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Biomedical subjects

M D Devous

Publications and source records attributed to M D Devous.

At least 19 recordsLinked to original sources
PubMed1997

Evaluation of neurologic function in Gulf War veterans. A blinded case-control study.

OBJECTIVE: To determine whether Gulf War-related illnesses are associated with central or peripheral nervous system dysfunction. DESIGN: Nested case-control study. PARTICIPANTS: Twenty-three veterans with factor analysis-derived syndromes (the cases), 10 well veterans deployed to the Gulf War (the deployed controls), and 10 well veterans not deployed to the Gulf War (the nondeployed controls). METHOD: With investigators blinded to group identities, participants underwent objective neurophysiological, audiovestibular, neuroradiological, neuropsychological, and blood tests. MAIN OUTCOME MEASURES: Evidence of neurologic dysfunction. RESULTS: Compared with the 20 controls, the 23 cases had significantly more neuropsychological evidence of brain dysfunction on the Halstead Impairment Index (P=.01), greater interside asymmetry of the wave I to wave III interpeak latency of brain stem auditory evoked potentials (P=.02), greater interocular asymmetry of nystagmic velocity on rotational testing, increased asymmetry of saccadic velocity (P=.04), more prolonged interpeak latency of the lumbar-to-cerebral peaks on posterior tibial somatosensory evoked potentials (on right side, P=.03, and on the left side, P=.005), and diminished nystagmic velocity after caloric stimulation bilaterally (P values range from .02 to .04). Cases (n=5) with syndrome 1 ("impaired cognition") were the most impaired on brain stem auditory evoked potentials (P=.005); those (n=13) with syndrome 2 ("confusion-ataxia") were the most impaired on the Halstead Impairment Index (P=.006), rotational testing (P=.01), asymmetry of saccadic velocity (P=.03), and somatosensory evoked potentials (P< or =.01); and those (n=5) with syndrome 3 ("arthro-myo-neuropathy") were the most impaired on caloric stimulation (P< or =.01). CONCLUSIONS: The 3 factor-derived syndromes identified among Gulf War veterans appear to represent variants of a generalized injury to the nervous system.

Adult↗
PubMed1997

Brain single-photon emission CT with HMPAO and safety of thrombolytic therapy in acute ischemic stroke. Proceedings of the meeting of the SPECT Safe Thrombolysis Study Collaborators and the members of the Brain Imaging Council of the Society of Nuclear Medicine.

BACKGROUND: To reliably identify patients at risk for symptomatic hemorrhagic transformation (SHT), future trials of thrombolysis for acute ischemic stroke might use a vascular imaging protocol applicable to a multicenter setting. The goal of this commentary is to address the safety of intravenous thrombolysis with the recombinant tissue plasminogen activator (rTPA) and potential solutions offered by single-photon emission CT (SPECT) as a noninvasive brain perfusion imaging modality. SUMMARY OF REVIEW: Even if patients with severe stroke, extensive ischemic changes on CT scan, advanced age, and high blood pressure are excluded from thrombolytic therapy, this cannot completely guarantee the safety of using rTPA. Brain SPECT scanning with hexamethylpropyleneamine-oxime (HMPAO) may help to screen out patients at risk if performed in addition to clinical and CT tests. The knowledge of pretreatment severity, extent, and location of ischemia might identify good versus poor responders to rTPA therapy. HMPAO-SPECT is widely available and feasible to perform without delaying rTPA therapy. Rigorous quality control and use of reproducible visual and semiquantitative methods of interpreting SPECT are necessary for implementation of SPECT technology in multicenter clinical trials. CONCLUSIONS: The major obstacle to general acceptance of thrombolytic therapies and rTPA in particular is the fear of symptomatic hemorrhagic transformation, and because HMPAO-SPECT might reliably identify patients at high risk of symptomatic hemorrhagic transformation, the clinical value of HMPAO-SPECT in patient selection for thrombolysis during the first hours of acute ischemic stroke should be determined through a prospective clinical trial.

