Utilizing Repetitive Transcranial Magnetic Stimulation to Improve Language Function in Stroke Patients with Chronic Non-fluent Aphasia

Summary

We explore the use of repetitive transcranial magnetic stimulation (rTMS) to improve language abilities in patients with chronic stroke and non-fluent aphasia. After identifying a site in the right frontal gyrus for each patient that responds optimally to stimulation, we target this site during ten days of rTMS treatment.

Abstract

Transcranial magnetic stimulation (TMS) has been shown to significantly improve language function in patients with non-fluent aphasia¹. In this experiment, we demonstrate the administration of low-frequency repetitive TMS (rTMS) to an optimal stimulation site in the right hemisphere in patients with chronic non-fluent aphasia. A battery of standardized language measures is administered in order to assess baseline performance. Patients are subsequently randomized to either receive real rTMS or initial sham stimulation. Patients in the real stimulation undergo a site-finding phase, comprised of a series of six rTMS sessions administered over five days; stimulation is delivered to a different site in the right frontal lobe during each of these sessions. Each site-finding session consists of 600 pulses of 1 Hz rTMS, preceded and followed by a picture-naming task. By comparing the degree of transient change in naming ability elicited by stimulation of candidate sites, we are able to locate the area of optimal response for each individual patient. We then administer rTMS to this site during the treatment phase. During treatment, patients undergo a total of ten days of stimulation over the span of two weeks; each session is comprised of 20 min of 1 Hz rTMS delivered at 90% resting motor threshold. Stimulation is paired with an fMRI-naming task on the first and last days of treatment. After the treatment phase is complete, the language battery obtained at baseline is repeated two and six months following stimulation in order to identify rTMS-induced changes in performance. The fMRI-naming task is also repeated two and six months following treatment. Patients who are randomized to the sham arm of the study undergo sham site-finding, sham treatment, fMRI-naming studies, and repeat language testing two months after completing sham treatment. Sham patients then cross over into the real stimulation arm, completing real site-finding, real treatment, fMRI, and two- and six-month post-stimulation language testing.

Introduction

Aphasia-an acquired deficit of language ability-is a common and often debilitating consequence of stroke². Although some degree of recovery from aphasia after acute stroke is typical, many patients experience at least some degree of persistent deficits, and existing language therapies are generally considered to be only modestly effective in facilitating recovery^3-5. Recent years have seen the emergence of noninvasive stimulation techniques such as transcranial magnetic stimulation (TMS) as promising potential treatment approaches for a variety of deficits after stroke, including aphasia. TMS employs the principle of electromagnetic induction and....

Protocol

1. Pre-Treatment Evaluation

1. Recruit patients who meet the eligibility requirements for the study. These criteria include a single, unilateral, left hemisphere ischemic stroke that spares the supplementary motor area (SMA), mild to moderate non-fluent speech (defined as the ability to produce meaningful words and at least a 2-4 word length string), between the ages of 18 and 75 and at least six months post-stroke.
2. Additionally, all potential patients must be able to name at least three of the first 30 items on the Boston Naming Test¹⁵, an average of at least three pictures out of 20 when presented with ten sets of picture-naming stimuli....

Results

In the site-finding phase of this investigation, most but not all patients respond optimally on the picture-naming task to stimulation of the right pars triangularis¹⁴. In our experience, patients' performance on picture naming is most consistently facilitated by stimulation of the ventral posterior aspect of the pars triangularis (Figure 3).

Long-term improvement in performance on standardized language assessments is illustrated in Figure 4. This .......

Discussion

The goal of this article is to detail the steps for identifying a responsive target site in the right hemisphere in patients with chronic non-fluent aphasia. By doing so, we are able to stimulate that target region therapeutically, assess the effects of stimulation on language ability, and use low-frequency rTMS to elicit long-term improvements in naming and fluency in patients with chronic non-fluent aphasia. Our approach replicates and extends methods used by prior investigators, most notably Naeser and colleagues^.......

Materials

List of materials used in this article

Name	Company	Catalog Number	Comments
Rapid transcranial magnetic stimulator	Magstim
3.0 Trio Scanner	Siemens
8 channel head coil	Siemens
Brainsight neuronavigational system	Rogue Research