Meralgia paresthetica caused by hip-huggers in a patient with aberrant course of the lateral femoral cutaneous nerve

Unusual causes for meralgia paresthetica: systematic review of the literature and single center experience

Meralgia paresthetica is often idiopathic, but sometimes symptoms may be caused by traumatic injury to the lateral femoral cutaneous nerve (LFCN) or compression of this nerve by a mass lesion. In this article the literature is reviewed on unusual causes for meralgia paresthetica, including different types of traumatic injury and compression of the LFCN by mass lesions. In addition, the experience from our center with the surgical treatment of unusual causes of meralgia paresthetica is presented. A PubMed search was performed on unusual causes for meralgia paresthetica. Specific attention was paid to factors that may have predisposed to LFCN injury and clues that may have pointed at a mass lesion. Moreover, our own database on all surgically treated cases of meralgia paresthetica between April 2014 and September 2022 was reviewed to identify unusual causes for meralgia paresthetica. A total of 66 articles was identified that reported results on unusual causes for meralgia paresthetica: 37 on traumatic injuries of the LFCN and 29 on compression of the LFCN by mass lesions. Most frequent cause of traumatic injury in the literature was iatrogenic, including different procedures around the anterior superior iliac spine, intra-abdominal procedures and positioning for surgery. In our own surgical database of 187 cases, there were 14 cases of traumatic LFCN injury and 4 cases in which symptoms were related to a mass lesion. It is important to consider traumatic causes or compression by a mass lesion in patients that present with meralgia paresthetica.

Lateral Femoral Cutaneous Nerve Decompression Guided by Preoperative Ultrasound Mapping

Injury to the lateral femoral cutaneous nerve (LFCN) from compression or entrapment may result in meralgia paresthetica, a painful mononeuropathy of the anterolateral thigh. Surgical decompression of the LFCN may provide relief when conservative management fails. However, the considerable anatomic variability of this nerve may complicate surgical localization and thus prolong operative time. Herein, we report the use of preoperative high-resolution ultrasonography to map the LFCN in a patient with bilateral meralgia paresthetica. This simple, noninvasive imaging technique was seen to be effective at providing precise localization of the entrapped and, in this case, bilateral anatomically variant nerves. Preoperative high-resolution ultrasound mapping of the LCFN can be used to facilitate precise operative localization in the treatment of bilateral meralgia paresthetica. This is especially useful in the setting of suspected unusual nerve anatomy.

Sonographic and electrophysiologic findings in patients with meralgia paresthetica

OBJECTIVE

This study was aimed to demonstrate the usefulness of ultrasonography in the diagnosis of meralgia paresthetica (MP).

METHODS

Clinical data, sensory nerve conduction study and sonographic findings of 23 patients with unilateral MP were analyzed retrospectively. Twelve healthy subjects were recruited for the optimal cut-off value for the cross-sectional area of LFCN to diagnose MP using receiver operating characteristic curves.

RESULTS

The median value of the cross-sectional area of LFCN in healthy subjects was 3mm(2) and in the affected and unaffected sides in patients with MP, they were 11 and 6.5mm(2) around the anterior superior iliac spine level. The optimal cut-off value for the diagnosis of MP was 5mm(2). The location of LFCN on the affected side was superior to the inguinal ligament in 12 out of 23 cases (50%).

CONCLUSION

Ultrasonography is useful in the diagnosis of MP as a supplemental diagnostic tool, which gives important information about the morphologic changes that occur in the LFCN and its course.

SIGNIFICANCE

To the best of our knowledge, this is the first report to suggest that describe the cutoff value of the cross-sectional area of LFCN for the diagnosis of MP using ultrasonography.

High-resolution ultrasonography in the assessment of meralgia paresthetica

INTRODUCTION

Meralgia paresthetica can be difficult to diagnose, as neurophysiological studies are often hard to interpret due to excess fatty tissue and the varying anatomy of the lateral femoral cutaneous nerve.

METHODS

We retrospectively analyzed the use of high-resolution ultrasound (HRU) for confirming clinical meralgia paresthetica and compared results with nerve conduction studies.

RESULTS

In all 6 patients evaluated, HRUs showed significantly enlarged nerve diameter and in 3 enlarged cross-sectional area, 4 had absent nerve potentials, and in 2 the potentials could not be recorded on either side.

CONCLUSIONS

HRU seems promising for confirming meralgia paresthetica and can accurately localize nerve entrapment.

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.

Sonographic assessment of the lateral femoral cutaneous nerve

PURPOSE

To evaluate the ability of high-frequency sonography to evaluate the lateral femoral cutaneous nerve (LFCN).

METHODS

A cadaveric study was performed on 5 cadavers to outline the normal course of the LFCN. Next, 37 LFCNs in 21 volunteers were evaluated via sonography with a 5-13-MHz linear-array transducer.

RESULTS

The LFCN was easily identified in our dissections. It always entered the thigh under the inguinal ligament and coursed superficially to the sartorius muscle. In 2/10 (20%) cases, anatomical variants were observed. Sonography revealed the LFCN in 26/37 (70%) cases. The relationships of the nerve with the deep circumflex iliac artery, the anterior superior iliac spine, and the sartorius were visualized. Neuromas were observed bilaterally in 1 volunteer.

CONCLUSION

The LFCN can be seen in the groin with the aid of sonography.