the clinical symptoms of stroke patients are subluxation of the shoulder joint , abnormal 
 muscle tone and decreased motor control ability , decreased coordination ability , associated 
 reaction , pain in the musculoskeletal systems , weakness of muscle strength in the upper 
 extremity , and sensory disorder1 . thus , 
 stroke causes decreased motor control of the upper extremity resulting in disability in 
 independent daily living such as putting on clothes , eating , and personal management2 . physical therapy approaches that aim to 
 improve upper extremity motor function of stroke patients are used in clinical practice . however , with most intervention methods , patients do not achieve full regeneration or 
 activation of the central nervous system3 . recently , scientific advances , have allowed attention to be paid to direct and selective 
 stimulation of the brain using methods based on neuroplasticity of the central nervous 
 system . transcranial direct current stimulation ( tdcs ) activates the brain non - invasively without 
 pain and can change neural structures in the motor cortex , there by inducing 
 neuroplasticity4 . furthermore , tdcs 
 stimulates the damaged area of the brain of stroke patients with 12 ma current , resulting 
 in polarization of cranial nerves , which improves motor learning and functions4 . mirror therapy ( mt ) uses visual feedback to 
 induce recovery of motor functions in the upper extremity . movements of the non - paretic hand 
 of a stroke patient are reflected in a mirror to create an optical illusion as if the 
 paretic hand moves normally . this means that neuroplasticity can be changed by activating 
 the mirror neuron system involved in motor learning and imitation by observing actions 
 without physical movement5 . studies of tdcs and mt have mainly been conducted with subacute stroke patients within 6 
 months after stroke onset when neurological recovery can occur quickly after stroke . however , few studies have been conducted of tdcs , a method for stimulating the central 
 nervous system which is effective at eliciting functional recovery in stroke patients , in 
 parallel with mt , which is a simultaneous visual illusion effect . thus , this study aimed to 
 determine the effect of mt with tdcs on functional motor recovery of the upper extremity of 
 chronic stroke patients . subjects were 
 randomly divided into two groups : 14 patients in the experimental group ( mt with tdcs ) and 
 13 patients in the control group ( without mirror + tdcs ) . the selection criteria were as 
 follows : a score of 24 or higher on the mini mental state examination - k ( mmse - k ) indicating 
 no cognitive impairment , stroke onset more than 6 months earlier , and no orthopedic or 
 neurological disease history . participants who met the inclusion criteria and agreed to 
 participate in the study received a general explanation of the trial , and gave their written 
 informed consent . all procedures were reviewed and approved by the institutional ethics 
 committee of eulji university hospital . all the subjects received tdcs for 20  min followed 
 by a 5-min rest . then the experimental group received mt , while the control group performed 
 the same exercise as the experimental group using a mirror that did not show the non - paretic 
 upper extremity . all subjects received 
 this intervention for 45-min three times a week for 6 weeks . originally , 30 subjects 
 participated in this study , but one patient with cognitive disability and two patients who 
 complained of headache and during the tdcs application were retired from the study during 
 the experiment . subjects were seated on a chair in a comfortable position with both arms on the armrest in 
 a relaxed position . a sponge electrode of 75  cm ( area ; 24  cm ) for 
 tdcs ( phoresor ii auto model pm 700 , iomed , salt lake city , usa ) was soaked in 0.9% 
 physiological saline and applied to the head of the patient using as tight a band as 
 possible without creating discomfort . the anode electrode was attached to c3 and c4 , the 
 primary motor cortex ( m1 ) , while the cathode electrode was attached to the supraorbital area 
 of the non - paretic side according to the international 10/20 system . the paretic hand was hidden behind a 3535  cm mirror , and the non - paretic hand was put in 
 front of the mirror . subjects looked at the upper extremity of the non - paretic side 
 reflected in the mirror and observed the movement . the mt program consisted of pronation , 
