Nociceptive Processing in Acute Cutaneous Nerve Entrapment Syndrome

Nociceptive Processing in Acute Cutaneous Nerve Entrapment Syndrome: a Quantitative Sensory Testing Analysis.

Rationale: Chronic abdominal pain is a frequently occurring condition. Although hardly ever considered, the abdominal wall is the primary cause in 10-30% of cases. Most often it is caused by entrapment of an intercostal nerve in the anterior rectus sheath, the Anterior Cutaneous Nerve Entrapment Syndrome (ACNES). Treatment consists of local anaesthetic injections combined with methyl-prednisolon. When ineffective, a neurectomy at the site of penetration out of the ventral rectus sheet should be considered. This neurectomy however is effective in 73% of cases, leaving some 25% of patients in pain. Whether these refractory ACNES patients suffer from underlying pathologic pain disorders is subject to investigation, by using quantitative sensory testing (QST).

Objective: To investigate nociceptive processing and possible underlying pathological pain processing mechanisms in ACNES patients.

Study design: An observational case-control study.

Study population: Patients treated for ACNES (n = 50) compared to healthy controls from an existing database.

Measurements: Quantitative sensory testing (QST) of nociception, performed after treatment of ACNES for both successfully treated and refractory patients in comparison to healthy controls. Visual Analogue Scores (VAS) measured before, during and after testing procedures. Pain Anxiety Symptom Scale (PASS) and Pain Catastrophizing Scale (PCS) questionnaires.

Main study parameters: Pressure pain and electrical pain thresholds as investigated by QST. Secondary study parameters are VAS-scores and results of PASS and PCS questionnaires.

Study Overview

• Status: Completed
• Conditions: Anterior Cutaneous Nerve Entrapment Syndrome (ACNES)
• Intervention / Treatment: Other: Quantitative Sensory Testing analysis

• Study Type: Observational
• Enrollment (Actual): 50

Contacts and Locations

Study Locations

• Netherlands
  • Nijmegen, Netherlands
    • Radboud University Medical Centre

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: 18 years and older (Adult, Older Adult)
• Accepts Healthy Volunteers: No
• Genders Eligible for Study: All

• Sampling Method: Non-Probability Sample

Study Population

Study population will consist of ACNES patients that have been treated both successfully and refractory. The control group will consist of demographically equal healthy controls from an existing database

Description

Inclusion Criteria:

1. Patient has been diagnosed with abdominal complaints, matching ACNES:

   • Patient had a constant site of tenderness that is superficially located with a small (<2cm2) area of maximal tenderness.
   • The most intense pain could be localized with the tip of one finger.
   • Tenderness increased by abdominal muscle tensing (Carnett's test).
2. has been treated (successfully and unsuccessfully) for ACNES.
3. Patient is at least 18 years old on the day the informed consent form will be signed.
4. Patient is willing and able to comply with the trial protocol.
5. Patient is able to speak, read and understand the local language of the investigational site, is familiar with the procedures of the study, and agrees to participate in the study program by giving oral and written informed consent prior to screening evaluations.

Exclusion Criteria:

1. Abdominal complaints were due to a condition other than ACNES (e.g. pain related to scar tissue).
2. Patient has (a history of) another (chronic) pain syndrome that interferes with the interpretation of QST results.
3. Patient has (a history of) Raynaud syndrome or fenomenon, or a medical disorder that interferes with the study measurements or may pose a risk for the patient.
4. Patient does not feel a pinprick test to the lower extremities, due to affected sensory input (e.g. neuropathy as a result of diabetes mellitus).
5. Female patient is pregnant during the course of the study.

Study Plan

How is the study designed?

Design Details

• Observational Models: Case-Control
• Time Perspectives: Prospective

Number of groups / cohorts

2

Cohorts and Interventions

Group / Cohort	Intervention / Treatment
Healthy controls	Other: Quantitative Sensory Testing analysis
ACNES patients; Patients being treated in past for anterior cutaneous nerve entrapment syndrome	Other: Quantitative Sensory Testing analysis

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
pressure pain threshold	The pressure pain threshold (pPT) will be determined by pressing an electronic pressure algometer, which has a surface area of 1 cm2, on a distinct muscles. The patient will be asked to say 'now' when the sensation is rated as unpleasant. The pressure will be increased at a rate of 50 kPa/sec until the pPT is reached.	> 6 weeks after treatment

