Table II.

Characteristics of the seven retrieved studies

Study	Level of evidence	Number of patients	Male/female	Age [years]	Diseases
Diamant et al. (1968) [26]	II	10	6/4	39 (average)	10 Lumbar rhizopathies
Keshari et al. (2008) [27]	II	18	_	42 (average)	9 Discogenic pain and 9 scoliosis
Bartels et al. (1998) [28]	II	24	_	_	11 Back pain and 13 scoliosis
Bamrtann et al. (1996) [29]	III	4	3/1	46-55	4 Chronic intractable pain
Strobel et al. (1997) [30]	II	20	_	_	10 Low back pain and 10 fibromyalgia
Vormann et al. (2001) [31]	II	82	30/52	46/50 (average)	82 Low back pain
Moore et al. (1991) [32]	III	18	_	_	18 Back pain