Repetitive Transcranial Magnetic Stimulation for Post-Stroke Visual Field Defects

July 19, 2021 updated by: Nevine El Nahas, Ain Shams University

The Efficacy of Navigated Perilesional Repetitive Transcranial Magnetic Stimulation on Post-Stroke Visual Field Defects

Visual field defects (VFD) usually do not show improvement beyond 12 weeks from onset. Plasticity occurs in areas of residual vision (ARV) at the visual field which are the functional counterpart of partially damaged brain regions at the areas around brain lesion. Few treatment options are currently available for post-stroke VFD. In this pilot study, the effect of repetitive transcranial magnetic stimulation (rTMS) applied to these areas on VFD in patients with cortical infarction will be studied. Patients will be divided into two groups; an active group which will receive active stimulation and a sham group which will receive placebo stimulation through a sham coil.

Study Overview

Status

Completed

Conditions

Intervention / Treatment

Detailed Description

Visual functions are widely distributed over large areas within the cerebrum. Secondary to such wide distribution, visual field defects (VFD) are a common outcome of brain insults especially cerebrovascular stroke whether hemorrhagic or ischemic. Among these, homonymous hemianopia is the most frequently encountered VFD in clinical practice. VFD ranges from 8.3% to 16% in the chronic stage of stroke, while it reaches 25% in acute and subacute stages of stroke. In other studies, it was reported to be even higher. In a database of 11900 stoke patients, VFD was found in 60.5% with homonymous hemianopia accounting for 35%.

These VFDs usually show some degree of improvement within few months from onset secondary to resolution of edema and diaschisis, yet by 3 to 6 months the condition tends to become stationary with no further improvement and only 5% of patients will show full recovery of their visual field. In some studies recovery was mostly along the first 10 days of insult followed by decrease in recovery rate that nearly stops 10-12 weeks after insult. Beyond this time point, very few cases develop spontaneous recovery.

Plasticity occurs in areas of residual vision (ARV) at the visual field borders rather than areas of absolute blindness. These ARVs are the functional counterpart of partially damaged brain regions at the perilesional areas. Recovery of function - both early in life and in adults - is stimulation dependent. This stimulation can be either through visual experience, behavioral training or brain stimulation. To the investigator's knowledge, direct current stimulation (DCS) is the only brain stimulation modality that has been studied in cases of VFDs. Results showed that DCS can expand visual field in stroke patients with the effects being stable over time.

In the current study, it is hypothesized that stimulation of the perilesional seemingly healthy brain tissue close to the visual cortex would result in clinical improvement based on the concept of ARVs. To achieve this precise targeting, navigated rTMS would be the most suitable technique.

The investigators aim to study the effect of navigated repetitive transcranial magnetic stimulation (rTMS) applied to perilesional areas on patients with cortical visual field defects (cVFD) due to stroke.

This is a randomized sham-controlled clinical trial that will be conducted in the neuromodulation research lab, neurology department, Ain Shams University. The study is approved by Ain Shams University faculty of medicine local research ethics committee (REC).

Procedures:

3D MRI: An MRI Brain T1WI with 200 cuts of 0.9 mm sections will be obtained. Segmentation of the head model will be done to separate scalp, skull and brain layers. A three-dimensional virtual head model will then be created for each patient.

Target Selection: The target for stimulation will be determined and marked for each patient using a neuronavigation system on his virtual head model. Targets will be selected along the perilesional area in the nearest seemingly healthy tissue to the visual cortex based on the following steps:

  1. ARV (grey zone) will be identified in the perimetry of the patient.
  2. Corresponding area in the 3D head model will then be determined based on visuotopy of the primary visual cortex.

Study Type

Interventional

Enrollment (Actual)

32

Phase

  • Not Applicable

Contacts and Locations

This section provides the contact details for those conducting the study, and information on where this study is being conducted.

Study Locations

  • Egypt
      • Cairo, Egypt, 11591
        • Neuromodulation Research Lab, Neurology Department, Ain Shams University Hospital

Participation Criteria

Researchers look for people who fit a certain description, called eligibility criteria. Some examples of these criteria are a person's general health condition or prior treatments.

Eligibility Criteria

Ages Eligible for Study

14 years to 66 years (Adult, Older Adult)

Accepts Healthy Volunteers

No

Genders Eligible for Study

All

Description

Inclusion Criteria:

  • Patients with a brain imaging showing vascular lesion involving visual cortical area
  • Duration of at least 3 months.

