Biomedical subjects
Publications and source records attributed to A L Day.
Primary subarachnoid hemorrhage represents 10 percent of strokes. Aneurysm is the most common cause, accounting for 28,000 cases of hemorrhage annually in North America. Headache is the most prominent feature and heralds the moment of rupture.
Somatosensory or brain stem auditory evoked potentials (EPs) were monitored during 50 aneurysm procedures. Base line EPs were obtained shortly after the induction of general anesthesia and were recorded continuously during operation. Absolute latency, interpeak latency, and cortical EP amplitude were subsequently determined. Statistical analysis confirmed that significant changes in these parameters are routine during aneurysm operation. Arbitrary definitions of abnormal latency and amplitude changes led to an excessive false-positive/false-negative rate. From the time of dural opening to the time of closure, prolongation of central conduction time, decrease in cortical amplitude, or disappearance of the EP was predictive of postoperative sensory or motor deficit in all patients monitored, except those undergoing operation on basilar artery aneurysms. In basilar aneurysm cases, outcome could not be reliably predicted with either EP technique.
A rare case of malignant fibrous histiocytoma of the cervical carotid artery is presented. Erosion of the vessel wall by this neoplasm resulted in dissection and pseudoaneurysm formation. The etiology and diagnosis of and the therapeutic alternatives for this unique disorder are discussed briefly.
The authors describe the use of a new contact argon laser scalpel designed specifically for hand-controlled cutting and hemostasis. This instrument delivers energy precisely to targeted tissue and produces minimal damage to adjacent healthy structures. Potential clinical applications are discussed.
A new argon laser scalpel (ALS) that delivers radiation to tissue by direct contact was used to perform endarterectomies on atherosclerotic rabbit aortas in vivo. The resultant effects were compared to those induced by CO2 laser (CO2) and conventional surgical endarterectomy (END) to determine whether this instrument might be useful in the treatment of occlusive cerebrovascular disease. Light microscopy of the treated aortic segments revealed significantly more atheroma removed and less damage to the underlying media in the ALS segments compared to the CO2 segments. Electron microscopy showed that the ALS surface and distal intima-media interface were smoother and more even than those of the CO2 or END groups. Prostacyclin synthesis, as measured by 6-keto-prostaglandin F1a levels, was significantly reduced in the ALS compared to the END and control segments. These results indicate that the ALS is superior to CO2 in performing open laser endarterectomies, but such treatment places the atherosclerotic blood vessel at greater risk for thrombotic complications during the early postoperative period that does surgical endarterectomy. It is conceivable that a contact laser may be useful in the smooth welding of the distal edge of an atheroma (i.e., during carotid endarterectomy) and for the transcatheter ablation of surgically inaccessible obstructions of the cerebral circulation.
A patient with known internal carotid artery occlusion developed transient ischemic attacks in the distribution of the occluded vessel. Arteriography demonstrated a thrombus clearly originating from the internal carotid artery stump, which was unassociated with significantly stenotic atherosclerotic disease of the ipsilateral common or external carotid arteries. Stump angioplasty and endarterectomy led to complete and sustained cessation of further symptoms.
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Pure word deafness is a rare behavioral disorder in which the comprehension of spoken language is grossly disturbed, but the abilities to speak, read, write, and process nonverbal auditory stimuli remain intact. This disorder is caused by superior temporal gyrus lesions in the dominant hemisphere that isolate Wernicke's area from incoming auditory information. This involved area is supplied by cortical middle and posterior temporal end-artery branches of the middle cerebral artery. Among approximately 100 extracranial-intracranial bypass procedures performed at our institution in the past 5 years, three patients developed the syndrome of pure word deafness. A cortical or posterior temporal branch of the middle cerebral artery was utilized as the recipient artery in each instance. In all cases, the deficit was transient, delayed (i.e. the patient did not awaken from anesthesia with the deficit), and unrelated to the preoperative deficit. The syndrome of pure word deafness may be more common after bypass than is currently recognized. Localized arterial spasm, dysautoregulation secondary to operative manipulation, or focal brain swelling may be operative mechanisms in the development of this and other delayed, reversible deficits related to bypass surgery.
