Full-endoscopic discectomy for thoracic disc herniations: a single-arm meta-analysis of safety and efficacy outcomes.

INTRODUCTION: Surgical intervention is the treatment of choice in patients with thoracic disc herniation with refractory symptoms and progressive myelopathy. Due to high occurrence of complications from open surgery, minimally invasive approaches are desirable. Nowadays, endoscopic techniques have become increasingly popular and full-endoscopic surgery can be performed in the thoracic spine with low complication rates. METHODS: Cochrane Central, PubMed, and Embase databases were systematically searched for studies that evaluated patients who underwent full-endoscopic spine thoracic surgery. The outcomes of interest were dural tear, myelopathy, epidural hematoma, recurrent disc herniation, and dysesthesia. In the absence of comparative studies, a single-arm meta-analysis was performed. RESULTS: We included 13 studies with a total of 285 patients. Follow-up ranged from 6 to 89 months, age from 17 to 82 years, with 56.5% male. The procedure was performed under local anesthesia with sedation in 222 patients (77.9%). A transforaminal approach was used in 88.1% of the cases. There were no cases of infection or death reported. The data showed a pooled incidence of outcomes as follows, with their respective 95% confidence intervals (CI)-dural tear (1.3%; 95% CI 0-2.6%); dysesthesia (4.7%; 95% CI 2.0-7.3%); recurrent disc herniation (2.9%; 95% CI 0.6-5.2%); myelopathy (2.1%; 95% CI 0.4-3.8%); epidural hematoma (1.1%; 95% CI 0.2-2.5%); and reoperation (1.7%; 95% CI 0.1-3.4%). CONCLUSION: Full-endoscopic discectomy has a low incidence of adverse outcomes in patients with thoracic disc herniations. Controlled studies, ideally randomized, are warranted to establish the comparative efficacy and safety of the endoscopic approach relative to open surgery.

Testing spatial heterogeneity with stock assessment models.

This paper describes a methodology that combines meta-population theory and stock assessment models to gain insights about spatial heterogeneity of the meta-population in an operational time frame. The methodology was tested with stochastic simulations for different degrees of connectivity between sub-populations and applied to two case studies, North Sea cod (Gadus morua) and Northeast Atlantic sardine (Sardina pilchardus). Considering that the biological components of a population can be partitioned into discrete spatial units, we extended this idea into a property of additivity of sub-population abundances. If the additivity results hold true for putative sub-populations, then assessment results based on sub-populations will provide information to develop and monitor the implementation of finer scale/local management. The simulation study confirmed that when sub-populations are independent and not too heterogeneous with regards to productivity, the sum of stock assessment model estimates of sub-populations' SSB is similar to the SSB estimates of the meta-population. It also showed that a strong diffusion process can be detected and that the stronger the connection between SSB and recruitment, the better the diffusion process will be detected. On the other hand it showed that weak to moderate diffusion processes are not easy to identify and large differences between sub-populations productivities may be confounded with weak diffusion processes. The application to North Sea cod and Atlantic sardine exemplified how much insight can be gained. In both cases the results obtained were sufficiently robust to support the regional analysis.

Propofol-induced sleep: polysomnographic evaluation of patients with obstructive sleep apnea and controls.

OBJECTIVE: The localization of upper airway obstruction in patients with obstructive sleep apnea (OSA) may optimize treatment. Nasoendoscopy during propofol sedation allows such an evaluation, but the effect of this drug on respiratory patterns and muscle relaxation is unknown. The objective of the present study was to determine through polysomnography whether propofol would change sleep parameters. STUDY DESIGN: Prospective study of subjects submitted to polysomnography under sedation with propofol. SETTING: Tertiary referral center. SUBJECTS AND METHODS: Fifteen non-obese subjects (4 controls/11 OSA patients) were submitted to two diurnal polysomnograms (90-120 minutes of sleep), with and without the use of propofol. The parameters presence of snoring, apnea-hypopnea index (AHI), oxygen desaturation, and sleep architecture were compared. RESULTS: The use of propofol did not induce snoring in the control subjects, whereas 100 percent of the OSA patients snored. AHI and mean oxygen saturation (SaO(2)) did not differ significantly between examinations with and without sedation. However, minimum SaO(2) differed significantly (P < 0.05) with sedation, being lower during propofol sedation. Propofol also significantly changed the sleep architecture, with a significant increase in N3 sleep (P < 0.005) and total abolishment of rapid eye movement sleep (P < 0.0005) during propofol sedation. CONCLUSIONS: These preliminary results allow us to infer that sedation with propofol changes sleep architecture but permits respiratory evaluation, because the main respiratory parameters evaluated in OSA are maintained. These preliminary results support the view that nasoendoscopy under propofol sedation is a promising examination for management of this disease.

Measurement of body size and abundance in tests of macroecological and food web theory.

1. Mean body mass (W) and mean numerical (N) or biomass (B) abundance are frequently used as variables to describe populations and species in macroecological and food web studies. 2. We investigate how the use of mean W and mean N or B, rather than other measures of W and/or accounting for the properties of all individuals, can affect the outcome of tests of macroecological and food web theory. 3. Theoretical and empirical analyses demonstrate that mean W, W at maximum biomass (W(mb)), W when energy requirements are greatest (W(me)) and the W when a species uses the greatest proportion of the energy available to all species in a W class (W(mpe)) are not consistently related. 4. For a population at equilibrium, relationships between mean W and W(me) depend on the slope b of the relationship between trophic level and W. For marine fishes, data show that b varies widely among species and thus mean W is an unreliable indicator of the role of a species in the food web. 5. Two different approaches, 'cross-species' and 'all individuals' have been used to estimate slopes of abundance-body mass relationships and to test the energetic equivalence hypothesis and related theory. The approaches, based on relationships between (1) log(10) mean W and log(10) mean N or B, and (2) log(10) W and log(10) N or B of all individuals binned into log(10) W classes (size spectra), give different slopes and confidence intervals with the same data. 6. Our results show that the 'all individuals' approach has the potential to provide more powerful tests of the energetic equivalence hypothesis and role of energy availability in determining slopes, but new theory and empirical analysis are needed to explain distributions of species relative abundance at W. 7. Biases introduced when working with mean W in macroecological and food web studies are greatest when species have indeterminate growth, when relationships between W and trophic level are strong and when the range of species'W is narrow.