Mechanisms of Neuromuscular Fatigue Post Stroke

NCT ID: NCT01688570

Last Updated: 2015-11-05

Basic Information

• Recruitment Status: COMPLETED
• Clinical Phase: EARLY_PHASE1
• Total Enrollment: 27 participants
• Study Classification: INTERVENTIONAL
• Study Start Date: 2011-08-31
• Study Completion Date: 2015-05-31

Brief Summary

While baseline weakness is clearly an important factor that contributes to disability post stroke, neuromuscular fatigue (the acute reduction in force production) of the paretic musculature likely compounds strength deficits and further exacerbates disability. The proposed study aims to improve our understanding of the mechanisms of neuromuscular fatigue in people post stroke in order to optimize strength training. In healthy individuals, both central (neural) and peripheral (muscle) factors are determinants of neuromuscular fatigue, but preliminary data from our laboratory suggests a greater contribution of central components to neuromuscular fatigue in the paretic musculature. Although cortical pathways are clearly disrupted post stroke, it is likely that brainstem pathways, known to have neuromodulatory effects on spinal motor circuitry, are more involved in the sustaining of force in the paretic leg, compared to the non-paretic and control legs. Therefore, the purpose of this proposal is to examine the role of descending neuromodulatory pathways of the brainstem in neuromuscular fatigue post stroke (Aim 1) and to correlate brainstem-related changes in neuromuscular fatigue to walking function (Aim 2). The investigators propose that stroke survivors' decreased capability to sustain force overtime results from the diminished ability of spinal motoneurons to respond to brainstem neuromodulatory inputs (serotonin (5-HT) and norepinephrine (NE)). Aim 1 will quantify stroke-related decreases in motor output sensitivity to a 5-HT and NE reuptake inhibitor (SNRI), serotonin antagonist, or placebo during sub-maximal intermittent fatiguing knee extension contractions. If motoneurons are desensitized to descending monoamines in chronic stroke patients, then they will be less sensitive to the effects of drugs that increase monoamine levels. The investigators predict that in response to the SNRI or serotonin antagonist, the paretic leg will show less change in time to task failure and a smaller reduction in strength as compared to the non-paretic and control legs. For Aim 2, the investigators predict that stroke subjects with the highest walking function will demonstrate the greatest fatigue-related changes in response to the SNRI. This proposal adopts an innovative model of motor impairment post stroke by including the role of subcortical structures in neuromuscular fatigue.

Conditions

Stroke

Study Design

• Allocation Method: RANDOMIZED
• Intervention Model: CROSSOVER
• Primary Study Purpose: BASIC_SCIENCE
• Blinding Strategy: DOUBLE

Study Groups

Duloxetine

Neuromuscular fatigue testing with duloxetine dose

Group Type: ACTIVE_COMPARATOR

duloxetine

Intervention Type: DRUG

Single dose, orally (pill), 30 mg, taken 6 hours prior to start of the testing session. Subjects will only take a single dose of duloxetine once.

Cyproheptadine

Neuromuscular fatigue testing with cyproheptadine dose

Group Type: ACTIVE_COMPARATOR

Cyproheptadine

Intervention Type: DRUG

Single dose, orally, 8 mg, 6 hours prior to the start of the respective testing session. Subjects will take a single dose of cyproheptadine once.

Placebo

Neuromuscular fatigue testing with placebo dose

Group Type: PLACEBO_COMPARATOR

Placebo

Intervention Type: DRUG

Single dose, orally, 6 hours prior to the start of the respective testing session. Subjects take a single dose once.

Interventions

duloxetine

Single dose, orally (pill), 30 mg, taken 6 hours prior to start of the testing session. Subjects will only take a single dose of duloxetine once.

Intervention Type: DRUG

Cyproheptadine

Single dose, orally, 8 mg, 6 hours prior to the start of the respective testing session. Subjects will take a single dose of cyproheptadine once.

Intervention Type: DRUG

Placebo

Single dose, orally, 6 hours prior to the start of the respective testing session. Subjects take a single dose once.

Intervention Type: DRUG

Other Intervention Names

Cymbalta

Eligibility Criteria

Inclusion Criteria

General

• be at least 18 years of age
• Cognitively able to give informed consent Stroke

-≥ 6 months post diagnosis of unilateral cortical stroke

• residual leg paresis

Exclusion Criteria

General

• chronic low back or hip pain
• major psychiatric disorders (e.g. depression
• substance abuse
• head trauma
• neurodegenerative disorder
• any uncontrolled medical disorder (e.g. hypertension)
• taking any medication or supplement (e.g. St. John's Wort) that has 5-HT or NE mechanisms of action(including Monoamine oxidase inhibitors (MAO) inhibitors)
• narrow angle glaucoma
• chronic liver or kidney disorders Stroke
• history of multiple strokes
• people who are unable to follow 2 step commands
• people who cannot walk ≥ 10 ft without physical assistance.

• Minimum Eligible Age: 18 Years
• Eligible Sex: ALL
• Accepts Healthy Volunteers: Yes

Sponsors

Medical College of Wisconsin

OTHER

Sponsor Role: lead

Responsible Party

Phillip Nelson, MD

Assistant Professor

Responsibility Role: PRINCIPAL_INVESTIGATOR

Principal Investigators

Philip A. Nelson, MD

Role: PRINCIPAL_INVESTIGATOR

Medical College of Wisconsin

Locations

Medical College of Wisconsin

Milwaukee, Wisconsin, United States

Countries

United States

Other Identifiers

UL1RR031973-02

Identifier Type: NIH

Identifier Source: org_study_id

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