Vasospasm of the vertebrobasilar system was induced in seven dogs by the intracisternal injection of autologous blood. Somatosensory and brain stem auditory evoked potentials were recorded before and after the induction of angiographically confirmed vasospasm. Additionally, somatosensory evoked potentials were monitored during graded hypotension to 40 mm Hg. There was no significant alteration in the evoked potentials by vasospasm or hypotension. Detailed clinical examination and postmortem histopathological studies did not demonstrate any focal neurological deficit or infarction attributable to vasospasm. Previous studies have noted close correlations between decreased cerebral blood flow and evoked potential alterations. Induced hypotension to a mean arterial pressure of 40 mm Hg in the presence of documented vasospasm was not sufficient to cause evoked potential changes, focal neurological deficit, or pathological evidence of infarction in the canine model.
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Five patients with isolated ptosis and a paresis of ocular elevation in abduction consistent with an isolated superior division III nerve palsy are reported. In all instances the III nerve appeared to be involved before its reported anatomic bifurcation into a superior and an inferior division, in the anterior cavernous sinus.
The cerebral hemispheres may be mutually inhibitory. An injured hemisphere may continue to be inhibited while the uninjured hemisphere is released from inhibition, inducing attentional bias. Patients with neglect might therefore benefit from transection of the corpus callosum. To test this hypothesis, we ablated the frontal arcuate gyrus alone or several months after corpus callosum transection in monkeys. Neglect was significantly worse in animals with a corpus callosum transection. Therefore, the hemispheres may be mutually excitatory or compensatory, and a callosal transection would not be therapeutic. Because the rate of recovery in the two groups was not different, recovery seemed to be an intrahemispheric phenomenon.
The clinical, angiographic, and surgical characteristics of 31 patients with high-grade middle cerebral artery (MCA) stenosis or occlusion (jointly termed "MCA obstructions") referred for cerebral revascularization by extracranial-intracranial (EC-IC) bypass are reviewed. Overall, 12 (66%) of the 18 patients with stenosis and all 13 (100%) of those with complete occlusion experienced clinically evident infarctions. Twenty-five of these patients underwent arteriography at least twice during their clinical course. Eleven (44%) demonstrated significant improvement in flow or complete resolution of obstruction on their second study. Ten of these 11 were patients in whom the initial arteriography was done within 2 weeks of symptom onset. Five other patients with stenosis exhibited obstruction that was worse on serial arteriography without surgical intervention. The high incidence of resolution of MCA obstructions indicates that surgery should not be contemplated in most instances until delayed arteriography has been performed, at least 6 weeks after the onset of symptoms. Proximal embolic sources, such as the cervical carotid bifurcation, should receive carotid endarterectomy and repeat arteriography in appropriate patients prior to consideration of EC-IC bypass. Persistent high-grade MCA obstructions are thereafter potential candidates for EC-IC bypass, since leptomeningeal collateral vessels are marginal in their protective ability. Overall, of 15 patients who underwent an EC-IC bypass procedure, 14 were either stable or improved postoperatively, and 13 have been free of any further ischemic events without the use of major anticoagulant agents.
