M. J. G. Harrison

The impact of microemboli during cardiopulmonary bypass on neuropsychological functioning.

Background and Purpose Microemboli have been implicated in the etiology of neuropsychological deficits after cardiopulmonary bypass. This study examined the incidence of high‐intensity transcranial signals (microemboli) and their relation to changes in neuropsychological performance after surgery. Methods Transcranial Doppler ultrasonography was used to measure middle cerebral artery blood flow velocity and detect microemboli. The number of high‐intensity transcranial signals was determined and related to a neurological examination and absolute changes in neuropsychological performance as well as the number of patients considered to exhibit a neuropsychological deficit. Data were available on 100 consenting patients undergoing routine cardiopulmonary bypass. Fifty of the patients were randomly assigned to a procedure that included a 40‐&mgr;m arterial line filter, and 50 had the procedure without any arterial line filter. Results Significantly more patients were found to have neuropsychological deficits in the group without the arterial line filter at both 8 days (P<.05) and 8 weeks (P<.03) after surgery. In addition, more “soft” neurological signs were found in the nonfiltered group 24 hours after surgery (P<.05). More high‐intensity transcranial signals were found in the nonfiltered group, and the number of high‐intensity transcranial signals was found to be related to the likelihood of a patient having a neuropsychological deficit at 8 weeks. Conclusions These data suggest that neuropsychological deficits after routine cardiopulmonary bypass are related to the number of microemboli delivered during surgery. Furthermore, the numbers of microemboli may be reduced by including a 40‐&mgr;m filter on the arterial line. (Stroke. 1994;25:1393‐1399.)

Psychosocial interventions for caregivers of people with dementia: A systematic review

The content of interventions for caregivers of dementia patients is highly varied. None of the reviews conducted to date have focused on evaluating the effects of the content of interventions exclusively for dementia caregivers, and this issue is not well understood. The purpose of this review was to first identify the type of components (e.g. education, counselling) that have been utilized in psychosocial/psycho-educational interventions for dementia caregivers, and to evaluate the success of the different components or combination of components in producing positive outcomes for dementia caregivers. Forty studies were included in the review. Approximately two-thirds of the interventions did not show improvements in any outcome measures. Among those studies, which did demonstrate improvements, the inclusion of social components (e.g. social support) or a combination of social and cognitive (e.g. problem solving) components seemed to be relatively effective. It is important to note, however, that these analyses were based on small numbers and the review was limited by a number of methodological issues (e.g. poor description of interventions). To advance our understanding of the efficacy of psychosocial interventions for caregivers of people with dementia, a more systematic approach is required. Intervention components need to be carefully contrasted in appropriately designed studies of sufficient size.

Microemboli and Cerebral Impairment During Cardiac Surgery

Arterial microemboli, which may be reduced by arterial line filtration, have been proposed as a factor con tributing to cardiopulmonary bypass (CPB)-related cerebral dysfunction. The authors report on a study investi gating the effects of arterial line fil tration on the incidence of microemboli and the neuropsycho > 50mmHg, flow 1.8-2.4L/m2/min) was standardized and continuously monitored. Transcranial Doppler measured middle cerebral artery blood velocity and the incidence of microembolic events (MEE). Forty patients (median age fifty-six years, range forty-three to seventy) have completed the protocol. MEE oc curred in all patients during aortic cannulation and at inception of by pass. During bypass, patients with filtered CPB had fewer MEE (0-10 per thirty minutes) than nonfiltered CPB patients (30- > 250 per thirty minutes) did. Seven of 20 nonfiltered CPB patients showed soft neurologic signs on the first postoperative day compared with 3/20 in the filtered CPB group (P = 0.27, Fishers). The filtered CPB patients performed bet ter on a verbal memory test (P < 0.01, Wilcoxon) at eight weeks than the nonfiltered CPB group did.

Impairment of cerebral function following cardiac and other major surgery.

