Tracheal allograft reconstruction: the total North American and worldwide pediatric experiences.

BACKGROUND: We reviewed both the North American and the total worldwide pediatric experience with tracheal allograft reconstruction as treatment for patients with long segment and recurrent tracheal stenosis. METHODS: The stenosed tracheal segment is opened to widely patent segments. The anterior cartilage is resected and the posterior trachealis muscle or tracheal wall remains. A temporary silastic intraluminal stent is placed and absorbable sutures secure the chemically preserved cadaveric trachea. After initial success with this technique in Europe, several North American centers have now performed the procedure. The cumulative North American experience includes 6 patients (3 adults and 3 children). Worldwide, more than 100 adults and 31 children, aged 5 months to 18 years, with severe long segment tracheal stenosis have undergone tracheal allograft reconstruction. RESULTS: In North America, 5 of 6 patients have survived, with one early death due to bleeding from a tracheal-innominate artery fistula in a previously irradiated neck. Worldwide, 26 children survived (26 of 31 = 84%) with follow-up from 5 months to 14 years. Only 1 of 26 pediatric survivors (1 of 26 = 3.8%) had a tracheostomy. CONCLUSIONS: Tracheal allograft reconstruction demonstrates encouraging short- to medium-term results for patients with complex tracheal stenosis. Allograft luminal epithelialization supports the expectation of good long-term results.

Otoacoustic emissions in normal and hearing-impaired children and normal adults.

Although distortion-product otoacoustic emissions (DPOEs) have been studied in adults recently, there is little information regarding them in young children. DPOEs and click-evoked otoacoustic emissions (CEOEs) were measured from a same group of normal and hearing-impaired children (age 4 through 10 years) and normal adults (age 22 through 29 years). Measurements of DPOEs in 13 children's ears with normal hearing showed higher levels of emissions in the 700- to 1400-Hz and 5.7-kHz regions relative to the data obtained in 10 normal adult ears. The 22 ears of children with sensorineural hearing loss demonstrated agreement between pure-tone audiograms and "DPOE audiograms." Measurements of CEOEs revealed that the average level of emission in 15 normal-hearing children's ears was slightly lower than that previously obtained in newborns, but slightly higher than that of adults. In children, the CEOE spectral components in the 4- to 6-kHz region were lower than in newborns, but higher than in adults. These results support the view that the DPOEs and CEOEs comprise a valuable tool in assessment of cochlear function in subjects of all ages.

On the use of adaptive procedures in binaural experiments.

Adaptive psychophysical procedures have been routinely used in monaural experiments for many years, but only sparsely used in binaural experiments. In this letter, (1) the increasing use of adaptive procedures in binaural experiments is documented; (2) factors that determine their appropriateness are discussed; and (3) data that attest to their usefulness are presented.

Effects of lidocaine infusion in cats after unilateral labyrinthectomy.

In the auditory/vestibular system, intravenous lidocaine hydrochloride administration has been reported to provide transient relief from severe tinnitus, reduce dizziness and emesis accompanying Meniere's disease, and sometimes improve audiometric thresholds in sensorineural hearing loss. In this study, the labyrinth was destroyed unilaterally in a series of cats. Animals constantly fell and demonstrated prominent contralateral nystagmus and a rotary motion of the head. Within four hours of a 4-mg/kg intravenous lidocaine hydrochloride injection, the cats were able to ambulate freely without falling. The nystagmus was reduced, and there was virtual absence of the rotary head motion. In contrast, the controls had persistent signs of vestibular disturbance. These results demonstrate that lidocaine infusion ameliorates the effects of unilateral labyrinthectomy in cats and thus may be a potential antivertiginous agent.