Neuropathic thigh pain treated with lateral cutaneous nerve of the thigh block

30th January 2007 at 17:26 GMT by Dr C.A.Jenner MB BS, FRCA. Permalink.

Case report of the presentation and treatment of a patient with neuropathic thigh pain due to a metastatic lesion

Introduction

A 59 year old lady presented to the Pain Clinic with pain in the left anterior thigh. In her past medical history she had had breast cancer of the breast some 4 years earlier. This had been treated with a mastectomy, local radiotherapy and chemotherapy. Unfortunately, approximately 2 years later, she was found to have a single metastatic nodule which was found in the pubic bone, which gave her pain.

Local radiotherapy for metastatic nodule

It was decided to give her some local fractions of radiotherapy to this single metastasis. The radiotherapy was beneficial and the pain from the metastasis diminished. However, unfortunately, she was left with pain in the left thigh. This pain was described as a constant, burning pain in the left part of the left anterior thigh.

Examination findings

On examination, she had burning pain and pain on light touch (allodynia) and exaggerated pain on pin prick (hyperalgesia) over the anterolateral part of the left thigh, corresponding with the L1/2 dermatome and the territory of the lateral cutaneous nerve of the thigh.

Diagnosis of neuropathic thigh pain

We concluded that this lady had had local radiation damage to the lateral cutaneous nerve of the thigh when this was applied to the solitary pubic metastasis. The lady was already on Gabapentin 300 mg three times a day. This was increased to 400 mg twice a day and a lateral cutaneous nerve of the thigh block was performed.

Lateral cutaneous nerve of the thigh block technique

This involved identifying the exit point of this nerve which is approximately 10 cm inferior and medial to the anterior superior iliac spine. This was done using aseptic technique, 2 mls of 1% Lignocaine was infiltrated into the skin and then a small 23 gauge needle was inserted underneath the skin and 80 mg Depo-Medrone was carefully infiltrated into the area, along with 3 mls of 0.5% Bupivacaine. The discomfort immediately started to dissipate.

At 6 weeks follow up the lady still had a significant reduction in pain and hypersensitivity and it was decided to repeat the lateral cutaneous nerve of the thigh block.