Evaluation of cerebral function after carotid endarterectomy.

Neuroimaging methods have failed to disclose correlation between degree of cerebral atrophy and blood flow in carotid artery stenosis patients. Moreover, intellectual improvement after carotid endarterectomy does not correlate fully with neuroimaging data in such patients. We performed brain electrical activity mapping and psychological testing before and 4 weeks after operation in 28 patients with symptomatic, high-grade, carotid stenosis. Postoperatively, electroencephalographic (EEG) mean frequency and absolute theta power improved significantly (p < 0.01). Mean frequency increased >1 Hz in most areas while power decreased dramatically, mainly because of resolution of high-voltage foci in 8 patients. Differences were conspicuous in both frontal lobes irrespective of the operated side, which suggests changes in perfusion affecting the whole brain. This is a positive effect of endarterectomy. Mini-Mental test and Set Test for verbal fluency had a positive correlation with the qEEG changes. Quantitative EEG as a measure of cerebral function has disclosed discriminative improvement in the early postoperative period. Our results support the thesis of improvement subsequent to endarterectomy.

Central conduction time of magnetic brain stimulation in attention-deficit hyperactivity disorder.

Twenty-seven children and adolescents aged 4 to 18 years, fulfilling the Diagnostic and Statistical Manual of Mental Disorders, 4th edition (DSM-IV) criteria for attention-deficit hyperactivity disorder, were included in this study. The diagnosis was determined by a pediatric neurologist and a psychologist examined all 27 subjects with tests that included the Wechsler Intelligence Scale for Children-Revised (WISC-R) and reading, writing, handedness, personality, and anxiety scores. Subjects with histories of epilepsy, head injury, drug abuse, or psychotic disorders were excluded. Culturally based causes or emotional disorders were also excluded. Transcranial magnetic stimulation was performed on all subjects, with recording of the motor evoked potential at the biceps brachii. Central motor conduction time was calculated by cervical root stimulation. Due to shape variability, the amplitude of the motor responses was not measured in the study. The mean value of central conduction time in the subjects was very significantly increased (P < .001) compared to that in a group of normal controls, case-matched for IQ, age, and sex. A central motor conduction time greater than 12 ms indicates abnormality. A second finding in the subjects was the significant difference of central conduction time on the side-to-side stimulation (P = .03). These findings are correlated with delay in the maturation of the corticomotoneuronal system and might provide neurophysiologic data for diagnosis.

[Early diagnosis of glaucoma with pattern-ERG]. / Diagnostic précoce du glaucome avec l'ERG par inversion de damier.

PURPOSE: Current electrophysiological techniques for diagnosis of glaucoma include pattern-electroretinogram (PERG) and visual evoked potentials (VEP) but PERG has been recognized over the last decade as a good functional indicator of retinal ganglion cells. METHODS: An investigation has been carried out on 171 eyes of 89 subjects using both PERG (gold foil electrodes) and VEP. One group of 32 subjects with ocular hypertension (OHT) and another group of 27 subjects having simple chronic glaucoma (SCG) were compared with a control group of 30 healthy age-matched subjects. RESULTS: For PERG, the amplitude of the P50 and N95 components was measured but statistically significant differences were shown for N95 only in SCG (p < 0.01) and OHT (p < 0.05). FFT analysis on each PERG showed a dominant frequency of 3.3 Hz for OHT subjects versus 9.9 Hz for those of the control group. For VEP, the amplitude and latency of P100 was analysed. P100 latency showed significant delay (p < 0.05) in the SCG group only. CONCLUSIONS: These findings suggest that N95-amplitude is the most sensitive electrophysiologic parameter for early glaucoma detection. By comparing data of this work with a previous study using wire (anchor shaped) electrodes we demonstrate higher amplitude and lesser variability of the N95 component for gold foil electrodes, therefore this latter type of recording is acknowledged as the most sensitive for detection of early impairment of ganglion cells in HTO patients.

[Obstructive sleep apnea syndrome in childhood]. / Síndrome de apnea obstructiva del sueño en la infancia.

