B. Todd Troost

Risk Factors and Solutions for the Development of Neurobehavioral Changes After Coronary Artery Bypass Grafting

BACKGROUND As operative mortality for coronary artery bypass grafting has decreased, greater attention has focused on neurobehavioral complications of coronary artery bypass grafting and cardiopulmonary bypass. METHODS To assess risk factors and to evaluate changes in surgical technique, between 1991 and 1994 we evaluated 395 patients undergoing coronary artery bypass grafting with an 11-part neurobehavioral battery administered preoperatively and at 1 and 6 weeks postoperatively. Patients were instrumented with 5-MHz focused continuous-wave carotid Doppler transducers intraoperatively to estimate cerebral microembolism as an instantaneous perturbation of the velocity signal. Microembolism data were quantitated and compared with surgical technical maneuvers during operation and with neurobehavioral deficit (> or = 20% decline from preoperative performance on two or more neurobehavioral tests) postoperatively. These data and patient demographics were statistically analyzed (chi2, t test) and the results at 2 years (1991 and 1992; group A) were used to influence surgical technique in 1993 and 1994 (group B). RESULTS Significantly associated with new neurobehavioral deficits were increasing patient age (p < 0.05), more than 100 emboli per case (p < 0.04), and palpable aortic plaque (p < 0.02). Group B patients had a significant decline in the neurobehavioral event rate (group A, 69%, 140/203; versus group B, 60%, 115/192; p < 0.05) of postoperative neurobehavioral deficits at 1 week and at 1 month (group A, 29%, 52/180; versus group B, 18%, 35/198; p < 0.01). The stroke rate was less than 2% in both groups (p = not significant). Modifications of surgical technique used in group B patients included increased use of single cross-clamp technique, increased venting of the left ventricle, and application of transesophageal and epiaortic ultrasound scanning to locate and avoid trauma to aortic atherosclerotic plaques. CONCLUSIONS Neurobehavioral changes after coronary artery bypass grafting are common and associated with cerebral microembolization. Surgical technical maneuvers designed to reduce emboli production may improve neurobehavioral outcome.

Nimodipine neuroprotection in cardiac valve replacement: report of an early terminated trial.

BACKGROUND We conducted a double-blind, randomized clinical trial in patients undergoing cardiac valve replacement to determine whether nimodipine, a dihydropyridine calcium antagonist, reduced the risk of new neurological, neuro-ophthalmologic, or neuropsychological deficits-common complications associated with cardiac surgery-1 week after surgery. METHODS AND RESULTS Enrollment for a total of 400 patients started in May 1992 and was stopped in September 1994, with 150 patients randomized to the study. Nimodipine was given to the patients during the perioperative period. Patients underwent examinations before surgery and at approximately 1 week, 1 month, and 6 months after surgery. Major adverse events, including deaths and strokes, were monitored monthly. The trial was terminated early because of both an unexpected disparity in death rates between groups and a lack of evidence of a beneficial effect of nimodipine. New deficits were observed in 72% of the placebo group versus 77% of the nimodipine group (p=.55). In the 6-month follow-up period, 8 deaths (10.7%) occurred in the nimodipine group (n=75) compared with 1 death (1.3) in the placebo group (n=74) (p=.02). Major bleeding occurred in 10 patients in the nimodipine group versus 3 in the placebo group (13.3% versus 4.1%; P=.04). Six (46.2%) of the 13 patients with major bleeding died compared with 3 deaths (2.2%) among the 136 patients without major bleeding. CONCLUSIONS Our findings add to the growing evidence that calcium antagonists have a prohemorrhagic effect in some patients and suggest that nimodipine use should be restricted perioperatively in patients scheduled for cardiac valve replacement.

