Challenges in regional anaesthesia for transfemoral amputation due to sciatic nerve liquefactive necrosis: A case...

Transfemoral amputation (TFA) under regional anaesthesia alone can pose multiple challenges to anaesthesiologists. Here, we present what is likely the first reported case of liquefactive necrosis of the sciatic nerve, resulting in a challenging subgluteal sciatic nerve block.

A 52-year-old woman with multiple comorbidities was scheduled for an urgent left TFA under regional anaesthesia due to ascending infection. Considering the high risk, a suprainguinal fascia iliaca block was performed under ultrasound with a perineural catheter. Visualisation of the sciatic nerve and the posterior femoral cutaneous nerve (PFCN) was unsuccessful due to undetectable neurosonoanatomy. The motor response, using a nerve stimulator, to the suspected sciatic nerve also failed. 0.375 % levobupivacaine 20 ml was administered in the area of the suspected nerves using piriformis and other sonoanatomical landmarks. Amputation was carried out without additional analgesia or sedation. Intraoperatively, the sciatic nerve was found to be distorted macroscopically due to liquefactive necrosis. Postoperatively in the high dependency unit, her pain control was satisfactory with perineural infusion.

The inability to identify the sciatic nerve due to liquefaction is a peculiar encounter in this patient. Still, it suggests an unusual cause for the difficulty in visualising and stimulating peripheral nerves.

Due to the fact that the sciatic and PFCN lie closer together when they exit the sciatic foramen under the piriformis, a sufficient volume of local anaesthetic during a sciatic nerve block may spread around and anaesthetise the PFCN.