Biomedical subjects
W R Selman
Publications and source records attributed to W R Selman.
Therapeutics for focal cerebral ischemia.
A review of the therapeutic modalities available for the treatment of focal cerebral ischemia is presented. The theoretical aspects and present practical applications of each treatment are discussed. The possibilities for future research and for the implementation of new modalities are indicated.
New design for an implantable vessel occluder.
A new implantable balloon cuff for experimental cerebral artery occlusion is described. The device consists of a small silastic balloon connected to a pressure sensitive valve and reservoir by a spring reinforced catheter. The unique features of this occluder and its insertion and function are discussed.
Computerized tomographic diagnosis: pitfalls for neurosurgeons.
Computerized tomography as a diagnostic procedure is characterized by its high sensitivity but limited specificity. This lack of specificity may result in an erroneous diagnosis and, possibly, in ill-advised therapy unless clinical and objective data are carefully considered in interpreting the study. The most common pitfalls encountered are the phenomena of contrast enhancement of infarcts and mass effect associated with infarcts. Many different pathological processes can have similar enhancement patterns. The evolution of high density, acute hemorrhage to isodense areas in the chronic hematoma can become a serious diagnostic problem unless an appropriate history is available. The authors discuss 30 cases in which misinterpretation of CT scans resulted in erroneous diagnoses. Seventeen of these patients underwent operation.
Protein kinase C activity in permanent focal cerebral ischemia.
Protein kinase C (PKC) activity was investigated in a model of focal stroke in the rat. Following 6 h of left middle cerebral artery occlusion, rat brains were frozen in situ. In the peripheral ischemic zone, total PKC activity declined by close to two-thirds (1.07 +/- 0.35 vs 2.77 +/- 0.12 nmol/min/mg protein; p less than 0.05, n = 4), and the proportion of total activity associated with the particulate fraction decreased from 33.3 +/- 1.5% to 16.2 +/- 1.4% (p less than 0.01, n = 4). Thus, overall particulate PKC activity in the ischemic zone was less than 20% of control. The cerebral energy metabolite profile of tissue from the ipsilateral hemisphere, corresponding to the region where samples were obtained for PKC activity assay, suggests that this tissue may have been part of the ischemic penumbra before further deterioration.
Transoral microsurgical odontoid resection and spinal cord monitoring.
Four patients underwent transoral resection of the odontoid with utilization of microsurgical technique and spinal cord monitoring of somatosensory cortical evoked responses. All patients improved following surgery, and no operative morbidity or mortality was encountered. Spinal cord monitoring enhances the safety of the procedure and, reapplied at a later date, detects information of prognostic value.
Naloxone therapy during focal cerebral ischemia evaluation in a primate model.
Conflicting reports have appeared in the literature regarding the effect of the opiate antagonist naloxone on ischemic neurologic deficits. We report the results of a study using naloxone in our model of focal cerebral ischemia in the awake primate. A total of 14 adult baboons were subjected to six-hour occlusion of the left middle cerebral artery (MCA). Seven animals served as controls and seven received treatment with naloxone (5 mg/kg) beginning 30 min after MCA occlusion and continuing until two hours after reperfusion. All animals developed profound hemiparesis and homonymous hemianopsia within seconds of inflating the MCA occluder. Acutely, therapy with naloxone partially reversed ischemic neurologic deficits in five of the seven treatment animals. Within minutes of receiving the loading dose of naloxone, responding animals were more alert and demonstrated improvements in motor function. Naloxone did not affect mortality: Three animals in the treatment group and two in the naloxone group died secondary to malignant intracranial pressure within 48 hours of the ischemic episode. In animals surviving the ischemic insult however, treatment with naloxone significantly improved neurologic outcome at 10 days (p less than 0.05). Neuropathologic examinations in these animals revealed amelioration of ischemic tissue damage, with three of the five suffering only small focal areas of infarction. (All control animals suffered large infarcts of the MCA territory.) Our results verify that naloxone can reverse ischemic deficits, and more importantly may improve the outcome from focal ischemic insults.
Use of the delayed mask for improved demonstration of aneurysms on intraarterial DSA.
PURPOSE: We retrospectively explored the use of the delayed mask technique for intraarterial digital subtraction angiography (IADSA) to demonstrate the anatomy of aneurysm necks. METHODS: The delayed mask technique was utilized in 22 patients who had craniotomies for aneurysms demonstrated at angiography. The operative notes were compared to the angiographic findings of both the traditionally masked IADSA and the delayed mask IADSA. In addition, an in vitro model was constructed to examine the relationship between the size of the aneurysm neck and the ability to indirectly define its anatomy by demonstrating the flow jet. RESULTS: In 12 of 22 cases, the delayed mask technique demonstrated a systolic jet that was not demonstrated by traditional subtraction techniques. In nine of 12 cases, the delayed mask technique gave more specific information regarding the size, location, and orientation of the aneurysm neck. CONCLUSION: The delayed mask technique can add important information regarding the anatomy of aneurysm without adding time or risk to the procedure.
The use of intraoperative fluoroscopy and spinal cord monitoring for transoral microsurgical odontoid resection.
The transoral approach to the upper cervical spine has not gained wide acceptance. A reliable intraoperative method to determine the necessary extent of dissection and degree of decompression, as well as to evaluate spinal cord function, should improve the safety and applicability of the transoral approach. Four cases of anterior cervical cord compression were successfully treated by odontoid resection employing a microsurgical transoral approach. Intraoperative fluoroscopy monitored the depth of dissection and adequacy of decompression. Somatosensory cortical evoked potentials (SSEP) allowed assessment of spinal cord function that could be correlated with surgical decompression. In addition, follow-up examination revealed that SSEP was an intraoperative prognosticator of subsequent neurologic improvement.
Cost-effectiveness of emergency intraarterial intracerebral thrombolysis: a pilot study.
PURPOSE: To assess the clinical efficacy and cost-effectiveness of emergency thrombolysis as a treatment strategy for thromboembolic intracerebral events. METHODS: Thirty-four patients with symptoms suggestive of middle cerebral artery occlusion were included. Eight of these patients were treated with intraarterial urokinase. Effectiveness was determined by comparing the admission National Institutes of Health stroke score to the 24-hour National Institutes of Health stroke score. The cost and length of stay of both populations were derived and used as measures of direct cost. The likelihood of admission to extended care facilities and estimated length cost of admission was used as a measure of indirect cost. RESULTS: The control population became slightly worse, with a change in National Institutes of Health score of -0.5, whereas the treated population improved slightly, with a change in National Institutes of Health score of +5.12. Analysis of the direct costs data between the two populations revealed a slight increased mean for the treated population ($15,202) as compared with the control population ($13,478). The unpaired t test, however, revealed no significant cost difference between the two groups. By reducing the number of completed strokes by one third or by decreasing the severity by the same factor (as shown in our study), the likelihood of admission to an extended nursing facility also is decreased. The cost saving per patient from extended care facilities is approximately $3435. CONCLUSION: The emergency application of intraarterial thrombolysis with urokinase results in a statistically significant positive change in National Institutes of Health score by at least five points. A statistically significant benefit is realized through the use of intraarterial urokinase. A statistically insignificant additional cost is shown by this study. This insignificant cost is more than offset by the saved nursing home costs.