Dalia Levy

Middle Ear Gas Composition and Middle Ear Aeration

Partial pressures of the gases in the middle ears of 14 guinea pigs were measured continuously on-line with a specially designed mass spectrometer. The average values were carbon dioxide 67.55 mm Hg, oxygen 48.91 mm Hg, and nitrogen 596.54 mm Hg. These values confirm earlier measurements and show that the gas composition of the middle ear differs basically from that of air and resembles that of venous blood. These findings are indicative of bilateral diffusion between the middle ear cavity and the blood. We propose that under physiologic as well as under pathologic (ie, atelectatic) conditions, the gas content of the middle ear is also controlled by diffusion. This mechanism fits well with the fluctuating character of atelectatic ears. Thus, a negative middle ear pressure could be secondary to excessive loss of gases through increased and excessive diffusion, although additional mechanisms are probably also involved. A likely contributing factor is poor pneumatization of the mastoid, with consequent absence of a physiologic pressure regulation mechanism by its pneumatic system.

Revisiting benign paroxysmal positional vertigo pathophysiology.

Benign paroxysmal positional vertigo is the most common peripheral cause of vertigo. Although its pathophysiologic mechanisms remain unclear, different locations have been attributed throughout the last century, from the days of Bárány. Disease was initially located by Dix and Hallpike in the utricle, but later, Schuknechts works elicited the cupulolithiasis and canalolithiasis theories, localizing the pathology to the semicircular canal system and mainly to the posterior one. However, conflicting evidences from temporal bone studies accumulated against this theory, which suggest other explanations. Although this clinical entity is well defined, and can usually be effectively treated with certain physical maneuvers, its pathophysiology is still obscure and is being critically discussed in this article, which reviews the milestones of benign paroxysmal positional vertigo understanding.

Cerumen removal: Comparison of cerumenolytic agents and effect on cognition among the elderly

Cerumen impaction may affect hearing and decrease hearing acuity, thus decreasing cognitive functions among the elderly. The objective of this study was to compare the safety and the efficacy of three cerumenolytic agents and to assess the effect of cerumen removal on cognition. Thirty eight elderly subjects (mean age: 78 years, total 76 ears) were treated with either Auro®, Cerumol® or the newer CleanEars®, and the change in the degree of ear canal occlusion was examined after a week. In addition, a change in cognition following cerumen removal was evaluated using Ravens standard progressive matrices (RSPM) test. There was no difference regarding the eventual degree of occlusion between the three treatment groups. Only in the CleanEars® group a complete resolution of obstruction in both ears was achieved. A statistically significant difference between the RSPM score before and after the removal of cerumen was found. Using CleanEars® is as effective and safe as other agents and may be advantageous due to its spray application. Removal of cerumen significantly improves the well-being of elderly patients.

Gas Composition of the Human Nose and Nasopharyngeal Space

Since it was established that middle ear (ME) gas composition is closer to venous gas composition than to air, the question arose regarding the composition of gas which enters the ME from the nasopharynx. Using a mass spectrometer, gaseous partial pressure was measured at three locations in the nose and nasopharynx of 6 volunteers. All three locations showed similar gas composition (O2 = 15.7%, CO2 = 4.5%, N2 + Ar = 79.8%) which is similar to expired air. The gas that enters the ME via the Eustachian tube is a mixture closer to the final ME gas equilibrium than is air. This minimizes the changes in steady state ME gas composition incurred by gas influx into the ME.

Dependence of Middle Ear Gas Composition on Pulmonary Ventilation

The middle ear (ME) steady state gas composition resembles that of mixed venous blood. We changed arterial and venous blood gases by artificially ventilating anesthetized guinea pigs and measured simultaneous ME gas changes during spontaneous breathing, hyperventilation, and hypoventilation. During hyperventilation, PaCO2 and PvCO2 (a = arterial, v = venous) decreased from 46.0 and 53.0 mm Hg to 17.9 and 37.5 mm Hg, respectively, while PaO2 and PvO2 (85.6 and 38.2 mm Hg) did not change. This was accompanied by an ME PCO2 decrease from 70.4 to 58.8 mm Hg and a PO2 decrease from 36.8 to 25.4 mm Hg. During hypoventilation, PaCO2 and PvCO2 increased to 56.8 and 66.4 mm Hg, while PvO2 decreased to 21.8 mm Hg. The ME PCO2 increased simultaneously to 88.8 mm Hg and the ME PO2 decreased to 25.4 mm Hg. The ME PO2 decrease during hyperventilation may be explained by a 33% decrease in ME mucosa perfusion, calculated from the ME ventilation-perfusion ratio. This study shows that ME gas composition follows fluctuations of blood gas levels and thus may affect total ME pressure.

