Homeostatic sleep regulation in habitual short sleepers (sleep episode < 6 h, n = 9) and long sleepers (> 9 h, n = 7) was investigated by studying their sleep structure and sleep electroencephalogram (EEG) during baseline conditions and after prolonging their habitual waking time by 24 h. In each sleep episode, total sleep time was > 3 h longer in the long sleepers than in the short sleepers. Sleep deprivation decreased sleep latency and rapid eye movement (REM) density in REM sleep more in long sleepers than in short sleepers. The enhancement of EEG slow-wave activity (SWA; spectral power density in the 0.75-4.5 Hz range) in non-REM sleep after sleep loss was larger in long sleepers (47%) than in short sleepers (19%). This difference in the SWA response was predicted by the two-process model of sleep regulation on the basis of the different sleep durations. The results indicate that short sleepers live under a higher "non-REM sleep pressure" than long sleepers. However, the two groups do not differ with respect to the homeostatic sleep regulatory mechanisms.

ObjectivesEvidence comparing the effectiveness of surgical and conservative treatment of symptomatic lumbar disc herniation is controversial. We sought to compare short-term and long-term effectiveness of surgical and conservative treatment in sciatica symptom severity and quality of life in patients with lumbar disc herniation in a routine clinical setting.MethodsA prospective cohort study of a routine clinical practice registry consisting of 370 patients. Outcome measures were the North American Spine Society questionnaire and the 36-Item Short-Form Health Survey to assess patient-reported back pain, physical function, neurogenic symptoms and quality of life. Primary outcomes were back pain at 6 and 12 weeks. Standard open discectomy was assessed versus conservative interventions at 6, 12, 52 and 104 weeks. We filled in missing outcome variable values with multiple imputation, accounted for repeated measures within patients with mixed-effects models and adjusted baseline group differences in relevant prognostic indicators by inverse probability of treatment weighting.ResultsSurgical treatment patients reported less back pain at 6 weeks than those receiving conservative therapy (−0.97; 95% CI −1.89 to −0.09), were more likely to report ≥50% decrease in back pain symptoms from baseline to 6 weeks (48% vs 17%, risk difference: 0.34; 95% CI 0.16 to 0.47) and reported less physical function disability at 52 weeks (−3.7; 95% CI −7.4 to −0.1). The other assessments showed minimal between-group differences with CIs, including the null effect.ConclusionsCompared with conservative therapy, surgical treatment provided faster relief from back pain symptoms in patients with lumbar disc herniation, but did not show a benefit over conservative treatment in midterm and long-term follow-up.

The pathophysiology of peri-lesion boundary zones in acute brain injury is highly dynamic, and it is now clear that spreading-depression-like events occur frequently in areas of cerebral cortex adjacent to contusions in the injured human brain. An automated method to assay microdialysate from peri-lesion cerebral cortex in 11 patients with intracranial haematomas requiring surgery was used. Perfusate (2 lL/min) flowed directly into a flow-injection system for assay of glucose and lactate at intervals typically of 30 secs each. Four channels of electrocorticogram (ECoG) were recorded from a subdural strip adjacent to the catheter. Several patterns of change in metabolites were identified in different time domains. Overall, the number of transient lactate events was significantly correlated with the number of glucose events (r 2 ¼ 0.48, P ¼ 0.027, n ¼ 10). Progressive reduction in dialysate glucose was very closely correlated with the aggregate number of ECoG events (r 2 ¼ 0.76, P ¼ 0.0004, n ¼ 11). It is proposed that the recently documented adverse impact of low dialysate glucose on clinical outcome may be because of recurrent, spontaneous spreadingdepression-like events in the perilesion cortex.

In view of the hypothesis that adenosine is involved in sleep regulation, the effects of the adenosine antagonist caffeine on sleep and sleep EEG were investigated in eight young males. Compared to the placebo condition, caffeine (100 mg) administered at bedtime prolonged sleep latency and reduced sleep efficiency and stage 4 of non-rapid eye movement sleep (NREMS). Electroencephalographic slow-wave activity (SWA, spectral power density in the 1.75-4.5-Hz band) was reduced, whereas power density in the spindle frequency range was slightly enhanced. The suppression of SWA was limited to the first NREMS episode. Caffeine reduced the power density mainly in the lowest delta band, in contrast to the changes during physiological sleep that encompass both the delta and theta bands. Caffeine levels in saliva, assessed in a separate experiment, decreased from 7.5 mumol/l in the first hour of sleep to 3.5 mumol/l in the seventh hour. In the night following caffeine administration, stage 4 sleep had reverted to the baseline level, but sleep latency was still increased, and stage 2 sleep, as well as SWA in the first NREMS episode, were reduced. The data show that even a low dose of caffeine affects the sleep EEG. However, the effects of caffeine did not completely mimic the spectral changes observed during physiological sleep.

Chronic subdural haematoma (cSDH) is one of the most frequent neurosurgical entities. Current treatment options include burr hole craniostomy, twist drill craniostomy or craniotomy. While burr hole craniostomy is the most often used technique, there are no studies analysing the use of one vs. two burr holes in respect to recurrence rates and complications. This retrospective study included 76 (age: 60 +/- 12 years) patients presenting with cSDH admitted in our institution from January 2004 to December 2005. A total of 21 (27%) patients underwent bilateral craniostomy. The patients were assessed using the Markwalder Scale (2 +/- 0.71), Glasgow Coma Scale (14 +/- 1) and measuring the haematoma thickness (1.8 +/- 0.7 cm). The decision to perform one or two burr hole was made according to the personal preference of the treating neurosurgeon. All patients underwent irrigation and placement of closed-system drainage. Out of the 97 haematoma, 63 (65%) haematomas were treated with two burr holes, whereas 34 (35%) were treated with one burr hole. Patients with one burr hole had a statistically significant (p < 0.05) higher recurrence rate (29 vs. 5%), longer average hospitalization length (11 vs. 9 days) and higher wound infection rate (9% vs. 0%). A multivariate regression analysis identified the number of holes as single predictor for postoperative recurrence rate (r(2) = 0.12; p < 0.001). In this study, the treatment of cSDH with one burr hole only is associated with a significantly higher postoperative recurrence rate, longer hospitalization length and higher wound infection rate.

5-ALA-induced fluorescence is a useful and promising intraoperative tool for the visualization of meningioma tissue. The novel findings demonstrated in this study in terms of high fluorescence and poor correlation with histological findings highlight the usefulness of this technique as a routine visual tool to achieve optimal resection of meningiomas.

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Experiments were carried out to test the hypothesis that lactate reduces the neurotoxicity of glutamate in vivo. MAP2 immunohistochemistry was used to measure lesion size, and microdialysis to measure the changes in glucose and lactate in the extracellular compartment. After implantation of a microdialysis probe 100 mM glutamate with or without 6 mM lactate was added to the perfusion medium and infused into the cortex of unanesthetized rats. Infusion of 100 mM glutamate for a period of 30 min produced a lesion of 6.05 +/- 0.64 mm(3), an increase in lactate of 124 +/- 19% above basal and a 21 +/- 9% reduction of glucose below basal level. When 6mM L-lactate was perfused together with 100 mM glutamate there was a significant reduction in the size of the lesion and there was no reduction in dialysate glucose. When L-lactate was replaced with D-lactate the lesion size and the increase in dialysate lactate were greater than after glutamate alone. The neuroprotective role of L-lactate is attributed to its ability to meet the increased energy demands of neurones exposed to high concentrations of glutamate.