EFFECT OF ANODAL TRANSCRANIAL DIRECT CURRENT STIMULATION ON NAMING IN APHASIC PATIENTS WITH ACUTE ISCHEMIC STROKE
Phase: PHASE3
Conditions: Acute Ischemic Cerebrovascular Disease, Post Stroke Aphasia, Aphasia Following Cerebral Infarction, Aphasia, Acquired
Sponsor: Dr. Ram Manohar Lohia Hospital

1 
 
EFFECT OF ANODAL TRANSCRANIAL DIRECT 
CURRENT STIMULATION ON NAMING IN APHASIC 
PATIENTS WITH ACUTE ISCHEMIC STROKE 
 
 
Protocol Number: IEC/ABVIMS/RMLH/1093 
National Clinical Trial (NCT) Identified Number: Pending 
Principal Investigator: Ashish Kumar Duggal 
Sponsor: Dr. Ram Manohar Lohia Hospital 
Version Number: v.1 
21 March 2026 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 

2 
 
  
INDEX 
 
 
 
Topic 
Page 
Introduction 
3-4 
Review of literature 
5-7 
Lacunae in existing knowledge 
8 
Research question 
9 
Research hypothesis 
9 
Aims and objectives 
10 
Material and methods 
11-16 
References 
17-18 
 
 
 
 
 
 
 
 
 
 
 
 
 
  

3 
 
INTRODUCTION 
Stroke is one of the most devastating diseases, incurring significant morbidity and mortality. 
Incidence and prevalence of stroke have increased with time, with younger individuals also 
being affected. As of 2019, the global incidence of stroke was estimated to be 12.2 million(1), 
and prevalence was estimated to be 101 million(1). DALYs (disability adjusted life years) lost 
due to stroke were estimated to be 143 million(1), and deaths due to stroke were estimated at 
6.55 million(1) . Stroke was found to be the second-leading cause of death globally and the 
third-leading cause of death and disability combined.(1) 
Impairment in communication, in the form of aphasia or dysarthria and motor dysfunction in 
the form of hemiparesis or hemiplegia, are the two most significant morbidities suffered by 
survivors of stroke. Global estimates of occurrence of aphasia due to stroke is in the range of 
20-40%. (2,3) Indian studies estimate aphasia due to stroke occurs in 21-38% of patients. (4) 
It has been stated “one never recovers from aphasia; one recovers with aphasia.” (5) An 
inability to communicate effectively can often hamper one’s quality of life in the form of 
mental health issues, unemployment with financial burdens, and social isolation. 
Studies have focused on rehabilitation from aphasia, using various forms of behavioural 
aphasia therapy such as Constraint induced Language Treatment, Melodic Intonation therapy 
and Speech Entrainment.(4) Non-invasive Brain Stimulation (NIBS) methods such as 
Transcranial Magnetic Stimulation (TMS) have also been used for rehabilitation from 
aphasia.(4) Transcranial Direct Current Stimulation, another form of NIBS, is a newcomer to 
the field to aphasia rehabilitation, with limited number of studies overall. (5) 
Transcranial direct current stimulation (tDCS) is a painless, non-invasive, cortical stimulation 
technique, which is carried out with a battery-driven device, and involves application of 
electrodes to the scalp, with a weak current flowing between the electrodes, through the 
brain.(6) 
 
The effects of tDCS on brain function are hypothesized to be neuromodulatory.(6,7) tDCS is 
believed to be capable of inducing synaptic plasticity through mechanisms of long-term 
potentiation (LTP) and long-term depression (LTD). At the synaptic level, these changes are 
believed to be carried out by NMDA receptors of glutaminergic neurons. Therefore, tDCS may 

4 
 
have therapeutic potential for treating dysfunctions of the brain, occurring due to stroke or any 
other neuropsychiatric pathology, by facilitating recovery-related plastic changes. 
  
The effect of tDCS on aphasia recovery in patients with ischemic stroke has only recently been 
explored. However, the results have not been consistent and there is still scarcity of data 
regarding effects of tDCS in stroke. 
 
With this background, we hypothesize that application of tDCS to prespecified areas in the 
brain would lead to better outcomes in language function, as compared to sham application, in 
patients with acute ischemic stroke and aphasia. 
  
