Quantitative Sensory Testing and Conditioned Pain Modulation in patients after cervical percutaneous cordotomy

Cervical percutaneous cordotomy (CPC) is an invasive treatment, which sometimes
is applied in palliative pain care. During a CPC, the spinothalamic tract is
unilaterally destructed (level C1-C2) with a series of radiofrequency-lesions.
The needle for the radiofrequency lesion is positioned under fluoroscopy or CT
guidance. After the procedure, the vital sensibility of the contralateral side
of the body, caudal to dermatome C5, is interrupted.

The guideline *diagnostiek en behandeling van pijn bij patiënten met kanker*
worked out by '' de Nederlandse Vereniging voor Anesthesiologie' provides
these recommendations:
-Unilateral cordotomy can be applied in cases of unilateral pain, caudal to
dermatome C5
-Bilateral cordotomy is not recommended
-Cordotomy can only be applied in patients with a maximum life expectancy of 1
to 2 years
-Cordotomy should only be performed in clinics with expertise in this area.

Quantitative sensory testing (QST) has been developed in Germany by the German
Research Network on Neuropathic Pain, DFNS, to characterize the somatosensory
phenotype of patients with neuropathic pain. QST is a standardized measurement
which assesses the integrity of the entire peripheral nerve (receptor to
brain), by applying several mechanical en thermal stimuli to the skin. In
2006, an article was published, where the authors describe reference values,
obtained by applying the QST measurement to 180 healthy volunteers.

The QST measurement can be performed bilaterally within one patient, in this
case the patient provides his or her own control values, In the current
literature there has been one article published where patients were subjected
to quantitative clinical tests after a CPC. However, this article was published
before the standardized QST measurement was developed. Applying the
standardized QST measurement to patients who underwent a CPC can yield
valuable information concerning the integrity of the several neurological
modalities after spinothalamic tract destruction.
Furthermore, performing a conditioned pain modulation (CPM) test on patients
after CPC has not been described in the literature. We propose to assess
whether the CPM is altered after CPC. We hypothesize that the pain tolerance is
increased after interruption of the vital sensibility, however we do not know
the contribution of the vital sensibility to the mechanism of CPM. Therefore
performing this study is of crucial importance for understanding this
mechanism.

To perform sensory testing in patients who have undergone a cervical
percutaneous cordotomy. The sensory testing include 'quantitative sensory
testing' according to the *the German Research Network on Neuropathic Pain*
protocol and a *conditioned pain modulation* test, to determine the function of
the inhibitory pain mechanism.

We propose a prospective cohort study. Patiënt will be subject to sensory
testing (quantitative sensory testing and conditioned pain modulation), which
will be conducted in an outpatient setting.
We expect to include the required number of patients within 18 months.

The burden for the patient is a onetime visit to the outpatient clinic of the
Erasmus MC Hospital in Rotterdam. The sensory testing will take approximately
two hours. The sensory testing is non-invasive and there is no risk for
permanent (tissue) damage.