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Physiology of the motor cortex in polio survivors
Author(s) -
Lupu Vitalie D.,
Danielian Laura,
Johnsen Jacqueline A.,
Vasconcelos Olavo M.,
Prokhorenko Olga A.,
Jabbari Bahman,
Campbell William W.,
Floeter Mary Kay
Publication year - 2008
Publication title -
muscle and nerve
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.025
H-Index - 145
eISSN - 1097-4598
pISSN - 0148-639X
DOI - 10.1002/mus.20913
Subject(s) - transcranial magnetic stimulation , motor cortex , poliomyelitis , physical medicine and rehabilitation , medicine , stimulation , electromyography , silent period , neuroscience , cardiology , psychology , pediatrics
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