Severe hyperhomocysteinemia and peripheral neuropathy as side effects of nitrous oxide in two patients with sickle cell disease.

Nitrous oxide (N2O) is a widely used anesthetic agent. We report two patients with sickle cell disease (SCD) who presented with complications following the use of N2O. Patient 1, a 15-year-old girl, presented severe hyperhomocysteinemia, pancytopenia, vitamin B12 deficiency, and peripheral polyneuropathy after massive use of N2O for pain management. At the 1-year follow-up, hyperhomocysteinemia and B12 deficiency had resolved, but she had persisting mild symptoms of polyneuropathy. Patient 2, a 17-year-old boy, presented only severe hyperhomocysteinemia, only partially corrected by initial B12 supplementation. Careful monitoring of N2O use, especially in patients with SCD, is mandatory to prevent complications.

P300, N400, aerobic fitness, and maximal aerobic exercise.

Electrophysiological effects of aerobic fitness and maximal aerobic exercise were investigated by comparing P300 and N400 before and after a maximal cycling test. Event-related potentials (ERPs) were obtained from 20 students divided into two matched groups defined by their aerobic fitness level (cyclists vs. sedentary subjects). The session of postexercise ERPs was performed immediately after body temperature and heart rate returned to preexercise values. At rest, no significant differences were observed in ERP parameters between cyclists and sedentary subjects. This finding argued against the hypothesis that ERP modifications may be directly assumed by aerobic fitness level. The postexercise session of ERPs showed a significant P300 amplitude increase and a significant P300 latency decrease in all subjects. Similarly, N400 effect increased significantly after the maximal exercise in all subjects. ERP changes were of the same magnitude in the two groups. The present study argues for a general arousing effect of maximal aerobic exercise, independently of the aerobic fitness level.

Cortical myoclonus in Angelman syndrome.

Angelman syndrome (AS) results from lack of genetic contribution from maternal chromosome 15q11-13. This region encompasses three GABAA receptor subunit genes (beta3, alpha5, and gamma3). The characteristic phenotype of AS is severe mental retardation, ataxic gait, tremulousness, and jerky movements. We studied the movement disorder in 11 AS patients, aged 3 to 28 years. Two patients had paternal uniparental disomy for chromosome 15, 8 had a >3 Mb deletion, and 1 had a microdeletion involving loci D15S10, D15S113, and GABRB3. All patients exhibited quasicontinuous rhythmic myoclonus mainly involving hands and face, accompanied by rhythmic 5- to 10-Hz electroencephalographic (EEG) activity. Electromyographic bursts lasted 35 +/- 13 msec and had a frequency of 11 +/- 2.4 Hz. Burst-locked EEG averaging in 5 patients, generated a premyoclonus transient preceding the burst by 19 +/- 5 msec. A cortical spread pattern of myoclonic cortical activity was observed. Seven patients also demonstrated myoclonic seizures. No giant somatosensory evoked potentials or C-reflex were observed. The silent period following motor evoked potentials was shortened by 70%, indicating motor cortex hyperexcitability. Treatment with piracetam in 5 patients significantly improved myoclonus. We conclude that spontaneous, rhythmic, fast-bursting cortical myoclonus is a prominent feature of AS.

Opercular myoclonic-anarthric status epilepticus.

We report 3 cases of opercular myoclonic status epilepticus (OMASE), characterized by fluctuating cortical dysarthria without true aphasia associated with epileptic myoclonus involving bilaterally the glossopharyngeal musculature. In this syndrome, the inferior rolandic area of either one or the other hemisphere is involved by an epileptogenic lesion of various etiology. Ictally, clonic expression was consistent with epilepsia partialis continua (EPC) and bilaterally and symmetrically involved palatal muscles (cases 1-3), tongue (cases 2 and 3), lips and chin (case 3), and inferior jaw (case 1) due to bilateral projections of the inferior corticonuclear pathways. Postictally, the main clinical sign was pseudobulbar palsy, consistent with Todd's palsy. In our cases, OMASE was either of vascular (cases 1 and 2) or tumoral origin (case 3). In adulthood, early recognition of OMASE, although nonspecific, may be important for early management of carotid occlusive disease because it usually indicates an acute opercular infarction.

Brainstem auditory evoked potentials. Differences related to physical activity.

Shorter sensory-motor reaction times have been reported in athletes compared with sedentary subjects. Previous results have shown significantly shorter visual evoked potentials (VEPs) latencies in a group of tennis players, but there was no difference between a group of rowers and control subjects. In the present study, the same groups were investigated in order to establish whether similar differences could be found in relation to brainstem auditory evoked potentials (BAEPs). Waves I to V latencies (Ls), interpeak latencies (IPLs) and wave amplitudes were measured. The results showed great differences related to gender. The I-III IPL was shorter in the females than in the males. Differences were also found in relation to physical activity. The most important feature was the significantly shorter III-V IPL observed in the rowers and in the tennis players of both genders compared with sedentary control subjects. In the males these differences were linked to training factors. Therefore, unlike VEPs which seemed to be linked to sports requiring high visual acuity, BAEPs seemed to be linked more widely to top-class physical activity and not to specific sensory aptitude. It was hypothesized that the shorter III-V IPL might be due to shorter synaptic transmission time in the superior olivary complex.

