Demonstration of Cutaneous Allodynia in Association with Chronic Pelvic Pain

Hi, I am John Gerald. I'm a professor of obstetrics and Gynecology at the Calgary Chronic Pain Center in the Department of Obstetrics and Gynecology at the University of Calgary in Calgary, Canada. Today we'll show you a procedure for identifying the presence of cutaneous allodynia on the abdomen and perineum.

We use this test to identify when a patient has developed a chronic pain state. This chronic pain state can occur after the development of a disease and after the treatment of the disease. And it's helpful for us to recognize this chronic pain state as it may indicate that it doesn't necessarily mean that there's been a recurrence of the disease that's causing the patient's pain.

Our patient today is a 22-year-old mother of one who's had pain for approximately 10 years from severe dysmenorrhea before she came to the clinic. This patient has had nine laparoscopies, including a laparoscopically assisted vaginal hysterectomy. These were all done for endometriosis, although she has had endometriosis.

This patient's problem now is primarily chronic pain state as evidenced by the cutaneous allodynia. She's currently on MS.Contin 75 milligrams twice a day, and gabapentin 1200 milligrams three times a day. And we're in the process of shifting her from the MS contin to methadone.

So today we're going to show you how to use the simple instrument that's available in any doctor's office to assess cutaneous allodynia. So let's get started. To begin the testing procedure, a cotton tipped culture stick is shown to the patient and brushed against her hand to demonstrate how the light pressure will feel on the abdomen.

Next, the patient is asked to note the point at which light pressure applied to the skin on the abdomen becomes painful. Okay, so I'm gonna run this Q-tip down your tummy, and you tell me when it gets sharp.Okay? Okay.The culture stick is then lightly drawn down the abdominal wall.

As the culture stick is drawn down the abdomen, the patient will either note the presence of no change in sensation or a sudden and discreet sharpness in sensation. This process is repeated until the entire area of cutaneous allodynia has been tested. A positive test is defined by the presence of a sudden sharp sensation.

Well, Stacey's layer used to run about here, which is about T 11, but it's now moving up and it's becoming higher in the level in the thoracic dermatome section. It extends down as far as probably L two in this, in the lower segment, and that's expanded as well. It used to run about in this duration in this area like this, but as her pain's been getting worse, so the areas of cutaneous adenia, The areas that test positive on the abdomen can be large or small and are most commonly bilateral in nature.

Okay, so this area is quite large in this patient's abdomen, but it's highly variable. In some cases, individuals will have only dime shaped areas, usually around here that are quite painful to touch. They can be unilateral or they can be bilateral.

They can be dumbbell shaped, but ordinarily they're sort of semi-circular and down to about L one. And they also are variable, depending upon whether or not there's a scar present as well. But ordinarily, they can start as very small areas and then expand to include both sides.

With abdominal testing completed, we can begin testing the peroneum. When the patient is ready to proceed. The cotton tipped culture stick is again shown to the patient and brushed against her hand to demonstrate how the light pressure will feel on the perineum.

The patient is then asked to note the point at which light pressure applied to the skin becomes painful, and the culture stick is lightly drawn across the perineum. Okay, I'm just gonna run this across your bottom and just tell me when it becomes sharp.Okay. Right There.

During testing of the perineum, the culture stick is drawn across the buttocks in a horizontal direction, going from the lateral aspect of the buttock toward the anus to cut across the S3 dermatome, the process is repeated On the contralateral side, the culture stick is then drawn in a posterior direction from the region of the labia majora, avoiding the vaginal area. A positive test is defined by the presence of a sudden sharp sensation on the perineum. A positive result is most commonly seen bilaterally.

On the S3 dermatome, We've just shown you how to identify the presence of cutaneous allodynia and the emergence of a chronic pain state. It's important to remember that this chronic pain state can occur as a consequence of active pelvic disease, such as endometriosis, or it may actually be present after the endometriosis has been treated. It can also be present with a reactivation of endometriosis.

The value of a positive test is that it may offer an alternative explanation for the cause of the patient's pain that does not necessarily require surgery. So that's it. Thanks for watching and good luck with your approach to chronic pelvic pain.