Operating environment for awake brain surgery - Choice of tests.

INTRODUCTION: The indication for awake brain surgery depends on a prerequisite, i.e. recognition that the brain area concerned is truly eloquent, and identification of one or more functions that must be preserved. These functions are determined preoperatively in collaboration with the patient, and neuropsychological tests considered to be the most relevant are performed in the operating room according to each team's technical preferences. OPERATING ENVIRONMENT: The neurosurgeon must choose transfer equipment considered to be relevant. Although a minimal technological environment is an option, a surgical team with great human wealth is essential, composed of specialized personnel with complementary skills. CHOICE AND IMPLEMENTATION OF INTRAOPERATIVE TESTS: The choice of intraoperative tests, which can be relatively simple for certain primary functions, can be much more difficult for high-level cognitive functions. No consensus has been reached concerning these tests, which must therefore be selected on an individual basis. Intraoperative testing must be based on preoperative multidisciplinary decisions made jointly by the neurosurgeon, neurologist, speech therapist and neuropsychologist. CONCLUSIONS: Numerous operating tools and technology transfers are available for neurosurgical teams performing awake brain surgery but none - or very few - of them constitutes a mandatory prerequisite. In contrast, the transition from the concept of eloquent brain area to that of brain functions that must be preserved requires highly skilled multidisciplinary human resources. This goal will be more likely achieved in centers highly specialized in functional oncological neurosurgery.

Chiari malformation and sleep related breathing disorders.

OBJECTIVE: To estimate the frequency, mechanisms and predictive factors of sleep apnoea syndrome (SAS) in a large group of children and adults with type I (CMI) and II (CMII) Chiari malformation (CM). BACKGROUND: The anatomical and functional integrity of both respiratory circuits and lower cranial nerves controlling the upper airway is necessary for breathing control during sleep. These latter structures may be altered in CM, and a few investigations have reported CM related sleep disordered breathing. METHODS: Forty-six consecutive unrelated patients with CM (40 CMI, six CMII), of which 20 were children (eight males) and 26 were adults (12 males), underwent physical, neurological and oto-rhino-laryngoscopic examination, MRI and polysomnography. RESULTS: SAS was present in 31 (67.4%) of the patients with CM (70% of CMI, 50% of CMII, including mainly children). Sixty per cent of children with CM exhibited SAS, including 35% with obstructive (OSAS) and 25% with central (CSAS) sleep apnoea syndrome. SAS was observed in 73% of CM adults (57.7% OSAS, 15.4% CSAS). Severe SAS was found in 23% of CM adults. Multiple regression analysis revealed that age, type II Chiari and vocal cord paralysis predicted the central apnoea index. CONCLUSION: SAS is highly prevalent in all age groups of patients suffering from CM. CSAS, a rare condition in the general population, was common among the patients with CM in our study. Sleep disordered breathing associated with CM may explain the high frequency of respiratory failures observed during curative surgery of CM. Our results suggest that SAS should be systematically screened for in patients with CM, especially before surgery.

[Diurnal consequence of insomnia: impact on quality of life]. / Les conséquences diurnes de l'insomnie: impact sur la qualité de vie.

Insomnia is not only a disease of sleep, it has also daily consequences: fatigue, irritability, impaired daytime functioning. These complaints are regent reported by the patients, however the objective tests assessing alertness in insomnia are usually not impaired when compared with good sleepers. We wanted to appreciate more accurately the daily consequences of insomnia, in terms of quality of life. 240 severe insomniacs (according to the DSM-IV criterias) and 391 good sleepers received a questionnaire on quality of life items. Depressed and anxious patients were excluded from this group. The questionnaire was built by a multidisciplinary group, based on insomniac's interviews. It was primarily tested in a small sample and then proposed in the entire group. Insomniac's quality of life appeared to be significantly impaired in comparison with good sleepers. They experienced more fatigue and more sleepiness during the daytime. They reported more attention disorders and memory complaints. They seemed to be more irritable and sensitive to the environment. At work they made more mistakes and had more sic leave. They also had poorer relationships with relatives and family than good sleepers.

[Disorders of wakefulness and sleep in blind patients]. / Troubles de la veille et du sommeil chez l'aveugle.

The goal of this paper was to summarize three studies focused on sleep/wake disorders in blind subjects. The first study was an epidemiology survey performed in 1073 blind subjects in comparison with non-blind controls. The blind had more episodes of insomnia and free running rhythms. They also took more sleeping pills and complained of more daytime somnolence. The seriousness of the sleep disorders was related to the seriousness of the blindness. In the second study, 78 blind children were compared with seeing children. They had more insomnia and more parasomnias but there was not any more free running. Finally, polysomnography was performed in 26 free running blind subjects in comparison with 26 controls. Total sleep time and sleep efficiency were lower in the blind. Sleep latency was increased and REM sleep was disturbed (longer latency and percentage decreases). There was no difference concerning slow wave sleep. Factorial analysis showed that factors such as being born blind, having ocular prosthesis, being single or having children had no influence on sleep. Working did however have an influence.

Calcium-induced and voltage-dependent inactivation of calcium channels in crab muscle fibres.

Inactivation of Ca channels was examined in crab muscle fibres using the voltage-clamp method. A satisfactory suppression of outward currents was attempted by the use of K+ blocking agents: TEA, 4AP and Cs ions instead of K+ ions applied extracellularly. The inactivation of Ca current appeared as a bi-exponential process. The faster component had a mean value of the time constant of 50 ms while the second component inactivated at a tenfold slower rate. The extent of inactivation of the faster component increased as the Ca current itself increased in different experimental conditions. Inactivation decreased when ICa was reduced for large applied depolarizations. The time constant of the faster calcium component also depended on the calcium current. Thus the results suggested that Ca2+ entry leads to inactivation of one component of calcium current in crab muscle. Substitution of Ca2+ ions by Sr2+ or Ba2+ ruled out the hypothesis concerning an accumulation process which would explain the decrease of the inward current. The second slower component of Ca current was better described by a voltage-dependent mechanism and its rate was not modified in Ca2+ rich solution or when the inward current was carried by Sr2+ or Ba2+ ions. Thus in crab muscle fibres, inactivation is mediated by both calcium entry and a voltage-gated mechanism.