A Pilot Study to Explore the Use of Skin Biopsy as Diagnostic Tool in Anterior Cutaneous Nerve Entrapment Syndrome (ACNES)

Maxima Medical Center12 enrolled

Overview

ACNES is a neuropathic pain condition of the abdominal wall. It is a clinical diagnosis based on patient's history and physical examination. No diagnostic test is available to confirm the diagnosis. This pilot study will determine if skin biopsies can be used as diagnostic test. Two 3mm biopsies will be taken and used to count the small nerve fibres in the skin. The number of small nerve fibres of the painful skin will be compared to non-painful skin. Skin biopsy and small fibre nerve count is already used as diagnostic test in patients with small-fibre neuropathy. The investigators hypothesize that patients with ACNES will have a reduced number of small nerve fibres in the affected skin, compared to the non-affected skin.

Study Type

INTERVENTIONAL

Allocation

Purpose

DIAGNOSTIC

Masking

NONE

Enrollment

Conditions

Anterior Cutaneous Nerve Entrapment Syndrome Nerve Entrapment Syndrome Chronic Pain Syndrome Diagnosis

Interventions

Skin biopsyPROCEDURE

Two 3mm skin biopsies from the abdominal wall will be taken. One at the triggerpoint of the pain, the second one at the contralateral, non-affected side of the abdominal wall. Lidocaine will be used for local anaesthesia of the skin, before the biopsies will be taken.

Eligibility

Sex: ALLMin age: 21 YearsMax age: 50 Years

Medical Language ↔ Plain English

Inclusion Criteria: * Duration of pain \>3 months * Newly diagnosed unilateral ACNES * Fully completed intake questionnaire * Obtained written informed consent Exclusion Criteria: * Inability to understand Dutch language * Bilateral ACNES * Previously administered injections with corticosteroids at trigger point (injection with a local anaesthetic is allowed) * Previous Pulsed Radiofrequency (PRF)-treatment at trigger point * History of open abdominal surgery * History of neurectomy * Known neuromuscular or neurodegenerative disease * Antiplatelet or anticoagulants use or known coagulation disorders * Disorder known to cause a reduced IENFD; * Diabetes * Hypothyroidism * Renal failure * Vitamin B12 deficiency * Monoclonal gammopathy * Alcohol abuse (\>5 IU a day) * Malignancies * Medication that cause neuropathy (for example chemotherapy)

Outcomes

Primary Outcomes

Intraepidermal Nerve Fibre density (IENFD)

Difference in IENFD (measured in IENF/mm) from both affected and non-affected side of the abdominal wall.

Time frame: Both biopsies will be taken at the same time, as their difference will be studied. The biopsies will be taken at the second outpatient visit, 2 or 3 weeks after the first visit, just after the second triggger point injection (standard of care).

Secondary Outcomes

Pain score

Average pain score, assessed using the Numeric Rating Scale (NRS) 0-10 before start of treatment. 0 no pain, 10 worst possible pain.

Time frame: Assessed at first outpatient visit, used as baseline data.

Duration of pain

Duration of pain in months before diagnosis

Time frame: Assessed at first outpatient visit, used as baseline data.

Treatment response

Patients will receive standard of care treatment for ACNES. Treatment is unsuccessful if \<50% pain reduction or when patients are not satisfied with their pain relief and want additional treatment.

Time frame: Treatment response will be assessed 2 to 6 weeks after each treatment (trigger point injections, PRF and neurectomy), as standard of care.