Brain embolic phenomena associated with cardiopulmonary bypass

Various biologic and non-biologic materials may be embolized to the brain after the use of cardiopulmonary bypass (CPB) pumps during open heart surgery but their relative frequency and importance are uncertain. Among the nonbiologic materials, Antifoam A, which contains organosilicates and silicon, continues to be employed as an additive to prevent frothing. Recent improvements in filtration and oxygenation techniques have clearly reduced the incidence of large emboli and complications like stroke but other neurologic sequelae following open heart surgery are common and in many cases poorly explained. A recently developed histochemical technique for the demonstration of the endothelial alkaline phosphatase (AP) was employed in a post-mortem study of brains from 8 patients and 6 dogs dying within a few days after open heart surgery employing cardiopulmonary bypass perfusion. Brains from 38 patients and 6 dogs who were not subjected to heart surgery were studied as controls with the same technique. The AP-stained slides are suitable for both light microscopic examination of the thick celloidin sections as well as a subsequent processing for high-resolution microradiography. Small capillary and arteriolar dilatations (SCADs) were seen in the test subjects/animals but not controls. SCADs were seen in all parts of the brain. Approximately 50% of the SCADs showed birefringence when examined with polarized light. SCADs are putative embolic phenomena and the exact nature and source of the embolic material is under investigation. A glycolipid component is indicated by preliminary studies. SCADs are difficult to find in routine paraffin sections and most if not all of the offending material seems to be dissolved during processing.(ABSTRACT TRUNCATED AT 250 WORDS)

Cerebrovascular reactivity in migraineurs as measured by transcranial Doppler.

Transcranial Doppler ultrasound is a relatively new diagnostic modality which allows the non-invasive assessment of intracranial circulation. A total of 10 migraine patients were studied and compared to healthy controls without headaches. Migraineurs during the headache-free interval demonstrated excessive cerebrovascular reactivity to CO2, evidenced by an increase in middle cerebral artery blood flow velocity of 47% ± 15% compared to 28% ± 14% in controls (p = 0.026). Differences between the two study groups revealed no significant decrease in middle cerebral artery blood flow velocity with hypocapnia. However, the differences between middle cerebral artery blood flow velocity during hyperventilation and CO2 inhalation were significantly different (p = 0.004) comparing migraineurs and controls. Instability of the baseline blood flow velocities was also noted in migraineurs during the interictal period. Characteristics which may allow differentiation of migraineurs from other headache populations could possibly be obtained from transcranial Doppler ultrasound flow studies.

A randomized, blinded trial of the antioxidant pegorgotein: No reduction in neuropsychological deficits, inotropic drug support, or myocardial ischemia after coronary artery bypass surgery

OBJECTIVE To determine whether patients receiving pegorgotein preoperatively would be less likely than patients receiving placebo to demonstrate postoperative cerebral or myocardial dysfunction and thus would be less likely to (1) demonstrate a decline in neuropsychologic testing after cardiopulmonary bypass, (2) receive inotropic drug support, or (3) demonstrate electrocardiographic signs of ischemia or infarction. DESIGN Prospective, randomized, blinded clinical trial. SETTING University teaching hospital and clinics. PARTICIPANTS Sixty-seven patients with normal left ventricular function undergoing elective, primary coronary artery bypass surgery. INTERVENTIONS Six to 18 hours before aortic cross-clamping, patients received a single dose of placebo (n = 22); pegorgotein, 2,000 IU/kg intravenously (n = 23); or pegorgotein, 5,000 IU/kg intravenously (n = 22). MEASUREMENTS AND MAIN RESULTS Patients in the three groups were similar; the mean ages were 65, 66, and 67 years, and there were seven, eight, and seven women in the placebo; pegorgotein, 2,000 IU/kg; and pegorgotein, 5,000 IU/kg groups. Fifty-one of 67 patients demonstrated neuropsychologic deficit 5 to 7 days postoperatively (n = 17, 19, and 15 for placebo, 2,000 IU/kg, and 5,000 IU/kg; p = NS). Median duration of cardiopulmonary bypass was longer in patients with two or more deficits at 4 to 6 weeks than in those with fewer than two deficits (121 v. 98 minutes; p = 0.04). No patient demonstrated a perioperative stroke. Twenty-seven patients required inotropic drug support after cardiopulmonary bypass (n = 8, 11, and 8 for placebo, 2,000 IU/kg, and 5,000 IU/kg; p = NS). Inotropic drug support was associated with history of angina (p = 0.01) and increasing weight (p = 0.03). Nine patients demonstrated early postoperative ischemia or infarction (n = 1, 7, and 1 for placebo, 2,000 IU/kg, and 5,000 IU/kg; p = 0.07). CONCLUSIONS This study showed no positive influence of pegorgotein on the incidence of any of the findings and showed a trend toward an increased incidence of myocardial ischemia or infarction.