Acute Disease↗
PubMed1996

Effects of four normalizing methods on data analytic results in functional brain imaging.

Functional brain imaging data may contain large individual differences in information about whole brain and regional levels of activity, and it is common to remove these differences using arithmetic transformation (normalization) prior to statistical analysis. As no single transformation is widely accepted, we examine the effects of four normalizing methods (ratioing, residuals from regressions on global cerebral blood flow, Z scores, and subject residual profiles) on 1) profile shape, 2) correlations between regions, 3) correlations between subjects, and 4) analysis of variance results. These effects are evaluated using an empirical data set consisting of regional cerebral blood flow values from 22 regions of interest in 46 depressed adults and 48 age-matched normal controls obtained by 133Xe single photon emission computed tomography. Results show that normalization method has substantial but different effects on characteristics of the data and statistical results. The rationing method appears to be an optimal choice for most analyses.

Adult↗
PubMed1996

Wisconsin card sorting activated regional cerebral blood flow in first break and chronic schizophrenic patients and normal controls.

Dynamic 133Xe single photon emission computed tomography (SPECT) was used to measure regional cerebral blood flow (rCBF) during the Wisconsin Card Sorting test (WCS) and the Number Matching task (NM) in six never-medicated first break schizophrenic and schizophreniform patients, seven chronic schizophrenic patients, and seven normal controls. Because of a difference in mean age between first break patients and normals, we adjusted rCBF data for age effects using ANCOVA. For age-adjusted absolute superior and middle frontal rCBF bilaterally, we found significantly less activation from NM to WCS in first break patients compared to normals. Similarly, for age-adjusted absolute and relative left middle frontal rCBF, we found significantly less activation in chronics compared to normals. Changes in age-adjusted global cerebral blood flow (gCBF) were not statistically significant among the three groups, but were in the same direction as activated absolute frontal rCBF. Because of the small number of subjects in each group, the results of this study should be regarded as preliminary and interpreted cautiously.

Adolescent↗
PubMed1996

Comparison of technetium-99m-HMPAO and xenon-133 measurements of regional cerebral blood flow by SPECT.

UNLABELLED: This study compares 99mTc-HMPAO count ratios and derived regional cerebral blood flow (rCBF) to 133Xe rCBF ratios and true rCBF (ml/min/100 g), respectively. METHODS: Technetium-99m-HMPAO distribution was evaluated in 14 patients and 5 normal control subjects. Immediately after 133Xe SPECT, subjects received 22 +/- 4mCi 99mTc-HMPAO, and images were acquired 15 min after injection. rCBF (ml/min/100 g, 133Xe) or regional count density (99mTc-HMPAO) were extracted from 24 ROI located 6 cm above the cantho-meatal line. These data were also normalized to global cerebral blood flow (gCBF) for 133Xe or to global count density (gCD) for 99mTc-HMPAO. Technetium-99m-HMPAO ROI data also were expressed in units of ml/min/100 g by relating gCD to gCBF. Comparisons between 133Xe and 99mTc-HMPAO were evaluated using a Bonferroni-corrected paired t-test and by linear regression analysis. RESULTS: Profile plots demonstrated agreement in the pattern of relative distribution between rCBF ratios (133Xe) and count density ratios (99mTc-HMPAO). Regression analysis indicated a significant correlation (r = 0.78), with a modest slope (0.52) and a large intercept (0.48). A closer correlation (r = 0.92) was found for the comparison between rCBF (133Xe) and derived 99mTc-HMPAO rCBF. The slope was closer to one (0.82) and the intercept closer to zero. This relationship was also examined during high rCBF after a subset of these subjects (n = 7) was injected intravenously with 1 g acetazolamide. Again, profile plots and regression analysis demonstrated agreement in the pattern of distribution (ratios) between 133Xe and 99mTc-HMPAO (r = 0.66). However, the slope was reduced and the intercept increased relative to resting data. Absolute flow correlations showed some improvement relative to the ratio data (r = 0.77). CONCLUSION: The distribution of 99mTc-HMPAO is linearly related to rCBF measured by 133Xe SPECT, although our data suggest that 99mTc-HMPAO mildly underestimates rCBF above 80 ml/min/100 g. These results are similar to our previous comparison of 99mTc-ECD and 133Xe.

