Table 2. Main characteristics of the sample in each included study.

Study	Inclusion criteria	Clinical characteristics	Previous treatments	Pain duration
Khedr et al., 2005 [35]	“Unilateral chronic neuropathic pain. The diagnosis was based on the criteria of the International Association for the Study of Pain (IASP).”	16 women and 8 men (mean (SD) age 51.5 (10.7) years).	”All patients had been treated with various medications, including anticonvulsants, narcotic or non-narcotic analgesics and antidepressants, without satisfactory pain control. Three of the patients with TN had persistent pain even after microvascular decompression”.	Mean duration of illness of 39 months.
Lindholm et al., 2015 [34] and Lindholm et al., 2016 [33]	“Chronic daily neuropathic pain ≥4 in severity using a numeric rating scale (NRS); Diagnosis was based on International Criteria for Headache Disorders (ICDH 2013).”	N = 16, two of them male, with a mean age of 59 (range, 37–74).	“All patients had been diagnosed and treated for neuropathic orofacial pain in Turku University Hospital. All patients were suffering from severe chronic drug-resistant pain.”	Mean age of 10,44 years (not provided in the article).
Galhardoni et al., 2014 [30]	“Patients diagnosed with Atypical Facial Pain under treatment for at least three months. Persistent pain after at least two years of pharmacological treatment without adequate control. Pain higher than 6 at the VAS for at least three months.”	N = 19, females and males, with a mean age of 53,28±12,39 (28–78 years).	“All patients had received at least two pharmacological treatments. 44,8% had at least one concomitant treatment.”	Mean age of 13,5 ±11,04.
Umezaki et al., 2015 [48]	“BMS diagnosis; patients experienced daily and deep bilateral burning sensation of the oral mucosa, burning sensation for at least 4–6 months…”	All subjects were women except for one man in both the real and sham groups. Total mean age was 63.9 years.	“Selective serotonin reuptake inhibitors (SSRIs) were prescribed to around 40% of the patients, but these did not adequately relieve the BMS pain.”	Mean duration of illness was 63.4 months.
Brandão Filho et al., 2015 [29]	“…had a diagnosis of muscular TMD pain according to IA and IB, Axis I of the Research Diagnosis Criteria for Temporomandibular Disorders; had a VAS pain score of four or greater, presented pain regularly for six months or longer; had a State-Trait Anxiety Inventory (STAI) score of more than 42.”	All subjects were women, mean age was 36,5 years (± 12,3).	None of the subjects was under pharmacological treatments during the study. No reports regarding previous therapies.	Mean duration of pain was 7,1 (± 4,9)
Donnell et al., 2015 [31]	“Daily chronic TMD pain and dysfunction for at least one year matching RDC/TMD Axis I Group I: Myofascial pain diagnosis not adequately controlled by previous conventional therapies (TMJ open-surgery naïve) for more than 1 year; with self-reported pain score of at least 3 on VAS …”	All subjects were women. Mean age was 35,2 years.	No reports regarding conservative therapies adopted.	Pain Duration: higher than one year.
Hagenacker et al., 2014 [32]	“Classical TN with or without concomitant permanent pain according to the beta-version of the 3rd edition of the International Classification of Headache Disorders (ICHD-3).”	5 men and 4 women. Mean age of 63 years (range: 49–82 years).	“All patients had additional medication with different combinations of antiepileptic drugs. None of the investigated patients had an invasive procedure prior to study inclusion.”	Mean duration of illness was 9.78 years (2 to 27 years).
Oliveira et al., 2015 [37]	“TMD diagnosis based on RDC/TMD Ia or Ib. All patients had to present mean orofacial mean pain intensity equal to or over 4/ 10 on a VAS, during the last 6 months.”	3 men and 29 women. Mean age of 23,80± 7,30 (active group) and 25,50 ± 6,30 (sham group)	No reports regarding previous therapies. Volunteers that had received previous treatment of physical therapy could not be included in the study.	Mean duration of illness was 29,80 ± 17,10 months (active group) and 33,70 ± 22,80 months (sham group).