 supination , flexion , and extension of both wrists , flexion and extension of the fingers , and 
 flexion and extension of the elbows . subjects performed 10 sets and rested for 2  min between sets . to help the subjects concentrate , every time a set was completed , a verbal compliment was given once . the box and 
 block test ( bbt ) , which measures the manual dexterity of stroke patients , counts the number 
 of blocks that can be moved from one box to another box in 1  min . subjects were requested to move the blocks as quickly as they could with motivational 
 compliments . the test - retest reliability is very 
 high r=0.96 for : the right hand , and r=0.94 for the left hand7 . to measure hand grip strength , a jamar hand dynamometer the measurement was conducted while the subjects 
 were seated on a chair with their upper arms close to the body , their elbows flexed at 90 , 
 and the wrist in the neutral position . the reliability of grip strength measurement has been reported as r=0.99 , which is 
 very high8 . the jebsen - taylor test is an 
 objective assessment tool that measures the functional hand tasks that are most widely used 
 in daily living . each test consists of writing , turning over a card , stacking checkers , 
 picking up small common object , simulated feeding , picking up a large light tin can , and 
 picking up a large heavy tin can . the reliability of this assessment tool has been reported as r=0.99 , which is 
 very high9 . the fugl - meyer assessment 
 ( fma ) assesses the motor functions , balance , and senses of stroke patients . in this study , 
 detailed items of the upper extremity function were used as the main assessment index , 
 without functional assessment of the lower extremity , and the coordination ability among the 
 shoulder , elbow , forearm , wrist , and hand was examined . the reliability of this assessment 
 tool has been reported as r=0.94 , which is very high10 . for statistical analysis in this study , spss 18.0 the data are expressed as mean standard 
 deviation within - group and between - group comparisons for all variables were performed by 
 using twoway anova . the homogeneity test of age , height , weight , and disease history between the experimental 
 and control groups found no significant differences between the two groups ( table 1table 1.general and medical characteristics of subjects ( n : 27)eg ( n=14)cg ( n=13)gender ( male / female)8/67/6age ( years)58.2910.6760.3810.19height ( cm)168.866.10167.088.52weight ( kg)62.868.1064.467.11causes ( infarction / hemorrhage)9/58/5affected side ( right / left)6/87/6since onset ( month)13.25.115.57.8modified ashworth scale ( g0/g1/g1+)5/6/37/6/0meansd , eg : experimental group , cg : control group ) . cg : control group after the intervention , the experimental group showed significant improvements in the bbt , 
 grip strength , and the fma ( p<0.05 ) , and a significant decrease in the jebsen - taylor test 
 ( p<0.05 ) . the control group showed a significant increase in grip strength after the 
 intervention ( p<0.05 ) , and a significant decrease in the jebsen - taylor test ( p<0.05 ) . comparison of the results after the intervention revealed that the experimental group showed 
 more significant increases in the bbt and grip strength than the control group ( p<0.05 ) 
 ( table 2table 2.comparison of the experimental group and the control group resultseg ( n=14)cg ( n=13)box and block test ( unit)pre25.2911.8123.009.16post37.219.6225.629.03grip strength ( kg)pre12.003.539.923.38post15.292.1612.312.72jebsen - taylor ( sec)pre122.9333.99120.0025.34post93.3628.03103.9212.33fugl - meyer assessment ( score)pre36.5011.0439.159.00post45.578.7641.8515.78meansd , p<0.05 , p<0.01 , eg : experimental 
 group , cg : control group ) . meansd , p<0.05 , p<0.01 , eg : experimental 
 group , cg : control group after 6 
 months , neurological function has recovered ; therefore , the physical therapeutic approach is 
 the focus during this period11 . this 
 study aimed to determine the effect of mt with tdcs on functional motor recovery in the 
 upper extremity of chronic stroke patients . although many studies have been conducted of recovery of motor function of the upper 
 extremity , stroke patients with decreased physical function have difficulty performing tasks 
 as well as decreased motivation for rehabilitation . therefore , a cognitive intervention that 
 increases the motivation of stroke patients is necessary . as a cognitive intervention 