Adult↗
PubMed1995

Cerebellar blood flow in schizophrenic patients and normal control subjects.

We used 133Xe dynamic single-photon emission computed tomography (DSPECT) to measure the resting cerebellar blood flow in 17 neuroleptic-free schizophrenic and schizophreniform patients and 13 normal control subjects. A subset of these subjects (11 patients and 7 control subjects) additionally underwent activation studies during the Wisconsin Card Sorting (WCS) and Number Matching (NM) tests. Baseline relative cerebellar blood flow was significantly lower in older patients than in age-matched control subjects. For absolute cerebellar flow, there was a significant difference between patients and control subjects in the overall activation response (patients: NM 13.4% increase, WCS 15.7% increase; control subjects: NM 3.1% decrease, WCS 0.0% change). This difference was more pronounced in older subjects. Cerebral blood flow significantly increased during NM (patients: 21.3% increase, control subjects: 6.5% increase) and WCS (patients: 16.5% increase, control subjects: 9.7% increase). The difference in the magnitude of cerebral NM activation between schizophrenic patients and control subjects, although not statistically significant, may call into question the appropriateness of using NM as a control task in schizophrenic patients. Finally, we found no differences between the effects of WCS and NM on cerebellar or cerebral blood flow. Because of the small number of subjects in each group, the results of this study should be interpreted cautiously.

Adult↗
PubMed1995

SPECT functional brain imaging. Technical considerations.

The technical aspects of functional brain single-photon emission computed tomography (SPECT) imaging, referring primarily to the most common SPECT brain function measure--regional cerebral blood flow--are reviewed. SPECT images of regional cerebral blood flow are influenced by a number of factors unrelated to pathology, including tomographic quality, radiopharmaceuticals, environmental conditions at the time of radiotracer administration, characteristics of the subject (e.g., age, sex), image presentation, and image processing techniques. Modern SPECT scans yield excellent image quality, and instrumentation continues to improve. The armamentarium of regional cerebral blood flow and receptor radiopharmaceuticals is rapidly expanding. Standards regarding the environment for patient imaging and image presentation are emerging. However, there is still much to learn about the circumstances for performances and evaluation of SPECT functional brain imaging. Challenge tests, primarily established in cerebrovascular disease (i.e., the acetazolamide test), offer great promise in defining the extent and nature of disease, as well as predicting therapeutic responses. Clearly, SPECT brain imaging is a powerful clinical and research tool. However, SPECT will only achieve its full potential in the management of patients with cerebral pathology through close cooperation among members of the nuclear medicine, neurology, psychiatry, neurosurgery, and internal medicine specialties.

Brain↗
PubMed1994

Linguistic performance and regional cerebral blood flow in persons who stutter.

In a series of studies regarding CNS dysfunction in stuttering, we have examined linguistic and motoric performance in the context of measures of brain function. Previous studies of adults with developmental stuttering identified alterations in brain function (metabolic and electrophysiologic) in cortical regions implicated in models of speech motor control and language processing. We also identified a sub-group of these subjects who exhibited linguistic performance deficits related to speech performance deficits. The present study examined the hypothesis that adults who stutter and who show linguistic performance deficits will also show metabolic alterations in cortical regions classically related to language processing, whereas adults who stutter but who do not show linguistic performance deficits will not show these cortical metabolic alterations. Significant relative blood flow asymmetry (left < right) was observed in middle temporal and inferior frontal cortical regions only for adults who both stuttered and showed linguistic performance deficits. Results support models that explicitly recognize that efficient integration of linguistic, motoric, and cognitive processes is critical to the production of oral/verbal fluency and to understanding sources of fluency failure.

