Xenon/CT quantitative local cerebral blood flow.
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Cerebrovascular Circulation↗
Biomedical subjects
M Gaviria
Publications and source records attributed to M Gaviria.
Do we evaluate outcome appropriately?
We discuss two different ways of measuring outcome in a sample of 20 patients who had intracranial aneurysm surgery. Patients were evaluated at discharge using the Karnofsky Scale and the Glasgow Outcome Scale. Six months after discharge we conducted a neuropsychiatric evaluation including cognitive, behavioral, and mood status assessment. Although 13 of our patients had a "good recovery', 18 had some neuropsychiatric impairment. We did not find statistical relationships between the discharge evaluation and the neuropsychiatric assessment at follow-up. We discuss the need for developing new outcome measures to pick-up neuropsychiatric deficits, beyond the traditional neurologic semiology.
Adult↗
Selective deficit of one language in a bilingual patient following surgery in the left perisylvian area.
We report on a right-handed bilingual patient with a left perisylvian arteriovenous malformation that caused a mild naming deficit evident only on formal language testing in both languages. Sodium amytal injected in the left carotid artery (Wada test) before surgery resulted in speech arrest for both languages. Following surgery for removal of the lesion she developed additional deficits in her native language without alteration in her second language. Selective impairment in one language after surgery demonstrates that each language has different anatomical representation within the perisylvian dominant area.
Adult↗
Successful methylphenidate treatment of apathy after subcortical infarcts.
A patient with prominent apathy secondary to multiple subcortical infarcts was treated successfully with methylphenidate. SPECT and reaction time testing showed selective improvement of frontal system function, consistent with a recent model of frontal-subcortical circuits and behavior.
Activities of Daily Living↗
Postoperative cognitive and single photon emission computed tomography assessment of patients with resection of perioperative high-risk arteriovenous malformations.
We studied the outcome of 10 patients who had undergone high-risk surgery for an arteriovenous malformation at our institution between November 1991 and November 1993. All of the lesions were located in the dominant (left) hemisphere. Perioperative risk was assessed by the location of the lesion in functionally eloquent cortex (seven patients) or deep structures (two patients) or the lesion's large volume (two patients). Our patients included six women and four men, and their ages ranged from 22 to 53 years (mean, 35.8). Our follow-up study included the evaluation of neurological sequelae but mainly emphasized the study of cognitive deficits (seven major functional clusters), the incidence of depression and behavioral changes, and the assessment of regional cerebral blood flow with single photon emission computed tomography. Six patients returned to a seemingly "normal" daily life with some minor deficits postoperatively, three developed contralateral hemiparesis, and one had disabling cognitive deficits. Our comprehensive cognitive assessment, in particular, showed that although patients might appear "normal" on a routine neurological examination, most patients showed a mild deficit in at least one cognitive function and three were severely impaired. In addition, the single photon emission computed tomographic studies pointed out hypoperfusion in more extensive regions than the surgical defects shown by magnetic resonance imaging or computed tomographic studies. These single photon emission computed tomography images helped to explain some of the cognitive and behavioral changes better than the anatomic studies. This information will make it possible for the physician to offer continuing supportive care for the patient in postoperative transition to normal life activities.
Adult↗
Neuropsychiatric sequelae of ischaemic cerebrovascular disease: clinical and neuroanatomic correlates and implications for the concept of dementia.
Neuropsychiatric disturbances along the continuum of cognitive disturbances in ischaemic cerebrovascular disease are reviewed and their neuroanatomic correspondences are explored. Depression, apathy, disinhibition, and delusions are common in ischaemic, cerebrovascular disease. Delirium, hallucinations, confabulations, akinesia, pathological affect, anxiety, and catastrophic reaction are less common, while manic syndromes appear rarely. Many of these neuropsychiatric syndromes remain poorly delineated. The presence of neuropsychiatric disturbance may not be correlated with the degree of cognitive disturbance. The implications of this finding for the concept of dementia are explored. The authors conclude that neuropsychiatric disturbances should be considered essential features of dementia.
Affect↗
A theory of cooperativity modulation in neural networks as an important parameter of CNS catecholamine function and induction of psychopathology.
Recent research in computational neuroscience has suggested that psychosis associated with disturbed catecholamine neurotransmission may result from disturbances in the gain parameters of neural networks that these same secondary neurotransmitters are thought to control. We propose a mathematical model based upon cooperativity theory used in thermodynamics to explain how the gain parameter that momentarily increases the effect upon the post-synaptic cell of a given weighted connection from the presynaptic cell could be instantiated in the fluctuating electrical conductance of the dendrite of a neuron without requiring extensive ion transport or utilization of the ATP energy cycle. More specifically we propose that catecholamine neurotransmission serves to maintain the dendrite in a cooperative state with regard to changes in electrical conductance due to impulse traffic alone. In this way we supply the neuron with an activity driven gain parameter that not only increases volume of neuronal output at very low energy cost but that also upscales cooperative effects at the mechanico-chemical level of the dendrite to the network level itself. An important implication of this model is that two extreme states for dendritic electrical conductance will occur if cooperativity is lost at the level of catecholamine depletion or excess due to drug effects. These are the AND gate effect in which dendritic conductance is so low that the neuron requires extensive synaptic activity in order to output significantly. We correlate this state with negative symptoms in schizophrenia and psychomotor retardation in depression as well as the rigidity in Parkinsonism. The other extreme is represented by the OR gated dendrite in which conductance is so high that even noisy input to the dendrite will lead to significant nerve cell output. We correlate this condition with the positive symptoms of schizophrenia, the agitated features of psychotic depression and the tremors of Parkinsonism.