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 

5 
 
REVIEW OF LITERATURE 
Transcranial direct current stimulation involves the placement of electrodes over the scalp, with 
the emission of a weak electrical current that flows between the two electrodes. (6,7) The 
electrodes are themselves named the anode and the cathode. Either one of them can be used for 
the experiment being conducted, based on the experiment design, in which case the main 
electrode is known as the target electrode, while the other electrode is known as the reference 
electrode. 
The electrodes can be placed in different montages; some montages place the reference 
electrode extracephalically, for example on the upper arm, while some montages place the 
electrodes “bihemispherically” to emit dual stimulation to two parallel cortices (e.g., the 
parietal cortices— Benwell et al., 2015). (Lindenberg et al., 2010). Various parameters that 
need to be decided prior to attaching the electrodes are the type of electrodes themselves, the 
size of the electrodes, the conducting material used, the stimulation duration, current intensity, 
and ramp up/ramp down times which need to be programmed. (6) 
Current flows between the electrodes during stimulation. The current passes through the brain, 
completing the circuit. Anodal stimulation is believed to depolarise the underlying cortical 
neurons, thereby making them more sensitive to action potentials and is hence known as 
“stimulatory”. Cathodal stimulation has the opposite effect, hyperpolarising the underlying 
cortical neurons, making them less likely to fire, and is thus known as “inhibitory”. (6,7) 
 
Effects of tDCS application can be measured in several ways. The most common method used 
is via behavioural measures, wherein the researchers aim to measure a given behaviour/activity 
that would otherwise not be observed under sham conditions. 
 
What makes tDCS a lucrative option for stroke rehabilitation programmes is the fact that it is 
a non-invasive method. The equipment is reusable, relatively inexpensive, portable, easy to 
apply, and can allow for reversible modulation of activity in specific brain regions. This has 
provided an invaluable tool for establishing brain-behavior relationships across a variety of 
cognitive, motor, social, and affective domains. (8) 
 

6 
 
So far, tDCS has been used to reduce symptoms of depression (9), it has been shown to reduce 
hallucinations in schizophrenia(10) and has also been used in autism spectrum disorder (11). 
 
In aphasia rehabilitation, several studies have been undertaken that have utilised tDCS. 
  
Monti et al, in a group comprising of 8 patients of chronic post stroke aphasia, with 4 patients 
of global aphasia and 4 patients of Broca’s aphasia, showed that cathodal tDCS improved 
naming accuracy in picture naming task. (12) 
 
Hesse et al, in a group comprising of 5 patients with subacute post stroke aphasia, of which 3 
patients had global aphasia and 2 patients had Wernicke’s aphasia, showed that anodal tDCS 
improved performance testing on Aachener aphasia test. (13) 
 
Baker et al, in a group of 10 patients of whom 6 had anomia and 4 had Broca’s aphasia, showed 
that anodal tDCS improved accuracy on picture naming test, and that the benefits lasted for 1 
week after treatment. (14) 
 
Kang et al, in a group of 10 chronic aphasia patients, of which 3 had global aphasia, 4 had 
Broca’s aphasia, 2 had anomia and 1 had transcortical aphasia, showed that cathodal tDCS 
increased accuracy on picture naming task 1 hour after the last session. (15) 
 
Jung et al, in a group of 37 patients, showed that cathodal tDCS improved the aphasia quotient 
on the Western aphasia battery validated for Korean. (16) 
 
What impedes its use in Stroke rehabilitation, especially its use in aphasia rehabilitation is the 
lack of comparable research available. Firstly, unlike several studies that examine effects of 
tDCS on healthy motor physiology, effects on healthy language networks haven’t been as 
thoroughly explored. (17,18,19) Secondly, so far it has been used experimentally in small scale 

7 
 
studies to investigate possible advantages of using tDCS and its possible role in rehabilitation. 
Since the studies are investigative, there is great variability among the protocols, the sampling 
and the results; furthermore, only studies with positive results tend to get published, leaving 
lacunae about methods or protocols that didn’t work . 
 
Additionally, across almost all the studies utilising tDCS in aphasia, tDCS hasn’t been used in 
isolation, but has always been used with other rehabilitative measures. As per American Heart 
Association, “inclusion of behavioral training in the majority of tDCS/aphasia studies may 
inhibit an understanding of what tDCS does autonomously to language functions.” (5) Though 
one can argue that an aphasia experiment without language training would deprive aphasic 
subjects of concomitant proven therapy, it might also enable better understanding of tDCS, 
introducing better paradigms which can then be combined with previously proven methods of 
rehabilitation. 
  
