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Biomedical subjects

P W Detwiler

Publications and source records attributed to P W Detwiler.

At least 19 recordsLinked to original sources
PubMed2000

Surgical treatment of lumbar spondylolisthesis.

This article provides an overview of studies that address the medical and surgical treatment of lumbar spondylolisthesis, both degenerative and isthmic. Although the efficacy of decompression for symptomatic lumbar stenosis recalcitrant to conservative treatment has been demonstrated, the addition of instrumentation to a fusion procedure remains controversial. The senior author's (VKHS) experience with pedicle screw fixation and fusion for lumbar spondylolisthesis, the addition of interbody fusion, and spinal navigation is reviewed.

Humans↗
PubMed1999

Lumbosacral junction fixation and fusion after complete L-5 spondylectomy. Case report.

The goals of surgery for metastatic disease of the lumbosacral spine are to relieve compression of the thecal sac and nerve roots, to resect malignant tissue, and to create a stable reconstruction of the spine. Reconstruction of the lumbosacral junction, specifically the L-5 vertebral body, is particularly challenging because the biomechanical properties of this level differ from other areas of the spine. A 40-year-old woman with intraductal breast carcinoma that metastasized to the L-5 vertebral body presented with progressive low-back pain, right-sided L-5 radiculopathy, and weakness. Magnetic resonance imaging revealed a pathological fracture of the L-5 vertebral body with compression of the cauda equina. The L-5 posterior arch, both facet joints and pedicles, and the posterior third of the vertebral body were removed via a posterior approach. A pedicle screw fixation system was applied from L-4 to S-1. The patient was repositioned, and a transabdominal approach was used to resect the anterior two thirds of the L-5 body, which was reconstructed using an allograft bone strut. An interference bone screw was placed through the inferior aspect of the allograft and screwed into the body of S-1 to provide stability for the reconstructive graft. The patient's clinical recovery was excellent. She was ambulating without difficulty when seen at 19-month follow-up examination. Complete spondylectomy by using this novel fusion technique was efficacious in the treatment of metastatic disease to the vertebral column.

Journal Article↗
PubMed1999

Long-term survival of a patient with invasive cranial base rhinocerebral mucormycosis treated with combined endovascular, surgical, and medical therapies: case report.

OBJECTIVE: Rhinocerebral mucormycosis is a clinical syndrome resulting from an opportunistic infection caused by a fungus of the order Mucorales. The prognosis of rhinocerebral mucormycosis, once considered uniformly fatal, remains poor. Even with early diagnosis and aggressive surgical and medical therapy, the mortality rate is high. We present a patient with rhinocerebral mucormycosis involving the paranasal sinuses and cranial base who experienced long-term survival after multimodality treatment. Clinical characteristics of the disease are discussed, and the literature is reviewed. CLINICAL PRESENTATION: A 24-year-old diabetic man presented with invasive rhinocerebral mucormycosis involving the paranasal sinuses, right middle fossa, and right cavernous sinus. INTERVENTION: The patient underwent endovascular sacrifice of the involved carotid artery and radical resection of the cranial base, including exenteration of the cavernous sinus. Reconstruction with a local muscle flap was performed. He continued to receive intravenous and intrathecal administration of antibiotics. CONCLUSION: Long-term survival with invasive rhinocerebral mucormycosis is rare, but possible, with aggressive multimodality treatment, including carotid sacrifice for en bloc resection of the pathology, when indicated.

Adult↗
PubMed1999

Cavernous malformations of the brainstem: experience with 100 patients.

