Sequential Localised Neuropathic Itch Following Drastic Weight Gain and Loss.

Dear Editor, A 56-year-old Indian woman with obesity underwent bariatric surgery (laparoscopic sleeve gastrectomy). She had gained 10 kg over the 3 years preceding the surgery after changing to a sedentary job. For 2 years, she had been having localised itch over the paraspinal region of her left upper back. Examination revealed a localised hyperpigmented patch over her left upper back (Fig. 1). The diagnosis was notalgia paresthetica (NP). After her surgery, the patient had rapid slimming initially. For the fi rst 2 weeks postsurgery, the patient was only given clear feeds and had rapid weight loss during this period. She lost 10 kg in the fi rst 3 months postsurgery. Three days postsurgery, she started feeling numbness over her right lower thigh and 13 days postsurgery, she felt itch and pain over the same area with the disappearance of the numbness. For the next 3 months, she experienced intermittent itch and pain over an area that correlated with the distribution of the lateral cutaneous branch of the femoral nerve and was diagnosed to have meralgia paresthetica (MP) (Fig. 2). There were no other external pressures on the nerve such as tight clothing or pressure during surgery. Discussion NP is not a rare condition but it is greatly under-recognised. NP is a form of peripheral sensory mononeuropathy and is thought to be secondary to nerve impingement or trauma affecting the posterior rami of the spinal nerves.1 It may result from compression by a space-occupying lesion or musculoskeletal structures, but no defi nite cause can be identifi ed in most cases. MP is another type of localised neuropathic dysaesthesia but it is rare. It is secondary to nerve entrapment of the lateral femoral cutaneous nerve, typically presenting with numbness, burning pain, itching or a tingling sensation localised to the unilateral anterolateral thigh.1 Numerous predisposing factors have been suggested, including diabetes mellitus, alcoholism, obesity (BMI >30), pregnancy, prolonged sitting, strenuous activity, direct trauma, lumbar disc herniation, iliaceous haematoma and tight clothing.1,2 Following gastric bypass surgery, the incidence of MP is estimated to be 0.5% to 1.4%.3 Compression of the thigh by the Gomez retractor has been a proposed mechanism.4 However, MacGregor and Thoburn reported 11 cases of MP, most beginning shortly after surgery (2 to 13 days), Neuropathic Itch —Carina M Grönhagen and Hong Liang Tey Letter to the Editor