[An analysis of the tumor growth rate in neuroma of the VIII cranial nerve using a digital image analysis system]. / Análisis de la tasa de crecimiento tumoral en el neurinoma del VIII par mediante la aplicación de un sistema de análisis digital de imágenes.

A digital image analysis system was used in a retrospective analysis of MRI findings in 9 patients with acoustic neuroma. Maximum and minimum tumor diameters and surface area were measured and tumor volume was calculated. All studies included intravenous injection of gadolinium (Gd-DTPA or DOTA) and axial and coronal sections. Tumoral growth rate was analyzed using the increase in tumor size ( T) tumor area doubling time (ADT), and tumor volume doubling time (VDT). The purpose of this study was to document the growth rate of acoustic neuromas with periodic MRI. In an era in which preservation of hearing and the facial nerve is a goal of acoustic neuroma surgery, knowledge of tumor growth rate should improve patient care.

Bone cement reconstruction of the ossicular chain: a preliminary report.

OBJECTIVE: To determine the feasibility and efficacy of using a bone cement, Oto-Cem, to reconstruct the ossicular chain. STUDY DESIGN: Prospective clinical trial on nine consecutively chosen adult patients with ossicular chain defects. PATIENTS AND SETTING: Nine patients with ossicular chain defects involving the long process of the incus were treated at the Carolina Ear and Hearing Clinic. The ossicular chain was reconstructed using bone cement by itself or in conjunction with a stapes prosthesis. MAIN OUTCOME MEASURES: Preoperative audiograms were compared with audiograms 3, 6, and 12 months after reconstruction. RESULTS: There was a mean pure-tone average (PTA) improvement of 15 dB in patients undergoing incus to stapes suprastructure reconstruction with the bone cement. The incus to mobile footplate reconstruction (using a stapes prosthesis attached to the newly reconstructed incus) resulted in a 34-dB PTA postoperative improvement. Two of the three patients with incus to oval window repairs experienced a 10-dB improvement in PTA. One of the three patients experienced a loss in speech discrimination and a 2-dB loss in PTA. CONCLUSIONS: Despite the limited number of patients, this preliminary study demonstrates the effectiveness of Oto-Cem in reconstructing a foreshortened incus. There was a substantial hearing improvement in all but one patient in the incus to stapes or the incus to footplate categories.

Analysis of patients with persistent dizziness after vestibular nerve section.

Vestibular neurectomy can be an effective operation for the control of persistent dizziness refractory to medical treatment or even endolymphatic sac surgery. Past studies have reported favorable results, creating an almost deceptive impression of the procedure's success rate. However, not all patients will respond favorably. Some will continue to have significant postoperative disequilibrium and, worse yet, persistent vertigo. To analyze the reasons for continued problems, 142 patients undergoing various surgical approaches employed to divide the vestibular nerve (retrolabyrinthine, middle fossa, retrosigmoid and translabyrinthine) were retrospectively, reviewed. Twenty-nine patients (20%) continued to have significant dizziness despite vestibular neurectomy. The reasons for failure were incomplete vestibular nerve section, poor central nervous system compensation, new vestibular disease in the opposite ear, obstructive anatomy, the presence of other central nervous system diseases, and unknown causes. This paper will detail the advantages and disadvantages of various vestibular neurectomy approaches and will present recommendations for further treatment of this difficult-to-manage group of patients.

Electrocochleographic effects of ear canal pressure change in subjects with Menière's disease.

This study examined the relationship between objective changes in electrocochleographic (ECochG) parameters and subjective changes in symptoms in a group of patients with Menière's disease/endolymphatic hydrops (MD/ELH) after application of positive and negative atmospheric pressure changes to the sealed ear canal. Our goals were to further examine the therapeutic effects of atmospheric pressure change on the treatment of MD/ELH, as reported by a series of Swedish studies, and to examine the utility of ECochG for monitoring these effects. By combining a clinical immittance unit and an evoked potential unit, ECochG responses were obtained from the tympanic membrane while different atmospheric pressures were applied indirectly to the middle ear via the external ear canal. For comparison, ECochG responses at various atmospheric pressures also were obtained for otologically normal subjects. For the MD/ELH group, there was a significant (p < 0.01) reduction in the abnormal summating potential/action potential (SP/AP) amplitude ratio, although the amplitude ratios did not become "normal." There was no significant effect of ear canal pressure change on ECochG components for the normative subjects. Although these findings were encouraging regarding the therapeutic effects of overpressure, they were not accompanied with changes in MD/ELH symptoms.

