Diagnostic features:
(1) burning pain, paresthesia, itching and numbness over the anterolateral thigh
(2) no motor loss
(3) pressure at the inguinal ligament medial to the anterior iliac spine may elicit pain and dysthesia in the nerve distribution
(4) normal electrophysiologic studies of the femoral nerve and quadriceps femoris muscle
(5) symptoms disappear after local nerve block
Mechanisms:
(1) Compression of the lateral femoral cutaneous nerve in thigh as it passes under the inguinal ligament.
(2) Compression of proximal segment by a retroperitoneal process, pregnancy or increased intra-abdominal pressure.
(3) Transection during appendectomy or other surgery.
(4) Enlargement of the quadriceps muscle.
Causative factors:
(1) obesity
(2) ascites
(3) retroperitoneal lymphoma or malignancy
(4) status post appendectomy or pelvic surgery
(5) excessive exercise of the lower extremities
(6) mass effect in the quadriceps muscle
(7) pregnancy
(8) increased intra-abdominal pressure of any cause
(9) compression by a belt, corset or clothing
(10) fracture of the anterior portion of the ilium
(11) marked pelvic tilt
Differential diagnosis:
(1) lumbar radiculopathy (electrophysiologic studies of femoral nerve and quadriceps femoris muscle will be abnormal)
