Anatomical variations of the thoracolumbar nerves with reference to transverse abdominal plane (TAP) block

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dc.contributor.advisor Briers, N. en
dc.contributor.postgraduate Smit, Bianca en
dc.date.accessioned 2016-06-10T07:18:41Z
dc.date.available 2016-06-10T07:18:41Z
dc.date.created 2016-04-22 en
dc.date.issued 2016 en
dc.description Dissertation (MSc)--University of Pretoria, 2016. en
dc.description.abstract Introduction The transverse abdominal plane (TAP), formed between the transversus abdominis muscle (TAM) and the internal oblique muscle (IOM), contains the thoracolumbar nerve plexus. The plexus is anaesthetised through a blind or ultrasound-guided TAP block, mainly used for post-operative pain management. Ultrasounds are not always readily available in the public sector, creating a need to improve the blind TAP block. The L1 nerve and its terminal branches, also running in the TAP, can be blocked with a TAP block or separately. By studying the anatomy of the nerve plexus, the TAP block and the iliohypogastric and ilioinguinal blocks could be improved. This study aimed to determine the course and branching patterns of the thoracolumbar nerve plexus, as well as the branching of the L1 nerve in the posterior abdominal wall before entering the TAP. Methods Bilateral dissections were done on 54 embalmed cadavers to examine the TAP by noting the number of nerves at the mid-axillary line (MAL) and at the linea semilunaris. The needle tip position, as well as the general branching patterns were evaluated. For the L1 dissections, the root contributions and branching patterns were evaluated before entering the TAP. Abdominal ultrasounds were taken bilaterally on 43 volunteers to measure depth, individual muscle layer thickness, and subcutaneous fat thickness on a line at the injection point and at the IOM and TAM tendon junction. Differences between sides and the effect of BMI categories were analysed. Results The average number of nerves from the MAL to the linea semilunaris increased by one nerve. The needle was in the correct plane in only 7.6% of cases, with the needle going too deep in 79.3% of cases. The pop method used in the blind TAP block ensures the needle tip is not too superficial, but it is easy to go deeper than required. A nerve was pierced in 6.5% of cases, while the mean distance between the needle tip and the closest nerve (4.56 mm 6.83 mm) indicated the needle tip is generally close enough to the nerves to provide anaesthesia without nerve damage. Nerve interactions observed includes branching or not, merging or not, or any combination thereof. Various variations were seen for the root contributions of the L1 nerve, affecting the innervation of the anterolateral abdominal wall. The fourth lumbar artery accompanied the L1 or its terminal branches to enter the TAP in 40.7% of cases. The IOM and TAM tendon junction appears as a hyperechoic dot on an ultrasound, which can be used as an additional landmark. Measurements revealed the needle should be advanced at least 2 cm and 3 cm in healthy and overweight BMI individuals respectively. Conclusions Notable differences were seen between the current study and studies using a different population, indicating the anatomy of the TAP block is specific to population. The anatomy surrounding the TAP showed significance for a South African population. By analysing the anatomy, this study adds ways to improve the blind and ultrasoundguided TAP blocks. en
dc.description.availability Unrestricted en
dc.description.degree MSc en
dc.description.department Anatomy en
dc.identifier.citation Smit, B 2016, Anatomical variations of the thoracolumbar nerves with reference to transverse abdominal plane (TAP) block, MSc Dissertation, University of Pretoria, Pretoria, viewed yymmdd <http://hdl.handle.net/2263/53046> en
dc.identifier.other A2016 en
dc.identifier.uri http://hdl.handle.net/2263/53046
dc.language.iso en en
dc.publisher University of Pretoria en_ZA
dc.rights © 2016 University of Pretoria. All rights reserved. The copyright in this work vests in the University of Pretoria. en
dc.subject UCTD en
dc.title Anatomical variations of the thoracolumbar nerves with reference to transverse abdominal plane (TAP) block en
dc.type Dissertation en


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