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Biomedical subjects

William T Couldwell

Publications and source records attributed to William T Couldwell.

At least 19 recordsLinked to original sources
PubMed2007

Celecoxib inhibits meningioma tumor growth in a mouse xenograft model.

BACKGROUND: Treatments for recurrent meningiomas are limited. We previously demonstrated universal expression of COX-2 in meningiomas and dose-dependent growth inhibition in vitro with celecoxib, a COX-2 inhibitor. We therefore tested the effects of celecoxib on meningioma growth in a mouse xenograft model. METHODS: Meningioma cell lines (IOMM-Lee, CH157-MN, WHO grade I primary cultured tumor) were transplanted into flanks of nude mice fed mouse chow with celecoxib at varying concentrations (0, 500, 1000, 1500 ppm) ad libitum. Tumors were measured biweekly and processed for MIB-1, Factor VIII, COX-2, and VEGF, and assayed with transferase-mediated dUTP-biotin nick-end labeling (TUNEL). RESULTS: Celecoxib reduced growth of mean tumor volume by 66% (P < .05), 25% (P > .05), and 65% (P < .05) compared with untreated controls in IOMM-Lee, CH157-MN, and benign tumors, respectively. IOMM-Lee tumors removed from celecoxib treatment regained a growth rate similar to the control. Blood vessel density decreased and apoptotic cells increased in treated flank tumors. Diminished COX-2 expression and VEGF were observed in treated IOMM-Lee tumors. Mean plasma celecoxib levels were 845, 1540, and 2869 ng/mL, for low-, medium-, and high-dose celecoxib, respectively. CONCLUSIONS: Celecoxib inhibits meningioma growth in vivo at plasma levels achievable in humans. Celecoxib-treated tumors were less vascular with increased apoptosis. IOMM-Lee tumors treated with celecoxib showed decreased COX-2 and VEGF expression. COX-2 inhibitors may have a role in the treatment of recurrent meningiomas.

Animals↗
PubMed2006

Update on endovascular therapies for cerebral vasospasm induced by aneurysmal subarachnoid hemorrhage.

Cerebral vasospasm remains a major source of morbidity and death in patients with aneurysmal subarachnoid hemorrhage (SAH). When vasospasm becomes refractory to maximal medical management consisting of induced hypertension and hypervolemia and administration of calcium channel antagonists, endovascular therapies should be considered. The primary goal of endovascular treatment is to increase cerebral blood flow to prevent cerebral infarction. Two of the more frequently studied endovascular treatments are transluminal balloon angioplasty and intraarterial papaverine infusion. These two have been used either alone or in combination for the treatment of vasospasm. Other pharmacological vasodilating agents currently being investigated are intraarterial nimodipine, nicardipine, verapamil, and milrinone. Newer intraarterial agents, such as fasudil and colforsin daropate, have also been investigated. In this article the authors review the current options in terms of endovascular therapies for treatment of cerebral vasospasm. The mechanism of action, technique of administration, clinical effect and outcomes, and complications of each modality are discussed.

Angioplasty, Balloon↗
PubMed2006

Posterior fossa brain tumors and arterial hypertension.

Hypertension caused by arterial compression of the rostral ventrolateral medulla is well described. Much less information is available on the association between neurogenic hypertension and posterior fossa brain tumors. To date, multiple reports have supported the impression that a small subpopulation of patients with posterior fossa tumors can present with arterial hypertension, and many of those patients achieved significant improvement of their hypertension after tumor resection and medullary decompression. To review the relationship between posterior fossa brain tumors and hypertension, we detail the history, basic science, and clinical reports along with an illustrative case regarding this topic.

Adult↗
PubMed2006

Glioblastoma multiforme of the pineal region.

Glioblastoma multiforme (GBMs) tumors are exceedingly rare tumors in the pineal region. We present three cases in which patients presented with a pineal/posterior third ventricular region mass and review all the previously reported cases in the literature. Pineal region GBM seems to be a very aggressive tumor with a high rate of leptomeningeal and ependymal metastatic disease. Patients usually present with signs and symptoms of hydrocephalus and Parinaud's syndrome. The clinical and radiological characteristics of pineal GBM do not differentiate it from other malignancies of this region, thus surgical biopsy is generally required for definitive diagnosis. Glioblastoma should be considered in the differential diagnosis of the pineal region tumors, especially when evidence of leptomeningeal or ependymal metastatic disease is present.

