scholarly journals Differences in Quantitative Architecture of Sciatic Nerve May Explain Differences in Potential Vulnerability to Nerve Injury, Onset Time, and Minimum Effective Anesthetic Volume

2009 ◽  
Vol 111 (5) ◽  
pp. 1128-1134 ◽  
Author(s):  
Nizar Moayeri ◽  
Gerbrand J. Groen
Keyword(s):  
Sciatic Nerve ◽  
Quantitative Data ◽  
Distal Femur ◽  
Onset Time ◽  
Neural Tissue ◽  
Nerve Blocks ◽  
Neurologic Sequelae ◽  
Tissue Changes ◽  
Femur Condyle

Background In sciatic nerve (SN) blocks, differences are seen in risk of nerve damage, minimum effective anesthetic volume, and onset time. This might be related to differences in the ratio neural:nonneural tissue within the nerve. For the brachial plexus, a higher proximal ratio may explain the higher risk for neural injury in proximal nerve blocks. A similar trend in risk is reported for SN; however, equivalent quantitative data are lacking. The authors aimed to determine the ratio neural:nonneural tissue within SN in situ in the upper leg. Methods From five consecutive cadavers, the region between the sacrum and distal femur condyle was harvested and frozen. Using a cryomicrotome, consecutive transversal sections (interval, 78 mum) were obtained and photographed. Reconstructions of SN were made strictly perpendicular to its long axis in the midgluteal, subgluteal, midfemoral, and popliteal regions. The epineurial area and all neural fascicles were delineated and measured. The nonneural tissue compartment inside and outside SN was also delineated and measured. Results The amount of neural tissue inside the epineurium decreased significantly toward distal (midfemoral/popliteal region) (P < 0.001). The relative percentage of neural tissue decreased from midgluteal (67 +/- 7%), to subgluteal (57 +/- 9%), to midfemoral (46 +/- 10%), to popliteal (46 +/- 11%). Outside the SN, the adipose compartment increased significantly toward distal (P < 0.007). Conclusion In SN, the ratio neural:nonneural tissue changes significantly from 2:1 (midgluteal and subgluteal) to 1:1 (midfemoral and popliteal). This suggests a higher vulnerability for neurologic sequelae in proximal SN, and may explain differences observed in minimum effective anesthetic volume and onset time between proximal and distal SN blocks.

scholarly journals Nerve Stimulator-guided Supplemental Popliteal Sciatic Nerve Block after a Failed Sciatic Block Does Not Increase the Incidence of Transient Postoperative Neurologic Sequelae

2011 ◽  
Vol 115 (3) ◽  
pp. 596-603 ◽  
Author(s):  
Antoun Nader ◽  
Mark C. Kendall ◽  
Robert Doty ◽  
Alexander DeLeon ◽  
Edward Yaghmour ◽  
...  
Keyword(s):  
Sciatic Nerve ◽  
Nerve Block ◽  
Sciatic Nerve Block ◽  
Cumulative Exposure ◽  
Nerve Blocks ◽  
Duration Of Symptoms ◽  
Neurologic Symptoms ◽  
Neurologic Sequelae ◽  
Distal Site

Background Supplemental peripheral nerve blocks are not commonly performed in adults because of concerns of cumulative exposure of the nerve to the local anesthetic as well as increased ischemia from epinephrine. The purpose of this study was to compare the incidence of postoperative neurologic symptoms after a failed subgluteal sciatic nerve block and a supplemental popliteal sciatic nerve block. Methods Five hundred twelve adult patients undergoing ambulatory surgery were prospectively studied (1 yr). Sciatic nerve blocks were performed using levobupivacaine 0.625% with epinephrine 1:200,000 (0.5 ml/kg). Patients who failed to achieve sensory and motor anesthesia at 30-60 min were given a popliteal sciatic nerve block (lidocaine 2% 10 ml + levobupivacaine 0.5% 10 ml). Subjects were contacted at 24 h to 48 h, 2 weeks, and 1 month. Symptomatic patients were contacted biweekly and reevaluated during follow-up surgeon visits until symptom resolution. Results Four hundred thirty-nine subjects were analyzed. Fifty-six received a popliteal sciatic nerve block. Four subjects (0.9%) had self-reported neurologic symptoms in the distribution of the sciatic nerve. Investigator-initiated follow-up revealed 33 subjects (8.7%) who received a single subgluteal sciatic block and 4 subjects (7.1%) after a supplemental sciatic nerve block with neurologic symptoms (P = 0.80). The median duration of symptoms was 4 weeks (95% CI 3-5) in the subgluteal and 4 weeks (95% CI 3-5) weeks in the popliteal group (P = 0.98). All symptoms resolved by 14 weeks postprocedure. Conclusion Blocking the sciatic nerve at a more distal site after a failed subgluteal sciatic nerve block does not appear to influence the incidence or duration of neurologic sequelae.