OBJECT: In this study the authors review surgical experience with cavernous malformations of the brainstem (CMBs) in an attempt to define more clearly the natural history, indications, and risks of surgical management of these lesions. METHODS: The authors retrospectively reviewed the cases of 100 patients (38 males and 62 females; mean age 37 years) harboring 103 lesions at treated a single institution between 1984 and 1997. Clinical histories, radiographs, pathology records, and operative reports were evaluated. The brainstem lesions were distributed as follows: pons in 39 patients, medulla in 16, midbrain in 16, pontomesencephalic junction in 15, pontomedullary junction in 10, midbrain-hypothalamus/thalamus region in two patients, and more than two brainstem levels in five. The retrospective annual hemorrhage rate was most conservatively estimated at 5% per lesion per year. Standard skull base approaches were used to resect lesions in 86 of the 100 patients. Intraoperatively, all 86 patients were found to have a venous anomaly in association with the CMB. Follow up was available in 98% (84 of 86) of the surgical patients. Of these, 73 (87%) were the same or better after surgical intervention, eight (10%) were worse, and three (4%) died. Two surgical patients were lost to follow-up review. Incidences of permanent or severe morbidity occurred in 10 (12%) of the surgically treated patients. The average postoperative Glasgow Outcome Scale score for surgically treated patients was 4.5, with a mean follow-up period of 35 months. CONCLUSIONS: The natural history of CMBs is worse than that of cavernous malformations in other locations. These CMBs can be resected using skull base approaches, which should be considered in patients with symptomatic hemorrhage who harbor lesions that approach the pial surface. Venous anomalies are always associated with CMBs and must be preserved.

Adolescent↗
PubMed1999

Sporadic unifocal infantile myofibromatosis involving the skull. Case report.

Infantile myofibromatosis involving the skull is a benign disease if there is a solitary lesion. However, the multifocal form with skull involvement may portend a lethal course in the 1st year of life if there is involvement of the heart, lungs, or gastrointestinal tract. The authors report the case of a 3-year-old boy with an enlarging left parietal skull lesion that had been present since infancy. Increasing pain and the need to obtain tissue for diagnosis led to resection of the lesion by means of a small craniectomy. Further evaluation revealed no other lesions. A distinctly rare disease is presented, and the need for staging in children younger than 2 years of age is suggested to rule out cardiac, pulmonary, or gastrointestinal involvement.

Child, Preschool↗
PubMed1999

Subdural hematoma from a Type I spinal arteriovenous malformation. Case report.

The authors report a patient in whom a subdural hematoma developed from a Type I spinal arteriovenous malformation (AVM). The patient became symptomatic with back pain, and magnetic resonance imaging revealed a spinal subdural hematoma. Selective spinal angiography, however, failed to demonstrate a pathological process. The patient underwent exploratory laminoplasty that revealed a subdural extraarachnoid hematoma with an underlying Type I spinal AVM, which was surgically obliterated. The patient recovered completely. Subdural hematomas that affect the spine are rare. Although a negative result was obtained using selective spinal angiography, exploratory surgery should be considered for the evacuation of a subdural hematoma and possibly for the definitive treatment of a spinal AVM.

Adult↗
PubMed1998

Medulloblastoma presenting with tentorial "dural-tail" sign: is the "dural-tail" sign specific for meningioma?

To the best of our knowledge, the association of a medulloblastoma with a "dural-tail" sign has not been previously reported. A 24-year-old male developed severe headaches and right-sided dysmetria that worsened over 1 month. Magnetic resonance (MR) imaging of the brain demonstrated a heterogeneously enhancing lesion in the posterior fossa. The lesion appeared to be tentortally-based and exhibited a characteristic "dural-tail" sign, which is considered pathognothonic for meningioma. Cerebellar tonsil ectopia and hydrocephalus were also present. The presumptive diagnosis of tentorial meningioma was made. The lesion was resected by a posterior fossa approach. At surgery, the appearance of the tumor was inconsistent with the diagnosis of meningioma, and histopathologic evaluation yielded the diagnosis of medulloblastonia. This case and the literature demonstrate that malignant tumors can present with the characteristic MR imaging appearance of a meningioma. This possibility must be considered when treatment is planned, especially if a nonoperative course is favored.

