Effect of Abdominal Wall Injections on Abdominal Pain

Primary outcomes

1. 1) To measure the change in abdominal wall pain 1-week, 1-month and 3-months following abdominal wall injections, with improvement defined as a 50% reduction in baseline pain score measured using an 11-point numeric scale.

   Time frame: 12 weeks

   Improvement is defined as a 50% reduction in baseline pain score measured using an 11-point numeric scale where 0 is no pain and 10 is the worst pain the patient has every felt.

2. 2) To determine patient characteristics, such as pain catastrophizing, associated with a response to abdominal wall injection

   Time frame: 12 weeks

   This will be measured by the following:

   Pain Catastrophizing Scale (PCS):

   Each question is rated on a scale of 0 to 4, where 0 is no catastrophizing, and 4 is significant catastrophizing.

3. 2) To determine patient characteristics, such as patient reported functional status, pain status, and global estimate status; associated with a response to abdominal wall injection

   Time frame: 12 weeks

   This will be measured by the following:

   Routine Assessment of Patient Index Data (RAPID) Questionnaire:

   Assessing patient-reported measures of function, pain, and patient global estimate status. First set of items are rated on a 4-point scale, ranging from 0 to 3, where higher scores indicate lower functioning. Second set of items are rated on a scale from 0 to 10 where the higher the number the more pain the person is experiencing. The third set is rated on a scale from 0 to 10 where 10 is the poorest overall status.

4. 2) To determine patient characteristics, within seven health domains, associated with a response to abdominal wall injection

   Time frame: 12 weeks

   This will be measured by the following:

   Patient-Reported Outcomes Measurement Information System-29 Scale:

   Assessing pain intensity using a single 0-10 numeric rating (0 is no pain, 10 is the worst pain ever felt) item and seven health domains.

5. 2) To determine patient characteristics, such as psychological inflexibility, associated with a response to abdominal wall injection

   Time frame: 12 weeks

   Psychological Inflexibility in Pain Scale:

   Items are rated on a 7-point scale, ranging from 1 to 7, where higher scores indicate greater levels of psychological inflexibility.

6. 3) To determine the rate of adverse events associated with abdominal wall injection.

   Time frame: 12 weeks

   Adverse events associated with abdominal wall injections include pain or discoloration at the injection site, a syncopal episode after the injection, allergic reaction to lidocaine or alcohol swab/chloroprep. There is a rare risk for seizures and injury to a muscle.

7. 4) To measure pain thresholds with use of heat, using quantitative sensory testing (QST) in patients receiving abdominal wall injections.

   Time frame: 12 weeks

   This will be measured by the following:

   Heat Pain Threshold and Pain Tolerance :. This task involves applying a series of heat sensations using a heat thermode (TSA-II Air, Medoc) to the subject's dominant inner forearm.

8. 4) To measure pain thresholds with use of temporal summation, using quantitative sensory testing (QST) in patients receiving abdominal wall injections.

   Time frame: 12 weeks

   This will be measured by the following:

   Temporal summation. For assessment of temporal summation (TS), punctate mechanical stimuli will be delivered to the dorsal surface of the dominant hand using a 300-gm nylon monofilament developed by the German Research Network on Neuropathic Pain.

9. 4) To measure pain thresholds with use of pressure thresholds, using quantitative sensory testing (QST) in patients receiving abdominal wall injections.

   Time frame: 12 weeks

   This will be measured by the following:

   Pressure pain threshold. Pressure pain threshold (PPTh) will be assessed via an algometer using pressure pain stimuli delivered to dorsal forearm (distal stimuli) and the trapezius (order counterbalanced).