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Biomedical subjects

G E Merwin

Publications and source records attributed to G E Merwin.

8 recordsLinked to original sources

Transoral approach to the upper cervical spine.

The transoral approach to pathology of the upper cervical spine is logical, but it is seldom used due to concerns about exposure and infection. The authors report on 16 consecutive patients requiring exposure from clivus through C3 for pathology, including spinal cord compression by rheumatoid pannus, craniovertebral anomalies, and tumor. Exposure was obtained using a Dingman mouth gag and soft palate retraction with silicone rubber sheeting. A horizontal "H" incision was made in the posterior pharyngeal wall creating three layers, closed separately, with attention to a watertight closure of the final mucosal layer. In no case was it necessary to divide the mandible, tongue, soft palate, or uvula. There were no deaths, wound breakdowns, infections, or persistent cerebrospinal fluid leakage. Patients with neurological indications improved postoperatively, and all tumors were grossly resected. Combined otolaryngology/neurosurgical exposure and treatment of pathology involving the upper cervical spine via the transoral approach is safe and effective. Functional results have been excellent, and no major complications were encountered.

Adolescent

Comparison of biomaterials for facial bone augmentation.

We compared the gross behavior of and microscopic response to implant materials currently in clinical use for facial bone augmentation at different sites in dogs. Materials evaluated include porous polytetrafluoroethylene carbon (Proplast), large-pore high-density polyethylene (Medpor), solid medical-grade silicone rubber (Silastic), polyamide mesh (Supramid), and autogenous rib bone. The subjects were 12 mixed-breed dogs and the materials were implanted directly on bone with periosteum removed at one of three sites in the dog's face (malar eminence, nasal dorsum, and chin). Animals were killed 3 months after surgery and stability of the implants was graded by manual manipulation. Blocks of tissue, including the study materials and underlying bone, were examined microscopically after sectioning. Stability results are tabulated and histologic appearance is described by site for each material evaluated. These data demonstrate marked variability of stability and cellular response depending on the site of implantation. From these data one may conclude that the site of implantation and implant movement are essential factors in determining the nature of the tissue response and fate of an implant. Solid and porous alloplastic materials show an acceptable tissue response, but neither demonstrates the ability to consistently provide an implant that is stable on underlying bone.

Animals

Lack of effect of carbonic anhydrase inhibition on direct measurements of endolymph bicarbonate.

In the past, sodium, potassium, and chloride have been measured in endolymph directly, but bicarbonate has been measured only indirectly. We sampled endolymph directly while monitoring endocochlear potentials in normal and methazolamide-treated guinea pigs. Bicarbonate was determined in samples by use of a method that depends on reduction of NADH to NAD linked to malate formation from oxaloacetate. In 11 normal animals, the bicarbonate in endolymph was 20.2 mM +/- 4,4 mM (mean +/- standard deviation); in six of these, plasma bicarbonate was 23.1 mM +/- 3.5 mM. Nine animals treated with methazolamide (carbonic anhydrase inhibitor) had an endolymph bicarbonate of 19.5 mM +/- 3.9 mM; plasma bicarbonate in five of these was 25 mM +/- 3.2 mM. Carbonic anhydrase inhibition did not significantly affect endolymphatic bicarbonate levels.

Animals

Arytenoid dislocation.

The reported incidence of arytenoid cartilage dislocation is low. This may be due to the wide range and orientation of motion allowed by the cricoarytenoid articulation and the laxity of its joint capsule. In two previously reported instances of arytenoid dislocation, the authors have suggested that endotracheal intubation is generally not sufficient to cause dislocation of an arytenoid cartilage, but that, in their cases, a predisposing factor had set the occasion for dislocation. In this communication, three cases of arytenoid cartilage dislocation, which each followed a single instance of endotracheal intubation are presented. In all three cases, painful swallowing was the main presenting symptom. Clinical features that differentiate arytenoid cartilage dislocation from vocal cord paresis are summarized. Early reduction of the dislocation, while the patient is under local anesthesia, is recommended, and the techniques are described in detail.

Adult

A double blind investigation of piracetam (Nootropil) vs placebo in geriatric memory.

Fifty-six hospitalized geriatric patients between the ages of 65 and 80 were given piracetam (Nootropil) 2400 mg/day or placebo on a double blind basis over a two month period. Every patient submitted to a battery of psychological tests before and after the two month trial. These tests included the Similarities, Vocabulary, Digit Symbol, and Block Design subtests of the Wechsler Adult Intelligence Scale; Graham Kendall Memory for Design; Benton Visual Retention; Hooper Visual Organization; Raven Colored Progressive Matrices A, AB, and B; Wechsler Memory Scale A and B; Porteus Maze and Finger Tapping. Patients who were unable to complete this battery were not included in this investigation. In addition, at pretreatment, 4 and 8 weeks, the patient completed a Profiles of Mood States, a Clinical Global Evaluation was done by the investigator, and laboratory determinations were performed. Fifty Patients completed the investigation (25 piracetam, 25 placebo). There were no significant statistical differences between the two groups of patients on all measures utilized except for the Clinical Global Evaluation, where 52% of the patients on piracetam showed minimal improvement versus 25% of the placebo group (P less than 0.05).

Aged

Necrotizing sialometaplasia of the nasopharynx.

Necrotizing sialometaplasia is an uncommon salivary gland disease originally described by Abrams et al in 1973. The disease may occur wherever salivary gland tissue is found. Theories on the etiology of this disorder have been advanced, but never definitely determined. Treatment consists of adequate biopsy and observation until healing occurs at six to eight weeks. While the disease is considered benign, its similarity to more aggressive neoplasms can be both disturbing and misleading to the patient and the clinician. Such a case of necrotizing sialometaplasia of the nasopharynx is presented to demonstrate the clinical and histological similarity of this disease to carcinoma. In this case, the patient first presented with a neck mass which could easily have been mistaken for a regional metastasis. The current literature is reviewed.

Diagnosis, Differential