INTRODUCTION: Obstructive sleep apnea syndrome (OSAS) is a common problem in children. It is characterized by a partial airway obstruction associated with hypoxemia and hypoventilation rather than complete airway obstruction. DEVELOPMENT: Adeno-tonsillar hypertrophy is the leading cause but there are other risk factors like craniofacial abnormalities. OSAS may lead to neurodevelopmental abnormalities, growth and cardiorespiratory failure. It differs significantly from adult OSAS in its clinical presentation, polysomnographic findings and management. In spite of the fact that the diagnosis is often made on a clinical basis, the definitive and differential one only can be made by polysomnography. CONCLUSION: An overview of this pathology and the different polysomnographic parameters used are reported. Efforts to detect sleep apnea syndrome should be employed in children who present with the symptoms discussed. New guidelines for pediatric polysomnography should help standardize methods.

[Monitoring of brain damage in patients with head injuries]. / Monitorización del daño cerebral en pacientes con traumatismo craneoencefálico.

INTRODUCTION: Early detection of impending cerebral ischemia in comatose patients is most important to avoid secondary insults to the injured brain. DEVELOPMENT: Whilst the computer tomography scan provides a static picture primarily concerned with details of structure, the electroencephalogram (EEG) is the objective source par excellence of information about brain function. The EEG represents the only biological activity suitable for continuous non-invasive monitoring of brain function. In this context, the cerebral function monitor (CFM) of Maynard and Prior (1969) provides a compressed array of amplitude variations and has benefited many critical patients. Among the invasive methods, direct monitoring of cerebral white matter oxygenation (tissular pressure of oxygen) is a promising new technique that has attracted considerable interest over the past four years. Recent studies on multimodal hemodynamic monitoring (intracranial pressure, cerebral perfusion pressure, PtiO2), place this latter technique as a primary basis for management decisions in the ICUs. We have studied four young injured patients, to compare early digital EEG recordings with tissular pressure of oxygen data. CONCLUSIONS: In general, there was agreement between EEG findings and tissular pressure of oxygen levels. The EEG helped with urgent data, though barbiturate therapy interfered in two cases.

Neurophysiological methods testing the psychoneural basis of attention deficit hyperactivity disorder.

Theories concerning the etiology of attention deficit hyperactivity disorder have evolved from the 1950s, when it was believed that an injury to or dysfunction of the diencephalon was the cause of the syndrome, to the present day, when delayed brain maturation is postulated as an explanation. Delay in laying down myelin can be investigated by newly developed techniques like computerized EEG and transcranial magnetic stimulation. In this study, a group of 15 children 3-7 years of age suffering from attention deficit were investigated using both methods in combination and were compared to a control group of 23 age-matched normal children. On the computerized EEG spectral analysis significant differences to the control group were found in areas O1 and O2 (P < 0.05, Student's t-test). With transcranial magnetic stimulation, the overall difference in right/left stimulation was statistically significant (P < 0.001). The results suggest delayed myelination at the brain stem reticular formation where the alpha rhythm is activated and at the corticospinal pathway as parts of a widespread involvement.

Electrophysiological methods in early glaucoma detection.

Electrophysiological methods like pattern electroretinogram and pattern visual evoked potentials may be the best approach for early glaucoma detection, as they have demonstrated to be sensitive to the ganglion cells functional changes. Reported values of both P50 and N95 pattern electroretinogram components differ widely, a fact perhaps related to a heterogeneous grouping of patients suffering from ocular hypertension and glaucoma, rather than to the type of technique utilized. This study is based on a total of 42 subjects: 14 normals, 16 subjects suffering from ocular hypertension, and 12 patients with glaucoma, with 79 eyes examined. Pattern electroretinogram and pattern visual evoked potentials were used as successive techniques. Setting condition for pattern electroretinogram, such as low temporal frequency (2 Hz), 30 min check size, high contrast (99%) and luminance (93 cd/m2), identified the N95 component as the best index for early glaucoma detection. In the control group N95 mean amplitude was 1.62 muV +/- 0.59 SD and showed almost significant difference with ocular hypertension (p = 0.07) and highly significant difference with the glaucoma group (p < 0.01), with decrement of 58.6% in the glaucoma group. P50 mean amplitude, on the contrary, did not show significant differences among the groups (Newman-Keul test), its reduction in glaucoma being 28%. The mean pattern visual evoked potentials latency was alos highly significant between glaucoma and control groups, but not between ocular hypertension and control groups; the mean amplitude did not show significant differences. A proportion of 26.6% abnormal pattern electroretinogram was found in the group suspected of having glaucoma where conventional methods had proved normal.(ABSTRACT TRUNCATED AT 250 WORDS)