Biomedical subjects

W F Young

Publications and source records attributed to W F Young.

At least 19 recordsLinked to original sources

PubMed2000

Cervical spondylotic myelopathy: a common cause of spinal cord dysfunction in older persons.

Cervical spondylotic myelopathy is the most common cause of spinal cord dysfunction in older persons. The aging process results in degenerative changes in the cervical spine that, in advanced stages, can cause compression of the spinal cord. Symptoms often develop insidiously and are characterized by neck stiffness, arm pain, numbness in the hands, and weakness of the hands and legs. The differential diagnosis includes any condition that can result in myelopathy, such as multiple sclerosis, amyotrophic lateral sclerosis and masses (such as metastatic tumors) that press on the spinal cord. The diagnosis is confirmed by magnetic resonance imaging that shows narrowing of the spinal canal caused by osteophytes, herniated discs and ligamentum flavum hypertrophy. Choice of treatment remains controversial, surgical procedures designed to decompress the spinal cord and, in some cases, stabilize the spine are successful in many patients.

Aged↗

PubMed2000

The effects of hypertonic saline on spinal cord blood flow following compression injury.

7.5% hypertonic saline was administered following spinal cord injury to test its effect on spinal cord blood flow. Four different groups of rats underwent 10 minutes of spinal cord compression (45 g) at the C3 to C5 levels. A fifth group was not injured, but received hypertonic saline (5 ml/kg) at 5, 15 and 60 minutes following injury. Somatosensory evoked potentials and spinal cord blood flow were measured prior to and for 4 hours following the injury. The administration of hypertonic saline caused a significant increase in flow when administered 5 minutes following injury. Topical nitroprusside administration did not cause any increase in spinal cord blood flow during this time period. Hypertonic saline administration at the later time periods did not increase spinal cord blood flow. The group of animals which were not injured, but received hypertonic saline also showed no significant change in flow. The somatosensory evoked response of the treated animals was maintained for 4 hours after the injury where as the untreated animals began to lose their evoked responses 3 hours after injury.

Animals↗

PubMed2000

Intraoperative measurement of spinal cord blood flow in syringomyelia.

The role of spinal cord ischemia in the pathophysiology of syringomyelia remains undetermined. Previous reports in the literature suggest that shunting of syringes can improve spinal cord blood flow. In order to determine the effects of syrinx decompression on spinal cord blood flow in patients with syringomyelia, we prospectively measured regional spinal cord blood flow (RSCBF) intraoperatively pre and post shunting in patients with symptomatic syringomyelia using laser doppler flowmetry. Six patients with MRI documented syringomyelia were studied (three with Arnold Chiari I malformation and associated syrinx and three with post-traumatic syringomyelia). Surgery was performed on all patients with either a syringopleural or syringoperitoneal shunt. Laser doppler blood flow and somatosensory evoked potentials were monitored prior to myelotomy and after shunt insertion. Results indicate that there was a significant increase in RSCBF after decompression of the syrinx. This study supports the hypothesis that spinal cord ischemia is important in the pathophysiology of syringomyelia and confirms previous reports in the literature regarding RSCBF in syringomyelia.

Adult↗

PubMed2000

Ruptured cerebral aneurysm in a 39-day-old infant.

A case of middle cerebral artery aneurysm in a 39-day-old infant is discussed. The unique characteristics of aneurysms in the pediatric age group which distinguish them from adults are male predominance, greater frequency in middle cerebral artery and posterior circulation. In addition, they demonstrate a greater frequency of large and giant aneurysms. Theories on the etiology of cerebral aneurysms in children are discussed.

Aneurysm, Ruptured↗

PubMed2000

Management approaches to adrenal incidentalomas. A view from Rochester, Minnesota.

Two biproducts of the revolution in diagnostic imaging techniques are unintended discoveries, and uncertainty for the patient and the clinician. To address the uncertainty associated with adrenal incidentalomas, clinicians need to understand the definition, differential diagnosis, and options for assessment with respect to functional status and malignancy potential. This article presents an algorithmic approach that addresses these issues.

Adenoma↗

PubMed2000

Growth hormone therapy for hypopituitary adults: time for re-appraisal.

