Hemianopsia, Infarction; Posterior Cerebral Artery, Stroke
Conditions
Keywords
Controlled clinical trial, Electric Stimulation Therapy
Brief summary
Occipital stroke is associated with homonymous visual field defects (occurring on one side of the visual field). Despite spontaneous recovery, some degree of defect is often permanent. Currently, no treatment exists for such visual field defects.The purpose of this study is to test the efficacy of a type of electrical brain stimulation method, transcranial alternating current stimulation, in reducing these type of visual field defects in their chronic stage.
Interventions
DEVICEActive tACS using DC-Stimulator MC
Transcranial alternating current stimulation (tACS) is administered using DC-Stimulator MC (NeuroConn GmbH, Ilmenau Germany). Stimulation is administered through two 5 cm2 saline-soaked electrodes placed in the Fpz position and on the right arm. Stimulation will consist of short blocks, during which stimulation frequency will be ramped up to 30Hz with maximum current of 1.5mA. Stimulation will be administered for 20 minutes on 10 consecutive weekdays.
DEVICESham stimulation using DC-Stimulator MC
Patients in the sham group will undergo the same preparations as the treatment group. This includes using an identical electrode placement and session duration as for the experimental arm. In order to create the effect of phosphenes, one 5Hz current burst per minute will be administered using the individual phosphene threshold of the patient. This is not expected to have therapeutic effects.
Sponsors
Academy of Finland
Helsinki University Central Hospital
Study design
Allocation
RANDOMIZED
Intervention model
PARALLEL
Primary purpose
TREATMENT
Masking
DOUBLE (Subject, Outcomes Assessor)
Eligibility
Sex/Gender
ALL
Age
18 Years to 75 Years
Healthy volunteers
No
Inclusion criteria
* Occipital ischemic or hemorrhagic stroke 6 months or older * Hemianopia or quadrantanopia demonstrated by standard automated perimetry * Visual field defect is stable across baseline * Presence of residual vision and detectable gradual transition between the the intact and absolutely blind parts of the visual field * Best corrected visual acuity for at least one eye better or equal to 0.4
Exclusion criteria
* Eye or central nervous system disease that interferes with the study * Cardiac pacemaker * Other metallic devices or implants precluding participation in MRI scans * Pregnancy or lactation period * Epileptic seizures in the past 10 years * Use of antiepileptic or sedative drugs * Expected low compliance due to substance abuse * Known active malignancy
Design outcomes
Primary
| Measure | Time frame | Description |
|---|---|---|
| Improved detection in the visual field defined as the percentage change of the stimulus detection rate in High-resolution perimetry (HRP) | Change between 3-7 days pre-treatment, at 3-7 days post-treatment, and at 2 months post-treatment | HRP is a computer-based perimetry using a supra-threshold stimulus. It is used to detect residual vision between the absolute defect and seeing field and to monitor subtle changes in perceptual ability. HRP is performed in fixation control using an eye tracker. The primary outcome measure will be the percentage change in HRP detection accuracy between pre-test and post-test measurements. |
Secondary
| Measure | Time frame | Description |
|---|---|---|
| The change in extent of visual fields in standard automated perimetry | Change between 3-7 days pre-treatment, at 3-7 days post-treatment, and at 2 months post-treatment | A secondary outcome measure will be the change in extent of visual fields i.e. mean threshold measured by means of standard automated perimetry. |
Countries
Finland
Contacts
Primary ContactTurgut Tatlisumak, MD, PhD
Outcome results
None listed