Table 2.

Characteristics of 5 selected studies on diagnostic accuracy of sonography as a confirmatory test for carpal tunnel syndrome

	Study type	Index test cut off value (median nerve CSA)†	Reference standard (clinical exam diagnosis criteria)
Kwon et al.15	Prospective case-control	10.7 mm2: at carpal tunnel inlet (level of pisiform)	Paraesthesias, pain and Phalen’s test
Pastare et al.16	Prospective case-control	9.0 mm2: at proximal entry of carpal tunnel	Paraesthesias
Altinok et al.17	Prospective case-control	9.0 mm2: at the level of pisiform	Pain, numbness, sensory disturbance and Tinel’s or Phalen’s test
Kele et al.18	Prospective case-control	11 mm2: at proximal edge of carpal tunnel (level of pisiform)	Paraesthesias, decrease in fine touch sensitivity, motor weakness and thenar atrophy
El Mediany et al.19	Prospective case-control	10.03 mm2: at carpal tunnel inlet	Paraesthesia, pain, swelling, weakness, clumsiness, sensory deficit, thenar atrophy and Phalen’s test

CSA: cross-sectional area

^†CSA value above which a patient was considered to have carpal tunnel syndrome. Some studies have demonstrated that a larger median nerve CSA at the proximal carpal tunnel inlet is a reliable criterion for CTS diagnosis with sonography, although the reason for the enlargement is uncertain ^21–22.