Experimental paralysis of tensor veli palatini muscle

Abstract

In an effort to study the effects of experimental paralysis of tensor veli palatini (TVP) muscle on Eustachian tube (ET) function and middle-ear (ME) status, botulinum toxin A (Oculinum) was injected into the TVP muscles of 8 Rhesus monkeys. Tubal function was tested longitudinally in 2 animals with tympanostomy tubes using the forced-response test, while in the remaining 6 animals; ME condition was documented daily using tympanometry. The postinjection tubal function was characterized by abolished active muscular function and decreased closing pressure. Activity associated with tubal dilations gradually reappeared by the fifth week. The lack of lumen constrictions following injection suggested that the TVP muscle is the cause of constriction as well as normal dilation. In 6 animals with intact tympanic membranes, 10 of the 12 ears developed flat tympanograms associated with otitis media with effusion (OME) within 8-30 days of injection and serous effusions were recovered by tympanocentesis in seven ears. These results show that a non-traumatic reversible functional obstruction of the ET was created by injecting botulinum toxin A into the TVP muscle. This functional obstruction was associated with the development of high negative ME pressure and serous effusion.

Mechanism and Rate of Middle Ear Fluid Absorption

“…The fall of the fluid level in this tube can serve as a measure of the rate of absorption of water from the middle ear cavity. Since it has been shown that paralysis of the tensor veli palatine muscle leads to obstruction of the eustachian tube [Casselbrant et al, 1988], all of the animals were paralyzed (and artificially ventilated) so that the eustachian tube pumping mechanism could not be activated and accordingly the eustachian tube itself was not patent, preventing clearance by the beating cilia of the mucociliary mechanism.…”

Deleterious sucking habits and atypical swallowing in children with otitis media with effusion

“…In the atypical swallowers the perioral muscles show a greater activity than masticatory muscles when compared with control subjects, as demonstrated by electromyographic studies [19]. In particular, past experiences postulated that hypertonia of the internal perioral muscle caused by swallowing dysfunction can produce a reflex hypertonia of the tensor tympani muscles and a relative hypotonia of the mTVP; this may result in an ineffective opening of the ET and poor ventilation of the middle ear cavity [20].…”

Successful Treatment of Autophonia with Botulinum Toxin: Case Report

“…Because there is a risk of such side effects (as seen in animal studies 10,11 ), we assume that they are dependent on the dose and on the site of application. In our case, a BT (type A) dose of 2.5 U into the salpingopharyngeal fold was optimal.…”

“…10,11 The BT-induced paralysis of the tensor veli palatini muscle was successful in a human case of palatal tremor. 18,21 Botulinum toxin interferes with presynaptic acetylcholine release at the neuromuscular junction and is established as a standard therapy for a wide spectrum of diseases.…”