The Effects of Three Different Approaches on the Onset Time of Sciatic Nerve Blocks with 0.75% Ropivacaine

2004 ◽  
pp. 242-247 ◽  
Author(s):  
Manuel Taboada ◽  
Juli??n ??lvarez ◽  
Joaqu??n Cort??s ◽  
Jaime Rodr??guez ◽  
Susana Rabanal ◽  
...  
Keyword(s):  
Sciatic Nerve ◽  
Onset Time ◽  
Nerve Blocks

Herpesvirus-Associated Proliferative Skin Disease in Frogs and Toads: Proposed Pathogenesis

2021 ◽  
pp. 030098582110063
Author(s):  
Francesco C. Origgi ◽  
Patricia Otten ◽  
Petra Lohmann ◽  
Ursula Sattler ◽  
Thomas Wahli ◽  
...  
Keyword(s):  
Molecular Mechanisms ◽  
Rana Temporaria ◽  
Skin Lesions ◽  
Bufo Bufo ◽  
Careful Examination ◽  
Altered Expression ◽  
Expression Of Genes ◽  
Cell Remodeling ◽  
Tissue Changes

A comparative study was carried out on common and agile frogs ( Rana temporaria and R. dalmatina) naturally infected with ranid herpesvirus 3 (RaHV3) and common toads ( Bufo bufo) naturally infected with bufonid herpesvirus 1 (BfHV1) to investigate common pathogenetic pathways and molecular mechanisms based on macroscopic, microscopic, and ultrastructural pathology as well as evaluation of gene expression. Careful examination of the tissue changes, supported by in situ hybridization, at different stages of development in 6 frogs and 14 toads revealed that the skin lesions are likely transient, and part of a tissue cycle necessary for viral replication in the infected hosts. Transcriptomic analysis, carried out on 2 naturally infected and 2 naïve common frogs ( Rana temporaria) and 2 naturally infected and 2 naïve common toads ( Bufo bufo), revealed altered expression of genes involved in signaling and cell remodeling in diseased animals. Finally, virus transcriptomics revealed that both RaHV3 and BfHV1 had relatively high expression of a putative immunomodulating gene predicted to encode a decoy receptor for tumor necrosis factor in the skin of the infected hosts. Thus, the comparable lesions in infected frogs and toads appear to reflect a concerted epidermal and viral cycle, with presumptive involvement of signaling and gene remodeling host and immunomodulatory viral genes.

scholarly journals Timing of Mouse Molar Formation Is Independent of Jaw Length Including Retromolar Space

2021 ◽  
Vol 9 (1) ◽  
pp. 8
Author(s):  
Daisy (Jihyung) Ko ◽  
Tess Kelly ◽  
Lacey Thompson ◽  
Jasmene K. Uppal ◽  
Nasim Rostampour ◽  
...  
Keyword(s):  
Onset Time ◽  
Ct Scanning ◽  
Micro Ct ◽  
Third Molars ◽  
Developmental Duration ◽  
Dental Lamina ◽  
Permanent Molars ◽  
Dental Epithelium ◽  
Space Conditions

For humans and other mammals to eat effectively, teeth must develop properly inside the jaw. Deciphering craniodental integration is central to explaining the timely formation of permanent molars, including third molars which are often impacted in humans, and to clarifying how teeth and jaws fit, function and evolve together. A factor long-posited to influence molar onset time is the jaw space available for each molar organ to form within. Here, we tested whether each successive molar initiates only after a minimum threshold of space is created via jaw growth. We used synchrotron-based micro-CT scanning to assess developing molars in situ within jaws of C57BL/6J mice aged E10 to P32, encompassing molar onset to emergence. We compared total jaw, retromolar and molar lengths, and molar onset times, between upper and lower jaws. Initiation time and developmental duration were comparable between molar upper and lower counterparts despite shorter, slower-growing retromolar space in the upper jaw, and despite size differences between upper and lower molars. Timing of molar formation appears unmoved by jaw length including space. Conditions within the dental lamina likely influence molar onset much more than surrounding jaw tissues. We theorize that molar initiation is contingent on sufficient surface area for the physical reorganization of dental epithelium and its invagination of underlying mesenchyme.

