Page 43 - Prosthetic voice rehabilitation-5th edition

pre-existing neuromuscular diseases (myasthenia gravis, Easton-Lambert syndrome, ALS), and simultaneous use of drugs, affecting neuromuscular junctions, such as amino- glycosides. 3.3.2.2 Application in PE segment hypertonicity The dose of Botox advised mostly is 50-100 MU (4 times as much in case Dysport is used), which is considerably higher than in most other indications in the head and neck region. The toxin is easily inactivated, which means that the vial, which contains 100 MU, should be kept in the refrigerator until use. The toxin is reconstituted in 2 to 4 cc normal saline and should be used within 6 hours after reconstitution. First, the position of the hypertonic bar of the PE segment should be determined.43 This can be achieved best with videofluoroscopy, which should be carried out in the same body posture wherein the injection will be performed afterwards. The upper and lower border of the hypertonic bar of the PE segment is marked in a resting position, using lead beads, taped on the skin. Next, the Botox solution can be injected unilaterally at the upper and lower marking site and halfway. We use 100 MU in a tuberculin syringe, injecting carefully between the carotid artery and the pharyngeal wall (it should be kept in mind that the carotid artery often is displaced medially after total laryngectomy). The needle is advanced onto the prevertebral fascia and then withdrawn 0.5-1 cm and Botox is injected at the upper border, lower border and midway those two. The procedure is best carried out under EMG guidance, using a hollow 27 gauge EMG needle. However, it is advisable also in this case to mark the hypertonic bar of the PE segment in order to be surer of the correct injection site.44-47 The effect of the Botox treatment can be noticed in 24 hours, and, interestingly enough, if a positive effect is obtained, it can last much longer than the normal physiologic effect, which persists, as already mentioned, between 3 and 6 months. It is not unusual that a single injection is sufficient to achieve a permanent effect.47 The video below shows an example of pre and post Botox treatment voicing. 43