalance and falls ( low values in the fog - q and fog - ac indicate little gait disturbances and good motor skills of the patient ; high values indicate more severe gait disturbances and reduced or deteriorated motor skills of the patient ). whereas table 1 only present results measured after a three - week follow - up the inventors realized an amelioration of gait disturbances in the patients , in particular with respect to “ freezing ” and “ small steps ”, when measured directly after 30 min of treatment ( data not shown ). therefore , in a next step the inventors analyzed the effect of the [ stn + snr ] protocol and [ stnmono ] protocol with respect to a ‘ short term ’ treatment and a ‘ long term ’ treatment . in the ‘ short term ’ treatment the symptoms of the patients were measured after 30 min of applying either the [ stn + snr ] protocol or the [ stnmono ] protocol . in the ‘ long term ’ treatment the symptoms of the patients were measured after 3 weeks of applying either the [ stn + snr ] protocol or the [ stnmono ] protocol . the results observed for two parkinson patients ( pd7 and pd8 ) are shown in the following table 2 and 3 : the inventors realized that the amelioration which can be observed after a 30 min of [ stn + snr ] deep brain stimulation disappeared after a treatment period of 3 weeks , i . e . tolerance develops . in the following a 70 year old patient with idiopathic parkinson &# 39 ; s disease suffering since two years for severe repetitive falls ( up to 10 times daily ) and gait disturbance was subjected to the following experiment : strategy 1 (“ kinetra ”): constant [ stn + snr ] deep brain stimulation , 130 hz , 3 . 0 v , 60 μs . strategy 2 (“ activa pc ”): at daytime ( group a ) the patient was [ stn + snr ] deep brain stimulated with 130 hz , 3 . 0 v , 60 μs . at nighttime ( group b ) the patient was [ stnmono ] deep brain stimulated with 130 hz , 3 . 0 v , 60 μs . in other words the inventors applied a dbs protocol in the wake or activity state of the patient which has a good effect on gait disturbance and falls , and change in the sleeping or resting state of the patient for a dbs protocol which is ineffective for gait problems and falls but effective for other parkinsonian motor symptoms . strategy 1 was effective ; however the patient developed tolerance within 2 to 3 days with severe falls . strategy 2 resulted in large reduction of falls ( up to ten times daily before group programming , only three falls in 10 week follow - up after introduction of groups a and b ). the inventors made similar observations with at least two further patients with substantial short term effect on combined stn + snr stimulation , but subsequent tolerance during the three - week follow - up . in fig3 the design of the apparatus for deep brain stimulation ( dbs ) as developed by the inventors is schematically illustrated . the apparatus 10 comprises an electrical pulse generator 10 which generates electrical impulses , at least one electrode 14 connected to the electrical pulse generator 10 , a control unit connected to the electrical pulse generator 10 , which control unit 16 is configured to control said electrical pulse generator 12 in accordance with several dbs protocols . the least one electrode 14 is adapted to deliver electrical impulses to brain areas of a living being 20 . the apparatus further comprises a sensor 18 configured to detect activity states of the living being 20 , such as an accelerometer , being fixed to the wrist of the living being 20 . closed - loop : the sensor 18 detects the activity state of the living being . when the living being is in a waking or activity state the sensor 18 delivers a first signal to the control unit 16 . the control unit 16 then runs a first dbs protocol and controls the electrical pulse generator 12 in accordance with said first dbs protocol . the least one electrode 14 then delivers electrical impulses to brain areas of a living being 20 in accordance with said first dbs protocol , e . g . simultaneously to the subthalamic nucleus ( stn ) and to the substantia nigra pars reticulata ( snr ) in an alternating order ( interleaved pulses ) ([ stn + snr ] deep brain stimulation ). when the living being is in a sleeping or resting state the sensor 18 delivers a second signal to the control unit 16 which is different from the first signal . the control unit 18 then runs a second dbs protocol and controls the electrical pulse generator 12 in accordance with said second dbs protocol . the least one electrode 14 then delivers electrical impulses to brain areas of a living being 20 in accordance with said second dbs protocol , e . g . to the subthalamic nucleus ( stn ) only ([ stnmono ] deep brain stimulation ).
the present invention relates to a method of treating movement disorders of a living being , a method of treating refractory gait disturbances of a human parkinson &# 39 ; s disease patient being affected by gait disturbances , and an apparatus for deep brain stimulation of a living being affected by movement disorders .