Biomedical subjects
Publications and source records attributed to J Pile-Spellman.
Advances in neuroradiologic methods that allow greater understanding of vasospasm are described. The authors review the role of angiography in the evaluation of vasospasm and subarachnoid hemorrhage. Computed tomography has proved to be the most valuable diagnostic technique for the prediction of vasospasm, and the authors describe relevant investigations and detail clinical effectiveness.
This study evaluated the changes in pathways of cerebrospinal fluid (CSF) outflow that accompanied acute and compensated hydrocephalus in the rabbit. Intraventricularly injected 99mTc antimony sulfide was used as a tracer of outflow pathways, and specified structures were counted 12 to 24 hours after injection. Fifteen rabbits were divided into three groups: 1) an acutely hydrocephalic group in which 3 cisternal injections of blood were followed by a study of CSF pressure, ventricular size, and CSF outflow pathways 1 week after the last injection; 2) a control group treated according to the same protocol, except that sterile saline was injected instead of blood; and 3) a chronic group also treated according to the same protocol but in which the animals were maintained an average of 4 weeks after the last blood injection. Ventricular size was measured by computed digitation and expressed as an area ratio of ventricle to brain (VBR). In control animals, 11.8% of the injected colloid dosage was found in cranial perineural lymphatic channels, and 4.8% appeared in the spinal cord. The mean CSF pressure was 149 +/- 20.2 mm H20 (mean +/- SE) and the mean VBR was 0.040 +/- 0.003. In animals evaluated 1 week after subarachnoid injection, accessory cranial perineural lymphatic outflow decreased significantly to 3.4%, and spinal cord activity increased to 9.8% (P less than 0.05, two-tailed t-test). These animals were hydrocephalic and had CSF pressure of 247 +/- 25.1 mm H20 (mean +/- SE) and VBR of 0.083 +/- 0.009.(ABSTRACT TRUNCATED AT 250 WORDS)
The advent of magnetic resonance (MR) imaging has marked a new era in neuroimaging--particularly in terms of diminishing the need for more invasive diagnostic procedures. A cautionary note should be sounded, however, about an important limitation of standard spin-echo MR studies. Two patients were referred for angiography because MR imaging indicated the presence of a "paraclinoid aneurysm." In retrospect, these findings were due instead to a pneumatized anterior clinoid. Angiography could have been avoided had this pitfall been recognized, and had a gradient-echo flow-imaging protocol been utilized. This latter approach (which does not replace spin-echo imaging) is more sensitive to flowing blood and thus allows differentiation of an air space from a nonthrombosed aneurysm.
Sixteen chordomas and nine chondrosarcomas of the clivus were evaluated with CT and MR either before (22 cases) or after (three cases) treatment with proton beam irradiation. The ability of these imaging techniques to provide information necessary to direct patient treatment was studied. The tumor was detected and its gross margins were identified by both techniques in all instances. No reliable diagnostic features allowing differentiation between these two tumors were encountered. MR generally was superior in defining the exact position of the brainstem and optic chiasm relative to the tumor, and it frequently provided superior information about tumor extension into the nasopharynx and cavernous sinus. CT was always better than MR in demonstrating tumoral calcification and in defining the exact anatomy of bone destruction. MR was generally superior to CT in demonstrating the position of the cavernous internal carotid artery relative to the tumor and often provided superior visualization of the vertebral and basilar arteries. In cases in which bone-induced artifact obscured the interface between the neural axis and tumor in the CT image, or in which the tumor had suprasellar extension and was likely to compress the optic chiasm and tracts, MR was of great value in planning irradiation therapy. The high occurrence of clinically asymptomatic signal intensity alterations in the MR studies of previously treated patients appears to limit the differential diagnostic value of this information. Given its greater availability and lower cost, CT appears to be the technique of choice for routine follow-up of previously treated patients.
The main objective of this study was to produce angiographic evidence of basilar artery constriction using the rabbit model. The technique described involves the transdural injection of blood into the cisterna magna on two different days. The results obtained show that vasoconstriction occurs over a time period that is comparable in duration to that seen in patients undergoing vasospasm as a result of subarachnoid hemorrhage. Further investigation should be done to evaluate the usefulness of the rabbit model as a verifiable tool in studying the etiology of vasospasm.