Finally, studies regarding the use of tDCS in patients with acute stroke with aphasia are also 
scarce. (20, 21) 
 
In light of the above information, we decided to use anodal tDCS autonomously, in patients 
with acute ischemic stroke with aphasia. 
 
 
 
 
 
 
 
 
 
 

8 
 
LACUNAE IN EXISTING KNOWLEDGE 
The use of transcranial direct current stimulation (tDCS) for the management of deficits 
developed in stroke is a relatively new type of management option. Many of the studies 
performed using tDCS have focused on improvements noted in hemiplegia as compared to 
aphasia, which is an equally disabling outcome of strokes. The results of these studies have 
not been conclusive and concordant with each other. 
 
In aphasia management, majority of the studies have focussed on subacute to chronic strokes, 
and since the use of tDCS is relatively new, the studies have not focussed on a particular type 
of deficit, or a particular type of stroke. Very few studies have focussed on the impact of 
solely using tDCS. Very few studies have focussed on acute strokes. The results of the studies 
have nevertheless, been encouraging. 
 
Improvements in aspects of language tested, after a single session of tDCS, is short lived. 
There is an unmet need to probe the utility of repetitive tDCS on aspects of language function 
in patients who are aphasic due to acute stroke. There is also a paucity of data in the Indian 
scenario regarding the same. 
 
 
 
 
 
 
 
 
 
 
 
 
 

9 
 
RESEARCH QUESTION 
 
Does transcranial direct current stimulation (tDCS) to prespecified areas of the brain lead to 
improvement in naming function of aphasic patients with Acute Ischemic Stroke? 
 
 
 
 
 
RESEARCH HYPOTHESIS 
 
Application of tDCS to prespecified areas in the brain leads to improvement in naming 
function of aphasic patients with Acute Ischemic Stroke. 
  
 
 
 
 
 
 
 
 
 
 
 
 
 

10 
 
AIMS AND OBJECTIVES 
AIM: To determine the effect of Anodal Transcranial Direct Current Stimulation on naming 
function of aphasic patients with Acute Ischemic Stroke. 
 
OBJECTIVES: 
 
Primary Objective: Difference of change in Accuracy between Anodal tDCS group and 
Sham tDCS group at 5 days on the ICMR Picture Naming Test.  
 
Co-Primary Objective: Difference of change in Reaction Time between Anodal tDCS group 
and Sham tDCS group at 5 days on the ICMR Picture Naming Test. 
 
Secondary Objectives:  
- 
Difference of change in Correct Response between Anodal tDCS group and Sham 
tDCS group at 5 days on the ICMR Picture Naming Test. 
- 
Difference of change in PNT Score between Anodal tDCS group and Sham tDCS 
group at 5 days on the ICMR Picture Naming Test. 
- 
Difference of change in Accuracy between Anodal tDCS group and Sham tDCS group 
at 4 weeks on the ICMR Picture Naming Test. 
- 
Difference of change in Reaction Time between Anodal tDCS group and Sham tDCS 
group at 4 weeks on the ICMR Picture Naming Test. 
- 
Difference of change in Correct Response between Anodal tDCS group and Sham 
tDCS group at 4 weeks on the ICMR Picture Naming Test. 
- 
Difference of change in PNT Score between Anodal tDCS group and Sham tDCS 
group at 4 weeks on the ICMR Picture Naming Test. 
 
 
 
 
 
 

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MATERIAL AND METHODS 
 
Place of Study: Department of Neurology, ABVIMS & Dr. RML hospital, New Delhi. 
 
Study design: Randomized, double blinded, sham controlled study. 
 
Sample size: The study of Eun Kyoung Kang, et al observed that post-stimulation response 
accuracy in tDCS was 31.9 ± 6.9 and in Sham stimulation was 29.9 ± 6.2. Taking these 
values as reference, the minimum required sample size with 80% power of study and 5% 
level of significance is 169 patients in each study group. For finite sample size taking 
population as 20, total sample size calculated is 19. To reduce margin of error, total sample 
size taken is 20 (10 per group). 
 
Formula used is: 
For comparing mean of two groups 
N>=2(standard deviation)2 X(Zα + Zβ)2 (mean difference)2 
Where Zα is value of Z (normal variate) at two sided alpha error of 5% and Zβ is value of Z 
(normal variate) at power of 80% and mean difference is difference in mean values of two 
groups. 
Pooled standard deviation= 
√(𝑆12 + 𝑆22)/2 
 
Where S1 is standard deviation of 1 group. and S2 is standard deviation of other group. Finite 
population correction factor:- 
SS>= n/ (1 + [(n − 1)/Pop]) 
 
Where Pop is population 
  
Calculations: 
Pooled standard deviation= 
=6.56 
N>=2(6.56)2 X(1.96 + .84)2 (2)2 
>=168.66=169(approx.) 

