How is botulinum toxin administered for pain management?

Updated: Mar 11, 2019
  • Author: Heather Rachel Davids, MD; Chief Editor: Elizabeth A Moberg-Wolff, MD  more...
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Therapy with botulinum toxin should be individualized for the patient and the clinician. The equipment needs should be determined according to the needs of the patient, the clinician's training, and the anatomic target for injection. For example, treatments for blepharospasm usually are given by simple subcutaneous injections around the eye without the use of special equipment; however, injections into the deep compartments of the low back, such as the psoas major muscle compartment, may require the use of special imaging techniques.

A 1.0 mL tuberculin-type syringe with 5/8-inch 25-gauge needle is adequate for superficial muscles. For small muscles (eg, facial muscles), a 1-inch 30-gauge needle is sufficient. For larger muscles, such as the hamstrings, a 1-inch or 1.5-inch 25-gauge needle is adequate.

For most limb muscles, the use of electromyography or motor point stimulation (e-stim) is recommended to identify muscles, particularly the smaller muscles in the forearm. For example, a commonly injected finger flexor muscle, the flexor digitorum sublimis (FDS), is nearly impossible to locate without electromyographic guidance. For the clinician who is developing his or her skills in identifying specific muscles for injection with botulinum toxin, the use of simple, audio-only electromyography may enhance the clinician's understanding of functional anatomy and aid the clinician in making decisions on injection localization. For muscles requiring electromyographic guidance, a cannulated monopolar needle cathode, through which botulinum toxin can be injected, is used. Surface reference (anode) and ground electrodes should be placed near the cathode needle.

After placing the patient in a position where the desired muscle can be relaxed, the motor point should be located. Botulinum toxin then can be given after aspiration to prevent intravascular injection. Alcohol, if used to clean the skin, should be allowed to dry completely to prevent toxin deactivation. The use of operating rooms or special procedure (sterile) rooms equipped with monitoring devices for the purpose of intramuscular injections using small caliber needles is not necessary. Most patients can be treated safely in an office setting by experienced clinicians.

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