Quantitative Sensory Testing (QST) - Does assessing ... - TI Pharma

5. QST in patients with tendinopathy
a clinical examination for positive (hyperalgesia, allodynia) and/or negative signs
(hypaesthesia) in addition to continuous ongoing pain. In our study tendinopathies could
not be related to negative signs. Furthermore the DN-4 interview did not demonstrate
that neuropathic pain descriptors could be used to describe the pain. With QST, no
obvious signs of dynamic allodynia were found, although static pinprick allodynia
could be demonstrated. Furthermore the patients did not have ongoing pain in rest but
only evoked by pressure and physical (sport) activities. We can therefore conclude that
– according to the Treede (2008)-criteria, PT in our patient population is not associated
with neuropathic pain.
However, sensitisation both centrally and peripherally may be a plausible explanation for
the pain in (patella) tendinopathies. The question is why it arises and becomes chronic
in some athletes but not in others. One explanation may be the extent of nociception
that was originally present as a result of an extensive anatomical defect, severe and
long-lasting nociception or (neurogenic) inflammation may cause more profound and
irreversible sensitisation than relatively minor injury (Abate et al 2009; LaMotte et
al 1991). However in general, athletes with chronic patella tendinopathy normally do
not mention such an ‘inciting event’ causing severe nociception. Furthermore, genetic
factors may be of importance, suggesting that some people tend to sensitises more
vigorously than others (Magra & Maffulli 2008; Wang et al 2002; Zubieta et al 2003).
Finally psychological and behavioral factors appear to play an important role in the
maintenance of sensitisation (Gracely et al 2004). We did not find any differences in the
psychological dimensions of the SCL-90 and POMS. The outcome of the psychological
dimensions in our population was average or below average compared to norm figures
of healthy subjects (Arrindel & Ettema 2003). Behavioral factors may be an underlying
factor explaining sensitisation in chronic tendinopathies such as not taking adequate
measures at the onset of pain e.g. overuse, playing or training with pain and not
taking rest adequately. Injured athletes appear to experience fewer consequences from
musculoskeletal pain and tend to accept pain during sports (van Wilgen et al 2010). This
behavior could be a risk factor leading to physiological changes in the central nervous
system. In contrast, another psychological risk factor, fear of movement, which we did
not specifically measure in this study may also be a risk factor (Silbernagel et al 2011).
Future research on this topic is warranted.
Explaining the pain in tendinopathy by sensitisation may give a better understanding of
‘successful’ treatments currently used for tendinopathy. The positive effects of slightly
painful eccentric programs or painful shock wave treatment without anesthesia on pain
relief may not have local effect on the tendon but a more central effect i.e. explained by
desensitisation of the CNS (Rompe et al 2009).