PubMed Health⌕ Search

Biomedical subjects

Dilantha B Ellegala

Publications and source records attributed to Dilantha B Ellegala.

15 recordsLinked to original sources
PubMed2026

Migration intentions among nigerian neurosurgeons: a national survey of workforce retention.

Physician emigration from low- and middle-income countries creates critical workforce shortages. This study explored factors influencing migration intentions among Nigerian neurosurgeons and trainees. We conducted an anonymized survey of consultant neurosurgeons, fellows, and residents practicing in Nigeria. Invitations were sent by email and professional messaging platforms, and snowball sampling was used to increase participation. The survey included quantitative and open-ended questions on demographics, income, migration plans, and retention factors. Seventy-nine respondents participated (61.5 % consultants; 93.7 % male; median age: 44 years). Nearly all practiced general neurosurgery (97.3 %), and many also performed trauma (65.3 %) and spine (61.3 %) neurosurgery. Most (85.7 %) reported that their earnings were insufficient to support their families. Nearly 40 % were considering emigration, most often citing financial pressures (88.5 %) and poor working conditions (63.5 %) as push factors. By contrast, personal or family ties (63.0 %) and relocation costs (45.2 %) were cited as reasons to stay. Respondents identified higher salaries (58.1 %) and greater investment in the health sector (51.4 %) as key measures to improve retention. In univariable analyses, younger age, income insufficiency, income dissatisfaction, and feeling undervalued at work were associated with migration intention. Financial insecurity emerged as the dominant driver of migration intentions among Nigerian neurosurgeons. In addition to salary increases, sustained investment in healthcare infrastructure and workforce support is essential to improve retention. International partnerships may complement these efforts by building neurosurgical capacity and mitigating brain drain.

Humans↗
PubMed2006

Principles of cerebral oxygenation and blood flow in the neurological critical care unit.

Cerebrovascular disease and trauma are leading causes of death in the United States. In addition to the initial insult to the brain, disturbances of cerebral oxygenation and metabolism underlie many of the secondary pathophysiological processes that increase both morbidity and mortality. Therefore, researchers and clinicians have sought to obtain a more thorough understanding of the physiological and biochemical principles of cerebral oxygenation and metabolism. New technologies capable of offering continuous and quantitative assessment of cerebral oxygenation may improve clinical outcomes. In this article, we review the physiological principles of cerebral metabolism, cerebral blood flow and their metabolic coupling, and cerebral oxygenation, with particular emphasis on variables that could be monitored and managed in an intensive care unit setting.

Blood Pressure↗
PubMed2006

Neuromonitoring in neurological critical care.

In this article, we review technologies available for direct monitoring of cerebral oxygenation and metabolic status, including jugular venous oxygen saturation, brain tissue oxygen tension, transcranial cerebral oximetry with near-infrared spectroscopy, Positron emission tomography oxidative metabolism, single-photon emission computed tomography/computed tomography perfusion and functional imaging, and cerebral metabolite measurement using microdialysis. We also introduce a novel method of monitoring cerebral perfusion that may substitute for direct monitoring of oxygenation in the future.

Brain Diseases↗
PubMed2006

Contrast ultrasonographic assessment of cerebral perfusion in patients undergoing decompressive craniectomy for traumatic brain injury.

