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

4. QST and neuropathic pain mechanisms
can be used to identify relevant subgroups of neuropathic pain patients, in this case
characterised by altered mechanical pain sensitivity. According to the DFNS QST
protocol, the geometric means of the numerical pain ratings for the different pinprick
stimuli are taken for further analysis (Konopka et al a; Maier et al 2010; Rolke et al
2006a; Rolke et al 2006b). As an addition to the QST protocol, we performed stimulus
response analyses, since these can be very informative and have been widely used to
assess hypo- and hyperalgesic cutaneous reaction in clinical pain models (Fuchs et al
2001; Magerl et al 2001; Segerdahl 2006) and in patients (Stiasny-Kolster et al 2004).
2. Method
The study adhered to the declaration of Helsinki and all procedures have been
approved by the medical ethical committee “Stichting Beoordeling Ethiek Bio-Medisch
Onderzoek, P.O. Box 1004, 9400 BA Assen, The Netherlands”, including patients and
healthy controls from the local region. All participants signed an informed consent
form.
2.1. Description of healthy controls
In total, 185 age-matched healthy volunteers (age range 25-75 years), 119 females (age
48.9 ± 10.5 years) and 66 males (age 51.9 ± 12.4 years) underwent the QST assessments
on their dorsal hand and dorsal foot. These body locations are indicated by Rolke et al.,
2006 as reference sides for QST (Rolke et al 2006a). A previous study concluded that
there were no significant differences in QST parameters between the right and left sides
of the body in healthy volunteers (Rolke et al 2006a), thus we obtained QST reference
values from one side of the body. In total, 370 QST reference values were obtained.
Healthy subjects were identified according to medical history. Subjects were specifically
questioned about previous injuries or diseases. The healthy subjects did not use pain
medication regularly and were free of medication at the time of the assessments.
2.2. Description of the patient cohort
Patients were recruited from the outpatient Department of the Pain Management
Unit of the University Medical Center Groningen, The Netherlands. All patients were
diagnosed as suffering from neuropathic pain by the physicians of the pain management
unit. Neuropathic pain diagnosis was made on grounds of coherent patient history,
medical history, physical examination, including neurologic function tests. Each
clinical diagnosis was additionally confirmed by an experienced pain specialist of the
Pain Management Unit based on patient’s files. In total, 127 neuropathic pain patients
(65 females age 52.4 ± 12.1 years and 62 males age 51.45 ± 12.4 years) underwent the
QST assessment, each at the area where the most profound pain was experienced (leg:
n=70, arm: n=29, thorax: n=12, back: n=4, abdomen: n=3, cervix: n=3, groin: n=2,