Cognitive dysfunction after on-pump operations: neuropsychological characteristics and optimal core battery of tests.

Postoperative cognitive dysfunction (POCD) is a mild form of perioperative ischemic brain injury, which emerges as memory decline, decreased attention, and decreased concentration during several months, or even years, after surgery. Here we present results of our three neuropsychological studies, which overall included 145 patients after on-pump operations. We found that the auditory memory span test (digit span) was more effective as a tool for registration of POCD, in comparison with the word-list learning and story-learning tests. Nonverbal memory or visuoconstruction tests were sensitive to POCD in patients after intraoperative opening of cardiac chambers with increased cerebral air embolism. Psychomotor speed tests (digit symbol, or TMT A) registered POCD, which was characteristic for elderly atherosclerotic patients. Finally, we observed that there were significant effects of the order of position of a test on the performance on this test. For example, the postoperative performance on the core tests (digit span and digit symbol) showed minimal impairment when either of these tests was administered at the beginning of testing. Overall, our data shows that the selection of tests, and the order of which these tests are administered, may considerably influence the results of studies of POCD.

Steroid myopathy in patients with chronic respiratory diseases.

BACKGROUND: Corticosteroid-induced myopathy is a well known clinical entity, and experimental studies showed decreased rate of protein synthesis and increased rate of protein breakdown in muscles of chronically treated animals. OBJECTIVE: The present observational study was aimed to evaluate skeletal muscle functions in asthmatics and patients with other chronic respiratory diseases treated by inhaled or oral corticosteroids. METHODS: Thirty six patients with respiratory diseases were included into the study. The physician-rated peripheral motor deficits scale, stepper test and ankle/wrist index were used for assessment of muscle functions. The effects of length of glucocorticoids intake on muscle functions were evaluated. RESULTS: Sixty five per cent of patients using corticosteroids daily during 1 year and longer reported weakness in legs, and 20% of these patients demonstrated objective signs of the muscle weakness. The performance on the stepper test was significantly worse in patients chronically using corticosteroids in comparison with the control group (10.9 ± 3.4 steps vs 16.1 ± 2.4 steps per 10s, respectively; F=21.6, p<0.001). In addition, a proportion of patients using corticosteroids for at least 18 months were characterized by muscle hypotrophy at a dominant leg. CONCLUSION: Chronic intake of inhaled corticosteroids induces clinically significant decrease of muscle functions at least after 1-year of daily treatment.

Neuropsychological Functions of µ- and δ-Opioid Systems.

Brain opioid innervation is involved in many pathophysiological processes related to drug addiction. The main idea of the present review is that µ-/δ-opioid innervation is an intrinsic component of the motor/approach behavior network, which is activated synergetically with dopaminergic mesocorticolimbic network. Contribution of opioid innervation to the motor/approach behavior processing includes generation of positive emotions and inhibition of pain and stress reactions in order that the individual would be able to reach the vital goal. We cite the neuroanatomical data which showed that motor subcortical nuclei contain the most abundant opioid innervation and its activation is an obligatory component of positive emotions. In the majority of life situations, motor/approach behavior network concomitantly activates pain/stress control opioid network. Intensive cognitive activity induces activation of opioid innervation as well, and both enhancing and impairing effects of opioid agonists on cognitive functioning were demonstrated. Overall, the functioning of endogenous opioid networks may be summarized as following: NO physical/cognitive activity = NO positive emotions plus NO pain/stress control. We suppose that contemporary findings concerning neuropsychological functions of endogenous opioid system explain many controversial issues in neuropsychiatric conditions predisposing to drug addiction and neurological mechanisms of opioid addiction.

Electroencephalography as a tool for assessment of brain ischemic alterations after open heart operations.

