Anatomy of the sphenopalatine artery and its implications for transnasal neurosurgery.

BACKGROUND: The knowledge of sinonasal vasculature is inevitable in transnasal neurosurgery. We performed an anatomical study on the sphenopalatine artery from the perspective of skull base procedures. METHODOLOGY: To analyse the anatomical landmarks of the sphenopalatine artery, arterial skull corrosion casts (26 head halves) underwent endoscopic transnasal phantom surgery. Furthermore, we performed microsurgical dissection on formaldehyde-fixated cadavers with arterial perfusion (14 head halves) as well as studied Cone Beam CT-scans of anonymised patients and cadavers (115 head sides). RESULTS: In our cadaveric material, the sphenopalatine foramen is located at the transition of the superior and middle nasal meatus (95.0%) or in the superior nasal meatus (5.0%). It is the main entry point of the branches of the sphenopalatine artery into the nasal cavity. In most cadaveric cases (25.0%), at this level there are 2 branches superiorly and 1 vessel inferiorly to the ethmoid crest. An average of 2.4 vessels leave the sphenopalatine foramen superiorly to the ethmoid crest, 97.8% of them belong to the sphenopalatine arterys posterior septal branches. An average of 2.1 branches leave the sphenopalatine foramen inferiorly to the ethmoid crest; all of them belong to the posterior lateral nasal branches. There are no cases with a single artery at the plane of the sphenopalatine foramen. We describe a triangular bony structure bordering the sphenopalatine foramen anteriorly which is built up by the palatine and ethmoid bone as well as the maxilla. According to the radiographic studies, this triangular prominence is surrounded superiorly by a posterior ethmoid cell (57.4%), the sphenoid sinus (41.7%) or the orbit (0.9%) with a varying contribution of the superior nasal meatus; inferolaterally by the maxillary sinus (98.3%) or the pterygopalatine and infratemporal fossa (1.7%) and inferomedially by the middle nasal meatus. The medial vertex of the bony triangle corresponds to the ethmoid crest of the palatine bone. In transnasal endoscopic surgery, the posterior lateral nasal branches of the sphenopalatine artery appear at the triangle's inferomedial edge, the posterior septal branches emerge at its superior edge. CONCLUSIONS: The triangular bony structure is a landmark to find and differentiate the posterior lateral nasal and posterior septal branches of the sphenopalatine artery and to identify the sphenoid sinus.

Human cadavers preserved using Thiel's method for the teaching of fibreoptically-guided intubation of the trachea: a laboratory investigation.

We assessed the suitability of human cadavers preserved using Thiel's method for teaching flexible fibreoptic tracheal intubation. Thirty-one anaesthetists unacquainted with this technique received didactic teaching followed by handling of the fibrescope on the Oxford teaching box. They then carried out fibreoptic intubations in two cadavers to establish a baseline sample of their intubation skills. Thereafter, we randomly assigned the trainees to two groups to practice fibreoptic intubation either on two distinct cadavers or on two airway manikins. After 7 days we re-assessed procedural skills using the same cadavers as at baseline. Intubation time was the primary outcome and secondary outcomes included the incidence of failed intubations. We also evaluated trainee satisfaction. The mean (SD) intubation time decreased from a baseline value of 74 (20) s to 35 (6) s in the cadaver group and to 56 (16) s in the manikin group. The effect of 'time' was significant (p = 0.002), indicating that both methods of training led to improvements. The training effect of the cadaveric method was greater than with the manikin method (p = 0.0016). Thirty-four failed intubations occurred at baseline vs. eight at the end of study (RR 0.24, 95%CI 0.11-0.51, p = 0.0002, NNT 9.6); six in the cadaver group and two in the manikin group (p = 0.22). We conclude that human cadavers preserved using Thiel's method are potentially better for teaching flexible fibreoptic tracheal intubation compared with manikins.

Suitability of a preserved human cadaver model for the simulation of facemask ventilation, direct laryngoscopy and tracheal intubation: a laboratory investigation.

BACKGROUND: Using fresh or formalin-embalmed cadavers has not been generally accepted for the purposes of teaching airway management. We investigated whether cadavers 'preserved according Thiel's embalming method' (PATEM) are suitable for the simulation of facemask ventilation and tracheal intubation by direct laryngoscopy. METHODS: This observational cluster sampling, controlled simulation study, included eight PATEM cadavers and eight manikins in two clusters. Twenty experienced anaesthetists were randomly assigned to execute 80 facemask ventilations and 80 tracheal intubations in both groups. The ease of facemask ventilation was the primary endpoint. The secondary endpoint was the composite outcomes of laryngoscopy and tracheal intubation. RESULTS: The success rate at the first attempt at mask ventilation was 74% (59/80 attempts) on cadavers and 41% (33/80 attempts) on manikins (P<0.0001). Twenty one subjects received an oral airway in both groups and succeeded in facemask ventilation 20 times on cadavers and four times on manikins (P=0.004). Two-handed technique mask ventilation was required 24 times on manikins and once on cadavers (P=0.0016). In one attempt on a manikin the mask ventilation was impossible. Poor laryngeal view (Cormack-Lehane grade 3) occurred 14 times among cadavers (17.5%) and once in manikins (1.25%) (P=0.007), whereas difficulties in tracheal intubation were encountered 16 times in cadavers (20%) vs 17 times in manikins (21.25%) (P=0.84). In a subjective evaluation the participants preferred the cadaver model over the manikins (P<0.0001). CONCLUSIONS: PATEM cadavers were better suited for facemask ventilation and provided a more realistic environment for laryngoscopy and tracheal intubation than the studied manikins.

