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Biomedical subjects

J M Tew

Publications and source records attributed to J M Tew.

At least 91 records · Page 5Linked to original sources
PubMed1989

Acute effect of the Nd:YAG laser on the cerebral arteriovenous malformation: a histological study.

The acute effect of Nd:YAG laser beam on cerebral arteriovenous malformations (AVMs) was examined. Histological examination of the specimens after treatment with the Nd:YAG laser revealed that the most prominent effect of the laser was shrinkage of the collagen of the vessels of the AVM, which led to laser-induced narrowing of blood vessels. The brain tissue confined to the resected AVM did not contain any histological evidence of acute damage. The resection of 10 cases of AVMs was safely accomplished with no morbidity or increased neurological deficits attributable to the laser technique.

Adolescent↗
PubMed1989

Repair of spinal dural defects with vicryl (polyglactin 910) mesh.

This study examined and compared the effectiveness of woven vicryl (polyglactin 910) mesh and lyophilized cadaver dura (Lyodura) for the repair of spinal dural defects. A woven vicryl mesh was used to repair spinal dural defects in 16 mongrel dogs. As an internal control, all animals had a separate dural incision that was closed with 9-0 vicryl suture. Animals were killed, and results were evaluated at 4, 8, 12, and 24 weeks. The repair of dural defects was achieved in all animals, and there were no cases of pseudo-meningocele formation, cerebrospinal fluid leakage, or postoperative infection. The vicryl mesh served as a latticework for formation of a neodural membrane. Inflammatory or reactive response to vicryl mesh was minimal, and no adhesion to underlying neural structures was noted. The neodural membrane formed in the animals in which lyophilized dura was employed was usually thicker than those in which vicryl mesh was used and was associated with thick arachnoid-neural adhesions in two of eight animals. We believe vicryl mesh is a suitable dural substitute and offers promise for use in clinical situations.

Animals↗
PubMed1989

The surgical anatomy and approaches to lesions of the lower basilar artery and vertebral artery union.

The neural and vascular anatomy of the posterior fossa and bony skull base is of interest to both neurosurgeons and otologists charged with the evaluation and management of patients demonstrating lesions in this region. Despite well described approaches to pathology in this area, access to the lower basilar artery and clivus remains a significant challenge. This report highlights the pertinent anatomic details of the fossa, describes the bony dimensions relevant to surgical access, and reviews two unconventional approaches to the lower basilar upper vertebral artery union.

Basilar Artery↗
PubMed1988

Cerebral arterial innervation by nerve fibers containing calcitonin gene-related peptide (CGRP): I. Distribution and origin of CGRP perivascular innervation in the rat.

The origin, density and distribution of calcitonin gene-related peptide (CGRP) immunoreactivity in cerebral perivascular nerves and the trigeminal ganglion of rats were examined in this study. CGRP immunoreactive axons were abundant on the walls of the rostral circulation of the major cerebral arteries in the circle of Willis. The fibers form a grid- or meshwork of longitudinal and circumferential axons studded with numerous varicose swellings. The density of CGRP fibers was particularly high at the bifurcation of major arteries. A few CGRP fibers cross the midline to innervate arteries on the contralateral side of the arterial tree. The arteries of the caudal circulation were sparsely innervated by CGRP fibers. In the trigeminal ganglion, about 30% of the ganglion cells had CGRP immunoreactivity. The cell size of most (75%) of CGRP neurons was less than 30 micron in diameter. There was no significant difference in staining density between small and large CGRP neurons. Unilateral transection of the maxillary and mandibular divisions of the trigeminal nerve caused a substantial decrease of CGRP immunoreactivity in the ipsilateral dorsal two-thirds of the trigeminal nucleus and cervical spinal cord but did not noticeably change the diameter of the vascular lumen or the densities of CGRP fibers in the walls of the cerebral arteries. In contrast, unilateral transection that included the ophthalmic division eliminated CGRP fibers on the ipsilateral cerebral arteries and eliminated CGRP immunoreactivity throughout the trigeminal nucleus in the brainstem and rostral cervical cord. In addition, these lesions caused a significant reduction in the diameter of the denervated arteries. The present study demonstrates that CGRP, a putative neurotransmitter/neuromodulator, is especially abundant in the rostral cerebral circulation and is derived from the ipsilateral ophthalmic division of the trigeminal nerve. In addition, the loss of CGRP perivascular nerves is associated with a reduction of the arterial lumen. This suggests that CGRP is a strong candidate as a nerve-derived trophic factor at trigeminal terminals and provides additional evidence that CGRP is a component in the trigeminovascular system influencing vascular diameter.

Animals↗
PubMed1988

Traumatic intracranial aneurysms in childhood: two cases and a review of the literature.