Adult↗
PubMed1993

Regional cerebral blood flow alterations in unipolar depression.

Forty-seven symptomatic inpatients and outpatients with major depression (13 nonendogenous, 23 endogenous, and 11 psychotic by Research Diagnostic Criteria) were compared with 138 normal control subjects. Absolute regional cerebral blood flow (rCBF, ml/minute/100 g) was measured with 133Xe single photon emission computed tomography. Flow ratios (region of interest/global flow) and residual scores (the difference between patient flow ratios and expected normal flow ratios, as derived from the control population) were also computed. Results revealed significant age x region x depression subtype interactions for absolute, ratio, and residual flow data. Consequently, a test of group means (or analysis of covariance) could not be used to examine between-group differences. Multiple regression analyses were employed to study the effects of age on rCBF. This analysis revealed that different, though sometimes overlapping, regions exhibited different age effects on rCBF in different depressive subtypes. Thus, diagnostic-subtype-dependent age effects on rCBF precluded comparisons of mean values within or across regions for subject groups, but distinguished between symptomatic depressed patients and control subjects and among patient groups. Possible causes of such effects include variations in duration of illness or medication history or sensitization phenomena.

Adolescent↗
PubMed1993

Brain blood flow SPECT in temporary balloon occlusion of carotid and intracerebral arteries.

It is important to determine preoperatively which patients can tolerate permanent occlusion of a cervical internal carotid or cerebral artery when such a procedure may be necessary to treat cerebrovascular or neoplastic lesions. Here we report our experience in combining temporary intra-arterial balloon occlusion with concomitant cerebral blood flow imaging in preoperative evaluation of such patients. Forty-two patients with a variety of cerebrovascular and neoplastic lesions underwent trial balloon occlusion of an internal carotid or intracerebral artery. Eight patients developed both neurologic symptoms as well as brain perfusion defects during trial occlusion. Nine others developed only perfusion defects. The remainder were asymptomatic and had negative scans. Brain blood flow imaging during intra-arterial balloon occlusion identified 17 patients potentially at risk for developing postsurgical ischemic deficits. Treatment alternatives to acute arterial sacrifice were developed for these patients.

Adolescent↗
PubMed1993

Comparison of technetium-99m-ECD to Xenon-133 SPECT in normal controls and in patients with mild to moderate regional cerebral blood flow abnormalities.

Technetium-99m-1,1-ethyl cysteinate dimer (ECD) has been proposed as a "chemical microsphere" for SPECT measurement of regional cerebral blood flow (rCBF). However, its distribution has not yet been compared in humans to an established rCBF measure. Therefore, we compared the uptake and distribution of ECD with rCBF measured by 133Xe SPECT in subjects with mild to moderate flow abnormalities and in normal volunteers. Blood and urine chemistries and vital signs were unchanged from pre-ECD values up to seven days postinjection. Profile plots demonstrated pattern agreement between rCBF ratios (133Xe) and ECD count density ratios. A significant correlation of rCBF ratios to ECD count density ratios was observed (r = 0.77), with a slope of 0.64 and intercept of 0.36. To explore whether or not the relationship between rCBF and ECD was dependent on absolute flow, ECD region of interest data were expressed in units of ml/min/100 g by equating global CBF (133Xe) and ECD global count density. A closer correlation (r = 0.88) was found for these data than for the count ratio data. The slope was closer to one (m = 0.83) and the intercept was closer to zero (b = 8.2). Also, a significant correlation was observed between ECD-derived rCBF and 133Xe rCBF in the lesion area (r = 0.92) for patients with well-demarcated rCBF lesions. The slope (0.80) suggested a slight underestimation of lesion flow by ECD. Finally, ECD clearance from cortical gray matter ROIs derived from high-resolution scans from 1 to 4 hr postinjection was slow (2.4%/hr). In summary, ECD is a safe and effective marker of regional cerebral perfusion. The distribution of ECD is linearly related to rCBF measured by 133Xe SPECT, although our data suggest a mild underestimation of flow at the high end of the normal range.

