Discussion

Meralgia Paresthetica (MP) was described by Bernhardt in 1878, and then the term was adopted by Roth in 1878, to describe a disorder caused by entrapment or damage to the lateral femoral cutaneous nerve (LFCN) as it passes underneath or through the inguinal ligament, characterized by tingling, numbness, or burning pain in the anterolateral aspect of the thigh. It most commonly occurs on one side, but in 20% of cases it appears bilaterally (5, 6).

Although most cases of LFCN entrapments (meralgia paresthetica) are idiopathic, different risk factors has been identified that might increases the risk of MP including, obesity, diabetes mellitus, prolonged leaning of the thigh against a bench or table, and direct pressure or trauma (6).

Hypothyroidism, one of the most common endocrine disorders, that has neurological manifestations, causing both mono and polyneuropathies (3, 7), however the exact mechanism is not fully understood, and with the most commonly involved nerves are the sural and median nerves [8], but to our knowledge there is only on unilateral meralgia parethetica case in hypothyroid patient who showed an immediate improvement of MP symptoms upon correction of the thyroid hormones (4).

In our patient different factors were involved that might have contributed to development of meralgia parethetica including, hypothyroidism, obesity, and the possibility of direct pressure from prolonged sitting and leaning in his office job as the patient stated his job might imply sitting for 6 – 8 hours/day. As MP has been reported in mimicking lumbar radiculopathy (6, 9, 10), this was excluded as a cause of his pain since the LFCNT is a branch of the lumbar plexus emerging from the L2 and L3 nerve roots which correspond to the anterolateral aspect of the thigh, however his MRI showed L5 S1 disc bulge with no corresponding signs and symptoms.

Moreover, our patients declined any signs or symptoms of hypothyroidism upon presentation to the clinic including, cold intolerance, fatigue, constipation, hair loss, and hoarseness, he has normal thyroid function, normal vitamin B12 level, and normal blood sugar profile, however continued to suffer from MP symptoms, which might lead to consideration of other involved mechanisms and factors such as obesity and prolonged direct pressure.

The diagnosis of MP, is often delayed as the condition is rarely considered, and is frequently mistaken for other disorders (5,6,11), unfortunately when the diagnosis and treatment is delayed or missed, this can lead to significant disability and suffering by the patient, and unnecessary investigations and tests (5, 12). The diagnosis of MP is mainly clinical (6, 13), which allude to the importance that clinicians should consider the possibility of MP whenever the patient reports anterolateral thigh symptoms such as pain, burning, tingling, numbness, paresthesia or dysesthesia (2, 4-6), especially in the presence of any risk factors such as DM, obesity, or hypothyroidism (2, 14). Also, the relief of pain or symptoms, after the injection of local anaesthetic could serve as a helpful diagnostic entity (6, 15, 16).

Other investigations such as Plain X-ray, CT or MRI of the lumbar spines could be performed to exclude other possible etiologies such as disc herniation or pelvic lesions (6). Additionally, blood tests must be considered including, vitamin B12 levels, blood sugar profile, and thyroid function testing, as MP has been associated with hypothyroidism (4, 6). If the diagnosis is still not confirmed electrophysiological tests are considered to confirm the diagnosis (17).

Treatment of Meralgia Paresthetica has been controversial (18), as evidence in the literature showed that most cases might recover spontaneously within 4–6 months of presentation (6, 19). However as first-line of therapy one should always consider to treat and/or to prevent any existing contributory factors, such as, life style modification, by weight reduction, not wearing tight clothes or belts, avoid the prolonged leaning or bending and to consider frequent movement, and stretching intervals (6).

Williams and Trzil (20) reported resolution of symptoms in up to 90% with conservative management including, Non-steroidal anti-inflammatory drugs, physical therapy, and local steroid injection (11), however in case of persistent or intractable pain, other measures such as, radiofrequency nerve ablation has been reported of good benefit (21, 22), or surgical intervention including neurolysis, transposition and neurectomy could be considered (15, 16, 18).