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William T Couldwell

Publications and source records attributed to William T Couldwell.

At least 19 recordsLinked to original sources
PubMed2005

Far-lateral transcondylar approach: surgical technique and its application in neurenteric cysts of the cervicomedullary junction. Report of two cases.

Neurenteric cysts are rare benign lesions of the central nervous system that are lined by endodermal cell-derived epithelium. Although they occur mostly in the spine, they can occur intracranially, most often in the posterior fossa. Neurenteric cysts that are located in the anterior cervicomedullary junction are even rarer and often require a skull base approach for adequate resection. The authors describe two cases of neurenteric cysts arising from the cervicomedullary junction that were resected via a far-lateral transcondylar approach. They discuss the surgical approach and operative nuances involved in removing these lesions, and review the clinical presentation of neurenteric cysts in this region as well as the neuroimaging characteristics, histopathological findings, and surgical management. Intraoperative videos are presented.

Adult↗
PubMed2005

Intraventricular tanycytic ependymoma: case report and review of the literature.

OBJECTIVE AND IMPORTANCE: Tanycytic ependymomas are a rare ependymoma subtype showing a marked predilection for the spine, with only a few reports of supratentorial tumors. We present a case of a tanycytic ependymoma arising from the lateral and third ventricle. CLINICAL PRESENTATION: The patient was a 55-year-old woman who complained of intermittent, progressively worsening dysequilibrium for several months. The neurologic exam in the neurosurgery clinic was without deficit. INTERVENTION: MRI of the brain revealed a 3-cm, minimally enhancing lesion centered in the superior aspect of the third ventricle. The tumor involved the left wall of the third ventricle, the septum pellucidum, and the anterior horn of the left lateral ventricle. Surgery was recommended for diagnosis and to prevent obstructive hydrocephalus. A gross total resection was achievedvia a transcallosal approach. Postoperatively, the patient remained neurologically intact. CONCLUSION: The long-term prognosis for tanycytic ependymomas is the same or slightly better than for other ependymoma subtypes. The current treatment plan includes gross total resection followed by radiologic surveillance. Repeat resection or radiation treatment will be recommended in the event of recurrence.

Cerebral Ventricle Neoplasms↗
PubMed2005

Intra-arterial papaverine infusions for the treatment of cerebral vasospasm induced by aneurysmal subarachnoid hemorrhage.

Cerebral vasospasm secondary to aneurysmal subarachnoid hemorrhage that has become refractory to maximal medical management can be treated with selective intra-arterial papaverine infusions. Papaverine is a potent vasodilator of the proximal, intermediate, and distal cerebral arteries and can improve cerebral blood flow (CBF). When infused intra-arterially using endovascular microcatheter techniques, papaverine can effectively increase angiographic vessel diameter, decrease prolonged cerebral circulation time, and improve cerebral oxygenation. However, one of the major disadvantages of papaverine is its transient nature, which can result in recurrent and/or persistent angiographic and clinical vasospasm that may require multiple repeated infusions, despite a successful response to the initial treatment. Intra-arterial papaverine can be used alone or in combination with balloon angioplasty. This article reviews the mechanism of action, technique of administration, effects on CBF, clinical results, and complications of intra-arterial papaverine for the treatment of cerebral vasospasm.

Brain↗
PubMed2005

Surgical outcomes in 118 patients with Rathke cleft cysts.

