Faculty Bibliography

Dizziness is often a patient's shorthand description of a variety of symptoms, many of which have nothing to do with balance. Vertigo consists of an abnormal sensation of motion, whereas dysequilibrium is a disturbance of balance without necessarily a sensation of motion. A careful history usually determines the nature of the patient's presenting symptoms, and a thorough workup will often give rise to a diagnosis. Vertigo of vestibular origin may be treated with a variety of medications or, when these fail, surgery. Surgery should preserve hearing when at all possible. Balance rehabilitation is a useful modality for the patient who does not compensate spontaneously or who does not respond to the medical or surgical treatment of imbalance

Cholesterol cyst (or granuloma) of the temporal bone, a recognized clinical entity distinct from cholesteatoma, is more common than previously thought. Apparently it is caused by obstruction of previously pneumatized temporal bone air cells. Surgical cure is achieved by drainage and reestablishment of normal pneumatization. This paper reviews 14 cholesterol cysts of the temporal bone, emphasizing the importance of preoperative imaging and surgical approach. Use of magnetic resonance imaging differentiates cholesterol cysts from cholesteatoma or other neoplasms. Computed tomography delineates the location of the lesion and defines temporal bone anatomy essential to surgical approach. The two studies together allow the surgeon to properly plan drainage, as in the case of a cholesterol cyst, versus excision or exteriorization, as in the case of cholesteatoma. The infralabyrinthine approach to a petrous apex cholesterol cyst is the procedure of choice when hearing preservation is desired

Forty-eight patients with cerebrospinal fluid leaks comprise this retrospective study. There were 39 traumatic and 9 spontaneous leaks. Nine patients were initially managed with bed rest and spinal drainage, but 3 patients in this group ultimately required surgical intervention for repair of their persistent leaks. Thirty-nine patients had surgery as initial therapy, with 33 extracranial repairs, 2 intracranial repairs, and 4 combined approaches. The extracranial approach was used in 36 of 42 patients, with an initial success rate of 86%

We have defined conditions permitting the in vitro growth of human laryngeal papilloma cells at the air-liquid interface. Using this model system, retinoic acid has been found to modulate the differentiation of human laryngeal papilloma cells along two different pathways. At low concentrations of retinoic acid [10(-9) mol/L and 10(-8) mol/L], the cells formed a stratified squamous epithelium with a differentiation-specific protein staining pattern identical to that found in vivo. At higher concentrations of retinoic acid [10(-7) mol/L and 10(-6) mol/L], the cells differentiated into a columnar epithelium with occasional ciliated cells, lacking the markers of squamous differentiation. Analysis of the human papillomavirus DNA content revealed that as the concentration of retinoic acid increased, the viral DNA content decreased. This system is proposed as a model to further investigate the differentiation defects of human laryngeal papilloma cells and the regulatory role of retinoic acid in the clinical expression of human laryngeal papillomatosis

Tumor invasion of the carotid artery is a potential indication for brachytherapy, which delivers a high dose of irradiation to residual tumor while limiting the dose to adjacent healthy tissues. The tolerance of carotid-sheath contents to varying doses of brachytherapy, however, has not been clearly established. In order to evaluate brachytherapy effects on carotid-sheath contents, after-loading catheters were implanted bilaterally in 3 groups of 6 rabbits each (18 rabbits). Iridium 192 brachytherapy doses of either 5000 cGy (rad), 9000 cGy, or 13,000 cGy were delivered unilaterally, with the contralateral neck serving as a nonirradiated control in each animal. There were no carotid ruptures and wound healing was normal. Two animals from each group were killed at 6, 20, and 48 weeks. Even at the highest dose (13,000 cGy), nerve conduction studies performed on the vagus nerve prior to sacrifice revealed no increased latency, histologic changes were minimal, and carotid arteries were patent. These observations suggest that the carotid-sheath contents in healthy rabbits could tolerate high doses (up to 13,000 cGy) of low-dose-rate interstitial brachytherapy without complications

Malformations of the arterial and venous systems often are manifested in the head and neck. Low-flow venous malformations are generally benign lesions; however, complications, such as bleeding, obstruction, pain, or cosmetic deformities, may warrant surgical intervention. Treatment of these lesions can be challenging. Laser photocoagulation, particularly with the neodymium-yttrium aluminum garnet (Nd-YAG) laser, has been successful in the majority of patients, with minimal morbidity and good results. Thirty-two patients with low-flow venous malformations of the head and neck were treated with the Nd-YAG laser using low-power density and intermittent short exposures in a punctate nonoverlapping technique. When possible, two glass slides were used to compress the lesion. There was excellent regression with minimal damage to the surrounding tissue. No major complications or morbidity, postoperative pain, or mortality occurred. Lesions occurring in some areas of the head and neck would not have been amenable to standard surgical excision. Follow-up period has ranged from 1 to 8 years. Nd-YAG laser photocoagulation has proved safe and effective for treatment of low-flow vascular malformations of the head and neck

Two experiments investigating the effects of auditory stimulation delivered via a Nucleus multichannel cochlear implant upon vowel production in adventitiously deafened adult speakers are reported. The first experiment contrasts vowel formant frequencies produced without auditory stimulation (implant processor OFF) to those produced with auditory stimulation (processor ON). Significant shifts in second formant frequencies were observed for intermediate vowels produced without auditory stimulation; however, no significant shifts were observed for the point vowels. Higher first formant frequencies occurred in five of eight vowels when the processor was turned ON versus OFF. A second experiment contrasted productions of the word 'head' produced with a FULL map, OFF condition, and a SINGLE channel condition that restricted the amount of auditory information received by the subjects. This experiment revealed significant shifts in second formant frequencies between FULL map utterances and the other conditions. No significant differences in second formant frequencies were observed between SINGLE channel and OFF conditions. These data suggest auditory feedback information may be used to adjust the articulation of some speech sounds

A two-microphone dereverberation technique was evaluated by obtaining speech recognition measures and preference judgments from normal-hearing and hearing-impaired listeners. Monaural speech recognition performance was measured for two reverberation conditions (0.4 second and 1.2 seconds) with and without processing. Binaural speech recognition performance was also measured for the unprocessed conditions. In addition, paired-comparison judgments of preference were obtained for all combinations of the processed and unprocessed monaural stimuli. For both groups of subjects, scores at the shorter reverberation time were significantly higher than scores for the longer reverberation time. For the normal-hearing subjects, processing to dereverberate had no significant effect on speech recognition performance. Binaural presentation of the unprocessed signal yielded significantly higher scores. For the hearing-impaired subjects, performance was significantly better in the unprocessed condition than the processed condition, but was not significantly different from the binaural condition. Paired-comparison judgments revealed differences in patterns of preference between normal-hearing and hearing-impaired listeners