Cardiac surgery is commonly associated with brain ischemia. Few studies addressed brain electric activity changes after on-pump operations. Eyes closed EEG was performed in 22 patients (mean age: 45.2 ± 11.2) before and two weeks after valve replacement. Spouses of patients were invited to participate as controls. Generalized increase of beta power most prominent in beta-1 band was an unambiguous pathological sign of postoperative cortex dysfunction, probably, manifesting due to gamma-activity slowing ("beta buzz" symptom). Generalized postoperative increase of delta-1 mean frequency along with increase of slow-wave activity in right posterior region may be hypothesized to be a consequence of intraoperative ischemia as well. At the same time, significant changes of alpha activity were observed in both patient and control groups, and, therefore, may be considered as physiological. Unexpectedly, controls showed prominent increase of electric activity in left temporal region whereas patients were deficient in left hemisphere activity in comparison with controls at postoperative followup. Further research is needed in order to determine the true neurological meaning of the EEG findings after on-pump operations.

Size of left cardiac chambers correlates with cerebral microembolic load in open heart operations.

Background. Microemboli are a widely recognized etiological factor of cerebral complications in cardiac surgery patients. The present study was aimed to determine if size of left cardiac chambers relates to cerebral microembolic load in open heart operations. Methods. Thirty patients participated in the study. Echocardiography was performed in 2-3 days before surgery. A transcranial Doppler system was used for registering intraoperative microemboli. Results. Preoperative left atrium and left ventricular end-systolic and end-diastolic sizes significantly correlated with intraoperative microembolic load (rs = 0.48, 0.57 and 0.53, Ps < .01, resp.). The associations between left ventricular diameters and number of cerebral microemboli remained significant when cardiopulmonary bypass time was included as a covariate into the analysis. Conclusions. The present results demonstrate that increased size of left heart chambers is an influential risk factor for elevated cerebral microembolic load during open heart operations. Mini-invasive surgery and carbon dioxide insufflation into wound cavity may be considered as neuroprotective approaches in patients with high risk of cerebral microembolism.

Alexithymia, depression and heart rate in candidates for cardiac surgery.

Effects of psychological traits on heart rate (HR) and heart rate variability (HRV) were evaluated in patients awaiting cardiac surgery. Alexithymics demonstrated slowed HR, whereas high cognitive performance was associated with elevated HR in 2-3 days before surgery. Depression negatively correlated with HRV low frequency power. These data are consistent with previous findings of diverse moderate stress effects on HR regulation in cardiologic patients and healthy subjects in accordance to differences in psychological characteristics.

Asymmetric cerebral embolic load and postoperative cognitive dysfunction in cardiac surgery.

BACKGROUND: The aim of the study was to determine the effects of asymmetric cerebral embolic load on cognitive functions. METHODS: Thirty-six open heart surgery (OH) and 26 coronary artery bypass grafting (CABG) patients were evaluated by neuropsychological and transcranial Doppler tests. RESULTS: OH was associated with a significantly larger microembolic load in comparison to CABG. In OH patients, the microembolic load at the left middle cerebral artery correlated with a verbal memory decline, whereas the microembolic load at the right middle cerebral artery correlated with a nonverbal memory deficit. CABG patients also showed a postoperative verbal memory decline which correlated with cardiopulmonary bypass length but not with microembolic load. CONCLUSION: Massive microembolic load during OH induces specific cognitive impairment in accordance to the brain region to which they are delivered. In atherosclerotic patients, the left temporal region is especially prone to perioperative ischemia.

EEG correlates of Wechsler Adult Intelligence Scale.

It was recently shown that cognitive functions requiring more widespread brain integration relate to slower EEG activity, whereas cognitive performance supported by local brain integration is associated with faster EEG components (Von Stein & Sarnthein, 2000). Associations were studied between performance on WAIS and resting EEG spectral parameters in heroin abusers and normal young males. The most prominent associations between WAIS and EEG variables were consistently registered in polar and lateral frontal/temporal derivations. WAIS subtests predominantly loading on retrieval from long-term memory stores were significantly associated with delta bands mean frequencies. Subtests with strong working memory component related to theta2 mean frequency at temporal leads. Subtests requiring problem-solving operations correlated with alpha bands parameters, whereas psychomotor speed was associated with beta power. The data are in agreement with the hypothesis of Von Stein & Sarnthein (2000).

Neural correlates of cognitive dysfunction after cardiac surgery.