 method , mt activates the frontal or parietal lobe in the corresponding motor region only 
 observing the behavior of others , and this area is called the mirror neurons . therefore , mt 
 could play an important role in learning a new skill or understanding others behavior , 
 which can be used to motivate stroke patients12 . in addition , tdcs , which performs non - invasive stimulation in the 
 brain of stroke patients , can elicit structural changes in neuroplasticity , thereby helping 
 stroke patients recover motor function in the upper extremity . the neurological mechanism of 
 tdcs is hyperpolarization of neurons in the brain by cathode stimulation , which reduces the 
 excitatory response in the cerebral cortex , while anode stimulation elicits depolarization 
 increasing the excitatory response13 . after the main intervention of this study , the experimental group showed a more significant 
 increase in bbt and grip strength than the control group did . this result is consistent with 
 the results of another study in which mt application improved stroke patients motor function 
 and senses in the two limbs of the paretic side12 . another study reported that mt improved functional recovery in the 
 upper extremity and performance of daily living activities of subacute stroke patients14 . this result was attributed to the optical 
 illusion of movement of the non - paretic side activating mirror neurons through mirror 
 reflection , thereby improving the movement of the paretic side . it was also reported that when 1ma anode direct current stimulation was applied to the 
 primary motor region of the brains of chronic stroke patients for 20  min , hand motor 
 functions improved in the jebsen - tayler test15 . another study reported that tdcs activated the damaged cerebral 
 cortex , thus helping positive functional recovery of the upper extremity16 . these results are similar to those of our 
 study indicating that depolarization of cell membranes is induced when the microcurrent of 
 tdcs is applied to cortical areas , changing the nmda receptors and activating the cerebral 
 cortex17 . this study demonstrated that , applying tdcs has a positive effect on the motor function 
 recovery of stroke patients in addition to the effect of mt . the visual illusion effect of 
 mt activated the damaged cerebral cortex directly , but selective stimulation of the central 
 nervous system helped activate the corticospinal tract of stroke patients . first , due to the small number of subjects , it is 
 difficult to generalize the results to all stroke patients . third , we did not separate subjects 
 by functional performance level and performed only simple tasks . therefore , these 
 limitations should be addressed in the future by including more subjects and studying tdcs 
 and mt simultaneously for a longer duration .
[ purpose ] this study aimed to determine the effect of mirror therapy ( mt ) with 
 transcranial direct current stimulation ( tdcs ) on the recovery of the upper extremity 
 function of chronic stroke patients . 
 [ subjects ] twenty - seven patients at least 6 months 
 after stroke onset were divided randomly into an experimental group ( 14 patients ) and a 
 control group ( 13 patients ) . 
 [ methods ] all subjects received tdcs for 20  min followed by a 
 5  min rest . 
 then the experimental group received mt while the control group conducted the 
 same exercises as the experimental group using a mirror that did not show the non - paretic 
 upper extremity . 
 the groups performed the same exercises for 20  min . 
 all subjects received 
 this intervention for 45-min three times a week for 6 weeks . [ results ] after the 
 intervention , the experimental group showed significant improvements in the box and block 
 test ( bbt ) , grip strength , and the fugl - meyer assessment ( fma ) , and a significant decrease 
 in the jebsen - taylor test . 
 the control group showed a significant increase in grip 
 strength after the intervention , and a significant decrease in the jebsen - taylor test . 
 comparison of the result after the intervention revealed that the experimental group 
 showed more significant increases in the bbt and grip strength than the control group . 
 [ conclusion ] 
 these results show that mt with tdcs has a positive effect on the functional 
 recovery of the upper extremity of stroke patients , through activating motor regions in 
 the brain , and thus plays an important role in recovery of neuroplasticity .