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Electrical Sensation Threshold (eST)	Electrical QST will be measured using a computerized electric stimulation device delivering constant current skin stimulation via self-adhesive electrodes. Electric sensation threshold (eST): when electric sensation is first felt.	> 6 weeks after treatment
Electrical Pain Threshold (ePT)	Electrical QST will be measured using a computerized electric stimulation device delivering constant current skin stimulation via self-adhesive electrodes. Electric pain threshold (ePT): when electric sensation is rated as unpleasant	> 6 weeks after treatment
Electrical Pain Tolerance Threshold (ePTT)	Electrical QST will be measured using a computerized electric stimulation device delivering constant current skin stimulation via self-adhesive electrodes. Electric pain tolerance threshold (ePTT): when electric sensation is intolerable.	>6 weeks after treatment
Electric Wind-Up Response (e-WUR)	Electrical QST will be measured using a computerized electric stimulation device delivering constant current skin stimulation via self-adhesive electrodes. Electric wind-up response (eWUR): rated pain after repeated stimuli	> 6 weeks after treatment
Visual Analogue Scale	Patients will be asked to mark on a 100mm VAS line the average pain in a pain diary. The boundaries of these lines are "no pain" on the upper left site and "unbearable pain" on the upper right site.	> 6 weeks after treatment

Other Outcome Measures

Outcome Measure	Measure Description	Time Frame
Pain and Anxiety Symptom Scale (PASS)	The pain anxiety symptom scale measures four aspects of pain related anxiety: 1) fear for pain, 2) cognitive anxiety, 3) flight or avoidance behavior, 4) physiological symptoms of pain. Elevated scores on this 40-item questionnaire indicate a high level of pain- related anxiety.	> 6wks after treatment
Pain Catastrophizing Scale (PCS)	Pain catastrophizing affects how individuals experience pain. The PCS yields a three component solution comprising ruminating ("I can ́t stop thinking about how much it hurts"), magnifying (e.g. "I'm afraid that something serious might happen"), and helplessness ("There is nothing I can do to reduce the intensity of my pain").	> 6wks after treatment
Hospital Anxiety and Depression Scale (HADS)	The Hospital Anxiety and Depression Scale is a 14-item questionnaire of which 7 of the items relate to anxiety (HADS-A) and 7 to depression (HADS-D). The scoring system used is a Likert scale (0 to 3 points) and therefore the data returned is ordinal. A patient can score between 0 and 21. The HADS aims to detect emotional disorder in patients under investigation and treatment in medical and surgical departments	> 6wks after treatment

Collaborators and Investigators

• Sponsor: Radboud University Medical Center
• Investigators: Principal Investigator: H. van Goor, Prof. MD, Radboud University Medical Center

Publications and helpful links

General Publications

• van Rijckevorsel DC, Boelens OB, Roumen RM, Wilder-Smith OH, van Goor H. Treatment response and central pain processing in Anterior Cutaneous Nerve Entrapment Syndrome: An explorative study. Scand J Pain. 2017 Jan;14:53-59. doi: 10.1016/j.sjpain.2016.09.014. Epub 2016 Nov 4.

Study record dates

Study Major Dates

• Study Start: June 1, 2013
• Primary Completion (Actual): May 1, 2014
• Study Completion (Actual): September 1, 2014

Study Registration Dates

• First Submitted: July 12, 2013
• First Submitted That Met QC Criteria: August 9, 2013
• First Posted (Estimate): August 12, 2013

Study Record Updates

• Last Update Posted (Estimate): November 17, 2014
• Last Update Submitted That Met QC Criteria: November 14, 2014
• Last Verified: November 1, 2014

More Information

Terms related to this study

• Keywords: Anterior cutaneous nerve entrapment syndrome; ACNES; chronic abdominal wall pain; CAWP
• Additional Relevant MeSH Terms: Pathologic Processes; Nervous System Diseases; Disease; Congenital Abnormalities; Genetic Diseases, Inborn; Neuromuscular Diseases; Neurodegenerative Diseases; Peripheral Nervous System Diseases; Heredodegenerative Disorders, Nervous System; Nervous System Malformations; Polyneuropathies; Syndrome; Nerve Compression Syndromes; Charcot-Marie-Tooth Disease; Hereditary Sensory and Motor Neuropathy
• Other Study ID Numbers: NL43583.091.13