Is Primary Hyperparathyroidism a Risk Factor for Papillary Thyroid Cancer? An Exemplar Study and Literature Review

Introduction Primary hyperparathyroidism (PHPT) is associated with several cancer types, including papillary thyroid carcinoma (PTC). Objective To explore further the relation between PHPT and PTC. Methods By considering patients with PHPT as extra-suspicious for PTC, we studied an exemplar group of patients with PHPT with a small (≤1 cm) thyroid nodule, which was negative in preoperative cytologic examination. During parathyroidectomy, a frozen section biopsy of the thyroid nodule confirmed PTC, as did the final surgical specimen, revealing that the preoperative cytology was false-negative. Additionally, relevant reports retrieved from the English literature addressing thyroid cancer and hyperparathyroidism were reviewed and processed. Results Four patients with PHPT were studied. Three had a multifocal thyroid disease, and three had neck lymph node metastasis. Processing previous report data supported an association between PHPT and PTC. Although thyroid nodularity among patients with PHPT was similar to the general population, PTC incidence was higher. This was true also for patients with secondary hyperparathyroidism. Conclusions This study emphasized that PHPT should be considered as a noteworthy risk factor for PTC. Fine needle aspiration of a thyroid nodule is the most valuable diagnostic procedure for thyroid cancer. Yet, false-negative results were reported in up to 10% of cases, especially in small, subcentimeter nodules. In line with our data and the literature, patients with PHPT should have both a detailed ultrasound addressing the thyroid and cytology of any thyroid nodule, including small subcentimeter lesions. Moreover, surgical flexibility, allowing intraoperative thyroid nodule sampling, should be considered even for “innocent” nodules.

Laryngeal cancer in acquired immunodeficiency syndrome.

With improved survival, more AIDS patients, especially heavy smokers and alcohol abusers, may be confronted with laryngeal squamous cell carcinoma. Since curative treatment may require aggressive combined therapy, these patients, often suffering from immunosupression and poor general condition, present unique therapeutic challenges. The objective of the study was to describe treatment dilemmas. This case report presents a detailed description of an AIDS patient with carcinoma of the larynx. A patient with T3N0M0 laryngeal carcinoma and AIDS underwent tracheotomy and biopsy, followed by severe neck and pulmonary infection. After convalescence, radiotherapy was administered, with no evidence of a disease during a 3.5-year follow-up. During his remaining life, the patient developed severe psychoaffective disorder, his immune state deteriorated until he demised from sepsis. In conclusion, patients with HIV infection, especially having a history of tobacco or alcohol abuse, should be carefully examined for head and neck carcinoma that is likely to be more aggressive. Following surgery, AIDS patients may have worse wound healing and a greater tendency to contract infections. Radiotherapy and especially chemotherapy may cause life-threatening complications. Although early detection may increase survival, curative treatment should involve many disciplines and extra caution.

Middle Ear Pressure Change as a Function of Body Position

To verify and assess immediate middle ear (ME) pressure changes as a function of body position.

Superficial parotidectomy for benign parotid lesions

Today, surgery for benign parotid tumors has evolved into a procedure that is both effective and safe. Only some 50 years ago, recurrence rates after surgical removal of pleomorphic adenomas ranged between 21% and 70%, because the technique of enucleation resulted in incomplete excisions. Dissection next to the tumor capsule provided the surgeon with a false sensation of safety for the facial nerve. The advent of facial nerve identification and preservation, with tumor removal along with an adequate amount of surrounding healthy parotid tissue, occurred in the early 1940s as a true change in philosophy. The operation, termed superficial parotidectomy, is now accepted by the majority of parotid surgeons as the procedure of choice for benign parotid tumors that reach no deeper than the “superficial lobe.” We present a review of the current literature, followed by a description of the surgical anatomy and operative technique.

Extraordinary Adult Thyroglossal Duct Cyst

This work received the approval of the Edith Wolfson Medical Center institutional review board (IRB). A 35-yearold man with schizophrenia presented with a longstanding painless huge anterior neck mass. The overlying skin was irritated, with a peau d’orange appearance (Figure 1). Accompanied by his family, he reported a previously known neck lump that had grown during recent years. He attended the clinic because of increasing dysphagia, discomfort, and drooling. There were no respiratory symptoms. Neither the patient nor his family members appeared disturbed by the extraordinary neck finding. The patient was pale, with a huge, soft, lobulated anterior neck mass measuring 30 3 24 cm, moving upon deglutition. The base of the tongue was pushed posteriorly by the cystic mass, causing a slight oropharyngeal obstruction and swallowing difficulties. However, the floor of the mouth was normal. Larynx appeared normal. A neck computed tomography (CT) study demonstrated a lobulated cystic neck mass, extending from the base of the tongue, adjacent to the floor of the mouth and anterior to the hyoid bone, the sternocleidomastoid muscles, and the normal-appearing thyroid gland (Figure 2). The differential diagnosis included thyroglossal duct cyst, cystic hygroma/ lymphangioma, thyroid neoplasm, epidermoid cyst, and plunging ranula, which may present as a midline neck mass. A diagnostic aspiration revealed abundant colloid, with a few pseudociliated epithelial cells, suggesting TGDC. Addressing the relatively large size, surgical planning mandated a wide horizontal neck incision to allow the safe exploration of the mass and its surroundings, including the hyoid bone, suprahyoid muscles, laryngeal skeleton, submandibular glands, and hypoglossal nerves. Partial excision of the body of the hyoid bone and the excess skin was also taken into consideration. Anticipating a possible difficult intubation, an awake, nasotracheal intubation was performed. The patient underwent an ‘‘extended’’ Sistrunk operation that included an en bloc resection of the cystic mass, along with the suprahyoid muscles that were adherent to it. A meticulous dissection of compressed nerves and vessels was necessary, in particular the left tortuous hypoglossal nerve. As planned, the middle portion of the hyoid bone, including a short, wide tract leading to the base of tongue and the overlying skin, was resected. The cyst colloid volume was 3 L. Pathological report confirmed thyroglossal duct cyst, with no signs of malignancy. The postoperative course was remarkable for worsening swallowing difficulties, which caused aspirations and required feeding gastrostomy and swallowing training. A remarkable improvement was observed at follow-up visits.