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Biomedical subjects

R W Porter

Publications and source records attributed to R W Porter.

At least 37 records · Page 2Linked to original sources
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↗
PubMed1999

Spinal arteriovenous malformations.

Spinal cord arteriovenous malformations encompass a variety of distinct lesions with aberrant connections between the arterial and venous circulation. Symptomatology and clinical presentation of such lesions are directly related to their location and particular pathophysiology. In the authors' surgical experience, 90% of patients have had the same or improved neurologic function and long-term follow-up.

Arteriovenous Malformations↗
PubMed1998

The natural history of trunk list, its associated disability and the influence of McKenzie management.

Lumbosacral list is a clinical sign that is frequently associated with low back pain and intervertebral disc lesions. This study examines the influence of McKenzie management on the natural history of trunk list. Patients with trunk list and low back pain were randomised into two groups: a control group receiving non-specific back massage and general back care advice, and a group treated according to the McKenzie protocol. Trunk list was measured over a period of 90 days and patients completed Oswestry Disability Questionnaires. There was a significantly greater resolution of list after 90 days in the group receiving McKenzie treatment compared to the control group. There was poor correlation between list magnitude and Oswestry scores. These data support previous observations that trunk list is not necessarily related to the degree of physical disability. The McKenzie method of assessment and treatment may assist in the resolution of trunk list, but it was ineffective in improving clinical condition.

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

Achilles tendon rupture and sciatica: a possible correlation.

The association between Achilles tendon rupture and sciatica was investigated by questionnaire in 138 patients who underwent repair of an Achilles tendon rupture, and in a group of individuals nominated by the patients, matched for age, sex, and occupation. A total of 102 patients (74%) and 128 peer nominated controls (71%) replied to the questionnaire. Of the 102 respondent patients, 18 had an officebased job, 47 were involved in skilled nonmanual work, and 16 were retired. Back pain had been experienced by 63 of the patients who replied to the questionnaire, and by 91 (75%) of the individuals in the control group (difference not significant). In about 30% of both groups, the pain confined them to bed for at least two days, and resulted in absence from work. Thirteen of the patients and 16 of the controls had undergone thoracic, lumbar, or sacral radiography. One individual in each group had received surgery for back pain. However, 35 of 102 patients had experienced sciatic pain before Achilles tendon rupture. Pain of a similar nature had been experienced by only 15 individuals in the control group (12%) (p < 0.001). Using this study design, we found a highly significant association between Achilles tendon rupture and sciatica. We propose that this association could be due to impaired afferent signals from the lower leg, or to similar collagen or vascular anomalies of the vertebral disc and the Achilles tendon.

Achilles Tendon↗
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↗
PubMed1998

The Henderson Trust Lecture. The development of the vertebral canal and associated neuro-physiological abnormalities.

In this lecture I have attempted to demonstrate that the size of the lumbar vertebral canal has clinical importance. The canal develops very early in life, and impaired growth at this time affects other growing systems. The patient with spinal stenosis has more than a spinal disadvantage. Improved obstetric and childhood care has the potential not only to prevent some of the troublesome back problems, but also to influence the health and neurological status in adult life. I hope that the first Henderson Trustees would have been encouraged by this lecture. It supports some of the philosophy that stimulated an interest in Phrenology. In the lumbar spine at least, the container-the vertebral canal-seems to have an important relationship to the function of its neurological contents.

Adult↗
PubMed1997

Significant antenatal factors in the development of lumbar spinal stenosis.

STUDY DESIGN: Adverse factors during pregnancy may permanently stunt the growth of the spinal canal. Subsequently, even in an optimal environment the canal cannot catch up in growth with the trunk and long bones because of its early maturation. The degree of retardation in canal size depends on the severity and timing of the adverse effect. The catch-up growth of the long bones mask the narrow canal, because the latter does not have growth potential, resulting in an adult of sufficient height and good proportions, but with a canal at risk for stenosis. OBJECTIVES: To investigate the influence of the antenatal environment on the growth of the lumber spinal canal. SUMMARY OF BACKGROUND DATA: To date, little is known about the effects of an adverse environment on the growth of the spinal canal, and no data have been reported on antenatal influencing factors. METHODS: Lumbar magnetic resonance imaging scans from 58 patients were examined. Dimensions of the central spinal canals were measured by computerized image analysis and compared with the subjects' obstetric data from their mothers' pregnancies. RESULTS: The L3 canal was found to be the most sensitive to the influence of the examined factors. Gestational age was the most significant factor; if short, it resulted in small adult canal. Small placental weight, greater maternal age, primiparity, low socioeconomic class, and low birth weight were also found to be significant in affecting the growth of the canal. CONCLUSIONS: An adverse antenatal environment does have a permanent, retarding effect on the growth of the lumbar spinal canal.