Animals↗
Comparative study of two transport systems for Vibrio cholerae.
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Culture Media↗
Associated diagnoses (comorbidity) in patients with borderline personality disorder.
The authors administered the Diagnostic Interview Schedule to 21 patients with borderline personality disorder. The patients met criteria for various other DSM-III diagnoses, meeting exclusion criteria in some cases, and not in other cases. Frequency distribution of each diagnosis and the diagnoses of each individual patient, are presented. Affective disorder was the most common diagnosis (85%). Of these, 62% had primary major depression, and 23% had secondary depression. Other diagnoses include bipolar disorder, dysthymia, panic, agoraphobia, alcohol and Drug abuse, somatization disorder, and many others. The authors conclude that while borderline disorder may be a sub-affective disorder, a specific diagnostic profile for this disorder that accounts for the presence of other Axis I and Axis II syndromes has yet to be delineated.
Adult↗
Panic disorder is borderline personality disorder.
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Adult↗
The process of acculturation: theoretical perspectives and an empirical investigation in Peru.
World-wide migratory patterns have led to an increasing interest in acculturation processes and their psychosocial and psychiatric sequelae. This paper reviews alternative theoretical approaches to the study of acculturation and identifies gaps in the current knowledge base. We then present empirical research on acculturation processes experienced by both Indian rural to urban migrants and White-Mestizo non-migrants in Lima, Peru. The study examined overall acculturation and five sub-dimensions: language use, customs, sociability, perceived discrimination and ethnic identity. The data show that second generation migrants are more highly acculturated across sub-areas and perceive less ethnic discrimination than first generation migrants. The first generation varied in acculturative level across sub-dimensions as a function of their age at the time of migration. Contrasts between the migrant and dominant group depicted a two-way process of culture change, but a process characterized by an inequality in the content exchanged in each direction. Socio-demographic correlates of acculturation were also found. These results are discussed in terms of the potential psychological consequences of alternative acculturative adaptations within the Peruvian social-structural context.
Acculturation↗
Prevalence, pathogenesis, and treatment of renal dysfunction associated with chronic lithium therapy.
From the analysis of several studies published from 1979 to 1986 comprising 1,172 patients, we estimated that glomerular filtration rate (GFR) was normal in 85% of unselected patients on chronic lithium therapy. The remaining 15% of patients displayed only mild reduction in GFR, clustering at approximately 60 mL/min. Thus, the data available to date do not support earlier concerns that long-term lithium therapy could eventuate into renal insufficiency. The most prevalent renal effect of lithium is impairment of concentrating ability, which we estimated to be present in at least 54% of 1,105 unselected patients on chronic lithium therapy. This defect translated into overt polyuria in only 19% of unselected cases. A renal lesion confined to the collecting tubule has been described in humans who have taken lithium for short periods of time. This lesion may represent the collecting tubule's response to the intracellular accumulation of lithium, which interferes with cAMP formation and results in an early and probably reversible inhibition of antidiuretic hormone (ADH)-mediated water transport. However, long-term lithium therapy may induce a progressive and partly irreversible defect in concentrating ability. The potential risk for dehydration associated with lithium-induced polyuria, as well as the discomfort inherent to this side effect, deserves evaluation and consideration for therapeutic intervention. Amiloride has additional advantages over conventional treatment of nephrogenic diabetes insipidus using thiazide diuretics. The action of amiloride on ADH-mediated water transport seems specific in as much as it is capable of preventing the uptake of lithium in high resistance epithelia and thereby prevents the inhibitory effect of intracellular lithium on water transport. Unlike thiazides, amiloride has a weak natriuretic effect and is less likely to increase plasma lithium levels by causing volume contraction. In addition, amiloride, by conserving potassium, obviates the need for potassium supplementation that is usually required to prevent hypokalemia when thiazides are used to treat lithium-induced polyuria. Since amiloride may prevent chronic intracellular lithium accumulation in the collecting tubule, future studies should elucidate whether amiloride also has a role in preventing lithium-induced chronic tubulo-interstitial damage.
Acidosis, Renal Tubular↗
Nortriptyline kinetics in Hispanic and Anglo subjects.