OBJECT: Microscopic Rathke cleft cysts are a common incidental autopsy finding, but some Rathke cleft cysts can become sufficiently large to cause visual impairment, hypothalamic-pituitary dysfunction, and headaches. In this study patients were evaluated pre- and postoperatively to ascertain the clinical significance of surgical intervention on endocrine and visual improvement. Factors correlated with cyst recurrence were also evaluated. METHODS: A retrospective analysis was conducted in 160 patients with Rathke cleft cysts who were treated between 1984 and 1995 and completed at least a 5-year follow-up period. Of these 160 patients, 118 initially exhibited symptoms of visual impairment or endocrine dysfunction, became symptomatic during the follow-up period, or were found to have cyst enlargement. These 118 patients underwent transsphenoidal surgery. Forty-two patients with incidental lesions that demonstrated no growth on magnetic resonance (MR) images were followed up without an operation. Complete resection, as observed on MR images 3 months postoperatively, was obtained in 114 (97%) of 118 patients. Vision improved postoperatively in 57 (98%) of 58 patients. Hypogonadism improved in 11 (18%) of 62 patients, growth hormone deficiency resolved in 14 (18%) of 78 patients, and hypocortisolemia resolved in one (14%) of seven patients. Twenty-two patients (19%) began to exhibit symptoms of diabetes insipidus, which had not been present preoperatively. The total 5-year recurrence rate was 18% (21 of 118 patients), with 12 patients requiring a repeated operation. Surgical and pathological factors that were found to be statistically associated with recurrence were the use of a fat and/or fascial graft for closure (p < 0.01) and the presence of squamous metaplasia in the cyst wall (p < 0.01). The extent of resection of the cyst wall was not associated with an increased rate of recurrence. In 42 (69%) of 61 patients the incidental cysts did not progress on imaging studies or clinically. CONCLUSIONS: This is the largest series of patients with symptomatic Rathke cleft cysts who received operative intervention and participated in the longest postoperative follow up reported in the literature. The high recurrence rate (18%) supports the theory that a relationship exists between a symptomatic Rathke cleft cyst and craniopharyngioma. Improvements in visual and endocrine dysfunction can be expected after surgical decompression of the optic apparatus and the hypothalamic-pituitary axis.

Adolescent↗
PubMed2005

Neurosurgical workforce trends in the United States.

OBJECT: The purpose of this study was to evaluate the US neurosurgery workforce by reviewing journal recruitment advertisements published during the past 10 years. METHODS: The number of available academic and private neurosurgical staff positions was determined based on recruitment advertisements in the Journal of Neurosurgery and Neurosurgery for the 10-year period from 1994 to 2003. Advertisements were evaluated for practice venue, subspecialization, and location. The numbers of active neurosurgeons and graduating residents also were reviewed. The number of advertised neurosurgical positions increased from 141.6 +/- 38.2 per year from 1994 through 1998 to 282.4 +/- 13.6 per year from 1999 through 2003 (mean +/- standard deviation, p < 0.05). The mean number of academic positions increased from 50.6 +/- 11.1 to 95 +/- 17.5 (p < 0.05), and the mean number of private positions rose from 91 +/- 30.4 to 187.4 +/- 6.8 (p < 0.05). Subspecialty positions represented a mean of only 15.6 +/- 5% per year during the first time period and 18.8 +/- 3% per year in the second period (p = 0.22), and therefore the majority of positions advertised continued to be those for generalists. The number of practicing neurosurgeons declined after 1998, and by 2002 it was less than it had been in 1991. The numbers of incoming and matriculating residents during the study period were static. CONCLUSIONS: The number of recruitment advertisements for neurosurgeons during the last 5 years has increased significantly, concomitant with a severe decline in the number of active neurosurgeons and a static supply of residents.

Advertising↗
PubMed2004

Aneurysms of the petrous internal carotid artery: anatomy, origins, and treatment.

Aneurysms arising in the petrous segment of the internal carotid artery (ICA) are rare. Although the causes of petrous ICA aneurysms remain unclear, traumatic, infectious, and congenital origins have been implicated in their development. These lesions can be detected incidentally on routine neuroimaging. Patients can also present with a wide spectrum of signs and symptoms, including cranial nerve palsies, Horner syndrome, pulsatile tinnitus, epistaxis, and otorrhagia. The treatment of petrous ICA aneurysms remains challenging. Treatment options include close observation, endovascular therapies, and surgical trapping with or without revascularization. Management dilemmas exist, particularly for incidental lesions found in asymptomatic patients. The authors review the literature and discuss the anatomy of the petrous ICA as well as the pathophysiological features of aneurysms arising in this region, and they propose a management paradigm with current treatment options.

Aneurysm↗
PubMed2004

Prophylaxis for deep venous thrombosis in neurosurgery: a review of the literature.