Adolescent↗
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

An in vitro study of the biomechanical effects of flexible stabilization on the lumbar spine.

STUDY DESIGN: Lumbar motion segments were tested in vitro to examine biomechanical changes after posterior fixation by a flexible device. OBJECTIVES: To assess changes in load distribution and conformation of vertebral structures after a flexible stabilization. This should provide the foundations for a scientific understanding of the immediate effects of this surgical procedure. METHODS: Hooks were placed over the proximal spinous process and the distal laminas of a motion segment and connected by a polyester braid. Tension applied to the braid then generated a compression of the posterior elements. The force between the articular facets, the displacement of the posterior anulus fibrosus of the intervertebral disc, and the change in the relative position of the adjacent vertebrae were measured as the applied tension was increased. RESULTS: Facet joint force, disc bulge, and vertebral angulation increased with applied tension until a position of "locking" was achieved, apparently when the bony margin of the superior half of the facet joint contacted the inferior pars interarticularis. A tension of between 50 to 100 N in the braid was required for this. Facet joint force was less than 40% of this, and disc bulge was only 0.15 mm. The extension of the motion segment was between 2 degrees and 8 degrees. CONCLUSIONS: The results suggest that if such a system is applied surgically, stabilization is produced by compaction of the bony margins of the facet joints. Only a relatively small proportion of the posteriorly applied load is carried by the facet joints themselves, and little angulatory change is expected with minimal disc bulge.

Aged↗
PubMed1997

Assessment of late results of surgery in talipes equino-varus: a reliability study.

UNLABELLED: The variability of a method for clinical and functional assessment of the long-term results of surgical correction of idiopathic congenital talipes equino varus was studied in ten boys and four girls (average age: 19.1 (SD 2.3 years); 22 affected feet) with radiographical evidence of fusion of the foot and ankle ossification centres. Patients were measured twice, 1 week-1 month apart, by the same investigator and were assessed twice on each visit. Assessment included anthropometry, functional assessment and subjective functional evaluation. Calf circumference, skinfold thickness, foot length and width were highly reproducible. Foot length was not significantly influenced by the operation whereas calf circumference, skinfold thickness and foot width were. Although highly reproducible, hopping was not significantly affected by operation. Active and passive range of motion were significantly different. Each was highly reproducible and both were significantly affected by the operation. Patients reported a high and highly reproducible (within two points) functional level. CONCLUSION: An assistant-administered functional questionnaire together with measurement of active and passive range of motion allows easy, valid and reproducible assessment of long-term results of surgery for idiopathic congenital talipes equino-varus correction. A significant effect of the number and type of operation was evidenced.

Adolescent↗
PubMed1997

Concurrent aneurysm rupture and thrombosis of high grade internal carotid artery stenosis: report of two cases.

BACKGROUND: The simultaneous presentation of aneurysmal subarachnoid hemorrhage and thrombosis of a high-grade internal carotid artery stenosis is rare, and their management raises several treatment dilemmas. METHODS: Two such patients with ruptured aneurysms are presented: one with high-grade internal carotid artery stenosis that progressed to occlusion and one with acute internal carotid artery occlusion. RESULTS: Both patients were treated with craniotomy for clipping of the ruptured aneurysm followed by carotid thromboendarterectomy. CONCLUSIONS: We advocate urgent surgical treatment of both lesions, dealing with the most symptomatic lesion first. These two cases demonstrate the importance of reestablishing blood flow in patients with an acutely thrombosed carotid artery.

Aged↗
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↗