Exclusion Criteria:

  • Visual field defects of ophthalmologic origin
  • Causes of severe visual impairment other than visual field defects
  • Drug abuse
  • Past history or family history of epilepsy
  • Skull bone defects
  • Implanted metallic devices

Study Plan

This section provides details of the study plan, including how the study is designed and what the study is measuring.

How is the study designed?

Design Details

  • Primary Purpose: Treatment
  • Allocation: Randomized
  • Interventional Model: Parallel Assignment
  • Masking: Double

Arms and Interventions

Participant Group / Arm
Intervention / Treatment
Active Comparator: Active Group
A total of 16, every other day sessions of rTMS at 10 Hz frequency will be applied to 4 locations along the perilesional area (see target selection). Intensity will be 100% of motor threshold, 25 trains - 40 pulses per train with 20 seconds intertrain interval and a total of 1000 pulses per session. The coil handle will be directed downwards at 45º of the sagittal plain to ensure that the induced electric field be perpendicular to the underlying gyrus.
Device: High frequency repetitive transcranial magnetic stimulation (rTMS)
10hz, 20 seconds intertrain interval, 40 pulses per train with a total of 1000 pulse per session given at 100% of motor threshold. A total of 16 sessions will be given to each patient.
Sham Comparator: Sham Group
Sham group will receive the same sessions as above with the exact same parameters yet a sham coil identical in shape and size to the active coil will be used instead. The sham coil produces sounds and sensations very similar to the active one.
Device: Sham stimulation
A sham coil will be used that is shielded so that it produces sounds and sensations similar to the active coil but does not produce therapeutic effects. 10hz, 20 seconds intertrain interval, 40 pulses per train with a total of 1000 pulse per session given at 100% of motor threshold. A total of 16 sessions will be given to each patient.

What is the study measuring?

Primary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Change in Mean Deviation (MD) of Automated Perimetry
Time Frame: 6 weeks
Change in mean deviation (MD) from baseline will be assessed using automated perimetry's full threshold 30-2 visual field test.
6 weeks

Secondary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Change in Visual Field Index (VFI) of Automated Perimetry
Time Frame: 6 weeks
Change in visual field index (VFI) from baseline will be assessed using automated perimetry's full threshold 30-2 visual field test.
6 weeks
National Eye Institute Visual Functioning Questionnaire-25 (VFQ-25)
Time Frame: 6 weeks
This questionnaire measures the dimensions of self-reported vision-targeted health status that are most important for the daily functioning of patients with visual field defects. It has 12 sub-scale scores each with a 0 to 100 scale. These sub-scale scores are then averaged to produce a 0 to 100 overall score where higher score represents better outcome.
6 weeks

Collaborators and Investigators

This is where you will find people and organizations involved with this study.

Sponsor

Ain Shams University

Publications and helpful links

The person responsible for entering information about the study voluntarily provides these publications. These may be about anything related to the study.

General Publications

Study record dates

These dates track the progress of study record and summary results submissions to ClinicalTrials.gov. Study records and reported results are reviewed by the National Library of Medicine (NLM) to make sure they meet specific quality control standards before being posted on the public website.

Study Major Dates

Study Start (Actual)

June 1, 2018

Primary Completion (Actual)

April 1, 2020

Study Completion (Actual)

June 5, 2020

Study Registration Dates

First Submitted

April 6, 2019

First Submitted That Met QC Criteria

July 13, 2019

First Posted (Actual)

July 16, 2019

Study Record Updates

Last Update Posted (Actual)

July 21, 2021

Last Update Submitted That Met QC Criteria

July 19, 2021

Last Verified

July 1, 2021

More Information

Terms related to this study

Keywords

Additional Relevant MeSH Terms

Other Study ID Numbers

  • 1801

Plan for Individual participant data (IPD)

Plan to Share Individual Participant Data (IPD)?

Yes

IPD Sharing Supporting Information Type

  • Study Protocol
  • Statistical Analysis Plan (SAP)
  • Informed Consent Form (ICF)

Drug and device information, study documents

Studies a U.S. FDA-regulated drug product

No

Studies a U.S. FDA-regulated device product

No

This information was retrieved directly from the website clinicaltrials.gov without any changes. If you have any requests to change, remove or update your study details, please contact register@clinicaltrials.gov. As soon as a change is implemented on clinicaltrials.gov, this will be updated automatically on our website as well.

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