Relationship between radiographic joint space narrowing, sonographic cartilage thickness and anatomy in rheumatoid arthritis and control joints.

OBJECTIVE: To validate ultrasound (US) for measuring metacarpal cartilage thickness (MCT), by comparing it with anatomical measurement using cadaver specimens. To correlate US MCT with radiographic joint space narrowing (JSN) or width (JSW) in patients with rheumatoid arthritis (RA). METHODS: Bilateral metacarpophalangeal (MCP) joints of 35 consecutive outpatients, with recent hand X-rays, were included in the analysis. Metacarpal and phalangeal cartilage of MCP 2-5 was assessed bilaterally by US. JSW and JSN were evaluated on X-rays by the van der Heijde modified Sharp method (vdHS). In addition, cadaver specimens of MCP 2-5 joints (n=19) were evaluated by anatomical measurement and US. RESULTS: The agreement (intraclass correlation coefficient) between sonographic and anatomical MCT on cadaver specimens of MCP joints was 0.61. MCT of individual MCP joints correlated with individual MCP JSN (r=-0.32, p<0.001) and individual MCP JSW (r=0.72, p<0.001). No correlation was found between phalangeal cartilage thickness and JSN in individual MCP joints. The US MCT summary score for MCP joints 2-5 correlated with summary scores for JSW (r=0.78, p<0.001), JSN (r=-0.5, p<0.001), erosion score of the vdHS (r=-0.39, p<0.001) and total vdHS (r=-0.47, p<0.001). CONCLUSIONS: Sonographic cartilage assessment in MCPs is closely related to anatomical cartilage thickness. Both JSW and JSN by radiography represent cartilage thickness in the MCP joints of patients with RA quite well. Thus, US is a valid tool for measuring MCT if radiographs are not available or in case of joint malalignment.

Perisynaptic aggrecan-based extracellular matrix coats in the human lateral geniculate body devoid of perineuronal nets.

The extracellular matrix surrounds different neuronal compartments in the mature nervous system. In a variety of vertebrates, most brain regions are loaded with a distinct type of extracellular matrix around the somatodendritic part of neurons, termed perineuronal nets. The present study reports that chondrotin sulfate proteoglycan-based matrix is structured differently in the human lateral geniculate body. Using various chondrotin sulfate proteoglycan-based extracellular matrix antibodies, we show that perisomatic matrix labeling is rather weak or absent, whereas dendrites are contacted by axonal coats appearing as small, oval structures. Confocal laser scanning microscopy and electron microscopy demonstrated that these typical structures are associated with synaptic loci on dendrites. Using multiple labelings, we show that different chondrotin sulfate proteoglycan components of the extracellular matrix do not associate exclusively with neuronal structures but possibly associate with glial structures as well. Finally, we confirm and extend previous findings in primates that intensity differences of various extracellular matrix markers between magno- and parvocellular layers reflect functional segregation between these layers in the human lateral geniculate body.

Layer-specific activity of tissue non-specific alkaline phosphatase in the human neocortex.

The ectoenzyme tissue non-specific alkaline phosphatase (TNAP) is mostly known for its role in bone mineralization. However, in the severe form of hypophosphatasia, TNAP deficiency also results in epileptic seizures, suggesting a role of this enzyme in brain functions. Accordingly, TNAP activity was shown in the neuropil of the cerebral cortex in diverse mammalian species. However in spite of its clinical significance, the neuronal localization of TNAP has not been investigated in the human brain. By using enzyme histochemistry, we found an unprecedented pattern of TNAP activity appearing as an uninterrupted layer across diverse occipital-, frontal- and temporal lobe areas of the human cerebral cortex. This marked TNAP-active band was localized infragranulary in layer 5 as defined by quantitative comparisons on parallel sections stained by various techniques to reveal the laminar pattern. On the contrary, TNAP activity was localized in layer 4 of the primary visual and somatosensory cortices, which is consistent with earlier observations on other species. This result suggests that the expression of TNAP in the thalamo-recipient granular layer is an evolutionary conserved feature of the sensory cortex. The observations of the present study also suggest that diverse neurocognitive functions share a common cerebral cortical mechanism depending on TNAP activity in layer 5. In summary, the present data point on the distinctive role of layer 5 in cortical computation and neurological disorders caused by TNAP dysfunctions in the human brain.