Visualizing Anterior Cutaneous Nerve Entrapment Syndrome (ACNES) and Lumbar Cutaneous Nerve Entrapment Syndrome (LUCNES) With Dynamic Infrared Thermography (DIRT)

Background

Anterior cutaneous nerve entrapment syndrome (ACNES) is caused by nerve entrapment in the abdominal wall. The entrapment is believed to occur at the exit point of the sensate nerve through the anterior fascia of the rectus abdominis muscle. The diagnosis is mainly based on patient history and clinical examination. Pain relief after local anaesthesia may support the diagnosis. Often patients go through many diagnostic procedures to exclude other possible causes of abdominal pain. In such, ACNES is often an exclusion diagnosis. Recently Weum and de Weerd published an article describing perforator-guided treatment of ACNES using botulinum toxin serotype A (BTA). Based on anatomical knowledge and clinical experience, they used color Doppler ultrasound (CDU) to visualize the vascular structures called perforators that accompany the nerves at the exit points through the anterior rectus fascia. They noticed that accurate placement of the needle at this exit point triggered the same pain as caused by ACNES. Their earlier publications on dynamic infrared thermography (DIRT) in perforator mapping show that the locations of perforators can be visualised as hot spots on the abdominal skin.

Based on their experimental and clinical experience, they found that lower back pain might be caused by nerve entrapment, similar as seen in ACNES. In a pilot study using CDU, they found that the point of maximal pain, as marked by the patient, corresponded with the exit point of a perforator through the lumbar fascia. Knowledge from the use of a lumbar artery perforator flap makes it very likely that the sensate nerve accompanies these perforator vessels. Recently de Weerd and Weum have suggested lumbar cutaneous nerve entrapment syndrome (LUCNES) as a name for this condition. DIRT can potentially be used to identify the locations of these perforators, thereby also indirectly identifying the location of nerve entrapment, when a point of maximal pain corresponds to a hot spot.

Although DIRT has been used in several patients as an adjunct to support the diagnosis of ACNES, there are no studies that have systematically evaluated the use of DIRT in the diagnosis of ACNES or LUCNES. If DIRT could contribute to confirm the diagnosis ACNES or LUCNES, such would be valuable for clinicians as well as patients. Today, ACNES is often a diagnosis made by excluding other causes of pain. If DIRT can be used a reliable technique in the diagnosis of ACNES and LUCNES, such would be of great psychological value to the patients and may contribute to reduced health care costs.

General practitioners are often the first health care providers that see patients with abdominal wall pain and lower back pain. Reliable perforator mapping with DIRT has until recently only been possible with expensive professional thermography equipment. Low-cost thermography cameras for smartphones are now available. If these cameras can provide reliable information on the location of perforators, and thereby also the location of nerve entrapment, general practitioners and other clinicians could use DIRT as a diagnostic tool for this patient group without expensive professional thermography equipment.