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Early Detection of Neurological Involvement in IDDM and NIDDM: Multimodal Evoked Potentials Versus Metabolic Control

Clarification of the extent and mechanisms of damage to the central nervous system in diabetes is a frontier of current neurological research. Our aim was to obtain ample electrophysiological documentation of possible neurological abnormalities in both insulin-dependent (IDDM) and non-insulin-dependent (NIDDM) diabetic patients with a short duration of disease and without overt complications, taking into account metabolic control. Group 1 comprised 11 IDDM patients, and group 2 included 14 NIDDM patients treated with diet alone; the duration of disease was <4 yr, and no concomitant clinicalcomplications were present. Age and sex-matched normal subjects formed groups 3 and 4. Pattern visual evoked potentials (VEP), brain stem auditory evoked potentials (BAEP), and somatosensory evoked potentials (SEP; after the stimulation of both median and tibial nerves) were recorded in all subjects, and metabolic control was evaluated in terms of glycemia and glycosylated hemoglobin. In group 1, significant abnormalities were found in the latency values ofVEP, median SEP, and tibial SEP compared with control subjects. Similar latency abnormalities were shown in group 2 for VEP, median SEP, and tibial SEP values and for wave I latency of BAEP. Glycosylated hemoglobin values were correlated with BAEP and SEP abnormalities in many patients in both groups. Furthermore, in group 2, glycemic values correlated with SEP abnormalities. We therefore conclude that neurophysiological abnormalities are present at different levels in IDDM and NIDDM patients only a few years after clinical diagnosis and before the appearance of overt complications, and these abnormalities seem to be correlated with metabolic-control status.

Abnormalities of Cognitive Functions in IDDM Revealed by P300 Event-Related Potential Analysis: Comparison With Short-Latency Evoked Potentials and Psychometric Tests

The possible influence of diabetes on the higher mnestic and cognitive functions has been investigated. The P300 wave latency, an endogenous electrophysiological event, was explored and compared with the multimodal short-latency evoked potential (EP) recordings (visual [VEP], brainstem auditory [BAEP], and median and tibial nerve somatosensory EPs [mSEP and tSEP, respectively]) and psychometric test measures in 16 insulin-dependent diabetic (IDDM) patients, in 16 age- and (IDDM) sex-matched nondiabetic subjects, and in a large normal reference population. The age of subjects, the duration of IDDM, and the metabolic control of patients were taken into account. P300 values were significantly increased in IDDM versus matched control subjects (P < 0.001), and 3 patients showed values above the reference value range. Abnormal VEP recordings were present in 1 of 16 patients, BAEP in 3 of 16, mSEP in 7 of 16, and tSEP in 6 of 16. Digit-span backward test results were significantly (P < 0.02) modified in the diabetic cohort. There was no tendency for anomalies of P300, short-latency EPs, and psychometric test values to be contemporarily present, except in 1 patient. Electrophysiological or psychometric abnormalities were not clearly correlated with the duration of IDDM or the degree of short-term metabolic control. These findings give evidence that 1) higher cognitive functions may be affected in diabetes as documented by P300 analysis and short-term memory tests, 2) endogenous electrophysiological analysis highlights neuropsychological changes not detectable by psychometric tests, 3) an alteration of evoked potentials was present in half of the IDDM subjects studied, and 4) anomalies of the CNS are patchily distributed in diabetes.

Parkinson disease: Electrophysiological (CNV) analysis related to pharmacological treatment

The contingent negative variation (CNV) was studied in a group of patients with Parkinsons disease. Testing was carried out 3 times: after a pharmacological wash-out period and at 15 and 30 days after the start of treatment with L-DOPA and bromocriptine. Peak and area CNV increased significantly after each treatment. The post-imperative negative variation (PINV) was observed in 6 out of 10 patients. The correlation found between electrophysiological functioning (CNV) measures and pharmacological treatment supports the view that dopaminergic brain activity mediates the generation of the slow negative event-related brain potentials.

