PDAP Pathophysiology

Qualitative and quantitative sensory testings were mainly utilized to study PDAP pathophysiology. Some investigators tried also to understand whether these tests may be helpful in the diagnostic process. Baad-Hansen et al., in a case-control study (level of evidence 3) found that QualST has an acceptable intra- and inter-examiner reliability (62). QualST is characterized by three intra-oral tests to conduct bilaterally to find somatosensory differences between the painful and non painful side. To have a diagnostic value, there should be a number of differences in side to side comparisons that would give at the same time enough sensitivity and specificity to distinguish PDAP patients from controls. In their study, authors could not find this number. 0/3 side to side QualST differences were found only in 3% of PDAP patients (sensitivity 97%), but only in 60% of healthy controls (too many false positives; specificity 60%). On the other hand if 2/3 or 3/3 QualST differences were found, specificity was high (low risk of false negatives), but too many PDAP cases would remain undiagnosed (low sensitivity). Authors concluded that it would be interesting to develop a QualST with more than three tests, in
Baad-Hansen et al., found fair to excellent intra- and inter-examiner reliability of the QST, depending on the parameter that was tested (39). However, the same authors concluded that QST alone cannot be used to diagnose neuropathic orofacial pain conditions because of too many false positives. They argue that QST may be an useful tool in specialized orofacial pain centers, as part of a more thorough evaluation (7). Porporatti et al., as a result of a systematic review of QST studies on PDAP patients, claim that some QST parameters (DMA1, DMA2, HPT, WUR) are reliable tools to differentiate PDAP patients from controls