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√(6.92 + 6.22)/2 
  
 
So total sample size to be taken is 169*2=338 
 
Finite population correction factor:- 
SS>= 338/ (1 + [(338 − 1)/20]) 
>=18.93=19(approx.) 
 
Assuming 20% attrition, each group will consist of at least 12 patients. 
 
Block Randomization 
Block Randomization with Sealed Envelope System: - In this technique, patients will be 
randomized in a series of blocks of 4, using an online randomization generator. Patients will 
be allocated to either of the groups (group A - true or group B- sham) in a 1:1 ratio. The 
randomization list will be generated by the biostatistician and transferred to a sealed opaque 
envelope, and each envelope will be opened by the primary investigator (supervisor) when 
the corresponding number of eligible participants is enrolled. However, the technician who 
administers the anodal tDCS procedure will know about the identity of the groups. A blinded 
investigator will record outcomes. Neither the patient nor the investigator knows which label 
represents which group, making this a double-blind study.  
 
Study population: Aphasic patients with acute ischemic stroke with left Middle Cerebral 
Artery territory infarcts. 
  
INCLUSION CRITERIA 
• 
Aphasic patients with left middle cerebral artery territory Acute Ischemic Stroke 
• 
Patients between 18-65 years of age. 
• 
Within 5 days of onset of stroke. 
 

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EXCLUSION CRITERIA 
 Patients with malignant Middle Cerebral Artery territory infarcts and previous clinical 
history of cerebral hemisphere stroke. 
 Patients with history of previous brain surgery or skull defect due to surgery e.g. 
craniectomy. 
 Patients with epilepsy. 
 Patients with history of significant head trauma in the last 1 month. 
 Patients with documented history of major depression prior to stroke. 
 Patients with alcohol/drug abuse in the past 6 months. 
 Patients with prior significant cognitive impairment. 
 Pacemaker in-situ, cochlear implant in-situ. 
 Pregnancy. 
  
PROCEDURAL DETAILS 
 All consenting patients recruited for the study will be evaluated clinically in detail. 
The patients will undergo aphasia testing using the Western Aphasia Battery and will 
be classified accordingly into the subtypes of aphasia. The patients will then be 
randomized into either the true stimulation group or the sham stimulation group as 
mentioned.  
Picture Naming Test  
 The Indian Council of Medical Research (ICMR) validated the Picture Naming Test 
(PNT), part of the ICMR MUDRA Toolbox for use in patients with Dementia. The 
PNT was used to objectively quantify Naming ability during and after sessions of 
anodal Transcranial Direct Current Stimulation. The ICMR PNT has been validated in 
five languages, including English and Hindi.  
 The ICMR PNT consists of 30 line drawings.  
 The administration of the test is as follows:  
- 
The pictures are shown one by one.  
- 
The subject has to identify each item by telling the first name that comes to 
their mind upon seeing the stimulus. 10 seconds are given for an unprompted 
response.  

14 
 
- 
If the subject is unable to name the image shown or makes an error during 
naming, cues are provided.  
- 
First, a category/semantic cue is provided, and the patient is given 10 seconds 
to name the picture.  
- 
If the subject fails to respond or responds incorrectly, a phonemic cue is 
provided, and the subject is again given 10 seconds to respond.  
- 
If the subject is still unable to respond or makes an error, the test moves on to 
the next picture.  
- 
Hence, the maximum time for naming an image is 30 seconds.  
- 
Care is taken that the entire test be conducted in the same language. 
Additionally, scoring is done based on the prespecified names provided. A few 
objects shown in the pictures may have more than one name, but the response 
accepted is the response prespecified in the validated PNT.  
The scoring for the ICMR PNT is as follows:  
 Correct response in the testing language spontaneously (without cues) (NL)= +3  
 Correct response in testing language with a semantic cue (NL) = +2  
 Correct response in testing language with a phonemic cue (NL) = +1  
 
 If the responses are given in another language, and not the testing language, the scores 
are marked as follows:  
- 
Correct response in the testing language spontaneously (without cues) = OL3  
- 
Correct response in testing language with semantic cue = OL2  
- 
Correct response in testing language with phonemic cue = OL1  
 
 Total correct responses are calculated as NL + OL.  
 If the subject makes an error in naming, it is marked as ER. If the subject is unable to 
name, the scoring is done as 0.  
For the purpose of our study:  
 The instructions provided for administering the PNT, as laid down by the ICMR, will 
be followed for scoring correct responses. Since all patients tested will have Hindi as 
their native language, there will be no OL responses.  

