Distal lesion of the lateral femoral cutaneous nerve

Inguinal segmental nerve conduction of the lateral femoral cutaneous nerve in healthy controls and in patients with meralgia paresthetica

A common entrapment site of the lateral femoral cutaneous nerve (LFCN) is in the vicinity of the inguinal ligament. However the more distal segment of this nerve can also be affected. Electrophysiological evaluation of this nerve is difficult. Additionally, available methods have failed in the lesion localization of LFCN. In this study, we aimed to evaluate nerve conduction study in different segments of the LFCN. Nerve action potentials of the LFCN were recorded with distal surface electrodes from a relatively distant point (about 30 cm caudal to the spina iliaca anterior superior). An electrical stimulus was given both 10 cm distal to the SIAS and at the level of the SIAS. Inguinal segmental and distal sensory nerve conduction studies were performed on the LFCN. Thirty-eight healthy controls and 34 patients with meralgia paresthetica (MP) were analyzed by this method. All patients with MP showed electrophysiological abnormalities. Slowed sensory conduction on the inguinal channel (p:0.0001) and loss of response were the most frequent abnormalities (44.7% and 31.6%). In one patient, the only abnormality was slowed sensory conduction at the distal site. Our findings suggest that this technique can help in diagnosis and lesion localization in MP.

Incidence of lateral femoral cutaneous nerve neuropraxia after anterior approach hip arthroplasty

BACKGROUND

Although injury to the lateral femoral cutaneous nerve (LFCN) is a known complication of anterior approaches to the hip and pelvis, no study has quantified its' incidence in anterior arthroplasty procedures.

QUESTIONS/PURPOSES

We therefore defined the incidence, functional impact, and natural history of LFCN neuropraxia after an anterior approach for both hip resurfacing (HR) and primary total hip arthroplasty (THA).

METHODS

We followed 132 patients who underwent an anterior hip approach (55 THA; 77 HR). We administered self-reported questionnaires for sensory deficits of LFCN, neuropathic pain score (DN4), visual analog scale, as well as SF-12, UCLA, and WOMAC scores at one year postoperatively. A subset of 60 patients (30 THA; 30 HR) was evaluated at two time intervals.

RESULTS

One hundred seven patients (81%) reported LFCN neuropraxia with a mean severity score of 2.32/10 and a mean DN4 score of 2.42/10. Hip resurfacing had a higher incidence of neuropraxia as compared with THA: 91% versus 67%, respectively. No functional limitations were reported on SF-12, WOMAC, or UCLA scores. Of the subset of 60 patients followed over an average of 12 months, 53 (88%) reported neuropraxia at the first followup interval with only three (6%) having complete resolution at second followup. Improvement in DN4 scores was observed over time: 3.6 versus 2.5, respectively.

CONCLUSIONS

Although LFCN neuropraxia was a frequent complication after anterior approach THA, it did not lead to functional limitations in our patients. A decrease in symptoms occurred over time but only a small number of patients reported complete resolution.

LEVEL OF EVIDENCE

Level III, therapeutic study. See Guidelines for Authors for a complete description of levels of evidence.