The incidence of deep venous thrombosis (DVT) and subsequent pulmonary embolism (PE) in patients undergoing neurosurgery has been reported to be as high as 25%, with a mortality rate from PE between 9 and 50%. Even with the use of pneumatic compression devices, the incidence of DVT has been reported to be 32% in these patients, making prophylactic heparin therapy desirable. Both unfractionated and low-molecular-weight heparin have been shown to reduce the incidence of DVT consistently by 40 to 50% in neurosurgical patients. The baseline rate for major intracranial hemorrhage (ICH) following craniotomy has been reported to be between 1 and 3.9%, but after initiation of heparin therapy this rate has been found to be as high as 10.9%. Therefore, neurosurgeons must balance the risk of PE against the increased risk of postoperative ICH from prophylactic heparin for DVT. The authors review the literature on the incidence of DVT and PE in neurosurgical patients, focusing on the incidence of ICH related to the use of unfractionated and low-molecular-weight heparin in this patient population.

Heparin↗
PubMed2004

False-negative magnetic resonance angiography with extracranial internal carotid artery stenosis: a report of two cases and review of the literature.

Magnetic resonance angiography (MRA) is increasingly used as a noninvasive means to assess internal carotid artery (ICA) stenosis. When used alone, however, MRA may not be sufficiently accurate in certain settings to determine whether ICA disease meets surgical criteria. Although MRA has been recognized to overestimate the degree of stenosis, the authors present two cases in which it severely underestimated arterial stenosis. Two male patients, 70 and 40 years old, respectively, were admitted with crescendo transient ischemic attacks. Their MRA studies suggested nonsurgical lesions of the ICA. After the patients continued to demonstrate clinical evidence of embolic disease, digital subtraction angiography (DSA) was performed on one patient, and the other received a gadolinium contrast-enhanced MRA. These tests revealed critical stenosis in each patient. Each was taken to the operating room for awake carotid endarterectomy with heparin anticoagulation and electroencephalographic monitoring. At surgery, both patients were found to have severely stenosed ICAs with complex plaques. MRA to determine whether ICA stenosis meets surgical criteria may not be sufficiently accurate in certain clinical settings. Additional imaging studies, such as confirmatory digital ultrasonography, MRA with gadolinium contrast, or DSA, may be required to determine the extent of carotid artery stenosis accurately.

Adult↗
PubMed2004

Comparison of radiosurgery and conventional surgery for the treatment of glomus jugulare tumors.

OBJECT: The optimal management of glomus jugulare tumors remains controversial. Available treatments were once associated with poor outcomes and significant complication rates. Advances in skull base surgery and the delivery of radiation therapy by stereotactic radiosurgery have improved the results obtained using these treatment options. The authors summarize and compare the contemporary outcomes and complications for these therapies. METHODS: Papers published between 1994 and 2004 that detailed the use of radiosurgery or surgery to treat glomus jugulare tumors were reviewed. Eight radiosurgery series including 142 patients and seven surgical studies including 374 patients were evaluated for neurological outcome, change in tumor size (radiosurgery) or percent of total resection (surgery), recurrences, tumor control, need for further treatment, and complications. The mean age at treatment for patients who underwent surgery and radiosurgery was 47.3 and 56.7 years, respectively. The mean follow-up duration was 49.2 and 39.4 months, respectively. The surgical control rate was 92.1%, with 88.2% of tumors totally resected in the initial surgery. A cerebrospinal fluid leak occurred in 8.3% of patients who underwent surgery and recurrences were found in 3.1%; the mortality rate was 1.3%. Among patients who underwent radiosurgery, tumors diminished in 36.5%, whereas 61.3% had no change in tumor size, and subjective or objective improvements occurred in 39%. Despite the presence of residual tumor in 100% of radiosurgically treated patients, recurrences were found in only 2.1%, the morbidity rate was 8.5%, and there were no deaths. CONCLUSIONS: Death and recurrences after these treatments are infrequent, and therefore both treatments are considered to be safe and efficacious. Although surgery is associated with higher morbidity rates, it immediately and totally eliminates the tumor. The radiosurgery results are very promising, although the incidence of late recurrence (after 10-20 years) is unknown.

Adult↗
PubMed2004

The prevalence of pituitary adenomas: a systematic review.