Long latency event-related potentials (P300) in gifted children.

In children, P3 latency decreases with increasing age. This decrease could be linked with the maturation of cognitive processes. According to this hypothesis, event-related potentials P3 were recording in gifted children to research an electrophysiological correlation with the mental precocity. Auditory long latency event-related potentials were recorded in 10 gifted children (IQs over 140) and 23 control subjects. The part of variance related to age was extracted by comparing deviations from regression line as a function of age. Stimulus-evoked N1 component latency was not statistically different in the two populations. Event-related P3 component latency was significantly shorter in the gifted children at Cz (P < 0.05). Inter-peak interval N1-P3 was significantly shorter at all three recording sites (P < 0.01 at Fz and CZ, P < 0.02 at Pz). These results suggest a relationship between the P3 component and cognitive ability in children.

Visual evoked potentials: differences related to physical activity.

Visually evoked potentials to patterned stimuli were recorded from tennis players, rowers and non-athlete control subjects. Each group consisted of 12 males and 12 females of similar age. Tennis players showed shorter P100 latencies compared to those of control subjects and rowers. This difference exists, in the same range, both in the male and in the females. The analysis of covariance and multiple linear regressions show that these shorter latencies cannot be explained by head circumference or by height. The hypothesis of a relationship between these shorter latencies and the specific qualities of racket players is suggested. A second experiment with squash players seems to confirm these first results.

[Prolonged confusion syndrome in the course of cyclosporine treatment: a state of confusion?]. / Syndrome confusionnel prolongé au cours d'un traitement par ciclosporine: état de mal à expression confusionnelle?

Cyclosporine is a potent immunosuppressant that is more and more widely used, particularly after organ transplantations. Many neurological side effects, including convulsions, that could be related to this drug, have been previously observed, most often with high blood concentrations. We report, for the first time, a case of prolonged confusion where a non convulsive status epilepticus may be discussed. It occurred in a 64-year-old woman, 17 days after a liver transplantation. The whole blood cyclosporine value was 230 micrograms/l (normal range: 100-200 micrograms/l) at the beginning of the status epilepticus. The cyclosporine imputability and the part of other factors that could have facilite are discussed.

Quantitative EEG abnormalities and asymmetries in patients with intracranial tumors.

Quantified EEG data of 50 patients with intracranial tumors (T) were compared to the data profile of 60 normal adults (N), using univariate and multivariate statistical analyses. EEGs were recorded from 16 derivations. Twelve spectral parameters were computed from each lead and used for statistical comparisons. The number of significant deviations (P less than 0.05) among univariate features did not separate the T subjects from the N subjects with an acceptable sensitivity. A significant improvement was achieved by using multivariate features and particularly asymmetry multivariate features which detected 49/50 of the T subjects. The proportion of correctly lateralized tumors was 43/48.

[EEG recorded after effort in triathletes. Influence of prior inhalation of hyperbaric oxygen]. / EEG quantifié après effort chez le triathlonien. Influence de l'inhalation préalable d'oxygène hyperbare.

Quantitative EEG was recorded during 3 sessions, once a week, in 10 high-level amateur triathletes, who regularly competed in triathlon. At each session, the EEG was recorded 15 min after a submaximal exercise test. During the second session, the exercise test came immediately after 30 min of hyperbaric oxygenation (100% oxygen at 2 atmosphere absolute pressure). The others conditions of the EEG recording were the same for the 3 sessions. The purpose of the work was to study the variations of the EEG power spectrum (from 1 to 20 Hz) which occurred between the 3 sessions. Descriptive analysis of the results show, after hyperbaric oxygenation, a diffuse increase of absolute power for several frequencies in the theta, alpha and beta bands.

[Electrophysiological study of a family of subjects presenting primary hypertrophic neuritis]. / Etude électrophysiologique d'une famille de sujets présentant une névrite hypertrophique primitive.

Primary hypertrophic neuritis (hereditary motor and sensory neuropathy types I and III) can easily be characterized in affected families by nerve conduction measurement. Such a study is reported in a family with two affected subjects from two successive generations, a man and one of his daughters (type I). Nerve conduction velocities (NCV) were dramatically low (down to 10 m/sec) in three other subjects from the second generation without any obvious clinical symptom. These cases show again the lack of correlation between electrophysiological data and clinical features in these affections. They emphasize the usefulness of electrophysiological diagnosis among subjects without any obvious clinical sign.

[Statistical EEG detection of subjects with intracranial tumors. Study of a sample of 40 quantified recordings]. / Détection statistique des EEG de sujets porteurs d'une tumeur intracrânienne. Etude sur un échantillon de 40 enregistrements quantifiés.

Spectral analysis of 16 channel EEG recordings was applied to 40 normal subjects (N) and 40 patients with supratentorial intracranial tumor (T). A set of 22 spectral parameters was computed from each lead. This study tries to evaluate if univariate and multivariate scoring techniques of quantified EEG data can achieve good separation of the two groups. A reference profile of data is derived from the standardized data of the group N. The 40 patients as well as the 40 normal subjects are compared to the reference data profile. Scorings from 264 univariate features do not separate the two groups. Scorings from a smaller number of multivariate features proved to be more powerful and distinguished 90% of patients. Badly classified subjects are discussed.