RA UK Project Grant
Development of a model of subperineural injection during ultrasound guided regional anaesthesia
Dr Shilpa Munirama
Routine clinical use of ultrasound has improved the outcomes of regional anaesthesia by allowing direct vision of needle and nerve, but there has been no reduction in accidental nerve damage. Nerves and adjacent tissues as well as needles are difficult to see. Nerve damage probably occurs by trauma and injection of local anaesthetic within the middle of the internal nerve bundles called fascicles. However, no test as yet is able to determine in what damage a needle does, where the local anaesthetic actually goes, and what changes in anatomy occur inside and outside nerve bundles.
Aims
We aim to scan isolated nerves under an ultrasound microscope, which can image with very high resolution (about 5 times normal for ultrasound) up to depths of 3 to 4mm. Our objective is to see if our high resolution ultrasound imaging is comparable to stained histological cross-sections prepared by an Anatomist. If so, we will use ultrasound to visualize what damage occurs when we place needles into nerves and where injected fluid goes.
Methods
Our intention is to scan the interscalene nerve roots and the sciatic nerve and compare internal structure with each other and with nerves obtained from fresh frozen cadavers. We will then place a needle either inside a nerve bundle (or fascicle) or between the nerve fascicle and the outer sheath of the nerve.
Expected outcome
We expect micro ultrasound to provide an image comparable to histology and to visualise nerve and fluid injection into the nerve.
Implications
A need exists for a new in-vitro model of nerve injection. If successful this model will be applicable to numerous studies for technology development in UGRA and cancer node biopsy.
