Intramuscular hemangiomas (IMH) are uncommon tumors in the head and neck region, occurring most often in the trunk and extremities. Preoperative misdiagnosis is common because of the deep location of these tumors. Ten recent cases of head and neck IMH are presented, five of which involve the masseter muscle--the most frequent site of involvement in the head and neck. Masseter IMH occurred almost exclusively in the pediatric age group. The clinical presentation, radiographic and histologic findings, treatment, complications, and outcome of these patients are presented. The vital role of preoperative diagnosis using magnetic resonance imaging (MRI) is discussed, as well as a review of the natural history of IMH and indications for surgical intervention.

Computed tomographic (CT) scans and magnetic resonance (MR) images obtained in 24 patients with cervical lymphadenopathy were retrospectively and blindly evaluated by two readers for the presence of central nodal necrosis (CNN) and extracapsular nodal spread (ENS). The CT studies were all enhanced, and the MR images were obtained with short repetition time (TR)/echo time (TE), long TR/double echo, and enhanced short TR/TE fat-suppressed sequences. Each MR imaging sequence was interpreted separately and then collectively. Sixty lymph nodes were identified with CT. Sensitivity for CNN was 16%-67% with the unenhanced MR pulse sequences, 50% with enhanced sequences, and 83%-100% with CT. The most accurate reading of MR images for CNN was with the unenhanced T1-weighted and T2-weighted images (86%-87%); the accuracy of CT was 91%-96%. The accuracy of MR imaging for detecting ENS was maximal with T1-weighted images (78%-90%). Gadolinium-enhanced, fat-suppressed images did not improve accuracy in evaluating CNN or ENS. CT is currently more accurate than unenhanced or enhanced MR imaging in detecting CNN or ENS.

Increasingly, third party payers are challenging the necessity of a hospital admission for endoscopic procedures. Direct laryngoscopy (DL), with or without open, rigid esophagoscopy or flexible, fiberoptic bronchoscopy, was evaluated for the incidence of perioperative complications and associated risk factors. A retrospective review of 200 in-patient admissions between 1987 and 1990 for direct laryngoscopy or panendoscopy is presented. Complications were classified as major for untoward events that required hospitalization for proper management. Complications were otherwise considered minor. The incidence of major complications was at least 19.5%, with minor complications occurring in 21% of patients. The total population was partitioned into subsets according to the occurrence of major complications, minor complications, and no complications. For the total population and each subset, distributions were developed by age, sex, habitus, physical status level, diagnosis of malignancy, presence of a malignant lesion in the aerodigestive tract, or medical history of head and neck surgery or radiation therapy. Statistical analysis indicates that these parameters do not offer reliable predictors of which patients are at risk for minor or major complications. It is concluded that all patients who undergo direct laryngoscopy are most safely managed in an in-hospital setting for a period on the order of 24 hours.

The etiology of an asymmetric sensorineural hearing loss can often be difficult to determine. Because a wide variety of pathologic processes may be responsible for the hearing loss, numerous diagnostic tests are usually used in the initial evaluation, including pure-tone audiometry, acoustic reflex testing, imaging, serologic testing, and auditory brainstem response testing. The diagnostic evaluations of 225 consecutive cases of asymmetric sensorineural hearing loss are reviewed. A cochlear site-of-lesion was demonstrated in the majority (194) of patients. Because all retrocochlear lesions (31) were associated with an abnormal auditory brainstem response, imaging should be performed in that group of patients. Magnetic resonance imaging offers greater specificity than computed tomography. Reflex decay, acoustic reflex testing, and rollover were all associated with a high false-negative rate. Whereas serologic testing for syphilis yielded several cases of otosyphilis, thyroid function testing was of little value. A diagnostic protocol for asymmetric sensorineural hearing loss is presented.

Continuous cultures of Botryococcus braunii race B were maintained at photosynthetic cell densities as high as 20 g dry weight per liter for up to 3 months. Growth associated triterpene hydrocarbon accumulation was nearly constant at 22.5% of dry weight for a range of growth rates maintained by daily replacement of 5-15% of the respective cultures. The ability to achieve high cell concentrations and oil levels of roughly 5 g triterpene oil/L resulted from a combination of high light (∼ 1/4 full sun for 15 h/day) and replenishing stoichiometrically balanced growth medium. Due to light-limited growth conditions, cell concentration dropped nearly linearly with increased dilution rate. This reduction in cell number resulted in increased productivity per cell at higher dilution rates and was accompanied by a dramatic increase in algae colony size from 0.09 to 0.343 mm at high dilution rate. This change in colony size resulted in an equally dramatic change in optical density (OD) per gram dry weight, which precluded use of simple correlations of OD and cell concentration. A trickle-film photobioreactor was also demonstrated as a scalable approach to achieving these ultra-high cell concentrations. Additional media analysis revealed a steady increase in photobioreactor conductivity suggesting an accumulation of ions may be the reason for rapid culture crash and washout observed at all dilution rates after several months of continuous operation. The volumetric productivity of 22.5 mg oil/L/photo-h reported here is more than an order of magnitude higher than previous reports for B. braunii race B, reflecting the high cell densities used in this work and substantiating a higher metabolic rate for B. braunii race B than previously surmised from its relatively long doubling times.