Case Reports↗
PubMed1998

Vascular decompression of a vertebral artery loop producing cervical radiculopathy. Case report.

Vertebral artery tortuosity and loop formation are rare causes of cervical radiculopathy. The authors present the case of a 70-year-old man with 9 years of progressive right-sided cervical and scapular pain but no history of trauma. Computerized tomography myelography and magnetic resonance imaging revealed an ovoid mass in the right C3-4 intervertebral foramen. The patient underwent a right C-3 and C-4 hemilaminectomy and a complete C3-4 facetectomy. A pulsatile vascular structure was found compressing the right C-4 nerve root. The bone overlying the vascular structure was removed, producing decompression of the nerve root. Immediate postoperative angiography showed that this lesion was a focal vertebral artery loop. The patient's symptoms resolved after surgery, supporting the use of vascular decompression of a cervical nerve root compressed by a vertebral artery loop for the relief of radicular symptoms.

Aged↗
PubMed1997

Lumbar stenosis: indications for fusion with and without instrumentation.

Although the efficacy of posterior decompression for symptomatic lumbar stenosis that is recalcitrant to conservative therapy is well proven, uniform agreement on the need for simultaneous arthrodesis is lacking. The variability in the rate of lumbar fusion with and without instrumentation has been attributed to a number of factors: advances in surgical technique; rapid development of instrumentation; radiographic advances in the diagnosis of disease entities of the lumbar spine; evolution in our understanding of bone healing; improved pre- and postoperative care; aggressive rehabilitation; patient compensation; hospital and surgeon reimbursement; better education of residents, fellows, and practicing neurosurgeons; and, most important, the lack of clear indications based on defined diagnostic categories. Based on review of the literature and their experience at the Barrow Neurological Institute, the authors have attempted to define indications for lumbar fusion with or without instrumentation based on defined diagnostic categories. Clear indications for fusion include trauma, tumor, or infection with two- or three-column injury, iatrogenic instability, and isthmic spondylolisthesis. Relative indications for fusion include degenerative spondylolisthesis, radiographically proven dynamic instability with pain or neurological findings, adult scoliosis, and mechanical back pain. Fusion is rarely indicated with discectomy, abnormal radiographs without appropriate findings (such as degenerative disc disease), facet joint syndrome, failed back surgery, or stable spinal stenosis.

Journal Article↗
PubMed1997

De novo formation of a central nervous system cavernous malformation: implications for predicting risk of hemorrhage. Case report and review of the literature.

The authors present a documented sporadic de novo cavernous malformation of the central nervous system (CNS) in a patient undergoing follow-up magnetic resonance imaging after resection of an acoustic neuroma. The authors believe that this is the first report of a de novo cavernous malformation in a patient without a familial history of this disease or a history of treatment with cranial radiation. The occurrence of de novo lesions invalidates the common assumption that cavernous malformations are congenital lesions. The use of this assumption to calculate bleeding risks retrospectively in patients with cavernous malformations is likely to underestimate the risk of symptomatic hemorrhage significantly. Consequently, the de novo formation of cavernous malformations may be more common than appreciated and may explain the higher bleeding rates reported in prospective compared with retrospective studies of these lesions.

Adult↗
PubMed1994

Effects of perfusion-induced edema on diastolic stress-strain relations in intact swine papillary muscle.