BACKGROUND: Pituitary adenomas display an array of hormonal and proliferative activity. Once primarily classified according to size (microadenomas, < 1 cm; macroadenomas, > or = 1 cm), these tumors are now further classified according to immunohistochemistry and functional status. With these additional classifications in mind, the goals of the current study were to determine the prevalence of pituitary adenomas and to explore the clinical relevance of the findings. METHODS: The authors conducted a metaanalysis of all existing English-language articles in MEDLINE. They used the search string (pituitary adenoma or pituitary tumor) and prevalence and selected relevant autopsy and imaging evaluation studies for inclusion. RESULTS: The authors found an overall estimated prevalence of pituitary adenomas of 16.7% (14.4% in autopsy studies and 22.5% in radiologic studies). CONCLUSIONS: Given the high frequency of pituitary adenomas and their potential for causing clinical pathologies, the findings of the current study suggest that early diagnosis and treatment of pituitary adenomas should have far-reaching benefits.

Adenoma↗
PubMed2004

Hyponatremia in the neurosurgical patient: diagnosis and management.

Hyponatremia is frequently encountered in patients who have undergone neurosurgery for intracranial processes. Making an accurate diagnosis between the syndrome of inappropriate secretion of antidiuretic hormone (SIADH) and cerebral salt wasting (CSW) in patients in whom hyponatremia develops is important because treatment differs greatly between the conditions. The SIADH is a volume-expanded condition, whereas CSW is a volume-contracted state that involves renal loss of sodium. Treatment for patients with SIADH is fluid restriction and treatment for patients with CSW is generally salt and water replacement. In this review, the authors discuss the differential diagnosis of hyponatremia, distinguish SIADH from CSW, and highlight the diagnosis and management of hyponatremia, which is commonly encountered in patients who have undergone neurosurgery, specifically those with traumatic brain injury, aneurysmal subarachnoid hemorrhage, recent transsphenoidal surgery for pituitary tumors, and postoperative cranial vault reconstruction for craniosynostosis.

Adult↗
PubMed2004

Contemporary management of prolactinomas.

Prolactin-secreting pituitary adenomas--prolactinomas--are the most common type of functional pituitary tumor. Treatment of hyperprolactinemia is indicated because of the consequences of infertility, gonadal dysfunction, and osteoporosis. Making the correct diagnosis is important because the first line of therapy is medical management with dopamine agonists. Medical therapy is effective in normalizing prolactin levels in more than 90% of patients, but longterm treatment may be required in some patients. Transsphenoidal surgery is usually indicated in those patients in whom medical therapy fails or cannot be tolerated, or in patients who harbor microprolactinomas. In experienced hands, a hormonal and oncological cure can be achieved in more than 90% of patients after transsphenoidal removal of microprolactinomas with minimal risks. Thus, surgery may be an option for microprolactinomas in a young patient who desires restoration of fertility and avoidance of long-term medical therapy. The authors review the diagnosis and management of prolactinomas, including medical therapy, surgical therapy, and stereotactic radiosurgery.

Bromocriptine↗
PubMed2004

Pituitary carcinoma: a review of the literature.

Pituitary carcinomas, defined as distant metastases of a pituitary neoplasm, are rare; fewer than 140 reports exist in the English literature. The initial presenting pituitary tumor is usually a secreting, invasive macroadenoma, with adrenocorticotropic hormone (ACTH)--and prolactin (PRL)--secreting tumors being the most common. The latency period between the diagnosis of a pituitary tumor and the diagnosis of a pituitary carcinoma is 9.5 years for ACTH-producing lesions and 4.7 years for PRL-secreting tumors. Survival after documentation of metastatic disease is poor; 66% of patients die within 1 year. Treatment options include additional surgery, radiotherapy, and chemotherapy, all of which are associated with poor results. Future studies will focus on identifying those invasive pituitary tumors most likely to metastasize and treating them aggressively before they progress to pituitary carcinomas.

Adrenocorticotropic Hormone↗
PubMed2004

Metastases to the pituitary gland.

