Introduction

The use of neurolysis on various peripheral sensory nerves for the treatment of neuropathic pain is increasingly frequent. The aim of this clinical case is to evaluate the possibility to control peripheral neuropathic pain in meralgia paresthetica.

Methods

A 78-year-old overweight female patient began to experience numbness and burning pain in the lateral region of her left thigh. This clinical picture has always been associated with problems of the lumbar spine. It presents protrusions on several levels which have determined sciatic nerve irritation. She was subjected to lumbosacral MRI (which shows protrusions) and EMG of the lower limbs. A careful evaluation of the EMG examination shows suffering of the left femorocutaneous nerve. The hypothesis arises is a case of meralgia paresthetica due to a nerve entrapment in the passage under the inguinal ligament. Once the ultrasound-guided block was performed (lidocaine 10 mg/ml 8 ml and dexamethasone 4 mg) the patient reports with astonishment the resolution of the pain symptoms. The benefit, assessed using the NRS scale, remains at values below 3 for about 1 month. Two two-minute freezing -70*C cycles are performed, interspersed with twenty seconds of defrosting and then at the end. The block is repeated during the procedure. It is advised to insist on weight loss and on the treatment with pregabalin that the patient finds effective, but if he doesn’t tolerate its sedative effect, it can be suspended.

Results

Neurolysis, from the literature review, appears effective in the treatment of neuropathic pain. The lesion produces a Wallerian degeneration of the axon. The connective tissue of the nerve is not damaged and can completely regenerate without problems. Studies evaluating efficacy in meralgia paresthetica are lacking. This clinical case proved its success.

Conclusions

The effectiveness in this case pushes for the execution of more extensive studies. After years of interpreting the problem as difficult to treat, it’s the first time that is described as a solvable problem. The treatment of peripheral neuroparic pain by ultrasound-guided neurolysis needs further quantitative tests, but it is presented as a method free of side effects and important complications. The ultrasound guide allows you to see and avoid the vessels that flow in the region, to observe the diffusion of the injected and to correctly place the needle with respect to the course of the treated nerve.

Bibliography

Onat SS, Ata AM, Ozcakar L (2016) Ultrasound-guided diagnosis and treatment of meralgia paresthetica. Pain Physician 19(4):E667–9

Payne, R., Seaman, S., Sieg, E. et al. Evaluating the evidence: is neurolysis or neurectomy a better treatment for meralgia paresthetica? Acta Neurochir 159, 931–936 (2017).