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Cardiac embolism accounts for a large proportion of ischemic stroke. Revascularization using systemic or intra-arterial thrombolysis is associated with increasing risks of cerebral hemorrhage as time passes from stroke onset. We report successful mechanical thrombectomy from a distal branch of the middle cerebral artery (MCA) using a novel technique. A 72-year old man suffered an acute ischemic stroke from an echocardiographically proven ventricular thrombus due to a recent myocardial infarction. Intraarterial administration of 4 mg rt-PA initiated at 5.7 hours post-ictus failed to recanalize an occluded superior division branch of the left MCA. At 6 hours, symptomatic embolic occlusion persisted. Mechanical extraction of the clot using an Attracter-18 device (Target Therapeutics, Freemont, CA) resulted in immediate recanalization of the MCA branch. Attracter-18 for acute occlusion of MCA branches may be considered in selected patients who fail conventional thrombolysis or are nearing closure of the therapeutic window for use of thrombolytic agents.
While malformations of the upper airway are rare, they present challenging management problems and have a potentially devastating impact during anesthesia. This case report describes the management of a patient with a massive supraglottic venous malformation as he underwent transvenous embolization.
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BACKGROUND AND PURPOSE: Preoperative embolization of arteriovenous malformations (AVMs) is thought to improve outcome following surgical resection of these lesions. The purpose of this study was to examine the cost associated with preoperative embolization and different surgical risk categories in the surgical treatment of brain AVMs. METHODS: In a review of 126 patients treated surgically for resection of AVMs, we noted the total days spent in the hospital and calculated the associated costs (from hospital and estimated professional fees). Surgical risk category was determined using the Spetzler-Martin grading system. We examined the effect of risk category, preoperative embolization, and outcome (Rankin score) on cost and inpatient days. RESULTS: Preoperative embolization and greater surgical risk were independently associated with higher total costs. Average adjusted cost for embolization and surgery was $78,400 +/- $4,900 versus $49,300 +/- $5,800 for surgery alone. Patients ranged in preoperative risk category from Spetzler-Martin grades II through V, with an average increase of $20,100 in total cost per Spetzler-Martin grade (95% CI, $13,500 to $28,100). Higher surgical risk category was also associated with more days spent in hospital, with an average increase of 6 days per increment in Spetzler-Martin grade (95% CI, 4 to 8). After surgical resection of an AVM, new neurologic deficits were associated with large differences in cost: $68,500 +/- $6,100 and 15 +/- 2 days in hospital for patients who were neurologically worse after surgery, versus $44,700 +/- $3,900 and 10 +/- 1 days for patients who were unchanged. CONCLUSION: Preoperative embolization in the treatment of AVMs is associated with higher cost but not more days in the hospital. Patients with higher Spetzler-Martin grade AVMs utilize more hospital resources, in part because they have poorer neurologic outcome, and postoperative deficits are associated with higher costs and more days in the hospital.
Twenty patients in whom CT had unequivocally demonstrated the presence of calcification in a diversity of lesions and who had undergone MR, performed at 0.6 T and with standard T1- and T2-weighted pulse sequences, were retrospectively studied to determine the MR signal-intensity characteristics of the calcifications and to assess the ability of MR to detect the presence of this abnormality. CT proved superior to MR in detecting and characterizing calcification. In seven of 20 cases, the apparent extent of calcification was equal by both imaging techniques, and in 13 of the 20 cases, CT showed more extensive abnormality. In five of the 20 cases, the calcifications were seen by MR as regions of profoundly reduced signal intensity, approximately equal to cortical bone, in all pulse sequences. In 12 of the 20 cases, the signal intensity was profoundly reduced in one or more, but not all, pulse sequences. T2-weighted pulse sequences were most sensitive in detecting calcification of signal void. Reviewed without knowledge of the CT findings, the MR images were interpreted as definitely indicative of the presence of calcification in three of the 20 cases. In seven of the 20 cases, the MR images raised the possibility of calcification but were less definitive than the CT findings. In 10 of the 20 cases, MR was judged indeterminate for the presence of calcification.