ICD-10-CM > G00-G99 > G50-G59 > G56 > G56.4 G56.4 Causalgia of upper limb Non-Billable/Non-Specific Applicable To Complex regional pain syndrome II of upper limb Type 1 Excludes complex regional pain syndrome I of lower limb (G90.52-)complex regional pain syndrome I of upper limb (G90.51-)complex regional pain syndrome II of lower limb (G57.7-)reflex sympathetic dystrophy of lower limb (G90.52-)reflex sympathetic dystrophy of upper limb (G90.51-) Codes G56.40Causalgia of unspecified upper limbG56.41Causalgia of right upper limbG56.42Causalgia of left upper limbG56.43Causalgia of bilateral upper limbs