15 
 
 Additionally, response times were noted for each picture named. If the patients could 
not name the pictures even after providing both semantic and phonemic cues, a 
response time of 30 seconds was noted. A calibrated stopwatch was used for marking 
the response times.  
 
The ICMR PNT will be performed on:  
• 
Day 0 (i.e. the day anodal tDCS/sham tDCS sessions were initiated, before the first 
session of anodal tDCS).  
• 
Day 1 (i.e. 1 day after the first session of anodal tDCS/sham tDCS, before the second 
session).  
• 
Day 5 (i.e. after 5 sessions of anodal tDCS/sham tDCS).  
• 
1 week +/- 2 days after the last session of anodal tDCS/sham tDCS, to look for the 
persistence of benefit, if any.  
• 
4 weeks +/- 2 days after the last session of anodal tDCS/sham tDCS, to look for the 
persistence of benefit, if any.  
 
The various parameters assessed in the study using the ICMR-PNT are defined as 
follows:  
• 
Accuracy is defined as the number of words spoken without the help of a semantic or 
phonemic cue on the ICMR Picture Naming Test 
• 
Correct Response is defined as the total number of words spoken, with or without the 
help of either a semantic or a phonemic cue on the ICMR Picture Naming Test. 
• 
PNT scores will be calculated for all the correct responses provided. The guidelines 
provided for the use of ICMR–PNT will be used. A response obtained without any semantic 
or phonemic cue is scored as 3. A response obtained with a semantic cue is scored as 2. A 
response obtained using both semantic and phonemic cues is scored as 1. No response 
obtained is scored as 0.  
• 
A stopwatch will be used to record the reaction times of the patient during the process 
of naming items on the PNT. Timings, as suggested by the ICMR-PNT guidelines, will be 
used. 10 seconds will be provided for the patient to name the picture without any semantic or 
phonemic cues. At the end of 10 seconds, the stopwatch will be paused, a semantic cue 
provided, and the patient then continued to be timed. At the end of the next 10 seconds, the 

16 
 
stopwatch will be paused again, a phonemic cue provided, and the patient then continued to 
be timed. A total of 30 seconds will be provided per picture for naming. Patients will be timed 
as per their responses with or without cues. Reaction time will be noted as 30 seconds if the 
patient fails to name the picture after both semantic and phonemic cues.  
 
tDCS Parameters:  
• 
Stimulation site: left Broadmann area 45 (Broca’s area) localized based on the 10-20 
system of electroencephalography. On the tDCS equipment, the montage created using the 
leads Fp2 and F3 corresponds to maximal stimulation of Broadmann area 45.   
• 
Reference electrode: Right supraorbital area (Fp2).  
• 
Electrode size: Gel electrodes.  
• 
Intensity of stimulation provided: 2mA.  
• 
Duration of stimulation provided: 20 minutes, with ramp up & ramp down of 10 
seconds each. Patients undergoing sham stimulation will receive stimulation for the first and 
last 10 seconds of 20 minutes period.  
• 
Number of sessions: 5 sessions in 1 week.  
• 
Task performed for assessment: ICMR Picture Naming test. (detailed above)  
 
The tDCS procedure will be conducted as follows: 
• 
The patients preferably seated in a chair. If the patients have evidence of dense 
hemiplegia with difficulty sitting in a chair or wheelchair, the sessions will be conducted with 
the patients in the semi-recumbent position to prevent dislodgement of the tDCS equipment 
during the sessions.  
• 
Once the tDCS cap iss placed on the head, care will be taken to part the hair from 
underneath the proposed area of electrode placement, to prevent the development of excess 
impedance.  
• 
Gel electrodes will then be placed over the scalp.  
• 
The tDCS machine will then be connected to the patient, and either true or sham 
stimulation will be provided.  
• 
During the stimulation sessions themselves, care will be taken to note any side effects 
such as an uncomfortable sensation due to the stimulation themselves.  
• 
A total of 5 sessions will be provided over 7 days. Care will be taken not to have a gap 
of more than 1 day between sessions.  

17 
 
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