Finding an Optimal Latency for Paired Associative Stimulation in People With Chronic Stroke
| Status: | Active, not recruiting |
|---|---|
| Conditions: | Neurology |
| Therapuetic Areas: | Neurology |
| Healthy: | No |
| Age Range: | 18 - Any |
| Updated: | 11/11/2017 |
| Start Date: | September 2014 |
| End Date: | December 2016 |
Effect of Different Interpulse Intervals of Paired Associative Stimulation on Cortical Excitability in People With Chronic Stroke
After a stroke, there is an exaggerated inhibitory influence from the non-stroke hemisphere
to the stroke hemisphere. Brain stimulation using repetitive transcranial magnetic
stimulation (rTMS) to the non-stroke hemisphere can decrease this inhibition. Paired
Associative Stimulation (PAS) may be a more effective way to produce this same inhibition, as
shown in healthy subjects. However, it is not known whether this will translate to people
with stroke. PAS consists of a peripheral nerve stimulus paired a short time later with a
cortical stimulus to change the excitability within the brain. Thus the investigators will
apply PAS to people with stroke, but the investigators need to first determine the most
effective interpulse interval (IPI) between the peripheral and cortical stimuli. Our research
question is which of three different IPIs is most effective in changing the excitability of
the brain.
The purpose of this study is to determine the optimal IPI between a peripheral nerve pulse
and a cortical stimulus that will be most effective in changing excitability of the brain in
people with chronic stroke. The investigators hypothesize that the cortical excitability of
the nonstroke hemisphere will be most inhibited with the latency-5ms condition.
to the stroke hemisphere. Brain stimulation using repetitive transcranial magnetic
stimulation (rTMS) to the non-stroke hemisphere can decrease this inhibition. Paired
Associative Stimulation (PAS) may be a more effective way to produce this same inhibition, as
shown in healthy subjects. However, it is not known whether this will translate to people
with stroke. PAS consists of a peripheral nerve stimulus paired a short time later with a
cortical stimulus to change the excitability within the brain. Thus the investigators will
apply PAS to people with stroke, but the investigators need to first determine the most
effective interpulse interval (IPI) between the peripheral and cortical stimuli. Our research
question is which of three different IPIs is most effective in changing the excitability of
the brain.
The purpose of this study is to determine the optimal IPI between a peripheral nerve pulse
and a cortical stimulus that will be most effective in changing excitability of the brain in
people with chronic stroke. The investigators hypothesize that the cortical excitability of
the nonstroke hemisphere will be most inhibited with the latency-5ms condition.
Numerous PAS studies have been done in healthy subjects and all have been done safely. The
proper interpulse interval in healthy individuals between the peripheral nerve stimulus and
the cortical stimulus is known to be "latency-5ms." However, this may be different in
individuals with stroke.
Specific Aim: what is the optimal interpulse interval to achieve the maximum inhibitory
effect in the nonstroke hemisphere?
We will recruit three subjects with chronic stroke. Electroencephalography (EEG) will be used
to determine the latency between the peripheral nerve stimulus and the sensory evoked
potential in each subject. We will then assess the following IPIs on each subject in a random
order: "latency" - 3ms, -5ms and -7ms. There will be a fourth condition of "latency" + 100ms
(known to have no effect) to be used as a control. The washout period will be at least one
week between each of these conditions.
The optimal IPI will be determined from these tests by comparing single pulse transcranial
magnetic stimulation (TMS) measures for cortical excitability. Prior to each treatment, each
subject will receive 20 single pulse cortical stimuli to serve as pretest data. The post
tests for each condition will consist of 20 single pulse cortical stimuli at 0, 5, 10, 15,
30, 45 and 60 minutes after the PAS condition. Data analysis will consist of a single-subject
analysis with the two standard deviation bandwidth method of each post-test compared to
pre-test.
We hypothesize that there will be no adverse advents and that this optimal IPI will be
"latency"-5ms.
proper interpulse interval in healthy individuals between the peripheral nerve stimulus and
the cortical stimulus is known to be "latency-5ms." However, this may be different in
individuals with stroke.
Specific Aim: what is the optimal interpulse interval to achieve the maximum inhibitory
effect in the nonstroke hemisphere?
We will recruit three subjects with chronic stroke. Electroencephalography (EEG) will be used
to determine the latency between the peripheral nerve stimulus and the sensory evoked
potential in each subject. We will then assess the following IPIs on each subject in a random
order: "latency" - 3ms, -5ms and -7ms. There will be a fourth condition of "latency" + 100ms
(known to have no effect) to be used as a control. The washout period will be at least one
week between each of these conditions.
The optimal IPI will be determined from these tests by comparing single pulse transcranial
magnetic stimulation (TMS) measures for cortical excitability. Prior to each treatment, each
subject will receive 20 single pulse cortical stimuli to serve as pretest data. The post
tests for each condition will consist of 20 single pulse cortical stimuli at 0, 5, 10, 15,
30, 45 and 60 minutes after the PAS condition. Data analysis will consist of a single-subject
analysis with the two standard deviation bandwidth method of each post-test compared to
pre-test.
We hypothesize that there will be no adverse advents and that this optimal IPI will be
"latency"-5ms.
Inclusion Criteria:
- stroke (ischemic or hemorrhagic) of greater than 6 months duration
- impairment in the paretic hand
- over 18 years old
- male or female
- on mini mental status exam must have score of 22 or higher
- must have elicitable motor evoked potential (MEP)
Exclusion Criteria:
- seizure within the past two years
- receptive aphasia
- epileptogenic medication
- major psychiatric disorder
- other interfering comorbidities
- pregnancy
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