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Biomedical subjects

W C Welch

Publications and source records attributed to W C Welch.

At least 19 recordsLinked to original sources
PubMed2001

Epidermoid cyst of the thoracic spine: case history.

Epidermoid cysts of the spinal cord are very rare tumors. We report a 31 year-old female who presented with a 5 months history of progressive lower extremity weakness and spasticity. Magnetic resonance imaging of the thoracic spine revealed a 2 cm intradural, extramedullary mass at the T4-5 level. A T4 and T5 osteoplastic laminotomy with complete removal of the intradural mass was performed. Intraoperative and final histological examination revealed an epidermoid cyst. Epidermoid cysts must be a consideration for intradural, extramedullary lesions of the spinal cord. Complete surgical resection offers the patient an opportunity for good neurologic outcome.

Adult↗
PubMed2001

Monoclonal antibodies to vascular endothelial growth factor (VEGF) and the VEGF receptor, FLT-1, inhibit the growth of C6 glioma in a mouse xenograft.

Monoclonal antibodies raised to peptide sequences of vascular endothelial growth factor (VEGF) and the VEGF receptor, FLT-1, inhibited the growth of C6 tumors growing subcutaneously in nude mice. Immunohistochemical analysis demonstrated antibody targeting of blood vessels, tumor cells, and macrophages. A control antibody demonstrated no growth inhibition or tumor uptake. An antibody to FLT- I impaired microvascular maturation and diminished the accumulation of tumor infiltrating macrophages. The antibodies demonstrated affinity for microvasculature and tumor cells in immunohistochemistry of human glioblastoma multiforme. Targeting VEGF and its receptors has potential in the treatment of tumors of the central nervous system. FLT-1 presents an attractive target due to its presence on multiple cell types.

Animals↗
PubMed2001

Smiling odontoid.

Explore the source record for details and available documents.

Accidents, Traffic↗
PubMed2000

Intraoperative SSEP detection of ulnar nerve compression or ischemia in an obese patient: a unique complication associated with a specialized spinal retraction system.

OBJECTIVE: To report a case of peripheral nerve compression caused by a specialized spinal retraction system, the Thompson-Farley retractor system, that most likely would not have been detected without intraoperative monitoring of the ulnar nerve. DESIGN: Bilateral median and peroneal nerve somatosensory evoked potentials (SSEPs) were monitored continuously during a C5 corpectomy, as was core body temperature. RESULTS: Within minutes after cervical soft-tissue retraction, the left ulnar nerve SSEP began to decline in amplitude. Peroneal nerve SSEPs were normal throughout the surgery; core body temperature remained at 36 degrees +/- 0.2 degrees C. After much effort to reposition the patient, the SSEPs returned to baseline and the Thompson-Farley system was replaced by a self-retracting system. CONCLUSIONS: To our knowledge, this is the first report of peripheral nerve compression caused by the Thompson-Farley retractor system. Even with careful positioning on the operating table, obese patients may be particularly at risk for upper arm compression. Continuous monitoring of SSEPs is suggested to prevent postoperative morbidity.

Diskectomy↗
PubMed2000

Microinvasive transaxillary thoracoscopic sympathectomy: technical note.

OBJECTIVE: To describe a two-port transaxillary thoracoscopic approach for thoracic sympathectomy that maximizes working space, improves manipulative ability, and enhances visualization of the surgical field. METHODS: Positioning of the patients was optimized to displace the scapula posteriorly, widen the avenue of approach to the sympathetic ganglia, and create a more direct route to the target. The semi-Fowler position permitted the lung apex to fall away from mediastinal structures, obviating a separate retraction port. A 30-degree endoscope allowed an unobstructed view of surgical progress, and anatomic relationships were manipulated in a temporal sequence to facilitate dissection. RESULTS: Microinvasive transaxillary sympathectomy was performed successfully in 13 patients, all of whom had a good outcome without complications. CONCLUSION: The modifications implemented increase the speed and safety of thoracoscopic sympathectomy while minimizing complications.

Axilla↗
PubMed2000

Current surgical management of metastatic spinal disease.

