Comparing Ways to Freeze the Nerve That Provides Thigh Sensation

Summary

Background

The sensation on the outside of portion of our thighs is provided by a nerve called the lateral femoral cutaneous nerve (LFCN). The investigators can inject freezing around the nerve to reduce the feeling around the thigh (i.e. anesthesia). Anesthesia, or freezing, of the lateral femoral cutaneous nerve can reduce pain for patients having A) hip and knee surgery \[1,2\], B) removal of a skin graft \[3\], and C) wound care. In addition, damage to the LFCN (i.e. Meralgia Paresthetica) has been associated with body armour and gun belt use in military and police personnel \[4\]. Although generally a benign condition, compression or injury to this nerve can be painful and require treatment. In addition, the actual variability in sensory distribution for this nerve has not been elucidated in a topographical fashion and will be measured in this study.

Finding the most efficient and effective method for anesthesia of the LFCN can improve and positively impact the quality of pain control for patients. Ultrasound has improved the accuracy and efficiency of various other regional anesthesia techniques, and could also impact the safety. Therefore the investigators hypothesize that ultrasound guided lateral femoral cutaneous nerve block using the subinguinal technique will be statistically more efficacious and efficient when compare to neurostimulation based blockade.

Conditions

• Meralgia Paresthetica

Interventions

DRUG

Nerve Injection- Nerve Stimulator

For the neurostimulation nerve injection technique, the initial puncture site will be located medial to the anterosuperior iliac spine, just caudal to the inguinal ligament \[7\]. The 22-gauge insulated needle will be connected to a stimulator set at a current of 1.5 mA, a pulse width of 300 ms and a frequency of 2 Hz. A paresthesia referred to the lateral aspect of the thigh at a minimal stimulatory threshold of 0.6 mA (0.3ms) will be sought prior to the injection of local anesthetic \[7\]. A total of 5cc of 2%Xylocaine will be injected for the nerve injection/anesthesia.

DRUG

Nerve Injection - Ultrasound

For the ultrasound nerve injection group, after skin disinfection, the inguinal region of patients will be scanned using a high-frequency (6 to 13 MHz) linear array transducer covered with a sterile plastic cover. An ultrasound image showing the inguinal ligament and anterior superior iliac spine (ASIS) will be obtained. Using an out-of-plane technique, a 22-gauge nerve block needle will be inserted 1-2 cm medial to ASIS. The needle will be advanced until its tip rests under the inguinal ligament, immediately ventral to the iliopsoas muscle \[6\]. A total of 5cc of 2%Xylocaine will be injected for the nerve injection/anesthesia.

Sponsors & Collaborators

• Canadian Forces Health Services Centre Ottawa

  lead OTHER

Principal Investigators

• Gaurav Gupta, MD · CF Health Centre Ottawa

Study Design

Allocation

RANDOMIZED

Purpose

DIAGNOSTIC

Masking

SINGLE

Model

PARALLEL

Eligibility

Min Age

18 Years

Max Age

60 Years

Sex

ALL

Healthy Volunteers

Yes

Timeline & Regulatory

Start

2015-11-30

Primary Completion

2016-02-29

Completion

2016-06-30