OBJECT: The aims of this study were to determine whether contrast-enhanced ultrasonography (CEU) could be used for noninvasive evaluation of cerebral perfusion in patients with traumatic brain injury (TBI) and to assess the effect of decompressive surgery on cerebral perfusion as measured by CEU. METHODS: Contrast-enhanced ultrasonography with intravenous administration of a microbubble contrast agent was performed in six patients with TBI undergoing decompressive craniectomy. Contrast-enhanced ultrasonography was performed through a bur hole before craniectomy and through the calvarial defect immediately after craniectomy and on postoperative Days 1 and 2. For the latter two studies, patients were placed in the recumbent position and at a 35 degrees incline to investigate changes in perfusion produced by modulation of intracranial pressure (ICP). Cerebral microvascular blood flow increased by almost threefold immediately after craniectomy, from a mean of 7.5 +/- 6.9 (standard deviation [SD]) to 20.9 +/- 11.6 (p < 0.05), and further improved on postoperative Day 1 (mean 37.1 +/- 13.9 [SD], p < 0.05, compared with postcraniectomy microvascular blood flow) without subsequent change on Day 2. The change in microvascular perfusion correlated inversely with the initial ICP (p < 0.01), indicating less recovery of flow when preoperative ICP was markedly elevated. On postoperative Days 1 and 2, head-of-bed elevation produced an increase in microvascular perfusion on CEU (mean 37 +/- 11 compared with 51 +/- 20, p < 0.05) and a small decrease in ICP (mean 16 +/- 5 mm Hg compared with 12 +/- 4 mm Hg, p < 0.05). In patients with parenchymal hematoma, CEU provided spatial information on perfusion abnormalities in the hemorrhagic core and surrounding tissues. CONCLUSIONS: Contrast-enhanced ultrasonography has potential for the intraoperative and bedside assessment of cerebral perfusion in patients with TBI. The technique may be appropriate for evaluating responses to therapies aimed at preventing secondary ischemia and for assessing regional perfusion abnormalities.

Adolescent↗
PubMed2005

Pioneers in the development of neurological surgery in Auckland, New Zealand: Robertson, Wrightson, and Mackenzie.

OBJECTIVE: To demonstrate the development of neurosurgery in Auckland, New Zealand, which has diverse roots and was influenced by geographical, socioeconomic, and international forces. METHODS: Historical records were examined, and interviews were conducted to determine the factors that shaped the development of neurological surgery in Auckland, New Zealand. RESULTS: Sir Carrick Robertson, a Scotsman, was one of the more enterprising general surgeons in Auckland. As early as the 1920s, he performed and published the results of several neurosurgical procedures. Later, Donald Mackenzie, another Auckland general surgeon, went abroad to gain neurosurgical experience from his North American and British colleagues. He returned and founded the Auckland Neurosurgical Department in 1945. David Robertson and Phillip Wrightson later joined the department, and they were instrumental in conducting early research on shunt systems, head injury, and pituitary tumors. The neurosurgical department Mackenzie founded went on to become the largest in New Zealand and presently serves metropolitan Auckland as well as both rural areas of New Zealand's North Island and many smaller Pacific island nations. CONCLUSION: Neurological surgery in Auckland was influenced largely by Great Britain, Australia, and North America, as well as by geographical and socioeconomic factors unique to the South Pacific. The achievements of these earlier pioneers in neurosurgery highlight their tremendous abilities and sheer determination to succeed.

History, 18th Century↗
PubMed2005

Characterization of genetically defined types of Charcot-Marie-Tooth neuropathies by using magnetic resonance neurography.

OBJECT: Charcot-Marie-Tooth (CMT) disease is a collection of related genetic disorders affecting peripheral nerves with an incidence of one in every 2500 individuals. A diagnosis of CMT disease has classically relied on a medical history, examination, and measurement of nerve conduction velocities. Advancements in genetic testing and magnetic resonance (MR) imaging techniques may provide clinicians with a more precise diagnostic armamentarium. The authors investigated MR neurography as a possible method to characterize CMT subtypes. METHODS: The authors performed MR neurography to evaluate sciatic nerves in the mid-thigh area of seven patients with genetically defined subtypes of CMT, one patient with chronic inflammatory demylinating polyneuropathy, and one patient without neuropathy. The authors correlate their findings with normal nerve conduction velocities (NCVs) and present their results as a descriptive case series. Although MR neurography could not be used to distinguish subtypes of CMT disease on nerve area or fascicle number, it appears to characterize phenotypic features and disease progression noninvasively in patients with some subtypes. CONCLUSIONS: In conjunction with NCV measurements, MR neurography may be useful in the diagnosis of CMT neuropathies and in monitoring disease progression.

