Transcranial magnetic stimulation after pure motor stroke

Area of Science:

• Neuroscience
• Neurology
• Rehabilitation Medicine

Background:

• Pure motor stroke (PMS) from lacunar infarcts can lead to subtle corticospinal pathway dysfunction.
• Assessing subclinical neurological deficits post-stroke is crucial for understanding long-term recovery and guiding rehabilitation.

Purpose of the Study:

• To evaluate the sensitivity of motor-evoked potentials (MEPs) using transcranial magnetic stimulation (TMS) in detecting subclinical corticospinal pathway impairment after pure motor stroke (PMS).
• To investigate persistent neurophysiological changes in patients with PMS, even after complete clinical recovery.

Main Methods:

• MEPs were recorded from the first dorsal interosseous muscle in 40 PMS patients and 20 healthy controls, 6+ months post-stroke.
• Clinical assessments included NIH stroke scale, MRC scale, Barthel Index, and the 9-hole peg test for hand function.
• Transcranial magnetic stimulation (TMS) parameters like motor threshold (MT), MEP amplitude, and central motor conduction time (CMCT) were analyzed.

Main Results:

• Patients showed significant differences in MT, MEP amplitude, and CMCT on the affected side compared to controls and their unaffected side.
• Abnormal MEPs were found in 86% of patients with persistent hand weakness.
• Even in patients with complete clinical recovery, increased MT and decreased MEP amplitude were observed on the affected side.

Conclusions:

• Neurophysiological abnormalities in the corticospinal pathway can persist after pure motor stroke, despite apparent clinical recovery.
• Transcranial magnetic stimulation (TMS) is a sensitive tool for objectively identifying these subclinical impairments.