Preoperative Ultrasound in Patients with Meralgia Paresthetica to Detect Anatomical Variations in the Course of the Lateral Femoral Cutaneous Nerve.

OBJECTIVE: Sometimes during surgery for meralgia paresthetica, it can be difficult to find the lateral femoral cutaneous nerve (LFCN). The aims of this study were to study the prevalence of different anatomical variations in patients, compare preoperative ultrasound (US) data with intraoperative findings, and investigate the effect of type of anatomical variation on duration of surgery and success rate of localizing the LFCN. METHODS: Fifty-four consecutive patients with idiopathic meralgia paresthetica who underwent either a neurolysis or neurectomy procedure were included. All patients preoperatively underwent US of the LFCN. Anatomical variations were categorized into type A, B, C, D, and E using the classification of Aszmann and Dellon. The cross-sectional area of the LFCN at the inguinal ligament and the distance of the LFCN to the anterior superior iliac spine were noted. Correlations with intraoperative findings were investigated, as well as the effect on duration of surgery and success rate of finding the LFCN. Clinical outcome was assessed using the Likert scale. RESULTS: The most frequent anatomical variant was type B (79%), followed by type C (9%), D (5%), and E (7%). No type A was encountered. Correlation between preoperative US and intraoperative findings was 100%. During surgery, the LFCN could be identified in all cases. Duration of surgery did not significantly vary for the different anatomical variants. CONCLUSIONS: Preoperative US is reliable in detecting anatomical variations of LFCN. This information can be very helpful in identifying the LFCN more frequently and easily during surgery, especially in more medial variants.

Ultrasonography and electrodiagnostic studies in ulnar neuropathy: an examination of the sensitivity and specificity and the correlations between both diagnostic tools.

PURPOSE: This study determines the sensitivity and specificity of ultrasonography (US) and electrodiagnostic studies in ulnar neuropathy at the elbow (UNE) in clinical practice and explores the correlation between both diagnostic tools. METHODS: Patients were classified on clinical grounds as UNE or patient controls. Electrodiagnostic studies were performed, and nerve cross-sectional area was measured by US. RESULTS: Sensitivity and specificity were examined in 30 cases of UNE and 33 patient controls. Electrodiagnostic studies had a sensitivity for UNE of 63.3% and a specificity of 87.9%. Ultrasonography had a sensitivity of 76.7% and a specificity of 72.7%. Ultrasonography is more sensitive if complaints exist for 6 months or less. If complaints persisted for more than 6 months, sensitivity and specificity of the electrodiagnostic studies were superior. Correlation was examined in 30 cases of UNE. There was no significant correlation between cross-sectional area and absolute motor nerve conduction velocities across the elbow, motor nerve conduction velocities slowing across the elbow, and compound muscle action potentials amplitude reduction. CONCLUSIONS: Ultrasonography is more sensitive if complaints exist for 6 months or less. Electrodiagnostic studies are more sensitive and specific compared with US for longer existing cases of UNE. No significant correlation could be demonstrated between both diagnostic tools.

Corticosteroid injection in patients with ulnar neuropathy at the elbow: A randomized, double-blind, placebo-controlled trial.

INTRODUCTION: We conducted a randomized, double-blind, placebo-controlled trial to evaluate the effect of ultrasound-guided corticosteroid injection in patients with ulnar neuropathy at the elbow (UNE). METHODS: Fifty-five patients were randomized between an ultrasound-guided injection of 1 ml containing 40 mg methylprednisolone acetate and 10 mg lidocaine hydrochloride or a placebo injection. The primary outcome was the subjective change of symptoms after 3 months. The secondary outcomes were change in electrodiagnostic studies and ultrasonography findings. RESULTS: A success rate of 30% was found in the corticosteroid injection group versus 28% in the placebo injection group. Only the nerve cross-sectional area changed significantly in the intervention group, from a mean of 11.9 mm(2) to 10.9 mm(2) . CONCLUSIONS: We could not demonstrate a positive effect of ultrasound-guided corticosteroid injection in UNE compared with placebo. Favorable outcomes may be attributed to the natural course of UNE or the effect of patient education.