Adult↗
PubMed2006

Inflammatory pseudotumor of the cavernous sinus and skull base.

Inflammatory pseudotumor is a non-neoplastic process of unknown etiology characterized by a proliferation of connective tissue with an inflammatory infiltrate. Intracranial inflammatory pseudotumors classically involve the cavernous sinus but can also occur in the supratentorial or infratentorial compartments and spinal canal. Symptoms are dependent on location, and, when present in the cavernous sinus, typically include cranial nerve palsies of those nerves in the cavernous sinus. These lesions are rapidly responsive to steroid therapy. Surgery is typically indicated for biopsy only, but complete resection may be justified for lesions outside the cavernous sinus.

Adult↗
PubMed2006

Simple closure following transsphenoidal surgery. Technical note.

The most common nonendocrine complication after transsphenoidal surgery is cerebrospinal fluid (CSF) leak. Many neurosurgeons have advocated the routine reconstruction of the floor of the sella turcica using autologous fat, muscle, fascia, and either cartilage or bone after transsphenoidal surgery to prevent postoperative CSF fistulas. However, the use of autologous grafting requires a second incision, prolongs operative time, and adds to the patient's postoperative discomfort. In addition, the presence of sellar packing may interfere with the interpretation of postoperative images. To avoid these disadvantages, the authors suggest that routine sellar reconstruction or closure after transsphenoidal surgery is unnecessary unless an intraoperative CSF leak is encountered. The incidence of postoperative CSF leakage in the patients reported on in this series is no higher than that reported by others, and no other complications such as pneumatocele have been encountered in approximately 2700 patients in whom no intraoperative CSF leak was encountered. The authors conclude that routine closure of the floor of the sella turcica or sphenoid is unnecessary in the absence of intraoperative CSF leak.

Cerebrospinal Fluid Rhinorrhea↗
PubMed2006

Development of contrast enhancement after long-term observation of a dysembryoplastic neuroepithelial tumor.

Dysembryoplastic neuroepithelial tumors (DNET) are usually benign lesions that arise in cortical regions and are discovered after new onset of seizure. These lesions have many different imaging characteristics. We report a patient with a presumed low-grade medial temporal lobe lesion that was followed for many years without any change in size or imaging characteristics. This previously non-enhancing tumor evolved to become contrast enhanced on routine imaging without apparent tumor growth. The patient underwent surgery, and the pathology was confirmed as a DNET with no atypical changes. This case demonstrates the potential that DNETs may exhibit a changing MRI pattern over time. Natural history, imaging characteristics, and management are reviewed.

Adult↗
PubMed2006

Cholesteatoma of the clivus.

Cholesteatomas (central nervous system epidermoids) can be found intradurally or extradurally in the central nervous system. Extradural intraosseous lesions are most commonly found in the petrous bone. The authors describe a unique case of a clival cholesteatoma in a 64-year-old woman who presented with headaches. No other neurological complaints or physical examination findings were noted. Magnetic resonance imaging showed an expansile lesion centered in the middle portion of the clivus. A large portion of the clivus was eroded. The lesion was explored via a transnasal trans-sphenoidal approach and granular debris was evacuated. The cystic lining was stripped from the surrounding bone, and the bone opening was widely fenestrated. Pathological examination showed keratinous debris with macrophages and an outer lining of benign epithelial tissue consistent with a cholesteatoma (epidermoid cyst). When surgically accessible, these lesions should be excised to prevent a recurrence. If inaccessible, marsupialization may be considered.

Case Reports↗
PubMed2006

Molecular, genetic, and cellular pathogenesis of neurofibromas and surgical implications.