Nortriptyline kinetics are compared between 10 Hispanic and 10 Anglo healthy, nondepressed volunteers matched for age, sex, and weight. All subjects were given a single oral dose of 75 mg of nortriptyline, and blood samples were drawn at various times over the next 96 hours. Nortriptyline concentration in plasma was determined by gas chromatography with nitrogen detector. From the nortriptyline concentration in plasma and time curve, various kinetic parameters were computed for each individual. There were large interindividual differences in various kinetic parameters. However, no statistically significant differences were found in any of the kinetic parameters between the Hispanic and Anglo groups. These results suggest that there are no major differences in pharmacokinetics and that purported hypersensitivity in Hispanic depressed patients to antidepressant treatment may be due to receptor hypersensitivity.
Absorption↗
Amelioration of polyuria by amiloride in patients receiving long-term lithium therapy.
Vasopressin-resistant diabetes insipidus is a common side effect of the treatment of affective disorders with lithium. We studied the effect of amiloride on lithium-induced polyuria in nine such patients receiving maintenance lithium therapy who had a vasopressin-resistant defect in urinary concentrating ability. After a mean (+/- S.E.) of 24 +/- 6 days of amiloride administration, the urine volume fell (from 4.7 +/- 0.6 to 3.1 +/- 0.3 liters per 24 hours; P less than 0.005), and the urine osmolality increased (from 228 +/- 35 to 331 +/- 34 mOsm per kilogram of H2O; P less than 0.001). The decrease in urine output was sustained during six months of observation in the absence of any significant change in plasma levels of lithium, potassium, or bicarbonate; urinary excretion of sodium or lithium; or creatinine clearance. Amiloride administration was also associated with a significant increase in urine osmolality (from 575 +/- 54 to 699 +/- 48 mOsm per kilogram of H2O; P less than 0.005) measured after fluid deprivation and the injection of exogenous vasopressin. We conclude that amiloride mitigates lithium-induced polyuria, at least partly, by blunting the inhibitory effect of lithium on water transport in the renal collecting tubule. Thus, amiloride may provide a specific therapy for polyuria in lithium-treated patients while obviating the need for potassium supplementation in the treatment of this kind of polyuria.
Adult↗
Pharmacologic evidence for specificity of pursuit dysfunction to schizophrenia. Lithium carbonate associated with abnormal pursuit.
Conflicting findings regarding the prevalence of abnormal smooth-pursuit eye movements in patients with major affective disorders call into question the specificity of impaired smooth-pursuit eye movements to schizophrenia. We report that pursuit is impaired in 88% of lithium carbonate-treated affective disorder patients whose pursuit was normal prior to receiving this drug. Over half of lithium carbonate-treated affective disorder patients in remission also showed impairment of smooth-pursuit eye movements. In conjunction with recent prevalence data on family members of psychiatric patients, the findings support the specificity of abnormal pursuit as a biological trait associated with schizophrenia, but not with the major affective disorders. The mechanisms by which lithium carbonate impairs pursuit are discussed.
Adult↗
Relatives of unipolar and bipolar patients have normal pursuit.
Impaired smooth pursuit eye movements are significantly less prevalent among the first-degree relatives of patients who have major affective disorders than among the first-degree relatives of schizophrenics. The distribution of normal and abnormal smooth pursuit among the relatives of unipolar and bipolar patients does not differ from that of normal individuals having no family history of major psychosis. Smooth pursuit impairment is thus specific to relatives of schizophrenic patients and is not characteristic of relatives of patients with major affective disorders.
Adult↗
Relapse of depression during continuation treatment: three clinical vignettes.
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Adult↗
Distal renal tubular acidosis with intact capacity to lower urinary pH.
The sine qua non for the diagnosis of distal renal tubular acidosis requires that the urinary pH cannot decrease maximally during systemic acidosis. A defect in distal acidification however, could also result from a decrease in the capacity (or rate) of distal hydrogen ion secretion. In this type of defect, the ability to lower the urinary pH during acidemia could be preserved as long as a certain capacity for hydrogen ion secretion remained. In this report, we describe four patients with deranged distal urinary acidification, in whom urinary pH was able to decrease (4.99 +/- 0.11) during acidemia. One of the patients had hyperchloremic metabolic acidosis whereas the remaining three were not spontaneously acidotic. In these patients, the defect for distal urinary acidification was disclosed by the inability of the urine-blood pCO2 gradient to increase normally (i.e., above 30 mm Hg) during bicarbonate loading. In contrast, a normal increase in the urine-blood pCO2 gradient was observed in each patient in response to neutral sodium phosphate infusion. The reabsorptive capacity of bicarbonate was not depressed in these patients, which indicated that the acidification process in the proximal nephron was intact. We propose that our four patients had a defect in distal urinary acidification caused by a reduction in the rate of distal hydrogen ion secretion rather than an inability to generate a steep pH gradient across the distal nephron. Our data also suggest that the inability to raise urinary pCO2 normally during sodium bicarbonate loading may be the most sensitive index of decreased distal urinary acidification available.
Acidosis, Renal Tubular↗