The advent of the production of large quantities of recombinant growth hormone (GH) has made it possible to have sufficient material to assess its efficacy in adult growth hormone deficiency (GHD). Although some studies have shown that patients who are severely deficient benefit from GH therapy, the spectrum of GHD is broad, and the degree of deficiency at times is very difficult to define. In some cases, benefit is not easily quantified, and some studies have claimed benefits that, although statistically significant, are either not clinically important or are so marginal as to be questionable in terms of cost, difficulty of administration and potential risks. The purpose here is to identify the current problems in the diagnosis of GHD, to discuss the rationale for GH therapy and to assess the potential effects of GHD as well as the benefits of GH therapy in GHD adults. We will include a commentary as to which effects appear more robust than others and which are likely to result in the greatest patient benefit. Finally, some attention will be paid to long-term safety issues that should be monitored to ensure that this medication is safe even for the patients with the greatest need.

Adult↗

PubMed2000

Syringomyelia presenting as a delayed complication of treatment for nocardia brain abscess.

OBJECTIVE: Syringomyelia is defined as a dilatation of the central canal of the spinal cord which often leads to neurologic impairment. Syringomyelia has not previously been reported as a late complication for the treatment of brain abscess. In this report, we review a case involving this unusual association. CLINICAL PRESENTATION: A 25 year-old woman sustained a nocardia brain abscess initially presenting as a pulmonary infection. Treatment led to the development of multiloculated hydrocephalus and syringomyelia. INTERVENTION: Treatment included placement of multiple ventriculoperitoneal shunts and a syringo-pleural shunt. This resulted in stabilization of neurologic symptoms. CONCLUSION: The possibility of developing syringomyelia should be considered in any case involving post-infectious hydrocephalus.

Adult↗

PubMed2000

Perianesthetic risks and outcomes of pheochromocytoma and paraganglioma resection.

UNLABELLED: Pheochromocytomas and paragangliomas are often surgically curable. However, resection of these tumors can be life threatening. We undertook this study to determine the frequency of, and risk factors for, perioperative complications in patients undergoing resection of pheochromocytoma or paraganglioma. We retrospectively reviewed the medical records of patients during 1983-1996 who underwent surgical resection of catecholamine-secreting pheochromocytoma or paraganglioma. Preoperative risk factors, adverse intraoperative events, and complications occurring in the 30 days after operation were recorded. Blood pressures were collected from manual records. The ranked sum test and Fisher's exact test were used for analyses. Adverse perioperative events or complications occurred in 45 of 143 patients (31.5%; exact 95% confidence interval, 24.0% to 39.8%). Of these 45 patients, 41 experienced one or more adverse intraoperative events. The most common adverse event was sustained hypertension (36 patients). There were no perioperative deaths, myocardial infarctions, or cerebrovascular events. Preoperative factors univariately associated with adverse perioperative events included larger tumor size (P: = 0.007), prolonged duration of anesthesia (P: = 0.015), and increased levels of preoperative urinary catecholamines and catecholamine metabolites: vanillylmandelic acid (P: = 0.019), metanephrines (P: = 0.004), norepinephrine (P: = 0. 014), and epinephrine (P: = 0.004). Despite premedication of most patients with phenoxybenzamine and a beta-adrenergic blocker, varying degrees of intraoperative hemodynamic lability occurred. IMPLICATIONS: Few patients who had pheochromocytoma or paraganglioma resection experienced significant perioperative morbidity and none died in the largest retrospective study on this topic to date. This study confirms the very good perioperative outcomes demonstrated in smaller studies on this high-risk population, and identifies several risk factors for adverse outcomes.

Adolescent↗

PubMed2000

Clinically silent corticotroph tumors of the pituitary gland.

