Clinical trial NCT04764045: The Significance of Peripheral Input
Official title: The Significance of Peripheral Input in Patients With Post Surgery Neuropathic Pain: Evaluation of Trigger Point Anesthesia. A Double-blind, Randomized, Controlled Exploratory Study
Study type: INTERVENTIONAL
Overall status: UNKNOWN
Phase: NA
Conditions: Neuropathic Pain
Keywords: Peripheral input
Trigger point injection
Post operative pain
Lead sponsor: Bispebjerg Hospital
Sponsor class: OTHER
First posted: 2021-02-21
Enrollment: 12
Sex: ALL
Minimum age (years): 18
Standard ages: ADULT
OLDER_ADULT
Accepts healthy volunteers: no
Allocation: RANDOMIZED
Intervention model: CROSSOVER
Primary purpose: BASIC_SCIENCE

Brief summary: The investigators want to examine trigger point injections of local anesthetics, in patients with post operative neuropathic pain, determine changes in sensory disturbances such as allodynia, hyperalgesia and thermal sensitivity and examine whether trigger point injections will attenuate pain in rest and activity.

Detailed description: The presence of cutaneous trigger points in the surgical incision of patients with post-surgery pain has been shown in our pain clinic, all patients have persistent pain for more than 3 month and different sensory disturbances.

Examinations with trigger point injections of local anesthetics have been used to determine the influence of peripheral changes and the significance of afferent input on persistent post-surgery neuropathic pain.

In the present study the investigators will document the influence of cutaneous trigger point injections for both subjective pain experience and objective findings in the area such as allodynia, hyperalgesia and thermal sensitivity. The investigators expect reduction in spontaneous pain intensity and de-crease in peripheral sensory disturbances and will determine the significance of peripheral input in persistent neuropathic pain.

The investigators aim to investigate whether injection of local anesthesia into trigger points compared with placebo (saline) injection will attenuate pain and normalize abnormal sensations, such as hyperalgesia and allodynia. The investigators believe this to be an important investigation to understand the mechanisms behind chronic post-surgery pain.

Eligibility criteria: Inclusion Criteria:

* Age \> 18 years old
* Patients with chronic pain (daily VAS pain scores \>30 mm) for at least 3 months after knee, shoulder or foot surgery
* Patients with at least one identifiable trigger point in relation to incision from the knee, shoulder or foot surgery. A trigger point is defined as an ar-ea in relation to the incision from surgery, in which a light pressure from a cotton pin radiate pain to the nearby area, and exudes a motor reflex causing withdrawal of the leg
* A written informed consent to participate in the study after having fully understood the contents of the protocol and restrictions

Exclusion Criteria:

* Patients who cannot cooperate
* Patients who cannot understand or speak Danish.
* Patients with allergy to the drugs used in the study
* Patients in treatment with vitamin K antagonists.
* Patients with other pain conditions
* Patients with diabetes

Primary outcomes:
measure: Change in worst pain in rest and in activity
timeFrame: 30 minutes
Secondary outcomes:
measure: Change in area of sensory disturbances
timeFrame: 30 minutes
measure: Change in warm and cold detection, threshold and tolerance before and after intervention in area with hyperalgesia compared to normal skin
timeFrame: 30 minutes
Other outcomes:
Locations:
city: Copenhagen
country: Denmark
facility: Bispebjerg Hospital
Study officials:
References:
citation: Wijayasinghe N, Ringsted TK, Bischoff JM, Kehlet H, Werner MU. The role of peripheral afferents in persistent inguinal postherniorrhaphy pain: a randomized, double-blind, placebo-controlled, crossover trial of ultrasound-guided tender point blockade. Br J Anaesth. 2016 Jun;116(6):829-37. doi: 10.1093/bja/aew071.
citation: Haroutounian S, Nikolajsen L, Bendtsen TF, Finnerup NB, Kristensen AD, Hasselstrom JB, Jensen TS. Primary afferent input critical for maintaining spontaneous pain in peripheral neuropathy. Pain. 2014 Jul;155(7):1272-1279. doi: 10.1016/j.pain.2014.03.022. Epub 2014 Apr 2.
citation: Haroutounian S, Ford AL, Frey K, Nikolajsen L, Finnerup NB, Neiner A, Kharasch ED, Karlsson P, Bottros MM. How central is central poststroke pain? The role of afferent input in poststroke neuropathic pain: a prospective, open-label pilot study. Pain. 2018 Jul;159(7):1317-1324. doi: 10.1097/j.pain.0000000000001213.