The mechanism through which edema reduces left ventricular compliance has not been defined. Accordingly, diastolic properties of in situ left ventricular swine papillary muscles were studied in three groups: control (n = 6, 4 degrees to 6 degrees C), edematous (150 mOsm/L coronary perfusion, n = 6, 4 degrees to 6 degrees C), and ischemic contracture (n = 8, 28 degrees C). Lagrangian stress (sigma) and strain (epsilon) were calculated from slow stretch data and approximated by sigma = alpha(e beta epsilon-1). The natural logarithm of stress versus strain was linear over the physiologic range of 0.05 < strain < 0.40. Hypotonic perfusions (1 L x 3) progressively shifted the stress-strain relationship upward and to the left. Compared to baseline, alpha increased significantly (p < 0.05) after perfusion 3 (6.7 +/- 2.1 baseline, 12.2 +/- 6.6 perfusion 1, 12.7 +/- 3.5 perfusion 2, and 42.9 +/- 16.3 gm/cm2 perfusion 3). The constant beta did not change significantly (13.0 +/- 1.5 baseline, 13.1 +/- 1.6 perfusion 1, 13.2 +/- 1.6 perfusion 2, and 14.1 +/- 1.4 perfusion 3). Right ventricular water content increased after each perfusion (77.1% +/- 1.4% baseline, 81.6% +/- 1.3%, 84.7% +/- 1.5%, and 86.9% +/- 1.7%, p < 0.05). With ischemic contracture, alpha increased from 61.9 +/- 17.8 to 173.1 +/- 61.5 gm/cm2 (p > 0.05) and beta increased insignificantly from 6.5 +/- 0.6 to 10.6 +/- 1.8 (p = NS). In the control group all variables were unchanged after 210 minutes. We conclude that myocardial stiffness increases with myocardial edema. This may explain decreased compliance in the edematous left ventricle.

Animals↗
PubMed1993

Quantitative effects of myocardial edema on the left ventricular pressure-volume relation. Influence of cardioplegia osmolarity over two hours of ischemic arrest.

We previously studied edema and left ventricular pressure-volume relations in a porcine heart model in which edema occurred even with hyperosmolar crystalloid cardioplegia. This susceptibility to edema was attributed to venous occlusion and an initial 20-minute period of ischemia. Results did not demonstrate reversal of edema by hyperosmolar perfusates. Accordingly, in the present study, heart weight, myocardial water content, and left ventricular pressure-volume curves were measured before and after perfusion-induced edema in eight isolated, arrested, hypothermic porcine hearts. Cardioplegic solution was infused 2.1 +/- 0.8 minutes after the onset of ischemia, and the atrioventricular ring was not clamped during the administration of cardioplegic solution. Cardioplegic solution (1 L) was infused at intervals of 33 +/- 6 minutes at 4 degrees C. Solution osmolarity was 380 (Stanford solution) or 294 mOsm/L (Plegisol solution). The perfusion sequence was 380-1, 380-2, 294-1, 380-3. Pressure-volume relations were assessed with the use of left ventricular volume at a pressure of 10 mm Hg and the ventricular chamber stiffness constant, beta, derived from P = alpha e beta V. Perfusions 380-1 and 380-2 did not affect the pressure-volume curve. Perfusion 294-1 increased heart weight and water content (p < 0.05) and decreased left ventricular volume at 10 mm Hg compared with perfusions 380-1, 380-2, and 380-3. In addition, beta increased (0.023 +/- 0.005 versus 0.029 +/- 0.006, p < 0.05) after perfusion 294-1, compared with 380-1. Correlation coefficients for linear regressions between left ventricular volume at 10 mm Hg and heart weight and water content were r = 0.84 and r = 0.70, respectively. We conclude that under conditions similar to those used clinically, the left ventricle of the pig does not develop edema with Stanford solution (380 mOsm/L). Edema does follow Plegisol solution (294 mOsm/L) cardioplegia. Edema and reduced compliance are incompletely reversed by hypertonic cardioplegia. The porcine left ventricle can usefully replicate the clinical model.

Animals↗
PubMed1992

Transoral-transclival clipping of a giant lower basilar artery aneurysm.

The authors discuss the choice of the transoral-transclival approach for the repair of a lower basilar artery aneurysm in a 32-year-old sickle-cell patient. Efficiency of approach and minimization of damage to vital structures support the use of this technique. The risks of cerebrospinal fluid fistula and meningitis are considered. One year after operation, the patient is neurologically intact.

Adult↗