Patients who underwent cardiac surgery and their relatives often complain on postoperative memory impairment. Most prospective neuropsychological studies also found postoperative cognitive decline early after surgery. Nevertheless, recently several reports questioned the existence of long-term brain alterations in these patient cohorts. The present review was aimed to clear up the true cardiac surgery effects on brain and cognitive functions. The reviewed data evidence that cardiac surgery interventions induce persistent localized brain ischemic lesions along with rapidly reversing global brain swelling and decreased metabolism. A range of studies showed that left temporal region was especially prone to perioperative ischemic injury, and these findings might explain persistent verbal short-term memory decline in a considerable proportion of cardiac surgery patient cohorts. Speed/time of cognitive performance is commonly decreased early after on-pump surgery either. Nevertheless, no association between psychomotor speed slowing and intraoperative embolic load was found. The rapid recovery of the latter cognitive domain might be better explained by surgery related acute global brain metabolism changes rather than ischemic injury effects. Hence, analyses of performance on separate cognitive tests rather than summarized cognitive indexes are strongly recommended for future neuropsychological studies of cardiac surgery outcomes.

Heroin abusers' performance on the Tower of London Test relates to the baseline EEG alpha2 mean frequency shifts.

Planning function deficit is the most consistent finding in neuropsychological studies of heroin addicts. The performance on the Tower of London Test (TLT) correlated with the duration of daily heroin abuse (DDHA) in our previous study. Alpha2 mean frequency in anterior/central derivations was also predicted by DDHA in the same patient population. This retrospective study was undertaken in order to understand better the relationships between observed neurological deviations in heroin abusers. Thirty-three heroin addicts and 12 healthy males were evaluated with 14 neuropsychological tests and resting eyes-closed electroencephalography (EEG). Multivariate tests showed that performance on the difficult (five-move) problems of TLT was strongly predicted by the EEG alpha2 mean frequency shifts, and these relationships were generally mediated by chronic heroin length. However, post-hoc analyses at separate leads demonstrated that the relationships between cognitive variables and alpha2 mean frequencies in the left hemisphere were independent of chronic heroin effects, whereas elevation of alpha2 frequency in the right hemisphere was strongly predicted by chronic heroin intake length. The patients with extremely high alpha2 mean frequency at the left central region were especially prone to failure in TLT due to the inability of the hypothesized alpha2-generating network, which normally projects to the central and temporal derivations bilaterally and to the right posterior temporal derivation to function appropriately. Hence, it was concluded that planning dysfunction in heroin abusers is related to alpha2 mean frequency shifts predominantly at the central regions.

EEG spectral power and mean frequencies in early heroin abstinence.

The purpose of the present study was to investigate cumulative heroin effects on brain functioning by studying relationships among electroencephalography (EEG) spectral power and mean frequencies and heroin abuse history. Eyes-closed resting EEG data were collected from the 19 monopolar electrode sites in 33 heroin abusers and 13 age-matched healthy volunteers. The mean age of the patients was 23.1+/-4.5 years, the duration of daily heroin abuse (DDHA) ranged from 4 to 44 months, the intravenous doses of heroin ranged from 0.04 to 1.00 g/day, the abstinence length ranged from 6 days to 4.5 months. General linear model (GLM) repeated measures procedure revealed a significant group effect on the distribution of the mean power spectrum between bands and mean frequencies in almost all analyzed derivations. Further analysis demonstrated that these intergroup differences were diversely related to at least three aspects of heroin-taking history. Frequency shifts in alpha2 range, most prominent in frontal and central derivations, were related to duration of daily heroin consumption. Slowing of alpha1 mean frequency, most prominent in central, temporal, and occipital derivations, was registered mainly in heroin addicts who abused high doses of the drug. Spectral power characteristics of brain electrical activities in our patient population were strongly predicted by abstinence length. The present results give grounds to suppose that chronic heroin-taking induces neuronal oscillation frequency changes, which may contribute to the development of antisocial trends and some semantic processes disturbances in these patients. Supplementary neurophysiological deficit is characteristic for heroin addicts who takes high doses of the drug, however, its relation to heroin abuse remains unclear. Pronounced desynchronization is observed in acute heroin withdrawal, and spectral power characteristics tend to normalize almost completely during several weeks of abstinence.