Patients undergoing routine coronary artery surgery (N = 76) were compared with those undergoing other major operations (N = 29) in a prospective multidisciplinary study designed to define the incidence of neurological and psychological sequelae. The preoperative state of the carotid and vertebral arteries was defined by digital subtraction angiography. Changes in clinical neurological examination, detailed neuropsychological testing, psychiatric assessment and cerebral blood flow were measured. All preoperative studies were repeated 8 days and 8 weeks after surgery. Clinical neurological examination was repeated in addition on the 1st postoperative day. New focal neurological signs were found in 8% of the cardiac patients and none of the comparison group 24 h after operation (P = 0.9). Global transient neurological dysfunction occurred in 59% of the coronary group in the 1st postoperative day compared with 21% in other forms of surgery (P = 0.0007) but this correlated with postoperative narcotic and sedative drugs. A deterioration in neuropsychological performance was detectable in 73% of coronary cases at 8 days which was more likely to occur with increasing age, longer bypass time and lower perfusion pressure, but similar neuropsychological changes also occurred in 50% of the comparison group. By 8 weeks, there was a significant improvement in the cardiac patients (37%, P less than 0.001) but not in the other group. Cerebral blood flow was reduced at 8 days in the coronary bypass patients but not in the comparison group suggesting that the mechanism of cerebral change may be different in the two groups.

Evidence of CNS impairment in HIV infection: clinical, neuropsychological, EEG, and MRI/MRS study

OBJECTIVES To identify by clinical examination, EEG, MRI, and proton spectroscopy, and neuropsychological assessment the prevalence of signs of CNS involvement in patients infected with HIV, and to relate such findings to the evidence of immunosuppression. METHODS The design was a cross sectional analysis of a cohort of male patients with infected HIV with an AIDS defining diagnosis or low CD4 count (<350), and seropositive asymptomatic subjects, both groups being followed up in a longitudinal study. Control groups consisted of seronegative subjects from the same genitourinary medicine clinics. RESULTS This report sets out the cross sectional findings at the seventh visit in the longitudinal study. Patients with AIDS had more signs of neurological dysfunction, poorer performance on a neuropsychological test battery, were more likely to have an abnormal EEG, and to have abnormalities on MRI. They more often had cerebral atrophy, abnormal appearing white matter, , and abnormal relaxometry and spectroscopy. There was little evidence of abnormality in seropositive people who had a CD4 count >350 compared with seronegative people from a similar background. CONCLUSIONS Detailed testing failed to disclose significant CNS impairment without immunosuppression in men infected with HIV. Findings from MRI and magnetic resonance spectroscopy (MRS) correlated with those of the neurological examination and neuropsychogical assessment. A combination of such assessments offers a simple surrogate for studies of CNS involvement in HIV disease.

The Transplant Effects Questionnaire (TxEQ): The development of a questionnaire for assessing the multidimensional outcome of organ transplantation — example of end stage renal disease (ESRD)

OBJECTIVES: To develop a questionnaire to assess the responses of transplant recipients to the receipt of an organ, including their self-care behaviour. DESIGN: Following a literature review, open-ended interviews and a focus group, a transplant questionnaire was developed. Two studies (Study 1: N = 231, Study 2: N = 105) were conducted to evaluate its psychometric properties. METHODS: A pool of 51 items was derived from themes identified in published studies and from interviews and a focus group discussion with renal transplant recipients. These were constructed into a questionnaire and were then administered to two renal transplant out-patients populations. Item responses of study sample 1 were subjected to principal components analysis (PCA) using varimax rotation to examine the structure of responses. In order to investigate the stability of the factor structure found in Study 1, item responses of the second sample were subjected to confirmatory factor analysis (CFA) using structural equation modelling. RESULTS: PCA indicated six factors that accounted for 64.2% of the variance. With extraneous items omitted, the final questionnaire derived from Study 1 has 24 items clustered around five conceptual coherent factors: worry about transplant (22.1%), guilt regarding donor (11.9%), disclosure (9.58%), medication adherence (8.73%), and responsibility (6.63%). CFA on the final 24-item version of the TxEQ revealed that the resulting model was a good fit for the Study 2 data (RMSEA = 0.08, pclose =.005). CONCLUSIONS: The TxEQ has potential application as a measure in the area of transplantation research. CFA demonstrated that the factor structure of the TxEQ is consistent across different renal transplant out-patients populations. Further research is currently in progress to assess other groups of transplant recipients and to examine its relationship to other measures.