The clinical and pathologic features of pituitary apoplexy were evaluated within the last 100 consecutive pituitary tumors surgically treated at this institution. From this group, ten tumor specimens exhibited pathologically verifiable hemorrhagic necrosis, including six with classic apoplectic onset; the hemorrhage in four patients was asymmetric. The tumors of symptomatic patients were large, with suprasellar and parasellar extension readily identifiable by neuroradiologic examination. All tumors within this group were chromophobic adenomas by light microscopy, and each of these tumors microscopically exhibited a sinusoidal arrangement with very prominent vascularity. Comparatively, those tumors with asymptomatic hemorrhage were all intrasellar and were encountered in younger patients who had exhibited prior endocrine disturbances. By light microscopy, two of these asymptomatic lesions were chromophobic and two were acidophilic adenomas. In contrast with larger tumors, however, increased vascularity or sinusoidal patterns were not a prominent feature within this group. Our experience suggests hemorrhage within pituitary tumors is a common event, but symptomatic bleeding generally occurs in older patients whose larger tumors contain a pathologic vascular predisposition. Urgent surgical decompression (usually transsphenoidal) in symptomatic patients produced great neurologic improvement in each case.
The clinical and anatomical features of 21 surgically treated saccular aneurysms of the posterior inferior cerebellar artery (PICA) are analyzed. Seventeen of these lesions originated from the PICA-vertebral junction, and four arose from distal PICA branching sites. Twelve lesions arose from the left PICA, nine were right-sided, and all were small (less than 12.5 mm). Most of these aneurysms occurred in females (16 of 21) and presented as classic subarachnoid hemorrhage. The lack of specific focal deficits prevented an accurate pre-angiographic determination of aneurysm location in most instances. Clinically significant vasospasm and aneurysm multiplicity occurred with approximately equal frequency as at other locations. The angiographic and surgical features of these lesions are determined by the course of the vertebral artery and PICA; that is, they occur at branching sites and at curves in the parent vessel, and point in the direction in which flow would have continued if the curve at the aneurysm's origin had not been present. Aneurysms at the PICA-vertebral junction usualthese lesions are determined by the course of the vertebral artery and PICA; that is, they occur at branching sites and at curves in the parent vessel, and point in the direction in which flow would have continued if the curve at the aneurysm's origin had not been present. Aneurysms at the PICA-vertebral junction usualthese lesions are determined by the course of the vertebral artery and PICA; that is, they occur at branching sites and at curves in the parent vessel, and point in the direction in which flow would have continued if the curve at the aneurysm's origin had not been present. Aneurysms at the PICA-vertebral junction usually occur at least 1 cm above the foramen magnum level, arise distal to the PICA origin in the angle between the two vessels, and are best approached by a paramedian incision with the patient in the lateral recumbent position. Isolated clipping of the aneurysm neck is essential in this instance, as trapping may compromise vital perforating arteries of the brain stem. More distal (retromedullary) PICA aneurysms are sometimes associated with another vascular anomaly (two cases in this series), and are best handled through a bilateral suboccipital craniectomy. Clipping of the neck is the preferred treatment, but trapping is usually safe, if necessary.
Massive, multifocal bleeding after the technically successful removal of a cerebral arteriovenous malformation (AVM) represents a frightening and usually catastrophic complication. This phenomenon, termed normal perfusion pressure breakthrough by Spetzler et al., is caused by the diversion of blood flow from the AVM into adjacent, maximally dilated, and nonautoregulating small vessels. We recently encountered three cases of cerebral AVM that exhibited breakthrough bleeding immediately after an apparently successful operation. In all cases, the surgeon was unable to control the resultant hemorrhage by standard microsurgical techniques. High dose barbiturate anesthesia, combined with blood pressure reduction to the lower levels of the normal cerebral perfusion curve, was then initiated in each case. Controlled hyperventilation, steroids, and osmotic dehydrating agents were also used to control intracranial pressure elevation. After maintenance of this regimen for several days, the patients were returned to the operating room for hematoma evacuation. At this time, bleeding was controlled easily and breakthrough did not occur. Although this regimen requires intensive anesthetic, pulmonary, and cerebral monitoring, it successfully salvaged all three patients. Two made immediate, remarkable recoveries, and the third patient is slowly improving. This protocol therefore seems promising for the management of the massive, uncontrollable cerebral swelling or bleeding that may occur as a consequence of AVM removal.
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