Physiology of the motor cortex in polio survivors

We hypothesized that the corticospinal system undergoes functional changes in long‐term polio survivors. Central motor conduction times (CMCTs) to the four limbs were measured in 24 polio survivors using transcranial magnetic stimulation (TMS). Resting motor thresholds and CMCTs were normal. In 17 s...

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Bibliographic Details
Published in:Muscle & nerve 2008-02, Vol.37 (2), p.177-182
Main Authors: Lupu, Vitalie D., Danielian, Laura, Johnsen, Jacqueline A., Vasconcelos, Olavo M., Prokhorenko, Olga A., Jabbari, Bahman, Campbell, William W., Floeter, Mary Kay
Format: Article
Language:English
Subjects:
Aged
Biological and medical sciences
Diseases of striated muscles. Neuromuscular diseases
Dose-Response Relationship, Radiation
Electric Stimulation - methods
Electromyography
Evoked Potentials, Motor - physiology
Fatigue
Female
Humans
intracortical facilitation
intracortical inhibition
Male
Medical sciences
Middle Aged
Motor Cortex - physiopathology
Motor Cortex - virology
Muscle, Skeletal - innervation
Neural Conduction - physiology
Neural Conduction - radiation effects
Neural Inhibition - physiology
Neural Inhibition - radiation effects
Neurology
Physical Endurance
plasticity
Poliovirus
post-polio syndrome
Postpoliomyelitis Syndrome - pathology
transcranial magnetic stimulation
Transcranial Magnetic Stimulation - methods
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Summary:We hypothesized that the corticospinal system undergoes functional changes in long‐term polio survivors. Central motor conduction times (CMCTs) to the four limbs were measured in 24 polio survivors using transcranial magnetic stimulation (TMS). Resting motor thresholds and CMCTs were normal. In 17 subjects whose legs were affected by polio and 13 healthy controls, single‐ and paired‐pulse TMS was used to assess motor cortex excitability while recording from tibialis anterior (TA) muscles at rest and following maximal contraction until fatigue. In polio survivors the slope of the recruitment curve was normal, but maximal motor evoked potentials (MEPs) were larger than in controls. MEPs were depressed after fatiguing exercise. Three patients with central fatigue by twitch interpolation had a trend toward slower recovery. There was no association with symptoms of post‐polio syndrome. These changes occurring after polio may allow the motor cortex to activate a greater proportion of the motor neurons innervating affected muscles. Muscle Nerve, 2007
ISSN:0148-639X
1097-4598
DOI:10.1002/mus.20913