Meralgia paraesthetica: Laparoscopic surgery as a cause then and a cure now.

Meralgia Paraesthetica (MP) is a rare condition, in which the patient experiences a burning sensation along the distribution of the lateral femoral cutaneous nerve of the thigh, due to entrapment neuropathy at the lateral end of the inguinal ligament as it exits the pelvis. There are several causes of this condition including laparoscopic inguinal hernioplasty. Diagnosed clinically, intervention is indicated for failed conservative measures. We herewith report a patient with MP and symptomatic cholelithiasis, treated for both laparoscopically. This is the third reported case in the literature that has been treated laparoscopically.

INTRODUCTION

Meralgia Paraesthetica (MP) is a syndrome of burning neuritic pain along the distribution of the femoral lateral cutaneous nerve of the thigh (FLCNT). Initially known as ‘Bernhardt Roth syndrome’, it was later called MP from the Greek words ‘meros’ (thigh) and ‘algos’ (pain). The FLCNT, derived from L2 and L3 roots, leaves the lateral border of Psoas major, and traverses the lateral end of the inguinal ligament to supply the upper lateral thigh.[1] Causes of MP range from obesity, diabetes, pelvic masses, pelvic osteotomy and spine surgeries to laparoscopic hernia repair and bariatric surgery.[2] The symptoms are usually aggravated by standing and relieved by sitting. Somatosensory evoked potential is a useful diagnostic test. The treatment options are injection of local anaesthetic, steroids[1] and pulsed radio frequency of FLCNT.[2] For patients unresponsive to the above, the surgical options are neurolysis with or without nerve transposition and nerve transection.[1] We describe here a case of MP with entrapment of the FLCNT that was cured with laparoscopic neurolysis, which is the third reported case in the literature.

CASE REPORT

A 55-year-old lady presented to us with a 6-year history of severe neuritic pain of upper lateral aspect of the right thigh, which radiated to the lower lateral aspect, with medical treatment being futile. Additionally, she had symptomatic gallstones.

General and local examination was unremarkable except for an area of hyperesthesia along the distribution of the right FLCNT. Injection of 2 ml of 2% xylocaine below the anterior superior iliac spine gave instantaneous relief. Diagnosis of cholelithiasis with MP was confirmed.

Laparoscopic surgery was planned, with intent to cure both pathologies. A 10 mm port was inserted in the umbilicus for the laparoscope and two 5 mm ports in both mid-clavicular lines at the level of the umbilicus, with an additional epigastric port. Following cholecystectomy, the parietal peritoneum over the right lower abdominal wall was incised in a curvilinear fashion 2 cm below and medial to the anterior superior iliac spine. The flap was raised inferiorly until the fascia over the psoas muscle was exposed and opened with a diathermy hook. The FLCNT was seen coursing laterally across the psoas major and entering the fibres of the inguinal ligament, thus dividing it into superior and inferior laminae [Figure 1]. The inguinal ligament was grasped and keeping the nerve under vision the fibres of the inferior lamina were divided, thereby freeing the nerve [Figure 2]. The peritoneal flap was then closed using 3-0 polydioxanone. She had an uneventful recovery with mild transient numbness in the area of distribution of the FLCNT that normalised in 3 months.

Figure 1

Showing right femoral lateral cutaneous nerve of the thigh (white arrow) splitting the inguinal ligament into superior (black arrow) and inferior laminae as it exits the pelvis

Figure 2

Showing the inferior lamina of the inguinal ligament being carefully divided using a hook diathermy (white arrow)

DISCUSSION

In the early phase of laparoscopic hernia repair, there were reports of nerve complications, including MP.[3] This is attributable to neural entrapment by the staples or mesh induced fibrosis and is prevented by the twin caveats of avoiding fixation devices in the triangle of pain, and leaving the fascia intact over the nerves. With maturity of the learning curve and better recognition of regional anatomy, the neural complications are much less in the recent years. Possibly lack of the same two factors was responsible for MP during the early era and later familiarity of the regional anatomy has led to its cure laparoscopically.

The FLCNT splits the inguinal ligament into superior and inferior laminae. Importantly the inferior lamina was divided, as superior laminar division is said to exacerbate symptoms. Laparoscopic neurolysis, reported earlier by Bhardwaj[4] and ADK Hill,[5] has given complete relief to our patient. This may well be the favoured option in the future. Variation of the anatomy of the nerve has been described.[4] This, would make an open surgical technique not only extensive but with limited success.