Neurofibromatosis 1 (NF1) is a common autosomal dominant disease characterized by complex and multicellular neurofibroma tumors. Significant advances have been made in the research of the cellular, genetic, and molecular biology of NF1. The NF1 gene was identified by positional cloning. The functions of its protein product, neurofibromin, in RAS signaling and in other signal transduction pathways are being elucidated, and the important roles of loss of heterozygosity and haploinsufficiency in tumorigenesis are better understood. The Schwann cell was discovered to be the cell of origin for neurofibromas, but understanding of a more complicated interplay of multiple cell types in tumorigenesis, specifically recruited heterogeneous cell types such as mast cells and fibroblasts, has important implications for surgical therapy of these tumors. This review summarizes the most recent NF1 and neurofibroma literature describing the pathogenesis and treatment of nerve sheath tumors. Understanding the biological underpinnings of tumorigenesis in NF1 has implications for future surgical and medical management of neurofibromas.

Animals↗
PubMed2006

Surgical strategies for recurrent craniofacial meningiomas.

OBJECTIVE: Recurrent cranial base meningiomas are among the most difficult tumors to treat surgically. Although they are histologically benign, these tumors often invade through the cranial base into the infratemporal and pterygopalatine fossae. We reviewed our experience with these tumors to describe the natural history of these lesions as well as provide a possible treatment paradigm. METHODS: Between 2000 and 2004, seven patients with meningiomas recurring through the cranial base into facial structures were treated at the University of Utah. Five patients were treated with transcranial approaches only, and two were treated with a combination of transcranial and transfacial approaches. RESULTS: The average age of our patients (6 women, 1 man) was 55 years. The original site of tumor was the sphenoid wing in four patients, the middle fossa in two patients, and the left frontal region in one patient. The average interval between the most recent tumor resection and recurrence into the face was 9.9 years. The mean number of resections a patient underwent before invasion into the face was two. All but one patient had adjunctive therapy (including either radiation or chemotherapy) before recurrence into the face. CONCLUSION: Meningiomas that recur into facial structures present a unique treatment challenge. These lesions have a high rate of recurrence once they have invaded through the cranial base. Although combined approaches may be necessary to achieve a gross total resection, these lesions can often be reached using standard transcranial techniques.

Adult↗
PubMed2006

Subependymomas: an analysis of clinical and imaging features.

OBJECTIVE: Subependymomas are slow-growing, benign tumors usually found incidentally in the fourth ventricle at autopsy. They are typically associated with the ventricular system and become apparent clinically only when symptoms of hydrocephalus or mass effect develop. We review clinical, histological, and contemporary radiographic presentations of 16 subependymomas, including 2 intraparenchymal tumors. METHODS: We retrospectively evaluated eight patients with pathologically proven subependymomas. Initial magnetic resonance imaging and magnetic resonance spectroscopy were reviewed when available. Imaging was also available on eight outside subependymoma cases reviewed by our radiology department. RESULTS: Twelve of these subependymomas were intraventricular, one was in the posterior fossa, two were intraparenchymal, and one was an intramedullary spinal cord tumor. These lesions were hypo- to hyperintense on T1- and T2-weighted magnetic resonance imaging, with minimal to moderate enhancement. Initial complaints included headache, seizures, tingling sensations, and weakness. Among our eight patients who underwent gross total resection with no adjuvant therapy, no recurrences have been noted on follow-up magnetic resonance imaging. CONCLUSION: Subependymomas are rare, representing only 0.51% of all central nervous system tumors operated on during an 8-year period at the University of Utah. Clinical symptoms were associated with tumor location: intracranial masses caused headaches, seizures, and neurological complaints, and spinal cord locations resulted in neurological deficit. The authors review the clinical presentation, management, and contemporary radiographic appearance of this rare tumor.

Adult↗
PubMed2006

The combined transmastoid retro- and infralabyrinthine transjugular transcondylar transtubercular high cervical approach for resection of glomus jugulare tumors.

Complex tumors OF the glomus jugulare present a surgical challenge because of their difficult location, extreme vascularity, and involvement with multiple cranial nerves. Modern microneurosurgical and cranial base techniques have enabled safe total removal of these complicated tumors. We describe a one-stage transjugular posterior infratemporal fossa approach for radical resection of glomus jugulare tumors located around the jugular foramen, the lower clivus, and the high cervical region from an anterolateral direction. This approach is a combination of transmastoid, suprajugular, transjugular, extreme lateral infrajugular transcondylar transtubercular, and high cervical approaches. Total exposure of the jugular foramen can be achieved, and multidirectional approaches can be performed, including infralabyrinthine/suprajugular, retrosigmoid/transcondylar/infrajugular, and transjugular exposures. Exposure of the vertical C7 segment of the infratemporal internal carotid artery and the lower clivus can be performed without permanent rerouting of the facial nerve. The details of this approach are described and illustrated in a stepwise fashion, and the microsurgical anatomy is reviewed.