OBJECTIVE: To determine the clinical presentation, imaging characteristics, microscopic and ultrastructural characteristics, and treatment outcomes of patients with clinically silent pituitary corticotroph adenomas. METHODS: All silent corticotroph adenomas diagnosed at the Mayo Clinic during the years 1975 through 1997 were selected from the files of the Mayo Tissue Registry. RESULTS: We studied 23 cases, occurring in 16 male and 7 female patients (age range, 11-79 yr; mean age, 48 yr), who presented with headaches (50%), visual field defects (61%), extraocular muscle paresis (13%), hypopituitarism (26%), and galactorrhea/amenorrhea (43%/29% of the female patients). No patients exhibited clinical hypercortisolism. All tumors were macroadenomas (2.4+/-0.8 cm; range, 1.5-4.0 cm) and exhibited suprasellar extension in 87% of the cases and hemorrhage, necrosis, and/or cystic changes in 61%. All tumors stained were variably periodic acid-Schiff-, adrenocorticotropic hormone-, and beta-endorphin-positive, particularly Subtype I lesions. Ultrastructural classification was performed in 19 cases. In a comparison of Subtype I and II tumors, differences were observed with respect to sex (male/female, 1.4:1 versus 6:1), preoperative hyperprolactinemia (5 of 16 versus 0 of 6 cases), preoperative hypopituitarism (9 of 16 versus 5 of 7 cases), radiographic or gross invasion (7 of 16 versus 5 of 7 cases), and partial or total postoperative pituitary failure (6 of 16 versus 6 of 6 cases). The overall median postoperative follow-up period was 4.9 years (range, 0.3-16.6 yr); 54% of the patients had persistent or recurrent tumors. CONCLUSION: Clinically silent corticotroph adenomas behave in an aggressive manner and are characterized by the following: lack of clinical signs or symptoms of Cushing's syndrome and normal cortisol levels; no or only minor elevations of serum adrenocorticotropic hormone levels; macroadenomas with hemorrhagic infarction; and presentation dominated by mass effect symptoms. The high persistence/recurrence rate underscores the need for long-term follow-up.

Adenoma↗

PubMed2000

Prevalence of primary aldosteronism among Asian hypertensive patients in Singapore.

Recent studies using the ratio of plasma aldosterone concentration (PAC) to PRA as the screening test for primary aldosteronism in hypertensive populations suggested that the prevalence may be as high as 5-15%, with well over half of the subjects having normal serum potassium concentrations. Despite an increasing clinical awareness of this entity, many clinicians are reluctant to consider routine screening for primary aldosteronism in essential hypertensive patients because there are few community-based prevalence studies of primary aldosteronism in different populations. Furthermore, genetic and environmental differences may affect the prevalence and presentation of primary aldosteronism in distinct populations. This study was designed to determine the prevalence of primary aldosteronism in the predominantly Chinese population in Singapore. Three hundred and fifty unselected adult hypertensive patients attending two primary care clinics had random ambulatory measurements for PAC (nanograms per dL) and PRA (nanograms per mL/h). Serum urea, creatinine, and electrolyte measurements were obtained simultaneously. Subjects with renal insufficiency (serum creatinine, >140 micromol/L) and those treated with glucocorticoids or spironolactone were excluded. Screening was considered positive if the PAC: PRA ratio was more than 20 and the PAC was more than 15 ng/dL (>416 pmol/L). Primary aldosteronism was confirmed with the determination of PAC after 2 L saline administered iv over 4 h. Adrenal computed tomographic (CT) scans were performed in biochemically confirmed cases of primary aldosteronism. Further localization with adrenal vein sampling was carried out in selected patients with equivocal findings on adrenal CT scan. Sixty-three (18%) of the 350 hypertensive patients (215 women and 135 men; age range, 23-75 yr) were screened positive for primary aldosteronism. Only 13 of these 63 subjects (21%) were hypokalemic (serum potassium, <3.5 mmol/L). Confirmatory studies were carried out in 56 (89%) of the subjects with a positive PAC:PRA ratio. Using a PAC above 10 ng/dL (>277 pmol/L) after saline infusion as the diagnostic cut-off, 16 of the 56 patients had biochemically confirmed primary aldosteronism. Hypokalemia was found in 6 of the 16 patients (37.5%) with primary aldosteronism. Subtype evaluation with adrenal CT scan and adrenal vein sampling indicated that half of the patients with primary aldosteronism may have had potentially curable unilateral adrenal adenoma. Our data suggest that primary aldosteronism occurs in at least 5% of the adult Asian hypertensive population, and approximately half of these individuals may have potentially curable, unilateral, aldosterone-producing adrenal adenoma. Our findings also confirm the poor predictive value of hypokalemia in both the diagnosis and the exclusion of primary aldosteronism.

Adult↗

PubMed2000

Adrenocorticotropic hormone-dependent Cushing's syndrome: sensitivity and specificity of inferior petrosal sinus sampling.