Ossiculoplasty with polymaleinate ionomeric prosthesis.

With the continued concern over the possible transmission of viral infections through homologous middle ear implants, there is increasing pressure to develop a truly biocompatible alloplastic middle ear prosthesis. The polymaleinate ionomer, which has been used in dentistry as a filling and luting material for more than 15 years, has recently been used to construct total and partial ossicular replacement prostheses. In an attempt to evaluate these new implants, a multicenter prospective clinical trial was initiated. To date, 92 patients have undergone implantation. The follow-up interval ranged from 3 months to 22 months. Although it is premature to discuss the long-term results, the preliminary surgical experience and audiometric data with these implants are reviewed. From a surgical perspective, the ionomeric prostheses were easily contoured with a diamond burr and were not prone to shattering. Preliminary follow-up audiometric data were available on 80 patients (59 partial ossicular replacement prostheses and 21 total ossicular replacement prostheses). Of the 59 partial ossicular replacement prostheses the air-bone gaps (average of 500 Hz, 1 kHz, 2 kHz and 3 kHz) were as follows: 0 dB to 10 dB, 15 (25%) of 59; 11 dB to 20 dB, 20 (34%) of 59; 21 dB to 30 dB, 11 (19%) of 59; and greater than 30 dB, 13 (22%) of 59. Of the 21 total ossicular replacement prostheses the air-bone gaps were as follows: 0 dB to 10 dB, 6 (29%) of 21; 11 dB to 20 dB, 6 (29%) of 21; 21 dB to 30 dB, 5 (24%) of 21; and greater than 30 dB, 4 (19%) of 21.

Normal summating potential to tone bursts recorded from the tympanic membrane in humans.

The use of tone-burst stimuli for electrocochleography (ECochG) may offer certain advantages over conventional broad-band clicks. Namely, the summating potential (SP) component can be examined at different frequencies and may be easier to define and measure. To apply these findings clinically, it would first be necessary to establish SP amplitudes as a function of tone-burst frequency in normal listeners. The purpose of the present study was to do this using the tympanic membrane (TM) as the primary ECochG recording site. ECochG was recorded from 20 normal ears. Stimuli included 500-, 1000-, 2000-, 4000-, and 8000-Hz tone bursts presented randomly at 90 dB nHL. Mean SP amplitudes at these frequencies were +0.19, +0.17, +0.08, +0.10, and +0.22 microvolts, respectively. Although mean amplitudes were slightly positive regarding baseline, individual amplitudes varied between -0.41 and +0.73 microvolts. This study offers additional evidence that the SP to tone bursts can be recorded from the TM. The normative data provided should be useful for extended studies involving clinical populations.

Human summating potential to tone bursts: observations on tympanic membrane versus promontory recordings in the same patients.

Electrocochleographic responses to tone bursts and clicks were recorded from the tympanic membranes (TMs) and promontories of six suspected Meniere's patients. Although the majority of ears had normal summating potentials (SPs), regardless of recording site and stimulus type, some displayed amplitude-enlarged SPs at both sites and to both types of stimuli. The following observations were made from these patients regarding the choice of recording approaches and stimuli for ECochG: (1) Although SP amplitudes at the promontory were approximately four times larger than corresponding TM values, response "patterns" leading to diagnostic interpretation were the same at both sites; (2) the majority of patients who displayed enlarged SP amplitudes to tone bursts also had enlarged SPs to clicks; and (3) with tone-burst stimuli, the amplitude of the SP alone was sufficient for diagnostic interpretation of the ECochG waveform.

