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In order to derive an input/output buffer information specification-like representation of laser diodes for high-speed optical interconnects, an analytical model is presented. It is an alternative to numerically solving the rate equations to simulate laser operation above the threshold current. It models the dynamic behavior of the carrier and photon density based on a transformation derived from the solution of the Lotka-Volterra differential equations. This transformation based on the Lambert W-function transforms the nonlinear phase space into a linear one, where the photon and carrier density is modeled by damped harmonic oscillations. Derived for a single-mode laser, the model has been extended to simulate lasers with multiple longitudinal modes. While the complexity of simulating lasers has been reduced, the model reproduces all key characteristics of the numerical solution [ABSTRACT FROM PUBLISHER]

Fibrin glue (Beriplast, Behring or Tissucol, Immuno) was used for 126 sublabial transseptal transsphenoidal operations in 119 patients from April 1981 to March 1987 in a variety of sellar pathologies together with septal bone and spongycel to seal the sellar floor and the anterior wall of the sphenoid sinus. The incidence of postoperative rhinorrhea was 1.6%. A review of the literature revealed an incidence of 1.5%-9.6% with the use of autologous tissue for sellar packing such as fat or muscle; fibrin glue combined with autologous grafts led to postoperative rhinorrhea in 1%-4.4%. The present results support the view that sellar and sphenoidal sealing with fibrin glue instead of muscle or fat tissue does not raise the incidence of postoperative rhinorrhea. [ABSTRACT FROM AUTHOR]

Objective: To evaluate the frequency, type and indications of nasal turbinate (NT) resection during endoscopic, anterior skull base surgery and to analyze factors that may have an impact on the need of NT removal., Methods: In this retrospective cohort study, 306 subjects (150 males and 156 females, mean age 55.4 ± 15.3 years) who underwent multidisciplinary, transnasal, endoscopic tumor surgery of the anterior skull base using 4-handed techniques between 2011 and 2019 at the Department of Otorhinolaryngology, Medical University of Graz, were included., Results: In the majority of interventions (n = 281/306; 91.8%), all NT were preserved. Significant factors influencing the need of NT resections turned out to be type of endoscopic approach (p < 0.001; V = 0.304), sagittal (p = 0.003; d = 0.481) and transversal (p = 0.017; d = 0.533) tumor diameter, tumor type (p < 0.001; V = 0.355) and tumor location (p < 0.001; V = 0.324)., Conclusions: NT can be preserved in the majority of patients undergoing tumor resection in anterior, transnasal, skullbase surgery and routine resection of NT should be avoided. Variables that have an impact on the need of NT resections are types of endoscopic approaches, sagittal and transversal tumor extension and tumor type. These factors should be considered in planning of surgery and preoperative information of patients., (© 2021. The Author(s).)

Objective: Endoscopic transsphenoidal approach has become the gold standard for surgical treatment of treating pituitary adenomas or other lesions in that area. Opening of bony skull base has been performed with burrs, chisels, and hammers or standard instruments like punches and circular top knives. The creation of primary bone flaps-as in external craniotomies-is difficult.The piezoelectric osteotomes used in the present study allows creating a bone flap for endoscopic transnasal approaches in certain areas. The aim of this study was to prove the feasibility of piezoelectric endoscopic transnasal craniotomies. Study Design. Cadaveric study., Methods: On cadaveric specimens (N = 5), a piezoelectric system with specially designed hardware for endonasal application was applied and endoscopic transsphenoidal craniotomies at the sellar floor, tuberculum sellae, and planum sphenoidale were performed up to a size of 3-5 cm(2)., Results: Bone flaps could be created without fracturing with the piezoosteotome and could be reimplanted. Endoscopic handling was unproblematic and time required was not exceeding standard procedures., Conclusion: In a cadaveric model, the piezoelectric endoscopic transsphenoidal craniotomy (PETC) is technically feasible. This technique allows the surgeon to create a bone flap in endoscopic transnasal approaches similar to existing standard transcranial craniotomies. Future trials will focus on skull base reconstruction using this bone flap.

Objective: Cholesterol granulomas are benign lesions that sometimes occur on the petrous apex (PA). We report our experience using an endoscopic endonasal approach to remove PA cholesterol granulomas., Material and Methods: A retrospective patient chart analysis was conducted at a tertiary care university hospital., Results: Four patients (3 females, 1 male) were included in this study. Patients' ages ranged from 27 to 78 years. Computed tomography (CT) and magnetic resonance imaging (MRI) for diagnosis and computer-assisted navigation were performed. The most common symptom was abducens nerve palsy. The largest granuloma measured 5 x 2 cm and was located on the left side. An endoscopic endonasal approach was chosen and navigation was applied (3/4 patients) to identify the optimal area for opening the granuloma. No complications occurred, and patients were free from recurrence during the follow-up period., Conclusion: The endoscopic endonasal approach to PA cholesterol granulomas is feasible and safe. Intra-operative navigation is recommended to identify the position of the internal carotid artery and determine the safest area for opening the granuloma without damaging the artery. Another advantage of this approach is an easier follow-up through diagnostic nasal endoscopy.

