Salicylate-induced changes in cat auditory nerve activity.

The purpose of this study was to measure, in the cat, spontaneous auditory nerve (AN) activity before and after injection with sodium salicylate. Ten cats were anesthetized, and the AN and round window (RW) were surgically exposed. Electrodes were applied to allow recording from three channels, including bipolar electrodes and monopolar electrodes located directly on the auditory nerve, in addition to an RW electrode. Spectral averaging of the spontaneous activity was performed before and during salicylate treatment. An increase in spectral activity near 200 Hz was noted in all cats by 3 hours after salicylate injection. This activity was present in bipolar, monopolar, and RW records, and was temporarily diminished or eliminated by injection of lidocaine. No such spectral changes were found in saline-injected control animals. These results show promise of developing a noninvasive, objective, quantitative measure of tinnitus for studies in animals and in man.

Review of cyanoacrylate tissue glues with emphasis on their otorhinolaryngological applications.

Cyanoacrylates were first synthesized by Ardis in 1949. However, it was not until Coover in 1959 discovered their adhesive properties that an interest arose in using these substances in surgical procedures. Over the past two decades the use of cyanoacrylates has been varied and widespread among the surgical specialties. methyl 2-cyanoacrylate (Eastman 910 Monomer), Isobutyl-cyanoacrylate (Bucrylate), and 2-cyano-butyl-acrylate (Histoacryl) were the most widely used. Because of its tissue toxicity methyl 2-cyanoacrylate was discarded. The consensus of various investigators was that the higher homologues, in particular Histoacryl could be safely used in human applications. The authors thought it would be important to ascertain how the academic departments of Otolaryngology perceived the role of cyanoacrylates within their specialty. A questionnaire was distributed to 115 academic centers: 47% of the departments responded and, of those, 34% indicated a current working knowledge of the cyanoacrylates. This response confirmed a very active interest in these tissue adhesives despite a lack of F.D.A. approval. The otologic applications of these adhesives has been well documented, but the literature is devoid of studies using cyanoacrylates in other aspects of Otolaryngology. The authors feel that these adhesives (in particular Histoacryl) have a role as an adjunctive technique in facial reconstructive and cosmetic surgery for autogenous cartilage grafting. A study using rabbits was designed to determine if Histoacryl could be used safely to overcome the technical difficulties (graft migration during healing and cartilage fracture during suturing) often encountered when performing autogenous onlay cartilage grafting. On the left ear of each rabbit, a cartilage graft was harvested and reimplanted at a second site on the same ear by suturing the perichondrium of the graft to the perichondrium of the donor site. On the right ear the graft was secured to the donor site with Histoacryl. The histological analysis of the rabbits' ears sacrificed at weekly intervals from 1 week to 1 month failed to demonstrate cartilage damage or tissue toxicity in the ears where Histoacryl was used. In conclusion, the authors contend that a role exists for the use of Histoacryl as an adjunctive technique in facial reconstructive and cosmetic surgery. The study will be continued to assess the long-term results of using Histoacryl for autogenous onlay cartilage grafting.

Remote extracochlear versus intracochlear recordings in the guinea pig.

A comparison was made of the whole-nerve action potential recorded from a wire electrode placed on the tympanic membrane (TM) (remote extracochlear recording) and than recorded from intracochlear electrodes in the first and third turn scala tympani of the guinea pig. Cochlear microphonics and summating potentials were also studied. The expected decreased sensitivity at the TM site was observed in all responses, although the microphonic (CM) was diminished more that the action potential (AP) as compared to the responses monitored via the ST1 electrode. Nevertheless, the TM-recorded cochlear potentials largely mimicked the ST1-recorded potentials in a qualitative manner, i.e., similar configurations of the CM pseudo-threshold functions. It was consistently observed that the N2 of the AP is proportionally larger (relative to N1) in the TM recording than in the ST1 recording. These phenomena were attributed to the complex spread of the bioelectrical potentials in the nonhomogeneous volume conductor formed by the tissues of the temporal bone. It was suggested that the observed change in the N1/N2 ratio at the different sites of recording is due to the different contributions of second-order neuronal discharges to the compound AP. In effect, the TM electrode "sees" proportionally more activity from second-order fibers than does the ST1 electrode, and the ST3 electrode, less.

Computerized tomographic evaluation of the middle ear and mastoid for posttraumatic hearing loss.

High resolution computerized tomography has been proven valuable in all aspects of temporal bone study. The importance of the procedure in evaluation of traumatic lesions, particularly of the middle ear, has been underemphasized. Damage to the middle ear may occur with blunt trauma, penetrating injury, or barotrauma. Conductive hearing loss and/or CSF otorrhea may result. Detailed evaluation of the ossicles is the hallmark of properly performed computerized tomographic evaluation.

Cephalexin in the treatment of acute and chronic maxillary sinusitis.

We evaluated the efficacy of cephalexin therapy in 104 patients with infectious maxillary sinusitis. Confirmation of diagnosis was made by x-ray film, antral puncture, and culture. Sixty-nine patients met all criteria for evaluation. The majority of patients received cephalexin, 1 gm/day in four divided doses for ten days, including the 48-hour period after the patient had become asymptomatic. Patients returned for observation one week and two weeks after initiating therapy. Satisfactory clinical results were obtained in 57 (83%). Results showed that cephalexin was effective in treating sinusitis and that adverse reactions were rare. Bacteriology results showed that many of the pathogens usually involved in infectious maxillary sinusitis were resistant to the recommended or frequently prescribed antibiotics. These same pathogens, however, did not show resistance to cephalexin.

Use of butyl-2-cyanoacrylate in rabbit auricular cartilage.

Since the nonsuture repair of blood vessels with methyl-2-cyanoacrylate was described in 1960, the advantages of a tissue adhesive over conventional sutures became evident. A survey of 115 otolaryngology programs showed that cyanoacrylates, mainly butyl-2-cyanoacrylate (B2C), are used more extensively than indicated in the literature. Cartilage grafts are commonly used in facial plastic procedures. In a study comparing B2C with conventional suture techniques in securing rabbit auricular cartilage autografts, sutures were used in the left control ear and B2C was used in the right experimental ear. Rabbits sacrificed at two weeks to 12 months showed graft viability in all samples and no statistically significant histologic difference between the grafts secured by either method.