Variations of Tendon Tap Force Threshold needed to Evoke Surface Electromyogram Responses after Botulinum Toxin Injection in Chronic Stroke Survivors

Babak Afsharipour*, Guijin Li, Sourav Chandra, William Z. Rymer, Nina L. Suresh

*Corresponding author for this work

Research output: Chapter in Book/Report/Conference proceedingConference contribution

Abstract

Botulinum toxin (BT) is a safe and effective neuromuscular blocking agent that is clinically utilized to reduce spasticity after stroke. It is often injected repeatedly at a minimum of 12-week intervals. BT targets the neuromuscular junction and chemically denervates muscle fibers from their corresponding spinal motoneurons (MN). We explored the effect of BT on the amplitude of the smallest tendon tap force (i.e. force threshold) required to elicit a detectable biceps brachii surface electromyogram (sEMG) reflex response. We hypothesized that after BT injection, the force threshold would increase due to a decrease in available efferent activation. Two chronic stroke survivors were recruited. Data were collected before and up to 18 weeks after BT injection. For each subject, sEMG responses were analyzed using high-density sEMG (HDsEMG) recordings, and the threshold tapping forces were identified and mapped for all channels. Unexpectedly, median threshold forces (MTF) decreased post-BT (B01: 30%, B02: 50%). However, after the initial decrease, MTF then increased progressively compared to pre-BT and peaked around 12 weeks (B01: ~4 folds, B02: 50%). This is likely because post-BT, fewer available muscle fibers would require larger tapping forces to evoke detectable sEMG responses. In the last recording session (> 12 weeks), MTF did not return to pre-BT levels, indicating that successive botulinum toxin injections may still be effective if spaced much further apart in time.

Original languageEnglish (US)
Title of host publication9th International IEEE EMBS Conference on Neural Engineering, NER 2019
PublisherIEEE Computer Society
Pages385-388
Number of pages4
ISBN (Electronic)9781538679210
DOIs
StatePublished - May 16 2019
Event9th International IEEE EMBS Conference on Neural Engineering, NER 2019 - San Francisco, United States
Duration: Mar 20 2019Mar 23 2019

Publication series

NameInternational IEEE/EMBS Conference on Neural Engineering, NER
Volume2019-March
ISSN (Print)1948-3546
ISSN (Electronic)1948-3554

Conference

Conference9th International IEEE EMBS Conference on Neural Engineering, NER 2019
CountryUnited States
CitySan Francisco
Period3/20/193/23/19

Keywords

  • botulinum toxin
  • grid electrodes
  • spasticity
  • stretch reflex
  • stroke
  • surface EMG
  • tendon tap

ASJC Scopus subject areas

  • Artificial Intelligence
  • Mechanical Engineering

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    Afsharipour, B., Li, G., Chandra, S., Rymer, W. Z., & Suresh, N. L. (2019). Variations of Tendon Tap Force Threshold needed to Evoke Surface Electromyogram Responses after Botulinum Toxin Injection in Chronic Stroke Survivors. In 9th International IEEE EMBS Conference on Neural Engineering, NER 2019 (pp. 385-388). [8717098] (International IEEE/EMBS Conference on Neural Engineering, NER; Vol. 2019-March). IEEE Computer Society. https://doi.org/10.1109/NER.2019.8717098