Despite advances in the treatment of many malignancies, a large number of cancer patients will require evaluation and possible surgical intervention for lesions that have metastasized or directly invaded the spinal column. The need for heightened awareness of and aggressive early intervention for spinal metastases is underscored by many studies that have reported a relationship between pretreatment and posttreatment neurologic function in these patients. Recommendations for operative intervention should be made following an evaluation of the patient by multiple specialties, both medical and surgical. In the last decade, advances in surgical techniques for tumor decompression and spine stabilization, neurophysiologic monitoring, and anesthetic expertise have allowed surgeons to perform more extensive procedures with improved outcomes and reduced morbidity. This article will review the factors favoring an operative recommendation in patients with metastatic spinal disease, preoperative evaluation, and available surgical options. Patients with symptomatic spinal metastases should receive early surgical consultation as part of a multidisciplinary approach to their disease process.

Humans↗
PubMed1999

Thyroid carcinoma with isolated spinal metastasis: case history and review of the literature.

An unusual case of metastatic follicular thyroid cancer presenting with symptoms of a radiculopathy at C6 is presented. The patient underwent a laminectomy and removal of tumor with resolution of his symptoms. He was found to have a well differentiated follicular thyroid carcinoma and subsequently had total thyroidectomy and 131I treatment. This patient's presentation raised questions about appropriate preoperative evaluation in this clinical scenario. This case highlights the importance of a thorough pre-operative work up for metastatic spine tumors. This should include evaluation of the thyroid consisting of thorough clinical history with particular attention to prior radiation exposure. Palpation of the thyroid also should be included as part of a routine pre-operative physical in cases of metastatic lesions of unknown origin. Thyroid function studies should not be utilized unless a clinical suspicion for thyroid cancer is raised during the examination.

Adenocarcinoma, Follicular↗
PubMed1999

Differential expressions of CD44 variants in tumors affecting the central nervous system.

BACKGROUND: The polymorphic cell adhesion molecule CD44 exists as a family of proteins generated by extensive alternative splicing of the CD44 pre-messenger RNA and marked posttranslational modification. The differential expression of CD44 isoforms in a variety of human cancers has been proposed to influence tumorigenesis and metastasis. In this study, CD44 gene expression was analyzed in primary and metastatic tumors and in cell lines derived from tumors that affect the central nervous system (CNS), including tumors metastatic to the spine. MATERIALS AND METHODS: Fifty-four samples were subjected to semiquantitative reverse-transcriptase polymerase chain reaction with CD44-specific primers and hybridized individually with probes specific for the CD44 variant (CD44v) exons v3 to v10. RESULTS: Compared with CD44v-positive breast cancer cell lines and CD44v-negative normal brain tissue, CD44v expression was weak in primary brain tumors and cell lines derived from normal brain and tumor tissue. However, high levels of isoforms encoding multiple-variant exons were shown in all metastatic brain tumors. In contrast, tumors metastatic to the spine were virtually negative for CD44v expression. Several rare CD44 isoforms composed of single-variant exons v3, v4, v6, or v9 were identified in primary brain tumors and may reflect their invasive potential or culturability in vitro. CONCLUSION: These data suggest differential expression of CD44v may substantially influence the end-organ site of metastasis for tumor cells destined for the CNS.

Antigens, Neoplasm↗
PubMed1999

Cervical intrathecal catheter placement for cerebrospinal fluid drainage: technical case report.

OBJECTIVE AND IMPORTANCE: The purpose of this report is to describe the placement and use of a cervical subarachnoid catheter for cerebrospinal fluid diversion. This technique provides an important alternative drainage system for patients whose clinical situations preclude lumbar spinal fluid diversion. CLINICAL PRESENTATION: Two patients were involved in accidents that resulted in traumatic dural tears. Both patients required thoracolumbar spinal reconstruction with instrumentation. Cerebrospinal fistulae developed, which were refractory to surgical reexploration. TECHNIQUE: A commercially available catheter was successfully placed in the cervical subarachnoid space under fluoroscopic guidance using a C1-C2 approach in both patients. Spinal fluid drainage was maintained for 5 days via this route, and this proved effective in resolving the cerebrospinal fluid fistula. No complications were observed with the placement or maintenance of the catheter. CONCLUSION: Cervical spinal fluid drainage is a feasible alternative for patients in whom lumbar access cannot be obtained or is contraindicated.