Only 1% of all pituitary surgeries are performed to treat tumors that have metastasized to the pituitary gland; however, in certain cases of malignant neoplasms pituitary metastases do occur. Breast and lung cancers are the most common diseases that metastasize to the pituitary. Breast cancer metastasizes to the pituitary especially frequently, with reported rates ranging between 6 and 8% of cases. Most pituitary metastases are asymptomatic, with only 7% reported to be symptomatic. Diabetes insipidus, anterior pituitary dysfunction, visual field defects, headache/pain, and ophthalmoplegia are the most commonly reported symptoms. Diabetes insipidus is especially common in this population, occurring in between 29 and 71% of patients who experience symptoms. Differentiation of pituitary metastasis from other pituitary tumors based on neuroimaging alone can be difficult, although certain features, such as thickening of the pituitary stalk, invasion of the cavernous sinus, and sclerosis of the surrounding sella turcica, can indicate metastasis to the pituitary gland. Overall, neurohypophysial involvement seems to be most prevalent, but breast metastases appear to have an affinity for the adenohypophysis. Differentiating metastasis to the pituitary gland from bone metastasis to the skull base, which invades the sella turcica, can also be difficult. In metastasis to the pituitary gland, surrounding sclerosis in the sella turcica is usually minimal compared with metastasis to the skull base. Treatment for these tumors is often multimodal and includes surgery, radiation therapy, and chemotherapy. Tumor invasiveness can make resection difficult. Although surgical series have not shown any significant survival benefits given by tumor resection, the patient's quality of life may be improved. Survival among these patients is poor with mean survival rates reported to range between 6 and 22 months.

Combined Modality Therapy↗
PubMed2004

Porous polyethylene implant for cranioplasty and skull base reconstruction.

OBJECT: Cranial reconstruction after skull base surgery is important for restoration of function and cosmesis. The authors describe their experience with the Medpor porous polyethylene implant for cosmetic cranioplasty and reconstruction after skull base surgery. METHODS: Medpor, a biocompatible implant, is flexible and can be contoured to facilitate surgical reconstruction of small to medium (< 8 cm) convexity or cranial base defects resulting from a variety of skull base approaches. This method provides similar cosmetic results to standard alloplast cranioplasty while decreasing operating time. The porous nature of the material allows ingrowth of soft tissue and bone to increase implant strength and decrease the risk of infection. This material can also be used safely in reconstruction of the cranium and skull base adjacent to the paranasal sinuses. CONCLUSIONS: The authors have used the Medpor porous polyethylene implant in 611 standard cranial and skull base procedures and have achieved excellent cosmetic results and no implant-related complications.

Absorbable Implants↗
PubMed2004

Prolactinomas.

Explore the source record for details and available documents.

Antineoplastic Agents↗
PubMed2004

Traumatic arteriovenous fistula of the posterior inferior cerebellar artery treated with endovascular coil embolization: case report.

BACKGROUND: High-flow intracranial arteriovenous (AV) fistulas associated with giant varices are rare lesions. These varices can present with symptoms from mass effect, spontaneous hemorrhage, and seizures to cardiac failure. Direct AV fistulas of the posterior inferior cerebellar artery (PICA) are extremely rare lesions, with only two cases reported in the literature. CASE DESCRIPTION: The authors present an unusual case of a 25-year-old male with a direct AV fistula of the PICA that resulted from a fracture of the occipital condyle. This high-flow AV fistula drained into a giant varix of the vein of the lateral recess that compressed the brainstem, resulting in a Wallenberg syndrome. The patient underwent embolization of the proximal PICA feeding the fistula with a Guglielmi detachable coil (GDC), which resulted in thrombosis of the varix. A postembolization angiogram showed occlusion of the PICA AV fistula and draining varix. A computed tomography (CT) scan performed at a 10-month follow-up visit showed dramatic decompression of the brainstem. Although the patient continued to have some sensory changes secondary to Wallenberg syndrome, he was otherwise doing well neurologically. CONCLUSION: The treatment of this lesion is difficult because of its location near the brainstem. Postocclusion edema or hemorrhage can result in mass effect and life-threatening brainstem compression. Our patient, whose AV fistula was caused by trauma, was treated effectively with GDC embolization.

Adult↗