Carotid Artery, Internal↗
PubMed2006

Increasing exposure of the petrous internal carotid artery for revascularization using the transzygomatic extended middle fossa approach: a cadaveric morphometric study.

OBJECTIVE: When internal carotid artery (ICA) sacrifice is planned in the management of difficult tumors or aneurysms at the cranial base, the petrous ICA may be a useful site for anastomosis for interpositional vascular bypass. However, exposure of the artery and performing an anastomosis in this region may be technically challenging because of the narrow working corridor. The authors describe a transzygomatic extended middle fossa approach that maximizes the exposure of the petrous ICA for performing the difficult anastomosis. METHODS: Bilateral dissections were performed on eight silicone-injected cadaveric head specimens. Exposure of the entire petrous ICA (horizontal segment, genu, and vertical segment) using the transzygomatic extended middle fossa approach was performed by the following steps. A frontotemporal craniotomy was performed followed by a zygomatic osteotomy. The temporal lobe dura was elevated extradurally to expose the posterior cavernous sinus and floor of the middle fossa. The middle fossa rhomboid was identified, which is bordered by V3 anteriorly, the GSPN laterally, the arcuate eminence posteriorly, and the petrous edge medially. Bone drilling was performed in the middle fossa rhomboid and Glasscock's triangle with care not to violate the cochlea. The horizontal and vertical segments of the petrous ICA were skeletonized entirely and mobilized from carotid canal. The V3 segment of the trigeminal nerve was retracted anteriorly to obtain more distal exposure of the ICA. An osteoplastic bone flap of the middle fossa floor lateral to the ICA was removed to increase the working space. A morphometric analysis was performed, quantifying the petrous ICA exposure, the surgical working corridor, and the angles of exposure. RESULTS: On average, the length of the horizontal petrous ICA exposed was 9.2 +/- 1.0 mm (range, 8.0-11.0 mm). Anterior retraction of V3 provided an additional 4.3 +/- 0.4 mm of carotid exposure (46.7% increase; P < 0.05). The length of the genu was on average 3.6 +/- 0.4 mm (range, 3.0-4.0 mm), and the length of the vertical segment of the petrous ICA was 13.1 +/- 2.0 mm (range, 10.0-15.0 mm). The average depth of the petrous ICA from the outer surface of the temporal bone was 30.6 +/- 1.1 mm (range, 30.0-33.0 mm) at the V3-ICA junction and 27.2 +/- 0.7 mm (range, 26.0-28.0 mm) at the ICA genu. The average diameter of the inner working corridor was 24.2 +/- 3.0 mm (range, 21.5-30.0 mm). Removal of the zygoma increased the outer working corridor from an average distance of 24.4 +/- 3.8 mm to 33.4 +/- 3.4 mm (36.9% increase in exposure; P < 0.05). The average angle of exposure was 66.5% greater (P < 0.05) with zygomatic arch removal (39.3 +/- 4.9 degrees) than without zygomatic arch removal (23.6 +/- 2.7 degrees). CONCLUSION: The transzygomatic extended middle fossa approach provides a wide surgical corridor for maximal exposure of the petrous ICA with minimized temporal lobe retraction. This large exposure facilitates vascular anastomoses at the petrous ICA and provides working room to maneuver instruments. The middle fossa rhomboid is a key landmark to identify the petrous ICA and to avoid neuro-otologic structures.

Anastomosis, Surgical↗
PubMed2006

Submandibular-infratemporal interpositional carotid artery bypass for cranial base tumors and giant aneurysms.