BACKGROUND AND PURPOSE: Determining the cause of Cushing's syndrome can be difficult. Bilateral inferior petrosal sinus (IPS) sampling after ovine corticotropin-releasing hormone (oCRH) stimulation is an established technique for the differentiation of pituitary from nonpituitary sources of adrenocorticotropic hormone (ACTH) production. The purpose of this study was to review our experience to determine the sensitivity and specificity of bilateral IPS sampling. METHODS: Between January 1990 and February 1997, 92 patients underwent 94 IPS sampling procedures. Indications for these patients with Cushing's syndrome included no discrete lesion on MR images or CT scans, a discrete lesion present on images but equivocal peripheral ACTH sampling after oCRH stimulation, and persistent Cushing's syndrome after trans-sphenoidal surgery. RESULTS: IPS sampling yielded six false-negative results and one false-positive result, manifesting an overall sensitivity of 92.2% and a specificity of 90.0% for detection of a pituitary source of ACTH after oCRH stimulation. Microadenoma lateralization by IPS sampling after oCRH stimulation agreed with the surgical location in 70.0% of the patients. The technical success rate of initial (presampling) bilateral IPS catheterization was 93.6%. Two serious complications occurred and consisted of a venous subarachnoid hemorrhage and a lower extremity deep venous thrombosis. CONCLUSION: Bilateral IPS sampling after oCRH stimulation is helpful in the evaluation of ACTH-dependent Cushing's syndrome. False-negative results, however, suggest that the possibility of a pituitary source must still be considered when no response to oCRH is documented. Interpetrosal ACTH gradient alone is not sufficient to lateralize the tumor reliably.

Adolescent↗

PubMed1999

Spinal epidural hematoma associated with tissue plasminogen activator treatment of acute myocardial infarction.

We report a case of tissue plasminogen activator-associated spinal epidural hematoma in a patient who underwent treatment for myocardial infarction. Diagnostic magnetic resonance imaging was used within 24 hr of coronary artery stent implantation. We review the literature on thrombolytic-associated epidural spinal hematoma and discuss its management. Cathet. Cardiovasc. Intervent. 48:390-396, 1999.

Fibrinolytic Agents↗

PubMed1999

Reversible catecholamine-induced cardiomyopathy in a heart transplant candidate without persistent or paroxysmal hypertension.

BACKGROUND: Both dilated and hypertrophic cardiomyopathy have been reported in patients with pheochromocytoma, who were almost always hypertensive. The outcome frequently has been fatal, yet cardiac dysfunction can be reversible after medical or surgical therapy for the pheochromocytoma. METHODS: We report the case of a patient with dilated cardiomyopathy without persistent or paroxysmal hypertension, who was found to have a pheochromocytoma during initial medical evaluation. RESULTS: The identification and treatment of the pheochromocytoma led to significant improvement in cardiac function and cardiac transplantation was avoided. CONCLUSIONS: This case illustrates some unusual features in pheochromocytoma-induced cardiomyopathy: (1) absence of persistent or paroxysmal hypertension, (2) initial presentation with acute myocardial infarction and normal coronary arteries, and (3) recurrent episodes of nonsustained ventricular tachycardia.

Adrenal Gland Neoplasms↗

PubMed1999

Distribution and regulation of proconvertases PC1 and PC2 in human pituitary adenomas.

Pituitary adenomas are members of the family of neuroendocrine cells and tumors which have secretory granules containing chromogranins/secretogranins and other proteins. Pituitary adenomas express the neuroendocrine specific proconvertases PC1 (also known as PC3) and PC2, which are important for the proteolytic processing of chromogranins/secretogranins molecules. We examined the distribution of PC1 and PC2 in primary cultures of 20 pituitary adenomas and analyzed the regulation of the proconvertase mRNAs and proteins by various secretagogues including hypothalamic hormones and phorbol ester to determine the role of PC1 and PC2 in CgA processing in pituitary adenomas. Although PC2 was present in all adenomas, there was a differential distribution of PC1 with PRL adenomas expressing lower levels of PC1 compared to other adenoma types by RT-PCR analysis, in situ hybridization and immunostaining. Treatment of primary cultures of pituitary adenomas with phorbol 12-myristrate 13-acetate (PMA) resulted in an increase in pancreastatin (PST) secretion in most pituitary adenomas and increased PC1 mRNA and protein expression in gonadotroph adenomas, but not in other types of adenomas. Analysis of a human pituitary adenoma cell line, immortalized by recombinant defective adenovirus (HP75), which expressed chromogranin A, FSH, PC1 and PC2 showed that PST was secreted by these immortalized cells. Treatment with TGF beta 1 resulted in an increase in PST secretion and in PC1 mRNA and protein. These results indicate that a) there is a differential distribution of PC1 in human pituitary adenomas with PRL adenomas expressing very little PC1 mRNA and protein and b) that PC1 expression in gonadotropin hormone-producing adenomas is regulated by PMA and TGF beta 1. These findings support the observation that chromogranin A is a substrate for the endoproteinase PC1 in human pituitary adenoma cells.

