Musculoskeletal Ultrasonography to Distinguish Muscle Changes in Complex Regional Pain Syndrome Type 1 from Those of Neuropathic Pain: An Observational Study.

Musculoskeletal ultrasonography (MSK USG) can identify myofascial structural lesions. We describe in this retrospective report the observational findings of USG data of muscles from limbs affected with neuropathic pain in 7 patients and compare them with muscles affected with complex regional pain syndrome type 1 (CRPS-1) in 7 patients. We highlight findings that distinguish between the 2 conditions. Musculoskeletal ultrasonography of muscles in CRPS was characterized by a variable or/and global intramuscular structural disruption with loss of muscle bulk. Adjacent muscles coalesced with one another to present an uniform hyperechogenic mass of tissue. Muscle edema was found in some patients. In comparison, MSK USG in muscles affected by neuropathic pain exhibited structural normalcy, but also showed considerable reduction in muscle bulk. Musculoskeletal ultrasonography shows promise as a diagnostic modality to distinguish between these 2 conditions which presently have only clinical diagnostic criteria to aid diagnosis.