Adult↗
PubMed1992

Brain blood flow related to acoustic laryngeal reaction time in adult developmental stutterers.

The 1980s witnessed renewed interest in the relation between developmental stuttering and central nervous system (CNS) abnormalities. We have reported differences between nonstutterers and developmental stutterers on electrophysiologic (QTE) and metabolic (rCBF) measures of brain function. A critical step in the interpretation of results of functional brain imaging studies is to determine the relation, if any, of identified CNS abnormalities to speech motor control in persons who stutter. In this study we addressed the interpretation of rCBF findings by asking whether we could identify patterns of impaired acoustic laryngeal reaction time (LRT) as a function of response complexity parallel to rCBF findings. Stutterer subgroups determined by clinical severity ratings were not differentiated by LRT values as a function of response complexity. Stutterers with relative blood flow asymmetry below the normal median value involving both left superior and middle temporal regions of interest (ROIs) showed significantly longer LRT for the complex response than did normal speakers and stutterers with above-normal median relative flow values to at least one of these temporal ROIs. Stutterer subgroups based on reduced cingulate flow alone were not differentiated by LRT values. Findings are consistent with Goldberg's (1985) model of CNS premotor processing. Findings also suggest that stutterer subgroups might be distinguished by the presence, loci, and relative magnitude of cortical and/or subcortical rCBF abnormality in regions that subserve a fluency-generating system.

Adult↗
PubMed1992

The use of acetazolamide-enhanced regional cerebral blood flow measurement to predict risk to arteriovenous malformation patients.

Regional hemodynamic disturbances may complicate the treatment of certain cerebral arteriovenous malformations (AVM) and occasionally produce life-threatening situations. Acetazolamide-enhanced quantitative regional cerebral blood flow studies were performed preoperatively in 35 patients to determine if patterns of vasoreactivity could be identified that might be markers for postoperative morbidity. Ipsilateral and contralateral regions of hypoperfusion were identified on resting studies, and a steal index was calculated by dividing the regional cerebral blood flow in the steal region by the flow in a normal cerebellar region. Flow in these regions of interest was again quantitated after the administration of acetazolamide, a known cerebral vasodilator. A delta value was calculated by subtracting the resting index values from the acetazolamide indices. Abnormally enhanced vasoreactivity (vasodilation) to acetazolamide stimulation was noted in these threatened territories in AVM that had perforating vessel feeding and angiographic steal phenomena, that developed hyperemic disturbances, and that resulted in poor outcomes. These findings call into question traditional theories of AVM-related hemodynamic decompensation and suggest unique smooth muscle derangements in cerebral vasculature in some AVM patients.

Acetazolamide↗
PubMed1992

Dual-isotope brain SPECT imaging with technetium-99m and iodine-123: clinical validation using xenon-133 SPECT.

Our phantom studies indicate that the energy resolution (9.7% FWHM) of a new three-headed single-photon tomograph (PRISM-3000) separates the distribution of 99mTc from 123I for 10% asymmetric or 15% or 10% centered 99mTc windows when combined with a 10% asymmetric 123I window. This technique is now applied to the simultaneous measurement of resting rCBF and changes induced by vasodilation (1 g acetazolamide) in 10 subjects with cerebrovascular disease. Resting and vasodilated 133Xe SPECT images were obtained first. Within 48 hr, 99mTc HMPAO was given at rest, acetazolamide injected, and after 20 min either [123I] IMP or [123I] HIPDM was administered. Subjects were scanned for 99mTc and 123I simultaneously using 10% asymmetric windows. Regression analyses demonstrated a linear relationship between 133Xe SPECT and dual-isotope SPECT measurements of lesion-to-cerebellum ratios in baseline (r = 0.92), vasodilated (r = 0.86) and rest-minus-vasodilated data (r = 0.85). Technetium-99m and 123I images obtained through dual-isotope imaging are by definition in perfect anatomic registration.

Acetazolamide↗