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Poster 76 Motor Unit Number Estimates Show Decreases in Paretic Muscles of Stroke Survivors

      Key Words

      Objective

      To assess degeneration of spinal motoneurons after stroke by estimating the motor unit number alterations in paretic muscles of stroke survivors.

      Design

      Repeated measures descriptive study.

      Setting

      Research laboratory in a rehabilitation hospital.

      Participants

      7 stroke subjects with a unilateral brain lesion resulting in hemipareis (checking spelling) of more than 1 year duration.

      Interventions

      Maximum M waves and voluntary surface electromyogram (EMG) at 5-10 different force levels (from minimum to maximum) were recorded respectively from both paretic and contralateral hypothenar muscles of each stroke subject. Motor unit number index (MUNIX) was derived for each examined muscle using the model developed by Nandedkar et al (2004).

      Main Outcome Measures

      M-wave and surface EMG recordings; clinical assessments including spasticity measures at the elbow, the Fugl-Meyer test and the Chedoke-McMaster test.

      Results

      A significant decrease in both the maximum M-wave amplitude and the MUNIX values was observed in the paretic muscles of stroke survivors compared with the contralateral muscles.

      Conclusions

      The current study presents a novel application of the MUNIX technique for examination of stroke survivors and provides further evidence of spinal motoneuron involvement following a stroke.