Citation

Lupu VD, Danielian L, Johnsen JA, Vasconcelos OM, Prokhorenko OA, Jabbari B, Campbell WW, Floeter MK. Muscle Nerve 2008; 37(2): 177-182.

Affiliation

EMG Section, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Building 10, CRC, 7-5680, 10 Center Drive, MSC-1404 Bethesda, Maryland 20892, USA.

Copyright

(Copyright © 2008, John Wiley and Sons)

DOI

10.1002/mus.20913

PMID

17990291

Abstract

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.

Language: en