Restoration of function in the paralyzed rabbit orbicularis oculi muscle by direct functional electrical stimulation.

Restoration of the ability to blink and protect the eye in the patient with facial paralysis remains a challenge. Although many treatments exist, no one approach corrects all the deficits associated with the loss of orbicularis oculi function. In this study, the author investigated the feasibility of restoring function by direct electrical stimulation of the paralyzed orbicularis oculi muscle in the rabbit model. Using a pacing device developed by the author, functional restoration of a normal-appearing blink was produced throughout 30 days of continuous pacing in six rabbits with transected facial nerves. Histologic evaluations of the paced tissues demonstrated no evidence of detrimental effects attributable to the electrical stimulation. The findings of this study support the feasibility of employing direct electrical stimulation to restore the function of paralyzed orbicularis oculi muscles. Potential applications may also exist in other areas in which peripheral denervation creates functional impairment.

Cocaine, lidocaine, tetracaine: which is best for topical nasal anesthesia?

The quality of nasal anesthesia obtained with three local anesthetic solutions (4% cocaine, 2% lidocaine in oxymetazoline, and 1% tetracaine in oxymetazoline) was evaluated in a randomized study. Each local anesthetic mixture was applied to the nasal septum of healthy volunteers using medication-soaked pledgets. Measurements of anesthetic effect (sensation threshold and pain perception) were made with Semmes-Weinstein monofilaments. Measurements were performed prior to local anesthetic application and 10 and 70 min after local anesthetic application. Subjects had greater increases in sensation threshold with tetracaine than with lidocaine or cocaine at both 10 and 70 min (P < 0.05). Subjects had greater decreases in pain perception with tetracaine than with lidocaine or cocaine at both time intervals (P < 0.05). Tetracaine mixed with oxymetazoline appears to be a superior topical anesthetic for nasal procedures.

Functional electrical stimulation for the treatment of bilateral recurrent laryngeal nerve paralysis.

We have previously presented the concept of electrophysiologic pacing of bilaterally paralyzed vocal cord abductors as a solution to the difficult problem incurred in this clinical situation. Initially, we demonstrated that it was indeed feasible to electrophysiologically pace abduction of the vocal cords synchronously with respiration, employing the EMG activity of the diaphragm as a trigger stimulus. Further research has led us to evaluate other possible physiologic trigger stimuli to ascertain which of these will prove most suitable in long-term pacing studies. In this article, we will report our preliminary results, employing negative intrathoracic pressure occurring with respiration--as detected by an implanted pressure transducer as a trigger stimulus. This device was interfaced with a muscle stimulator attached to electrodes placed in the cricoarytenoid muscles in five canines whose recurrent laryngeal nerves had been sectioned bilaterally. In all animals, obvious physiologic synchrony of vocal cord abduction and a reduction of negative inspiratory intratracheal pressure was achieved during electrical pacing. This reinforces our initial findings that it is indeed feasible to pace vocal cord abduction in bilateral recurrent laryngeal nerve paralysis with resultant return of physiologic normality to the glottis. Thus, functional electrical stimulation offers an alternative approach to the difficult problems incurred in the patient with bilateral recurrent laryngeal nerve paralysis. It also demonstrates that physiologic negative intrathoracic pressure activity occurring with inspiration can be a trigger source.

The effect of sterile inflammation on skin flap survival.

Several investigations have suggested that a sterile inflammatory reaction in a skin flap enhances flap survival. A chemical peel produces a mild chemical burn, which is one form of nonbacterial inflammatory response. Some authors advocate the concomitant use of face lift and chemical peel, while others caution that the peel might jeopardize the facial flaps. To determine whether the reaction caused by a chemical peel enhances or impairs skin flap survival, a study using miniature pigs was undertaken. Survival length of flaps treated with a chemical peel was compared to that of untreated flaps. A total of 36 dorsally based random flaps were used on three miniature pigs. Six identical 14 X 4 cm flaps were designed on each side of the pigs. A chemical peel was applied to the area of 18 of the proposed flaps 2 days prior to elevation. Alternate flaps on each side of the pigs were treated. As the flaps were elevated, the tips were examined to document the inflammatory response histologically. After 14 days, the surviving length of the flaps was measured. As determined by the Wilcoxon matched-pairs signed-ranks test, there was no significant difference between the treated and untreated groups. Our study shows that a nonbacterial inflammatory response produced by a chemical peel does not improve skin flap survival, at least not in pigs.

Electrophysiologic pacing of vocal cord abductors in bilateral recurrent laryngeal nerve paralysis.

We have reconfirmed our previous findings that controlled, reproducible, sustained, discrete vocal cord abduction can be achieved synchronously with respiration by electrophysiologic stimulation of the paralyzed posterior cricoarytenoid muscles. Moreover, we have demonstrated that this can be triggered synchronously by employing the normal physiologic chest wall movements that occur on respiration. To our knowledge, this represents the first report of functionally paced vocal fold abduction with respiration employing physiologic chest wall motions using an implantable device, and may represent an important step in the development of a physiologic approach to bilateral recurrent laryngeal nerve paralysis.