Adult↗
PubMed1998

Posterior epidural migration of an extruded lumbar disc fragment causing cauda equina syndrome. Clinical and magnetic resonance imaging evaluation.

STUDY DESIGN: Retrospective case report. OBJECTIVES: To illustrate the rare occurrence of cauda equina syndrome resulting from posterior epidural disc fragment migration documented by magnetic resonance imaging. SUMMARY OF BACKGROUND DATA: Disc fragment migration patterns are generally limited by the attachments of the posterior longitudinal ligament and its associated "midline septum" and "peridural" or "lateral membrane." The majority of symptomatic lumbar disc herniations are noted to be in a lateral position with resultant nerve root irritation. Although caudal, rostral, and lateral migration of disc fragments are common, posterior epidural migration of an extruded disc fragment has been reported only rarely, and only once in association with cauda equina syndrome. METHODS: The patient described in this report presented with an acute cauda equina syndrome. Investigation with magnetic resonance imaging revealed a posterior epidural mass, which was hypointense on T1-weighted and T2-weighted images. Postgadolinium imaging showed rim enhancement of the lesion. The preoperative differential diagnosis included epidural abscess, hematoma, or neoplasm. An urgent decompressive lumbar laminectomy was performed. At surgery, the lesion proved to be a massive extruded disc fragment. RESULTS: At the 1-year follow-up examination, the patient had recovered full motor, sensory, urologic, and sexual function. CONCLUSIONS: Extruded disc fragments may migrate posterior to the thecal sac. Magnetic resonance images of a posterior disc fragment may mimic those of other more common posterior epidural lesions.

Cauda Equina↗
PubMed1998

Lumbar spinal stenosis: a review of current concepts in evaluation, management, and outcome measurements.

The purpose of this review is to present current information from the literature regarding the pathoanatomy, clinical presentation, differential diagnosis, treatment, and outcome assessment methods for patients with lumbar spinal stenosis. Lumbar spinal stenosis is a frequently encountered condition, particularly in the elderly. Treatment requires an accurate diagnosis, but differential diagnosis of lumbar stenosis can be difficult. The literature to date has focused primarily on surgical treatment. The long-term efficacy of surgery has been questioned, and surgical procedures are associated with increased costs and risks of morbidity in an elderly population. A trial of conservative care is recommended in most cases, but there are presently no randomized controlled studies in the literature comparing surgical versus conservative management, or evaluating the effectiveness of any specific conservative treatment approach. The existing literature has further been criticized for having poorly defined outcome measures. The assessment of treatment outcomes should be multifactorial, including measures of pathoanatomy and impairments, as well as patient-centered measures such as level of disability, patient expectations, and satisfaction. The present level of understanding of lumbar spinal stenosis is deficient in many areas, including differential diagnosis, treatment, and outcome assessment. Future research should address these deficits to improve the management of patients with this condition.

Arthrodesis↗
PubMed1998

Correlation of late intraforaminal screw removal with somatosensory evoked potentials and neurologic improvement.

This case report describes the intraoperative improvement of somatosensory evoked potentials (SEPs) during the removal of a broached pedicle screw that had been placed in an unmonitored procedure 1 month earlier. Postoperatively, there was improved neurologic function and reversal of the neurologic deficit that had been caused by the first procedure. To our knowledge, this is the first report of a correlation of intraoperative SEP improvement with improved postoperative neurologic function after neurologic deficit because of nerve irritation or compression from a pedicle screw. Nerve damage occurs in about 15% of patients who undergo instrumentation after lumbar fusion. The potential utility of neurophysiologic methods during initial screw placement is suggested and supported, as proper use of such intraoperative tools may have prevented the need for the second procedure.

Adult↗
PubMed1998

Simultaneous somatosensory evoked potential and electromyographic recordings during lumbosacral decompression and instrumentation.

