The role of electromyography in guiding botulinum toxin injections for focal dystonia and spasticity

T. Ajax, Mark A Ross, R. L. Rodnitzky

Research output: Contribution to journalArticle

14 Citations (Scopus)

Abstract

The accuracy of placing the needle used for botulinum toxin (BTX) injection in muscles was assessed in 45 patients receiving BTX treatment for focal dystonia or spasticity. An electromyographer placed a needle capable of both injection and electromyography (EMG) recording in muscles selected for BTX injection. This was done while the EMG preamplifier was turned off to simulate BTX injection without EMG guidance. After switching on the preamplifier, needle placement was assessed by analysis of motor unit potential (MUP) rise time. If the MUP rise time was less than 500 μs, the needle was considered correctly placed. If MUPs were absent or distant, the needle was repositioned until MUP rise time was less than 500 μs. The distance the needle was repositioned was estimated in millimeters by direct observation. Forty-five patients had 381 separate BTX injections in 47 muscles. With initial needle placement, MUPs were absent in 2.8 percent and distant in 26.2 percent, resulting in repositioning (29 percent) an average distance of 3.0 mm (range 0.5 to 12 mm). In 2.4 percent of injections, only distant MUPs could be obtained despite repositioning. Judged by the percentage of initially correct needle placements and the distance of needle movement to achieve appropriate MUPs, the least accurate needle placements were in the forearm flexors and small leg muscles. The most accurate needle placements were in large lower extremity and paraspinal muscles. The needle used for BTX injection was not optimally situated in the intended muscle, as judged by MUP rise time, in 29 percent of the injection sites initially selected without EMG guidance. This suggests that EMG needle guidance may improve the needle localization within the intended muscle compared with anatomic localization alone. This may contribute to a better therapeutic response and reduce complications of BTX treatment.

Original languageEnglish (US)
Pages (from-to)1-4
Number of pages4
JournalJournal of Neurologic Rehabilitation
Volume12
Issue number1
DOIs
StatePublished - 1998
Externally publishedYes

Fingerprint

Dystonic Disorders
Botulinum Toxins
Electromyography
Needles
Injections
Muscles
Paraspinal Muscles
Forearm

Keywords

  • Botulinum toxin
  • Dystonia
  • Electromyography (EMG)
  • Endplate
  • Motor unit potential
  • Neuromuscular junction
  • Rise time
  • Spasticity

ASJC Scopus subject areas

  • Medicine(all)
  • Clinical Neurology
  • Rehabilitation
  • Neurology

Cite this

The role of electromyography in guiding botulinum toxin injections for focal dystonia and spasticity. / Ajax, T.; Ross, Mark A; Rodnitzky, R. L.

In: Journal of Neurologic Rehabilitation, Vol. 12, No. 1, 1998, p. 1-4.

Research output: Contribution to journalArticle

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