Adult↗
PubMed2003

Imaging tumor angiogenesis with contrast ultrasound and microbubbles targeted to alpha(v)beta3.

BACKGROUND: Angiogenesis is a critical determinant of tumor growth and metastasis. We hypothesized that contrast-enhanced ultrasound (CEU) with microbubbles targeted to alpha(v)-integrins expressed on the neovascular endothelium could be used to image angiogenesis. METHODS AND RESULTS: Malignant gliomas were produced in 14 athymic rats by intracerebral implantation of U87MG human glioma cells. On day 14 or day 28 after implantation, CEU was performed with microbubbles targeted to alpha(v)beta3 by surface conjugation of echistatin. CEU perfusion imaging with nontargeted microbubbles was used to derive tumor microvascular blood volume and blood velocity. Vascular alpha(v)-integrin expression was assessed by immunohistochemistry, and microbubble adhesion was characterized by confocal microscopy. Mean tumor size increased markedly from 14 to 28 days (2+/-1 versus 35+/-14 mm2, P<0.001). Tumor blood volume increased by approximately 35% from day 14 to day 28, whereas microvascular blood velocity decreased, especially at the central portions of the tumors. On confocal microscopy, alpha(v)beta3-targeted but not control microbubbles were retained preferentially within the tumor microcirculation. CEU signal from alpha(v)beta3-targeted microbubbles in tumors increased significantly from 14 to 28 days (1.7+/-0.4 versus 3.3+/-1.0 relative units, P<0.05). CEU signal from alpha(v)beta3-targeted microbubbles was greatest at the periphery of tumors, where alpha(v)-integrin expression was most prominent, and correlated well with tumor microvascular blood volume (r=0.86). CONCLUSIONS: CEU with microbubbles targeted to alpha(v)beta3 can noninvasively detect early tumor angiogenesis. This technique, when coupled with changes in blood volume and velocity, may provide insights into the biology of tumor angiogenesis and be used for diagnostic applications.

Animals↗
PubMed2003

Anemia, testosterone, and pituitary adenoma in men.

OBJECT: Older men with clinically nonfunctioning pituitary tumors have been noted to be anemic, to have hypopituitarism, and to have low serum levels of testosterone. The authors hypothesized that men with pituitary adenomas and hypogonadism have a physiologically related decrease in hematocrit. METHODS: A retrospective analysis was conducted of 216 patients older than 50 years of age who harbored pituitary adenomas. In 100 men serum testosterone levels and a complete blood (cell) count (CBC) were obtained before treatment; a CBC was also acquired in a series of women with pituitary adenomas. Using clinical laboratory standards, anemia was defined as a hematocrit less than 40% in men and less than 35% in women. Thirty-one (46.3%) of 67 men with low serum concentrations of testosterone were anemic. In men with low levels of testosterone, the average hematocrit was 39.9%, compared with 45.6% for men with normal testosterone levels (p < 0.001). Men with macroadenomas were most likely to have both anemia and a low serum concentration of testosterone. Anemia was associated with a low level of testosterone, adjusting for tumor size (odds ratio 19, 95% confidence interval 4.86-77.03). Of patients with anemia, 84% were men and 16% were women (p < 0.001). The prevalence of anemia in women was low and was not correlated with tumor size. Men receiving testosterone replacement therapy had a significantly higher hematocrit value than men with low or normal testosterone levels. CONCLUSIONS: These findings support a direct relationship between serum testosterone levels and hematopoiesis in men, and demonstrate that hematopoiesis is compromised in men who have low concentrations of testosterone due to a pituitary adenoma.

Adenoma↗
PubMed2003

Intrasellar schwannomas: report of two cases.