OBJECTIVE: Both motor and sensory neurological deficits have been reported after decompression and instrumentation of the lumbosacral spine. In this report, we describe a simple and effective method by which sensory and motor functions can be monitored simultaneously, using somatosensory evoked potentials (SSEP), spontaneous electromyographic (EMG) activity, and compound muscle action potential monitoring. The concomitant use of these monitoring techniques allows ongoing functional evaluation of the cauda equina and spinal cord during patient positioning, surgery, wound closure, and anesthetic emergence. METHODS: SSEPs were recorded continuously in response to peroneal or tibial nerve stimulation. EMG activity (both spontaneous and evoked) was recorded bilaterally from appropriate lower extremity muscle groups. All recordings (SSEP and EMG activity recordings) were obtained, stored, and reviewed simultaneously. RESULTS: SSEPs and EMG activity were simultaneously recorded for 44 patients. All patients in the study underwent surgical procedures to decompress and stabilize the lumbosacral spine, using pedicle screw instrumentation. In two cases, changes in SSEPs and spontaneous EMG activity were noted and were correlated with postoperative patient complaints. CONCLUSION: This report describes the concomitant use of powerful and simple tools that provide immediate, "early-warning" feedback to the surgical team concerning the sensory and motor functioning of the spinal cord and cauda equina. In addition, compound muscle action potential recording provides a tool for the identification of both levels and structures in the lumbosacral spine.

Action Potentials↗
PubMed1998

High incidence of occult neurogenic bladder dysfunction in neurologically intact patients with thoracolumbar spinal injuries.

PURPOSE: We determine the relationship between lower urinary tract function and somatic neurological status after thoracolumbar fracture. MATERIALS AND METHODS: Within 72 hours of thoracolumbar vertebral fracture we evaluated 44 consecutive patients, including 30 men and 14 women 17 to 84 years old (mean age 38.7), with occult neurogenic bladder dysfunction following incomplete thoracolumbar spinal injuries (American Spinal Injury Association impairment classifications C to E). The neurological level and degree of injury were established, and testing for perianal pinprick sensation and bulbocavernosus reflex was done. Video urodynamic evaluation was then performed between 3 and 14 days after injury but before spinal surgery. RESULTS: Urodynamics revealed neurogenic lower urinary tract dysfunction in all 10 patients with classification C, 82% with D and 41% with E (otherwise completely intact neurologically) impairment. Although pinprick sensation deficiency and decreased bulbocavernosus reflex correlated with injury classification, lower urinary tract dysfunction was present in 62% of the patients with intact pinprick sensation and in 59% with intact bulbocavernosus reflex. CONCLUSIONS: Neurologically intact patients with thoracolumbar spinal injuries may have neurogenic lower urinary tract dysfunction on urodynamics. Pinprick sensation and bulbocavernosus reflex are specific but not sensitive indicators of lower urinary tract dysfunction after spinal cord injury. Although these indicators, which demonstrate somatic nerve function, were absent in all patients with detrusor areflexia, intact pinprick sensation and bulbocavernosus reflex are not sensitive for predicting lower urinary tract function, which depends on autonomic nerve function. Urodynamic evaluation is mandatory for the complete evaluation of patients with incomplete lumbosacral spinal injuries.

Adolescent↗
PubMed1997

Persistently electrified pedicle stimulation instruments in spinal instrumentation. Technique and protocol development.

STUDY DESIGN: A prospective review was done of a new intraoperative technique developed to detect and prevent neurologic compromise during pedicle screw insertion. OBJECTIVES: To describe in sufficient detail the technique of persistently electrified pedicle stimulation instruments, so that this technique will be available generally to all clinical neurophysiologists and spine surgeons; and to demonstrate the use, typical results, interpretation, and protocol of the technique. SUMMARY AND BACKGROUND DATA: Fusion techniques that use pedicle instrumentation have the potential to cause nerve root injury. Several authors have proposed imaging and neurophysiologic methods to improve outcome. The present method represents a significant theoretical departure and advance from previously reported methods. METHODS: All relevant instruments used during pedicle instrumentation were converted easily, inexpensively, and quickly into monopolar stimulators with appropriate stimulus voltages to identify broaches of pedicle bone via evoked-electromyograms from relevant muscle groups. RESULTS: The persistently electrified pedicle stimulation instrument technique provided accurate intraoperative neurophysiologic information concerning pedicle, integrity in the patients studied. The protocol is standardized and adaptable easily, inexpensively, and quickly to most clinical applications. CONCLUSIONS: The persistently electrified pedicle stimulation instrument technique described here is useful for monitoring instrumented lumbar fusion procedures. The use of this protocol may help confirm intraosseous placement of pedicle screws and prevent neurologic injury.

Bone Screws↗