scholarly journals Subparaneural injection in popliteal sciatic nerve blocks evaluated by MRI

Open Medicine ◽  
2019 ◽  
Vol 14 (1) ◽  
pp. 346-353
Author(s):  
Benedikt Büttner ◽  
Alexander Schwarz ◽  
Caspar Mewes ◽  
Katalin Kristof ◽  
José Hinz ◽  
...  
Keyword(s):  
Sciatic Nerve ◽  
Local Anesthetic ◽  
Ultrasound Guidance ◽  
Resonance Imaging ◽  
Nerve Blocks ◽  
Cross Sectional ◽  
Neurological Sequelae ◽  
Patient Reported ◽  
Study Population ◽  
Intraneural Injection

AbstractIntraneural injection of a local anesthetic can damage the nerve, yet it occurs frequently during distal sciatic block with no neurological sequelae. This has led to a controversy about the optimal needle tip placement that results from the particular anatomy of the sciatic nerve with its paraneural sheath.The study population included patients undergoing lower extremity surgery under popliteal sciatic nerve block. Ultrasound-guidance was used to position the needle tip subparaneurally and to monitor the injection of the local anesthetic. Sonography and magnetic resonance imaging were used to assess the extent of the subparaneural injection.Twenty-two patients participated. The median sciatic cross-sectional area increased from 57.8 mm2 pre-block to 110.8 mm2 immediately post-block. An intraneural injection according to the current definition was seen in 21 patients. Two patients had sonographic evidence of an intrafascicular injection, which was confirmed by MRI in one patient (the other patient refused further examinations). No patient reported any neurological symptoms.A subparaneural injection in the popliteal segment of the distal sciatic nerve is actually rarely intraneural, i.e. intrafascicular. This may explain the discrepancy between the conventional sonographic evidence of an intraneural injection and the lack of neurological sequelae.

Ultrasound-guided approach for axillary brachial plexus, femoral nerve, and sciatic nerve blocks in dogs

2010 ◽  
Vol 37 (2) ◽  
pp. 144-153 ◽  
Author(s):  
Luis Campoy ◽  
Abraham J Bezuidenhout ◽  
Robin D Gleed ◽  
Manuel Martin-Flores ◽  
Robert M Raw ◽  
...  
Keyword(s):  
Sciatic Nerve ◽  
Brachial Plexus ◽  
Femoral Nerve ◽  
Ultrasound Guided ◽  
Nerve Blocks

Neonatal Seizures II. A Multivariate Analysis of Factors Associated with Outcome

PEDIATRICS ◽  
1982 ◽  
Vol 70 (2) ◽  
pp. 177-185 ◽  
Author(s):  
E. David Mellits ◽  
Kenton R. Holden ◽  
John M. Freeman
Keyword(s):  
Multivariate Analysis ◽  
Apgar Score ◽  
Onset Time ◽  
Adverse Outcomes ◽  
Neonatal Seizures ◽  
Prediction Of Outcome ◽  
Factors Associated ◽  
Early Predictors ◽  
Neurologic Sequelae ◽  
Minute Apgar Score

A multivariate analysis of perinatal events occurring in infants with neonatal seizures who were enrolled in the National Collaborative Perinatal Project allowed prediction of outcome. This prediction of death or of mental retardation, cerebral palsy, or epilepsy was empirically confirmed 64% to 83% of the time. In an infant with neonatal seizures, a five-minute Apgar score of less than 7, the need for resuscitation after 5 minutes of age, the onset time of the seizures, and a seizure lasting more than 30 minutes are the best early predictors of which infants will die or will have significant neurologic sequelae. It is hypothesized that neonatal seizures may be a better indicator of the severity or duration of intrauterine asphyxia than the Apgar score. In the neonate with seizures, the use of the formula may allow identification of infants at high risk for adverse outcomes.

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