# The puzzle of pain and its psychological implications: Differentiating complex regional pain syndrome from somatic symptom disorder

## TL;DR

This paper explores the challenges of distinguishing between Complex Regional Pain Syndrome and Somatic Symptom Disorder, both of which involve persistent pain and psychological factors.

## Contribution

The paper provides case examples and emphasizes the need for multidisciplinary collaboration in diagnosing and managing these conditions.

## Key findings

- CRPS and SSD share distressing somatic symptoms and psychological components, making differential diagnosis difficult.
- Multidisciplinary collaboration is essential to address both the physical and psychological aspects of these disorders.
- Consultation-liaison psychiatrists play a crucial role in evaluating and managing patients with CRPS or SSD.

## Abstract

One of the most concerning pain conditions is Complex Regional Pain Syndrome (CRPS), a nervous system disorder that may occur after a trauma, surgery, medical procedure, or prolonged immobilization. Its primary symptom is extreme and constant burning or freezing pain at the site of the inciting injury, often out of proportion to, and lasting longer than, the injury itself. A psychiatric condition that needs to be differentiated from CRPS is Somatic Symptom Disorder (SSD), which was added to the Diagnostic and Statistical Manual of Psychiatric Disorders, Fifth Edition (DSM-5) in 2013. It requires only a single physical (somatic) symptom (there may be more), but, equally important, the patient also must have thoughts, feelings, or behaviors that are clearly excessive relative to their physical symptom(s). Differentiating between CRPS and SSD can present a difficult diagnostic challenge but is necessary to improve the well-being of those affected. Both occur in inpatient and outpatient settings. For CRPS, diagnosis relies on assessment according to specific clinical criteria, because there are no definitive diagnostic tests. SSD is characterized by excessive preoccupation with somatic symptom(s), including pain, and there also are no definitive diagnostic tests. Because both conditions share the characteristic of distressing somatic symptom(s), and both have important psychological components, differential diagnosis often requires extensive investigation. To illustrate their diagnostic complexities, in addition to the existing literature, we use case examples of CRPS, SSD, and a combination of both. These cases highlight the need for multidisciplinary collaboration in evaluating and managing both disorders, in order to address both the physiological and the psychological components. Consultation-liaison psychiatrists, in particular, have requisite training in both domains and can have a crucial collaborative role, acknowledging both the extent of physical pain and addressing psychological dimensions, including anxiety, depression, and the magnification of underlying physical complaints.