Blood Leukotrienes in Headache: Correlation With Platelet Activity

SYNOPSIS

Low contrast stimuli enhance PERG sensitivity to the visual dysfunction in Parkinson's disease

The pattern electroretinogram (PERG) was recorded at different contrast levels (96%, 71%, 47%) in 10 Parkinsons disease patients before and during dopaminergic monotherapy. The data were compared to a control group of 8 normal subjects recorded with the same procedure. PERG P50 latency progressively increased as contrast was decreased both in normal subjects and patients; however, this trend was much more pronounced in PD patients without therapy; consequently in this group the difference between P50 latency obtained with 96% and 47% contrast was statistically significant (P = 0.01, analysis of variance corrected by post-hoc Tukey test). By contrast this was not seen in the control group. Statistical analysis (Bonferronis t test) showed at the 47% contrast level a significant P50 latency increase (P less than 0.01) in PD patients without therapy if compared with the control group. Dopaminergic monotherapy induced a P50 latency recovery in PD patients. We conclude that low contrast stimuli enhance PERG sensitivity to the visual dysfunction of PD patients. Moreover, the effects observed after therapy confirm that abnormal contrast response functions in PD patients are linked to dopaminergic deficiency.

Prognostic value of early somatosensory evoked potentials during carotid surgery: relationship with electroencephalogram, stump pressure and clinical outcome.

SummaryThe authors have reported on the prognostic value of continuous monitoring of somatosensory evoked potentials (SEP) in a survey of 25 patients who underwent carotid surgery. SEP recordings were correlated with the EEG, stump pressure (SP) values and clinical outcome. A non-cephalic reference was used for SEP recordings to allow the analysis of both subcortical and cortical components. During surgery the conduction time between SEP peaks relating to the subcortical components remained stable or showed minimum variations in all patients. During carotid clamping, SEP variations were observed in 9 out of 25 cases (36%). The application of an intraluminal shunt was accompanied by the return to normal values in 7 out of 9 patients. In the remaining two cases SEP abnormalities continued post-operatively and were accompanied by new neurological deficits. EEG changes during carotid clamping were associated with SEP modifications in 6 out of 7 cases, although they were not always correlated. Results confirm that SEP recordings provide useful data concerning the function of the CNS in anaesthetized patients and that, being sensitive to CBF changes, SEP monitoring acts as an indicator of cerebral ischaemia.

Identification of Blood Leukotrienes in Classical Migraine

SYNOPSIS

Early auditory evoked potential changes during hypoxic hypoxia in the rabbit

Early auditory evoked potentials and electroencephalograms were recorded in 10 rabbits during hypoxic hypoxia (5% O2 in N2 gas mixture) and after reoxygenation. In all experiments EEG flattening preceded the disappearance of the early evoked potential, whose recovery after reoxygenation was more rapid than that of the EEG. Significant increases in P3-P4 and P1-P3 interpeak latencies were observed during hypoxic conditions before the complete flattening of the early auditory evoked potential. In addition, negative relationships were found between the P3-P4 interpeak latency increase and mean arterial pressure reduction, and between the former and metabolic acidosis.

Transcranial Doppler Sonography in familial hemiplegic migraine

A patient affected by familial hemiplegic migraine underwent Transcranial Doppler Sonography twice: the first during a spontaneous attack with right hemiparesis and aphasia, the second during a headache-free period. During the attack the following haemodynamic changes were seen: (a) bilateral increase in the middle cerebral artery and anterior cerebral artery blood flow velocities (this increase was more pronounced on the left side), (b) decreased systo-diastolic ratio and pulsatility index on the right side, (c) increased systo-diastolic ratio and pulsatility index on the left side. Our results indicate that during the attack in this familial hemiplegic migraine patient a diffuse vasoconstriction of the basal cerebral arteries developed. Moreover, Transcranial Doppler Sonography data suggest that a prolonged vasoconstriction of the peripheral arterioles could play a role in determining the neurological symptoms in this syndrome.

Subjective posttraumatic syndrome. A comparison of visual and brain stem auditory evoked responses

Evoked responses testing including pattern visual evoked potentials (VEPs) and brain stem auditory evoked potentials (BAEPs) were performed in 57 subjects suffering from subjective posttraumatic syndrome (SPTS). 36 of them had loss of consciousness after head injury. Abnormalities were found in 12 subjects out of 57 (21%). In addition, the pathological findings by percentage were: 25% in subjects who had loss of consciousness after head injury (9 cases out of 36) and 14% in subjects without loss of consciousness (3 cases out of 21). Evoked response alterations were more frequent in subjects with frontal and/or occipital trauma; BAEP abnormalities were found to be more frequent than VEPs. Our findings suggest that evoked responses testing could be a useful noninvasive technique to evidence an organic dysfunction of CNS in some subjects with SPTS.