Tumours affecting the nose, paranasal sinuses and adjacent skull base are fortunately rare. However, they pose significant problems of management due their late presentation and juxtaposition to important anatomical structures such eye and brain. The increasing application of endonasal endoscopic techniques to their excision offers potentially similar scales of resection but with reduced morbidity. The present document is intended to be a state-of-the art review for any specialist with an interest in this area 1. to update their knowledge of neoplasia affecting the nose, paranasal sinuses and adjacent skull base; 2. to provide an evidence-based review of the diagnostic methods; 3. to provide an evidence-based review of endoscopic techniques in the context of other available treatments; 4. to propose algorithms for the management of the disease; 5. to propose guidance for outcome measurements for research and encourage prospective collection of data. The importance of a multidisciplinary approach, adherence to oncologic principles with intent to cure and need for long-term follow-up is emphasised.

Surgical treatment of intrameduallary spinal cord metastases (ISCM) has become increasingly effective in recent years. The advent of new imaging techniques combined with an enhanced understanding of the natural history of these tumors has improved the effectiveness of the available treatment options. The authors present three new cases of ISCM successfully treated with surgery. A review of 129 cases found in the literature is also discussed. Characteristic symptomology and presentation are reviewed with an eye toward improving diagnostic methodology. The natural history of ISCM is divided into three phases. Surgical intervention should be used early in phase 2.

Osteopenia is an important clinical manifestation of hyperprolactinemia. Bone loss in these patients has mainly been attributed to concomitant deficiency of gonadal hormones rather than to hyperprolactinemia per se. Parathyroid hormone-related peptide (PTHrP) is expressed in human mammary tissue, and elevated circulating PTHrP levels as well as concomitant hypercalcemia have been described during lactation. We sought to determine circulating PTHrP levels in patients with long-standing hyperprolactinemia and whether PTHrP may exert possible systemic effects on bone and mineral metabolism. We studied 45 patients (30 women and 15 men) with persisting hyperprolactinemia 6 +/- 4 years (mean +/- SD) after trans-sphenoidal surgery for prolactin-producing pituitary adenomas. PTHrP levels in 117 healthy controls were 10.6 +/- 7.3 pmol-eq/l (mean +/- SD). In hyperprolactinemic patients, plasma PTHrP was elevated to 30.3 +/- 13.4 pmol-eq/l (p < 0.001, n = 45), and in patients with humoral hypercalcemia of malignancy PTHrP levels were 52.9 +/- 29.6 (p < 0.001 to controls and hyperprolactinemic patients). Fifty-three percent of hyperprolactinemic patients (n = 24) had clearly elevated PTHrP levels (> 2 SD). Retrospective immunocytochemical studies of the removed pituitary adenomas from 19 patients generally showed a higher degree of immunoreactivity for PTHrP (1-34) in all but one case when compared with normal pituitary tissue. Patients with elevated circulating PTHrP levels showed in most instances strong immunoreactivity to PTHrP in 70-100% of tumor cells.(ABSTRACT TRUNCATED AT 250 WORDS)

Pituitary apoplexy with acute visual loss has to be considered as emergency operative indication. 3 cases presenting headache, rapid visual deterioration and ophthalmoplegia were operated upon from a transphenoidal approach. Immediate operative decompression proved to resolve the acutely evolved symptoms in all 3 cases.

From 118 transsphenoidally operated patients, 100 had a pituitary adenoma; 33 prolactinomas, 20 HGH-producing, 2 ACTH-producing and 45 inactive adenomas. The first transsphenoidal operation did not cause any mortality; after reoperation for suspected recurrence on follow-up, 2 patients died; thus, the global management mortality was 1.8%. As surgical complications, diabetes insipidus occurred in 5%, hypopituitarism in 4%. Age at operation was significantly higher in female patients with micro- than with macroprolactinomas, and also markedly higher in men than in women with prolactinomas. Preoperative serum prolactin levels were related to tumour size and age and demonstrated an important prognostic factor of postoperative cure. The prognosis of preoperative visual field defects was dependent on preoperative duration. During a follow-up period of 1-6.3 years, 7 patients were reoperated for recurrence of their tumour after intervals of 2-4.5 years; 6 of these patients had had inactive macroadenomas, 1 an ACTH-producing macroadenoma. In 3 of these patients, radiation therapy had been performed. The highest recurrence-rate (19%) among 100 patients was found in patients with inactive macroadenomas with a follow-up of more than 2 years.

The authors sought the simplest but still reliable method for evaluation of the functional reserve of the anterior lobe of the pituitary gland. The proposed test is stimulation of those various functions by injection of insulin, gonadotropin releasing hormone (LH-RH = GnRH) and thyrotropin releasing hormone (TRH). The test fulfils the clinical requirements. Furthermore it forms a valuable first step for the classification of more scientific problems.

A case is described of a jugulotympanic paraganglioma in a 64-year-old woman with extentions down the jugular vein to the clavicle and penetration of the cerebellar fossa. The symptoms, differential diagnosis, therapy and prognosis are discussed on the basis of this case report and compared with the literature. The importance of radiological investigation (e.g. selective angiography and computed tomography) in respect to diagnosis and determination of tumour size is emphasized. The diagnostic value of the immunohistochemical detection of neuron-specific enolase, a neuroendocrine cell marker and S-100 protein is stressed. The most favourable therapy, depending on tumour extension, seems to comprise preoperative embolisation, radical resection and postoperative radiotherapy.