OBJECTIVE AND IMPORTANCE: The complex regional anatomic features surrounding the sella turcica make the differential diagnosis of intrasellar and parasellar lesions complicated. Sellar and parasellar schwannomas are rare. With the exclusion of parasellar schwannomas arising from cranial nerves within the cavernous sinus and extending into the sella, there have been only two reported cases of true intrasellar schwannomas. CLINICAL PRESENTATION: We describe the clinical, radiological, and pathological features of two cases in which the histopathological diagnosis of schwannoma was confirmed with immunohistochemical analyses and/or electron microscopy. INTERVENTION: The two cases were grossly resected via a transsphenoidal approach. Follow-up monitoring revealed no evidence of recurrence. CONCLUSION: Schwannomas may atypically occur in the sellar region, in which they demonstrate the typical light microscopic, immunohistochemical, and ultrastructural features observed in the peripheral nervous system. New and existing hypotheses regarding the histopathogenesis of intrasellar and parasellar schwannomas are presented.

Adult↗
PubMed2002

Blood use in cerebrovascular neurosurgery.

BACKGROUND AND PURPOSE: This study reviews the perioperative use of red blood cell transfusion in cerebrovascular neurosurgery. The current algorithm for preoperative ordering of red cells is historical and dated. More blood is ordered than is actually transfused, and considerable variability exists between different institutions. We determine the use of blood transfusion in cerebrovascular surgery to develop a rational blood ordering practice. METHODS: Records of 301 patients undergoing cerebrovascular neurosurgery at the University of Virginia were reviewed to quantitatively evaluate red blood cell transfusion practices. The amount and reason for transfusion were noted in each case. RESULTS: In 126 patients undergoing carotid endarterectomy, there were no preoperative or intraoperative transfusions and 5 postoperative transfusions (4.0%). In 71 ruptured aneurysm patients, there were 2 preoperative blood transfusions (2.8%), 4 intraoperative transfusions (5.6%), and 15 postoperative transfusions (21.1%). Forty-seven patients underwent surgery for unruptured aneurysms, with no preoperative transfusions, 2 intraoperative transfusions (4.3%), and 8 postoperative blood transfusions (17.0%). Of the 54 patients undergoing surgery for arteriovenous malformations, 5 patients (9.3%) were transfused preoperatively, 4 were transfused intraoperatively (7.4%), and 22 were transfused postoperatively (40.7%). None of the 3 patients undergoing surgery for concomitant arteriovenous malformations and aneurysms received intraoperative blood transfusions, but 1 received blood both preoperatively and postoperatively, and another received a transfusion postoperatively only. The overall ratio of perioperative cross-match to transfusion in this series is 41.4. CONCLUSIONS: In vascular neurosurgery at our institution, blood has routinely been ordered excessively. We recommend an ABO-Rh type and antibody screen for aneurysm and arteriovenous malformation surgery and no screen for carotid endarterectomy to efficiently utilize transfusion therapy in cerebrovascular surgery.

Blood Grouping and Crossmatching↗
PubMed2002

The long-term significance of microscopic dural invasion in 354 patients with pituitary adenomas treated with transsphenoidal surgery.

