Sciatic Nerve Block Distal

Saphenous and Sural Nerve Injury Following Laser How to Avoid

Saphenous Nerve and Sural nerve injuries area potential complication of all endothermal treatments both endovenous laser and radiofrequencyablation. This presentation discusses this problem. It is mainly of concern to s,nurses and vascular technologists, but members of the public mainly also find it of interest.My own interest in this subject was stimulated by colleague and friend Ted King in Chicago.Ted has done a lot of al research on the saphenous nerve and sural nerve and theiranatomical relationship to the great saphenous vein and the small saphenous vein. Ted haskindly helped to direct my reading of the medical literature and he has generously sharedthe findings of his own research that was

presented to the European Venous Forum inJune 2010. Nerve injury may occur in over a third oflaser treatments of the great saphenous vein and nearly one in twenty small saphenous veintreatments. A recent study from Germany has even suggestedthat saphenous nerve injury is more likely after endovenous laser than after surgicalstripping. The study authors have proposed that in some cases the nerve may have beeninjured by the needle during administration of the tumescent local anaesthetic.Here are the mechanisms by which the nerve might possibly be injured. Firstly, the nervemight injured by the needle during the cannulation

of the vein itself. This is probably veryrare but it is possible that the nerve could be transected by the needle. Similarly, aneedle stick injury might occur during the administration of local anaesthetic causinga neurotemesis. Finally, the thermal ablation could cause the direct transfer of heat energyto the nerve causing a thermal neuropraxia a burn injury.These are the possible strategies to avoid nerve injury. Firstly, the nerve and veincan be imaged in transverse section to identify a site of cannulation where the nerve andvein are sufficiently far apart to minimise the risk of thermal energy transfer. Secondly,the vein and nerve can be imaged in transverse

section during the cannulation to ensure thatthe vein is cannulated directly and that the needle tip does not impinge on the nerve.Thirdly, the nerve, vein and needle tip can be kept in view during tumescent anaestheticadministration by scanning in transverse section at all times. Lastly, the needle should bewithdrawn immediately and the thermal ablation terminated immediately if pain is felt inthe sensory distribution of the nerve at risk. In fact, performing these treatments underlocal anaesthetic is much safer than under general anaesthetic for this very reason.When pain occurs, the treatment should be terminated or the needle withdrawn, makingthe possible risk of nerve injury less likely.

Here you can see that the saphenous nerveand the great saphenous vein are very close and in contact in the distal calf. The twolie within the saphenous fascia superficial to the tibia. In this case the nerve liesanterior to the vein. This would not be a good site for cannulation. Even if the needletip is kept in view and the vein is cannulated cleanly by which I mean the needle tip isnot allowed to stray near the nerve, it is likely that the nerve would be injured byadministration of local anaesthetic fluid. As this tutorial clip shows, distally the nerveand vein and nerve are in contact as the probe moves more proximally, the vein and nerveare separated by 10mm or more. The vein can

be easily identified by the fact that it collapsesflat with pressure from the transducer probe. The probe is moved proximally and distally. Here once again we can see the probe moving more distally, and the vein and the nervecoming into contact with each other the vein collapsing on pressure.Here is the appearance of the Sural Nerve in relation to the small saphenous vein. Theanatomy and ultrasound appearance of the sural nerve have been very nicely described by Ricci.This tutorial clip shows that further proximally the vein and nerve are separated by 10mm ormore. As the probe moves more distally, the vein and the nerve are in close contact. Thevein here is collapsing on light pressure

Sural Nerve Injury How to Avoid The Sural Nerve During Laser Vein Treatment

Sural nerve injury can occur in over 1 in10 small saphenous vein endothermal ablations. It can result in troublesome numbness in thesensory distribution of the nerve or it can cause burning pain in the heel and outsideof the foot. I am going to show you how the sural nerve can be identified on an ultrasoundscan and how the risk of sural nerve injury can be minimised during endothermal ablation.The sural nerve lies close to the small saphenous vein at the back of the calf and it is vulnerableto accidental injury during cannulation of the small saphenous vein, during the administrationof perivenous tumescent local anaesthetic and during the thermal ablation procedureitself. I am very grateful to Ted King

in Chicago who stimulated my interest in theanatomy of this nerve and who has done a lot of research on the zones of contact of thesural nerve and the small saphenous vein. In my opinion, the sural nerve should be visualisedin transverse section and its relationship to the vein established at the proposed pointof vein cannulation. Here you can see that the vein and nerve are very close and in contactin the distal calf here at 12cm above the malleoli. Further proximally, the vein andnerve are separated by 10mm or more. My practice is to visualise the nerve and vein in transversesection throughout the cannulation procedure, thereby minimising the risk of needle stickinjuries at this stage as well as during the

administration of tumescent local anaesthesiaagain ensuring that the local anaesthetic solution is generously administered betweenthe nerve and vein and minimising the risk of direct needle injury to the nerve. I havenever been a fan of cannulation under longitudinal section scanning and while I do not wish toreignite the debate of transverse section versus longitudinal section scanning for cannulation,in my hands at least, I believe that the small saphenous vein should be imaged in transversesection and the sural nerve kept in view at all critical stages of the endothermal ablation.I hope you have found this tutorial interesting. Please share your opinion in the box belowand don't forget to subscribe. Thank you for

watching.

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