Impaired gallbladder motility and delayed orocecal transit contribute to pigment gallstone and biliary sludge formation in β -thalassemia major adults

Figure 1 Sweat spot test (SST) for assessment of sympathetic autonomic nervous system[22,24,25]. The skin is coated with iodine and a fine emulsion of starch in arachis oil. Sweat is stimulated by intra-dermal injection of of 0.1 mL acetylcholine (the red dot indicates the point of injection). Denervated glands do not respond to the acetylcholine injection. A colorimetric reaction between starch and iodine is triggered by the sweat from stimulated glands, so that each pore appears as a small black dot after 2-5 min. A digital photo is taken and transferred to a magnifying software to measure the number and distribution of dots appearing in a standard squared grid of 529 mm² divided into 64 squared subareas. A normal SST implied a score 12 dots/subarea and/or < 8% of abnormal subareas (each square of the grid having less than 6 dots) according to Ryder[24] and to our group[25]. Only patients with both indices (SST score and % abnormal subareas) outside normal limits were considered to have a positive test. A: Normal and even distribution of sweating glands seen as black dots; B: Defective response in a β -thalassemia major patient with sympathetic autonomic neuropathy.