OBJECT: Pituitary adenomas are considered benign tumors; however, they may infiltrate surrounding tissues including the dura mater. In this paper the authors analyze the clinical significance of microscopically confirmed dural invasion by comparing a range of variables (age and sex of patients, adenoma type, adenoma size on magnetic resonance [MR] images, remission, residual pituitary disease, recurrence, survival, and disease-free interval after surgery) between patients with noninvasive adenomas and those with invasive ones. METHODS: Between 1992 and 1997 dural specimens were obtained in 354 patients with pituitary adenomas who underwent transsphenoidal surgery performed by the senior author (E.R.L.). Dural specimens were examined using routine histological methods and assessed for invasion by pituitary adenoma tissue. The dura was invaded by the pituitary adenoma in 161 patients (45.5%), and in 192 patients (54.5%) no evidence of dural invasion was found. Dural invasion was present significantly more frequently in the repeated surgery group (69%, 55 patients) than in the primary transsphenoidal surgery group (41%, 291 patients). The mean age of patients undergoing primary transsphenoidal surgery was significantly older in cases of invasive adenomas (50 years) compared with cases of noninvasive adenomas (43 years), and these age differences also correlated with adenoma size. Women tend to develop clinically evident, smaller adenomas at a younger age than men. Of the patients with pituitary adenomas that were 20 mm or smaller, 117 (76%) of 154 were women, whereas of the patients with adenomas that were larger than 20 mm, 74 (54%) of 137 were men. The frequency of dural invasion increased with increasing size of the pituitary adenoma as measured on MR images. In 291 patients who underwent primary pituitary surgery, the frequency of dural invasion according to adenoma size was 24% (< or = 10 mm), 35% (> 10 to < or = 20 mm), 55% (> 20 to < or = 40 mm), and 70% (> 40 mm). In patients who underwent primary transsphenoidal surgery, dural invasion was present in more than 50% of those with nonfunctioning adenomas and in 30 to 35% of patients with endocrinologically active adenomas. The mean diameter of the gonadotrophic adenomas and null-cell adenomas was significantly larger than that of each of the endocrinologically active adenomas. In 58 (20%) of 291 patients who underwent primary pituitary surgery there was residual pituitary disease postsurgery, and 20% of this subset of patients showed clinical improvement to such an extent that no further management was recommended. After pituitary surgery, residual tumor tissue was demonstrable significantly more frequently in patients with invasive adenomas than in those with noninvasive adenomas. Recurrences after initial remission (cure) of pituitary disease occurred in 18 (8.8%) of 205 patients between 2 and 79 months after primary pituitary surgery (median 25 months). The recurrence rate was not related to dural invasion in a consistent or significant fashion. Seven patients died between 14 and 79 months after pituitary surgery and all had invasive adenomas identified on gross observation at surgery and on microscopy. The survival rate was slightly but significantly decreased for patients with invasive adenomas (91%) compared with patients with noninvasive adenomas (100%) at 6 years postsurgery. CONCLUSIONS: The principal significance of dural invasion by pituitary adenoma is the persistence of tumor tissue after transsphenoidal surgery (incomplete adenomectomy; 20% in primary pituitary tumor resections). The increase in adenoma size with time and the concurrent development of dural invasion are the major factors that determine an incomplete adenomectomy. When the adenoma remains restricted to the sellar compartment or shows only moderate suprasellar extension, dural invasion may not yet have developed and conditions for complete selective adenomectomy are improved.

Adenoma↗
PubMed2002

Use of FloSeal hemostatic sealant in transsphenoidal pituitary surgery: technical note.

OBJECTIVE: Bleeding during transsphenoidal pituitary surgery can lead to a variety of operative difficulties. When the endonasal transsphenoidal approach is used, even mild intraoperative hemorrhage can lessen visibility in the confined operative field of view. This technical note describes the use of a hemostatic agent we have found of benefit in obtaining prompt hemostasis during this operation. METHODS: Operative records were reviewed for an 18-month period for all patients who underwent transsphenoidal surgery since we began using FloSeal hemostatic sealant in January 2000. RESULTS: During the study period, 293 transsphenoidal operations were performed for pituitary lesions. Of these, 20 procedures involved vigorous or persistent bleeding. When the standard techniques for hemostasis failed or were inadequate, FloSeal, a sterile mixture of a gelatin matrix and thrombin component mixed at the time of use, was applied to the site of hemorrhage by use of a 14-gauge angiocatheter to reach the sella. We observed complete hemostasis immediately on application of FloSeal in all cases except one, which required a second application. Hemostasis was obtained immediately after the second application. No operations were aborted during this period as a consequence of undue bleeding. CONCLUSION: We detail the method in which we use FloSeal in transsphenoidal surgery and report our impression of its effectiveness. FloSeal has been demonstrated to be safe and biocompatible as compared with hemostatic agents currently in use.

Adolescent↗