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Robert M. Crowell

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Robert M. Crowell and Yngve Olsson

✓ Impairment of microvascular filling was demonstrated in relation to focal cerebral ischemia in the monkey. Temporary or sustained middle cerebral artery (MCA) clipping was achieved with a microsurgical technique. Animals were sacrificed by perfusion with a carbon black suspension. Brains were fixed in formalin, and the extent of microvascular carbon filling was estimated grossly and microscopically. In most animals, MCA occlusion of 2 hours to 7 days produced diminished filling in small vessels in the MCA territory of supply. The impairment of filling was most pronounced in the deep subcortical structures but also affected the cortex in some animals. Temporary and sustained occlusion of equal duration produced roughly equivalent areas of abnormal filling. The impairment of vascular filling tended to be more extensive with increasing duration of occlusion. Hypotension during MCA occlusion caused almost total non-filling of the microvasculature in the entire MCA territory. Impaired filling of vascular channels may play a role in the pathogenesis of some clinical cerebrovascular diseases.

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Robert M. Crowell and Yngve Olsson

✓ Anastomosis of the superficial temporal artery (STA) to a middle cerebral artery (MCA) branch was completed about 2 hours after occlusion of the MCA root in 20 dogs. Occlusion of the MCA root without bypass grafting was performed in 11 control animals. All dogs were evaluated clinically. Two days to 3 months (usually 2 weeks) after surgery, STA catheter angiograms were made and the animals sacrificed by perfusion fixation. The brains were evaluated pathologically. Animals with patent or occluded STA-MCA bypass grafts fared better both clinically and pathologically than the controls. Hemorrhagic infarction and blood-brain barrier damage were common in untreated dogs and uncommon in treated animals. STA-MCA bypass grafts rarely led to occlusion of intrinsic collateral blood supply to the brain. The data suggest that prompt STA-MCA branch anastomosis might lead to restoration of neurological function and parenchymal structural integrity in certain patients with acute middle cerebral artery occlusion.

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Wesley Y. Yapor and Robert M. Crowell

✓ Two cases of saccular intracranial aneurysms arising from the superior hypophyseal artery take-off from the internal carotid artery are presented. The angiographic findings and technical details of the operative approach are discussed. Particular attention is focused on the use of fenestrated angled clips.

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Robert M. Crowell and James G. Wepsic

✓ Two teen-age male cousins with hereditary multiple exostoses developed cord compression secondary to chondrosarcoma. The clinical presentation, diagnostic work-up, surgical treatment, pathological findings, and postoperative course are described in each patient.

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Robert M. Crowell, Umberto DeGirolami and William H. Sweet

✓ The coincidence of arteriovenous malformation (AVM) and primary brain neoplasm is rare. We are reporting a case of oligodendroglioma within an arteriovenous malformation.

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James L. Stone, Terry Lichtor and Robert M. Crowell

✓ A patient with trigeminal neuralgia caused by a tortuous and ectatic vertebrobasilar artery is presented. He was treated with microvascular decompression using a fine silicone sling sutured to the dura over the petrous pyramid. The technical details are described.

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Andrea L. Halliday, Christopher S. Ogilvy and Robert M. Crowell

✓ True intracranial arteriovenous fistulas are rare. The authors report a case of a direct fistula between the intracranial portion of the vertebral artery and the lateral medullary venous system. The patient initially presented with a subarachnoid hemorrhage. An open surgical approach with clip obliteration of the lesion was used. The anatomy of this lesion and its surgical management are described.

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Thomas W. Smith, Umberto DeGirolami and Robert M. Crowell

✓ The long-term toxic effects of ethyl 2-cyanoacrylate adhesive were evaluated histologically in 25 cats. Fresh medical- or commercial-grade adhesive was introduced transorbitally into the subarachnoid space in the vicinity of the right middle cerebral artery. Three sham-operated animals served as controls. The animals were sacrificed at intervals ranging from 2 days to 6 months. For both medical- and commercial-grade adhesive, neuropathological examination disclosed acute and chronic granulomatous inflammation of the meninges and evidence of severe vascular damage, including vessel wall necrosis, inflammation, thrombosis, and occasionally hemorrhage. Most animals showed cerebral infarcts of variable size in the territories of distribution of the basal arteries which were in contact with adhesive. The results of this study show that ethyl 2-cyanoacrylate is capable of producing severe arterial and parenchymal damage. The risk of its deleterious effects should be weighed against its potential benefits. Clinical experience would suggest that ethyl 2-cyanoacrylate can be used in difficult situations as long as care is taken to protect the brain and local blood vessels.