OBJECTIVE: Cerebral revascularization is an important strategy in the surgical management of some complex cranial base tumors and unclippable aneurysms. A high-flow bypass may be necessary in planned carotid occlusion or sacrifice. The cervical-to-supraclinoid internal carotid artery bypass or cervical carotid-to-middle cerebral artery bypass are useful procedures to bypass lesions at the base of the cranium. We describe technical modifications of the submandibular-infratemporal interpositional saphenous vein (or radial artery) graft bypass technique specifically designed to avoid removal of the zygoma. METHODS: The saphenous vein or radial artery interpositional graft is tunneled through a burr hole created in the floor of the middle fossa via a submandibular-infratemporal route avoiding removal of zygoma and attachments of the masseter or temporalis muscles. RESULTS: The technique is demonstrated in one patient with removal of a malignant cavernous sinus tumor and in another patient with an unclippable giant carotid bifurcation aneurysm. CONCLUSION: The advantages of this approach include preservation of the facial anatomy and creation of a short and safe route for passage of the saphenous vein or radial artery graft.

Anastomosis, Surgical↗
PubMed2006

Pituitary apoplexy in the magnetic resonance imaging era: clinical significance of sphenoid sinus mucosal thickening.

OBJECT: The authors report their experience with pituitary apoplexy and evaluate the clinical significance of sphenoid sinus mucosal thickening found on magnetic resonance (MR) imaging. METHODS: The cases of 28 patients (19 males and nine females) with pituitary apoplexy were reviewed retrospectively. The mean age of the patients was 50 years (range 16-83 years), and the mean follow-up duration was 32 months (range 1-104 months). Admission MR imaging demonstrated hemorrhage or infarction in a pituitary tumor in each patient. A clinical grading scale for apoplexy was devised as follows: Grade I, presence of acute headache and/or endocrine abnormality (12 patients); Grade II, presence of the foregoing symptoms as well as cranial nerve deficit (visual and/or oculomotor; 15 patients); and Grade III, presence of all of these symptoms and a decreased level of consciousness (one patient). Twenty-five patients (89%) underwent early transsphenoidal resection within 9 days (80% within 72 hours) of diagnosis. Headaches and oculomotor paresis resolved completely in 100%, visual function resolved completely in 44% and partially in 56%, and hypopituitarism was reversed in 25%. Twelve patients (43%) required long-term hormone replacement therapy. Two of the three patients who were treated conservatively had prolactin-secreting adenomas, which were treated with dopamine agonist therapy. Thickening of sphenoid sinus mucosa was present in 22 patients (79%). Fifty percent of patients in Grade I and 100% of those in Grades II and III, including all those with persistent hypopituitarism and residual visual deficits, had thickened sphenoid sinus mucosa on MR imaging. Patients with thickened sphenoid sinus mucosa had larger tumors that compressed the optic chiasm or cavernous sinus, and these individuals also had a higher rate of cranial nerve deficits at presentation than those without mucosal thickening (73% compared with 0%). Patients with thickened mucosa had a higher rate of hypopituitarism and subsequent long-term hormone replacement therapy than those without thickened mucosa (55% compared with 17%). CONCLUSIONS: Thickened sphenoid sinus mucosa may correlate with higher grades of pituitary apoplexy and worse neurological and endocrinological outcomes.

Adenoma↗
PubMed2006

Decompression of cavernous sinus meningioma for preservation and improvement of cranial nerve function. Technical note.

Meningiomas are the most common tumors affecting the cavernous sinus (CS). Despite advances in microsurgery and radiosurgery, treatment of CS meningiomas remains difficult and controversial. As in cases of other meningiomas, the goal of treatment for CS meningioma is long-term growth control and preservation of neural function. Gross-total resection, the ideal treatment for meningioma, is not always possible to obtain in patients with CS meningiomas with an acceptable level of morbidity. Therefore, microsurgery and radiosurgery have recently been advocated as a combined therapy to achieve good control of tumor growth and favorable functional outcome. The authors describe a technique in which tumor volume can be reduced to a minimal residual amount, while preserving cranial nerve function. This enables the smallest field to be treated radiosurgically. The optic nerve is decompressed, and the tumor mass is reduced to provide at least a 5-mm interpositional distance between the optic nerve and the residual lesion. Direct decompression of the CS, with opening of the lateral and superior sinus walls, and piecemeal removal of the tumor in "safe" locations are performed to facilitate an improvement in cranial nerve function. The authors describe the use of this technique in a series of patients and demonstrate improvement of cranial nerve function in a subset of these patients.

Adult↗