Importance of early diagnosis of complex regional pain syndrome (CRPS-1 and CRPS-2): Delayed diagnosis of CRPS is a major problem

The PhD-thesis has studied clinical aspects and mechanisms of Complex Regional Pain Syndrome (CRPS), and includes three scientific papers. The aim was to study 1) diagnostic challenges in CRPS, 2) effect of secondary surgery on pain and clinical signs, and 3) whether differentiation of patients into subgroups based on thermal testing (neurophysiological profile) is correlated with pain. The analyses are based on a larger patient material of CRPS patients in Norway. Methods include clinical examination, medical history, review of previous medical records and specialist reports, EMG/Neurography and assessment of small fiber function by examining thermal thresholds (QST). We found a significant delay in CRPS diagnosis of 3.9 and 2.8 years respectively in papers 1 and 2. The majority of patients experienced deterioration after secondary surgical interventions. There is a large discrepancy between the patients' self-report and description in previous medical records for the risk factors early development of 1) intense disproportionate pain and 2) clinical signs of autonomic dysfunction. Differentiation of patients based on QST-profile was not correlated with presence or intensity of pain. However, we found a correlation between paroxysmal pain and allodynia (hypersensitivity) for both cold and light touch. conclusion, we claim that failure to recognize risk factors for the development of CRPS is important for delayed diagnosis. Secondary surgery on a CRPS-affected limb may worsen symptoms and should be avoided or delayed as far as possible. QST-profile is suitable for assessing small fiber function, but is not correlated with pain profile. Small fiber degeneration is not a dominant pathophysiological mechanism in CRPS. suggest that the correlations between paroxysmal pain, cold allodynia and allodynia to light touch are due to sensitization of peripheral nerve endings and that hyperexcitability is an important underlying pathophysiological mechanism.