Adenoma↗

PubMed1999

Isolated pyogenic osteomyelitis of the odontoid process.

A case of isolated pyogenic osteomyelitis of the odontoid process is reported. Diagnosis was made using magnetic resonance imaging. Aggressive treatment, including transoral drainage of the abscess, antibiotics and cervical immobilization, resulted in a successful outcome. A review of the world's literature revealed only 15 previous reports of this rare entity.

Adolescent↗

PubMed1999

Surgical outcome in patients with coexisting multiple sclerosis and spondylosis.

OBJECTIVES: Multiple sclerosis (MS) is a neuro-degenerative disease of unknown etiology which results in destruction of myelin. A variety of neurologic signs and symptoms are associated with MS and include myelopathy, extremity weakness, low back pain, sciatica and paresthesias. Many of these signs and symptoms are identical to those experienced by patients with spondylosis (e.g. spinal stenosis, disc herniations). The coexistence of MS with spondylosis can be problematic both for diagnosis and treatment. MATERIALS AND METHODS: During the period 1992 to 1996 we identified 7 patients with previously diagnosed MS who developed new syndromes which were thought to be related to a variety of degenerative spine conditions. The diagnosis of MS was based on standard clinical, immunological and neuroradiological criteria. RESULTS: Five of 7 patients demonstrated significant improvement after surgery. One patient experienced a transient MS exacerbation after surgery. CONCLUSIONS: From our series we concluded that surgery for degenerative spine conditions can be performed in a safe and effective manner in patients with coexisting multiple sclerosis.

Adult↗

PubMed1999

Tension pneumocranium, a rare complication of transsphenoidal pituitary surgery: Mayo Clinic experience 1976-1998.

We describe four cases of symptomatic pneumocranium, a rare, potentially life-threatening complication of transsphenoidal pituitary surgery. Symptomatic pneumocranium manifested as impaired mental status, headaches, and grand mal seizures, early in the postoperative course after transsphenoidal pituitary surgery. Furthermore, a Cushing response, including systemic hypertension and bradycardia (secondary to intracranial hypertension) was seen, which has not been previously described in association with symptomatic pneumocranium. We describe a previously unreported risk factor for tension pneumocranium, untreated obstructive sleep apnea. Other factors predisposing to tension pneumocranium in our patients included: cerebrospinal fluid leaks, postoperative positive-pressure mask ventilation, large pituitary tumors, and intraoperative lumbar drainage catheters. Surgical drainage of the pneumocranium and repair of any coexistent cerebrospinal fluid leak markedly improved neurologic status. Symptomatic pneumocranium occurring early in the postoperative course after transsphenoidal pituitary surgery is rare, but prompt recognition and treatment of this condition can be life-saving.

Adenoma↗

PubMed1999

The effects of pentoxifylline on spinal cord blood flow after experimental spinal cord injury.

Previous clinical and experimental investigations have suggested that pentoxifylline, a methylxanthine, can improve cerebrovascular circulation and reduce cerebral edema in cerebrovascular disorders. Pentoxifylline's mechanism of action includes such rheologic effects as enhanced red cell deformability, alterations in leukocyte activation, and modification of coagulation parameters. The purpose of our investigation was to determine the effects of pentoxifylline in an experimental spinal cord injury model. A compression device was used to cause a reproducible spinal cord injury in adult female albino rats. Spinal cord blood flow was monitored using a laser Doppler flow meter pre- and postinjury for 4 hours. The experimental group (N = 7) was injected with pentoxifylline 10 minutes prior to injury. The control group (N = 5) received an identical protocol, except that this group was injected with an equal amount of saline. Results of this investigation revealed that pentoxifylline treatment significantly increased spinal cord blood flow. In the pentoxifylline-treated group, spinal cord blood flow was significantly higher from 120 to 240 minutes postinjury compared with that of the control group. We conclude that via its multiple physiologic effects, pentoxifylline significantly improves spinal cord blood flow in experimental spinal cord injury.

Animals↗