Traumatic intracranial aneurysms in childhood are rare. To date, 67 well-documented cases in children have been reported. We present 2 additional cases and review the literature. Traumatic aneurysms can best be categorized based on mechanism of injury and location. Aneurysms secondary to penetrating trauma occur most commonly in teenage boys suffering gunshot wounds. Aneurysms secondary to nonpenetrating trauma occur at the skull base or in the periphery, with motor vehicle accidents and falls as the most common modes of injury. Skull base traumatic aneurysms most commonly involve the petrous, cavernous, or supraclinoid carotid artery and also show a predominance in teenage boys. Peripheral traumatic aneurysms can further be divided into distal anterior cerebral artery aneurysms secondary to trauma against the falcine edge and distal cortical artery aneurysms associated with an overlying skull fracture. Peripheral traumatic aneurysms tend to occur in younger patients with a less marked male predominance. Two-thirds of the patients suffered symptomatic aneurysmal hemorrhage, with an associated mortality rate of 31%. The clinical presentation, diagnosis, and treatment of traumatic intracranial aneurysms are discussed.

Adolescent↗
PubMed1988

Morbidity and mortality of carotid endarterectomy under local anesthesia: a retrospective study.

It has been shown that carotid endarterectomy reduces the incidence of stroke in patients with symptomatic extracranial occlusive vascular disease in the absence of major perioperative complications such as stroke or death. We present a retrospective study of 106 carotid endarterectomies performed under local anesthesia in 100 patients in whom transient ischemic attack (TIA) or minor stroke had occurred. Nonfatal stroke occurred in 2%, and TIA occurred in 1%. There was no perioperative mortality. Our study suggests that, under local anesthesia, even high risk patients can be operated safely and the majority of carotid endarterectomies can be performed without the use of an indwelling shunt. Meticulous surgical technique is of great importance for achieving low perioperative complications.

Adult↗
PubMed1988

Trapping of giant basilar trunk aneurysms. Report of two cases.

Two cases of successful trapping of giant basilar trunk aneurysms are presented. The aneurysms were trapped by clipping the basilar artery distal to the anterior inferior cerebellar arteries and proximal to the superior cerebellar arteries. The outcome was excellent in both cases. In the treatment of giant basilar trunk aneurysms, trapping the involved segment of the basilar artery is an effective way to obliterate and decompress the aneurysm. Preoperative assessment of potential collateral vascular supply, operative technique, and the efficacy of intraoperative monitoring are discussed.

Adult↗
PubMed1987

Persistent hypoglossal artery associated with basilar artery aneurysm.

A saccular aneurysm at the tip of the basilar artery in a patient with a persistent hypoglossal artery is reported. The persistent hypoglossal artery was arising from the left internal carotid artery. Both vertebral and posterior communicating arteries were absent bilaterally. The combination of a persistent hypoglossal artery and a basilar bifurcation aneurysm is a very rare occurrence. The anatomy of the cerebral circulation in this unique case is important for surgical planning.

Basilar Artery↗
PubMed1987

Intraoperative evoked potential monitoring.

There has been a tremendous growth in the use of evoked potential techniques in the orthopedic and neurosurgical operating rooms. The popularity of evoked potential monitoring has evolved from the surgeon's need to know the impact of surgical manipulations on the central nervous system. It is safe and practical to monitor the electrophysiological function of the cortex, brainstem, cranial nerves, and motor and sensory pathways in the spinal cord utilizing evoked potential techniques. This paper presents a review of these techniques.

Evoked Potentials↗
PubMed1987

Management of blunt injury to the internal carotid artery.

The management of vascular injury to the internal carotid artery (ICA) is controversial. We undertook a retrospective review of 14 patients with blunt injuries to the ICA and found three types of ICA injury, often presenting with delayed symptomatology. Six patients had intraluminal arterial stenosis or obstruction and were treated with anticoagulants. Five patients had pseudoaneurysms. Three of these were treated with balloon occlusion of the ICA above and below the orifice of the aneurysm, one with aneurysmorrhaphy, and one with resection and interposition vein graft. Three patients sustained a carotid cavernous fistula and were treated by balloon occlusion of the fistula while patency of the ICA was maintained. Treatment rendered all patients either asymptomatic or with residual deficits only. Angiography is essential to anatomically delineate the injury. The vascular surgeon, the neurosurgeon, and the interventional radiologist all make important contributions to the successful treatment of patients with blunt ICA injuries.

Adult↗
PubMed1987

Management of inoperable cerebral aneurysms by the navigational balloon technique.

