technetium-tc-99m-exametazime and Hypoglycemia

Regional brain injury in three neonates with hypoglycemic encephalopathy are presented using serial 99mTc-hexamethyl propyleneamine oxime (HMPAO) SPECT and, for comparison, MRI. During the acute stage, both 99mTc-HMPAO SPECT and MRI reveal abnormalities in the posterior cerebrum. Technetium-99m-HMPAO SPECT reveals further areas of insult, for example the frontal lobes. The degree of hypoperfusion correlates with the clinical severity of hypoglycemia during the neonatal period and subsequent neurological sequelae. Follow-up with HMPAO SPECT several months after insult demonstrates persistent hypoperfusion in some areas, mainly in the occipital and posterior parietal regions. MRI can depict morphological changes with superior resolution. Because morphological change generally follows slowly after functional change, MRI is less sensitive than HMPAO SPECT in detecting and predicting the extent of hypoglycemic cerebral injury during the acute phase. HMPAO SPECT during the acute stage is a valuable tool for evaluating the extent and severity of brain injury in neonates with hypoglycemic encephalopathy.

Topics: Brain; Brain Damage, Chronic; Cerebrovascular Circulation; Female; Follow-Up Studies; Humans; Hypoglycemia; Infant, Newborn; Magnetic Resonance Imaging; Male; Radiopharmaceuticals; Technetium Tc 99m Exametazime; Time Factors; Tomography, Emission-Computed, Single-Photon

The study was performed to investigate subclinical abnormalities in regional cerebral blood flow (rCBF) in patients with insulin-dependent diabetes mellitus (IDDM) and to correlate them with patients characteristics. After intravenous injection of technetium-99m hexamethylpropylene amine oxime (HMPAO), tracer uptake of the prefrontal, frontal and parieto-occipital zones was measured with a triple-head single-photon emission tomography (SPET) camera system in 35 IDDM patients outside an episode of hypoglycaemia. Tracer uptake values in 16 age- and sex-matched healthy volunteers served as reference values. Compared with healthy subjects, increased tracer uptake of both prefrontal regions and the left frontal region could be shown in diabetes. Tracer uptake was negatively correlated with the duration of diabetes in all investigated regions. In diabetic patients with a disease duration of more than 5 years (n=26), stepwise regression analysis revealed a significant positive correlation between their HbA1c levels and tracer uptake. Long-term diabetic patients with reduced (pre)frontal tracer uptake (n=8) had lower HbA1c levels than those without (8.4%+/-0.2% vs 9.3%+/-0.3%, P<0.05) and tended to have more frequently a history of hypoglycaemic coma (6/8 vs 6/18, P=0.06). It can be concluded that duration of diabetes contributes to subclinical changes in basal rCBF in IDDM as detected with HMPAO SPET of the brain. The positive correlation between the presence of regional hypoperfusion and lower HbA1c levels in long-term diabetic patients may be interpreted in the light of a presumed higher incidence of hypoglycaemia as metabolic control improves.

Topics: Adult; Brain; Case-Control Studies; Cerebrovascular Circulation; Diabetes Mellitus, Type 1; Female; Glycated Hemoglobin; Humans; Hypoglycemia; Male; Organotechnetium Compounds; Oximes; Regression Analysis; Technetium Tc 99m Exametazime; Time Factors; Tomography, Emission-Computed, Single-Photon

Regional distribution of cerebral blood flow was determined semi-quantitatively with 99Tcm-HMPAO brain SPET under basal conditions in Type 1 (insulin-dependent) diabetic patients of recent onset and longer disease duration, and related to metabolic control and history of hypoglycaemic events. Long-term diabetic patients showed significantly more alterations in regional cerebral blood flow than diabetics of recent onset and healthy controls. Regional hypoperfusion, predominantly localized in the fronto-temporal cortex, was almost exclusively observed in patients with long-term diabetes. The latter finding was related to lower HbA1c levels (i.e. better metabolic control) and to the frequency of impending hypoglycaemia, but not to age of the patient, duration of diabetes or to chronic diabetes complications. The incidence of hypoperfusion was comparable in patient groups with or without a medical history of hypoglycaemic coma. However, regions of hypoperfusion were larger in the patients who had experienced hypoglycaemic coma. It is concluded that regional cerebral hypoperfusion in long-term Type 1 (insulin-dependent) diabetics, as evidenced by HMPAO-SPET can be related to the frequency and degree of hypoglycaemic events and to tight metabolic control, which is however at the expense of an increased risk of recurrent hypoglycaemia.

Topics: Adult; Age of Onset; Blood Glucose; Brain; Cerebral Cortex; Cerebrovascular Circulation; Cohort Studies; Diabetes Mellitus, Type 1; Glycated Hemoglobin; Humans; Hypoglycemia; Insulin Coma; Organotechnetium Compounds; Oximes; Prevalence; Radionuclide Imaging; Reference Values; Regression Analysis; Technetium Tc 99m Exametazime

The effect of the paced auditory serial addition test (PASAT) on the regional uptake of 99mTc-exametazime was determined by single photon emission computed tomography. Twenty insulin-treated diabetic outpatients were scanned at rest and during the performance of the PASAT task using split-dose injection of tracer. When resting and activation scans were compared there were significant decreases in tracer uptake in the right anterior cingulate and left posterior cingulate areas during PASAT activation. The findings are compared with previous studies which had implicated the anterior cingulate area in the mechanisms of attention in humans and other animals. The potentially confounding role of anxiety during attentional tasks is discussed.

Topics: Adult; Anxiety; Arousal; Attention; Blood Glucose; Brain; Brain Mapping; Diabetes Mellitus, Type 1; Dominance, Cerebral; Female; Gyrus Cinguli; Humans; Hypoglycemia; Male; Middle Aged; Organotechnetium Compounds; Oximes; Problem Solving; Reaction Time; Regional Blood Flow; Serial Learning; Technetium Tc 99m Exametazime; Tomography, Emission-Computed, Single-Photon

Chronic hyperglycaemia and recurrent severe hypoglycaemia have both been implicated as causing cerebral damage in patients with diabetes. Although cognitive dysfunction and intellectual impairment have been demonstrated in patients with recurrent severe hypoglycaemia, structural correlates have not been described, and it is not known whether specific functional changes occur in the brains of affected patients. Regional cerebral blood flow was estimated by SPECT with 99mTechnetium Exametazime in 20 patients with IDDM. Ten patients had never experienced severe hypoglycaemia and 10 had a history of recurrent severe hypoglycaemia. Patient results were compared with 20 age- and sex-matched healthy volunteers. We observed differences between the two patient groups and the control group. Tracer uptake was greater in diabetic patients in the superior pre-frontal cortex. This effect was particularly pronounced in the group who had a history of previous severe hypoglycaemia. Patients with a history of recurrent hypoglycaemia also had a relative reduction in tracer uptake to the calcarine cortex. This suggests an alteration in the pattern of baseline regional cerebral blood flow in diabetic patients with frontal excess and relative posterior reduction in cerebral blood flow.

Topics: Adult; Analysis of Variance; Cerebrovascular Circulation; Cognition; Diabetes Mellitus, Type 1; Female; Humans; Hypoglycemia; Male; Middle Aged; Organotechnetium Compounds; Oximes; Recurrence; Technetium Tc 99m Exametazime; Tomography, Emission-Computed, Single-Photon