Optic neuritis due to acquired toxoplasmosis

A pediatric patient with well documented acquired toxoplasmic optic neuritis is presented. Use of immunoglobulin M immunofluorescent antibody studies allow easier identification of recently acquired toxoplasmosis. Toxoplasmic optic neuritis and retinitis should be considered along with toxoplasmic meningitis or encephalitis as complications of acquired toxoplasmosis. Therapy is available which may decrease the duration of visual symptomatology and reduce residual visual impairment.

Neuro-ophthalmologic manifestations of posterior fossa AVM

Recent studies of the vestibulo-ocular reflex have revealed a distinct pathway from the anterior semicircular canal to the contralateral oculomotor nucleus via the superior vestibular nucleus. Axons of this pathway ascend in the brachium conjunctivum, while axons of the other semicircular canal pathways ascend in the medial longitudinal fasciculus (MLF). We report two cases of primary position upbeat nystagmus where lesions of the brachium conjunctivum were suggested by computed tomography (CT) scans. One of these lesions was confirmed at autopsy. We concluded that primary position upbeat nystagmus, like downbeat nystagmus, is a type of central vestibular nystagmus resulting from an imbalance of vertical vestibulo-ocular reflex activity.

Left dural to right cavernous sinus fistula. A case report.

Direct carotid-cavernous sinus fistulas that present with signs and symptoms contralateral to the arterial supply of the fistulas are not uncommon. We present a thoroughly documented case of a dural-cavernous sinus fistula with symptoms exclusively contralateral to the arterial source, a rarer entity. The patient presented with a red, proptotic right eye and a history of transient horizontal diplopia and a “feeling of fullness” in that eye. Magnetic resonance imaging (MRI) of the brain and orbits performed at another hospital had shown no abnormalities. Carotid angiography performed on the right side was normal; carotid angiography performed on the left side showed a dural-cavernous sinus fistula, with shunting from branches of the left external carotid artery directly to the right cavernous sinus. Orbital duplex color-flow sonography showed reverse flow in a dilated right superior ophthalmic vein. This unusual manifestation of a dural-cavernous sinus fistula offers insight into the pathophysiology of arteriovenous fistulas involving the cavernous sinus, and is a reminder that bilateral injections are required when performing carotid angiography to characterize these disorders.

Emergency Transcranial Doppler Assessment of Intracranial Vertebral Artery Dissection

Despite its risks, contrast angiography is the method of definitive diagnosis of vertebral artery dissection. This presents the case of a 49‐year‐old white man with ischemic symptomatology in the posterior circulation in whom transcranial Doppler sonography suggested vertebral dissection, leading to confirmation by emergency angiography and rapid institution of therapy.

Botulinum toxin type A in themanagement of headache: a review of the literature and personalexperience

AbstractBotulinum toxin type A (BoNT-A) shows significant promise in the management of a variety of headache types including migraine, chronic daily headache, tension-type headache, and other head and neck pains. Confirmation of efficacy still awaits the report of well-controlled double-blind placebo-controlled trials; however, a mounting body of evidence suggests that BoNT-A is effective, well-tolerated and safe for the management of many headache disorders. In this paper, I review recent evidence on the efficacy of BoNT-A, and also report my personal experience with the treatment in over 600 headache patients.