Recurrent acoustic tumor after a suboccipital removal.

Surgery for acoustic tumors has several priorities. First and foremost is the preservation of life with the total removal of the tumor; second is the preservation of the facial nerve; and last, when applicable, is the preservation of hearing. During the suboccipital (retrosigmoid) removal of a tumor, the surgeon unknowingly may leave tumor remnants leading to regrowth. We present five cases of recurrent acoustic tumors after a suboccipital removal. Inadequate drilling exposure of the internal auditory canal was the probable direct cause for tumor recurrence. A translabyrinthine removal is the best approach for total exposure of the entire internal auditory canal. The consequences of small tumor remnants will be discussed as well as their clinical relevance. Current radiological imaging and surgical techniques that avoid residual tumor will be presented.

Applications of the KTP laser in chronic ear surgery.

Several types of lasers have been applied to otologic surgery for such procedures as laser stapedotomy and acoustic tumor vaporization. The KTP laser has even broader applications in the field of chronic ear surgery. A three and a half year experience with the KTP laser is described. This laser's performance characteristics makes it well suited for chronic ear surgery. A quartz fiber delivery device enables the surgeon hand control of the laser beam in a microscopic field. Several applications are reviewed. Specifically, the KTP laser has been effective in removing hyperplastic infected mucosa engulfing the stapes, in safely disarticulating a mobile stapes suprastructure for complete cholesteatoma removal, and in atraumatically removing previously inserted ossicles or other middle ear implants. The KTP laser enables the surgeon to avoid mechanical trauma possible with traditional instrumentation and obtain more effective disease removal.

Radiographic diagnosis, surgical treatment, and long-term follow-up of cholesterol granulomas of the petrous apex.

Cholesterol granuloma is an unusual lesion of the petrous apex. Accurate preoperative differentiation of the various lesions of the petrous apex by computed tomography scanning only has been difficult. We reviewed the clinical findings, computed tomography and magnetic resonance imaging scans, surgical approaches, and long-term follow-up in 10 patients with cholesterol granuloma of the petrous apex who were seen between 1971 and 1988. Headache and deficits of the 5th, 6th, 7th, and 8th cranial nerves were common presenting symptoms. Magnetic resonance imaging with special imaging techniques was accurate in diagnosing cholesterol granuloma in four patients preoperatively and three patients prior to revision surgery. The optimal surgical approach was chosen on the basis of clinical and radiographic findings and included the transsphenoidal, infralabyrinthine, transcochlear, and suboccipital routes. Our review reveals that magnetic resonance imaging is more specific than computed tomography in establishing a preoperative diagnosis and is also the technique of choice in follow-up. The long-term results are discussed.

Treatment of tinnitus with electrical stimulation: an evaluation of the Audimax Theraband.

Several treatment forms exist for tinnitus. These multiple treatments speak to the elusive etiology of tinnitus. Many authors have reported tinnitus reduction or elimination with electrical stimulation. This study evaluates a new device (Audimax Theraband) which delivers inaudible, transdermal, mastoid electrical stimulation. Thirty patients suffering from chronic tinnitus were evaluated in a single-blind crossover fashion. Since the electrical stimulation is inaudible, each patient served as his or her own control. Patients received actual or placebo stimulation over a period of 2 weeks. They rated their tinnitus levels and the effectiveness of the device before and after using the Theraband. Only 2 subjects out of 30 (7%) obtained true positive results. Side effects were minimal and reversible.

Oral desensitization to penicillin in necrotizing (malignant) external otitis.

Penicillin allergy can complicate the treatment of life-threatening infections. When a beta-lactam (penicillin) drug is the treatment of choice, true allergy can be safely overcome by a recent, oral method of desensitization to penicillin. Patients with positive skin test results can be desensitized within four hours with oral, subcutaneous, and then intramuscular administration of progressively increased doses of penicillin G. We used this method successfully in a patient with severe necrotizing (malignant) external otitis.