Intravascular navigation with nondetachable balloons is a safe, effective method of treatment for inaccessible aneurysms of the internal carotid artery. The rate of ischemic complications is lower than that associated with carotid ligation, and the rate of subsequent hemorrhage is lower than that associated with either carotid ligation or direct clipping. Therefore, for many internal carotid artery aneurysms that originate at or proximal to the ophthalmic artery, the nondetachable balloon technique is an alternative treatment choice. During a 7-year period, 21 aneurysms of the internal carotid artery were treated by the nondetachable balloon technique. All 21 aneurysms were successfully excluded from the circulatory system by either proximal occlusion or trapping of the aneurysm neck. This series consisted of 8 carotid-ophthalmic artery aneurysms, 11 carotid-cavernous aneurysms (6 spontaneous, 5 traumatic), 1 petrous segment aneurysm, and 1 cervical segment aneurysm. At 3 years of follow-up, the following incidences were noted: transient ischemia, 4.7%; infarction, 9.6%; and hemorrhage, 0%. The complications were 1 case of transient hemiparesis and 2 late ischemic events. Fifty per cent of the patients underwent follow-up computed tomography, and thrombosis of the aneurysm was confirmed in all except one case, which was partially thrombosed.

Adolescent↗
PubMed1987

The relationship between the capillary structure and hemorrhage in gliomas.

A 48-year-old man was admitted with the sudden onset of symptoms of stroke caused by hemorrhage in an oligodendroglioma. Despite surgery and antiedema treatment, the patient died. Histological evaluation revealed an oligodendroglioma with calcified capillaries of the retiform type. To further investigate this phenomenon, a total of 160 gliomas were reviewed: 90 glioblastomas multiforme, 30 oligodendrogliomas, and 40 astrocytomas. Sufficient data were available for clinical evaluation in 100 cases. Of these, 5% (two oligodendrogliomas and three glioblastomas multiforme) were related to clinically significant hemorrhages. Of the remaining cases, microhemorrhages were found in 53.0% of the glioblastomas, in 56.7% of the oligodendrogliomas, and in 10.0% of the astrocytomas. In each case reviewed, the capillaries were assigned to one of three groups: axial, retiform, or glomeruloid. Statistical analysis revealed a significant association between hemorrhages and retiform capillaries in all three types of tumors, except that in oligodendrogliomas the statistical significance held true when calcification of the capillaries was also present. Glomeruloid-type capillaries were only weakly associated with hemorrhages, and no association was found for axial capillaries. A large-scale prospective study is necessary to more precisely assess the role of each of the three types of capillaries in hemorrhages of gliomas. Based on data available so far, patients with glial tumors with retiform capillaries, confirmed on biopsy, should be carefully monitored to exclude possible intratumoral hemorrhage.

Astrocytoma↗
PubMed1987

Magnetic resonance imaging and computerized tomography scanning of herpes simplex encephalitis. Report of two cases.

The authors present two cases of herpes simplex encephalitis (HSE) in which computerized tomography (CT) scanning and magnetic resonance imaging (MRI) were performed. They also review the literature on the use of these imaging modalities in cases of HSE. The striking changes noted in these cases on T2-weighted magnetic resonance images in comparison to the CT findings suggest that MRI will help speed recognition of nonhemorrhagic HSE abnormalities.

Adult↗
PubMed1986

Successful laser-assisted excision of a metastatic midbrain tumor.

Metastatic lesions to the midbrain are rare. They are found in 1 to 3% of autopsy series of solitary brain metastases. The consensus of opinion in the current literature is that they are inoperable lesions and should be treated by radiation therapy alone. This is the first case report of a completely excised metastatic adenocarcinoma to the midbrain. The patient's clinical course has been stable, and there is no computed tomographic evidence of recurrence at 18 months follow-up.

Adenocarcinoma↗
PubMed1986

Antifibrinolytic therapy of experimentally grown malignant brain tumors.

This study was designed to evaluate the effect of an inhibitor of plasminogen activation on the growth of a human glioblastoma line grown in nude mice up to the seventh passage. The tumors produced plasminogen activators and showed histological characteristics similar to those of the original tumor. Three groups of mice were studied. Group A received 5% epsilon aminocaproic acid (EACA); Group B received 2.5% EACA; and Group C served as a control. There was no statistical difference among the three groups with regard to: 1) age at time of tumor transplantation; 2) the interval between implant and treatment; or 3) tumor volume at time of treatment. Blood measurements of EACA, performed in a limited number of animals, have shown that the drug at 5% concentration had reached toxic levels. Statistically significant differences between the three groups were noted in the following categories: 1) rate of tumor growth; 2) tumor volume at time of death, where Group A had smaller tumors than Group C; and 3) mean survival times of Groups A and B as compared to Group C. A statistically significant negative correlation was found between the rate of tumor growth and the length of survival of animals in Group C, while no correlation could be found for either Group A or B, indicating that the antifibrinolytic therapy modified this important biological variable. This study supports the hypothesis that the fibrinolytic system plays a role in the growth and development of malignant gliomas and that interference with the fibrinolytic system may retard the growth of these tumors grown in nude mice.

Aminocaproates↗