Neurological and neuropsychological performance in HIV seropositive men without symptoms.

Ninety five HIV seropositive and 32 seronegative homosexual men were recruited to a prospective study of the early features and natural history of the neurological manifestations of HIV infection. There was no evidence from the initial neurological examination, a neuropsychological test battery, nerve conduction studies, somatosensory evoked potentials from the legs, P300 event related auditory evoked potentials, magnetic stimulation of the motor cortex, or MRI scans that HIV infected men without symptoms in CDC groups II/III differed significantly from a well matched seronegative comparison group. Only the subgroup in CDC IV showed evidence of impairment, and this was restricted to their performance on some of the cognitive tests. The results imply that, despite early invasion of the CNS by HIV, major disturbances of function manifest themselves only when the patient becomes immunosuppressed. The importance of an appropriate comparison group and awareness of the potentially confounding influences such as age, education, exposure to alcohol and drugs, and mood and anxiety in such studies is stressed. The essentially negative findings are important in the understanding of the pathogenesis of neurological effect in HIV infection and in the design and interpretation of therapeutic trials.

Retinal microembolism and neuropsychological deficit following clinical cardiopulmonary bypass: comparison of a membrane and a bubble oxygenator. A preliminary communication.

To observe and quantify cerebrovascular microembolic events in the central nervous system during cardiopulmonary bypass, 40 patients having elective uncomplicated coronary surgery had retinal fluorescein angiograms 5 min before bypass was discontinued. Each patient also had 10 neuropsychological tests before and after surgery. A Harvey H1700 bubble oxygenator was used for 23 patients and a Cobe CML sheet membrane oxygenator was used for 17 patients. All 23 (100%) of patients in the bubble oxygenator group had retinal microvascular occlusions consistent with microembolism compared to 8/17 (47%) in the membrane oxygenator group (P less than 0.001). In those retinas with occlusions, the mean resultant area of non-perfusion was less in the membrane oxygenator group (0.11 mm2; n = 8) than in the bubble oxygenator group (0.29 mm2; P less than 0.01). Arterial PO2 levels during bypass were similar in both groups at moderate hypothermia, but the mean PaO2 during rewarming was higher in the bubble oxygenator group (27 kPa) than in the membrane group (13 kPa; P less than 0.001). Neuropsychological deficits were more common and more severe after bubble oxygenation than after membrane oxygenation, but in this small patient group, the difference was not statistically significant. We conclude that flat sheet membrane oxygenation during cardiopulmonary bypass may confer significant protection against cerebrovascular microembolism.

Cerebrovascular disease and functional outcome after coronary artery bypass surgery.

A series of patients undergoing coronary artery bypass surgery was studied prospectively to see if angiographic evidence of cerebrovascular disease proved predictive of the incidence of neuropsychological deficit 8 days or 8 weeks after surgery. In 47 patients, intravenous digital subtraction angiography was carried out preoperatively to assess the presence and severity of atheromatous changes in the carotid arteries; 51% had evidence of vessel wall disease and 17% had stenosis of at least one carotid artery in the neck, although only one patient had severe narrowing. Overall, 77% of these 47 patients showed a neuropsychological deficit as defined by a significantly reduced score in at least two of 10 tests administered 8 days after surgery. Eight weeks after surgery 36% still showed a deficit. The incidence of neuropsychological deficit was not significantly greater among those patients with angiographically visible carotid artery disease. The mechanism of surgery-related cognitive impairment is briefly discussed in the light of these findings.

Cortical and subcortical JC virus infection: two unusual cases of AIDS associated progressive multifocal leukoencephalopathy.

Two patients with AIDS and progressive neurological syndromes had necropsies that identified JC virus infection of the cerebral or cerebellar cortex. The unusual presentation of progressive multifocal leukoencephalopathy with grey matter involvement and normal cerebral imaging is discussed.