G90.521 Complex regional pain syndrome I of right lower limb

Billable ICD-10-CM code, FY2026. Acts as a Complication or Comorbidity (CC) as a secondary diagnosis.

Applies from G90 Disorders of autonomic nervous system

Excludes1 (never code together)

• dysfunction of the autonomic nervous system due to alcohol (G31.2)

Applies from G90.5 Complex regional pain syndrome I (CRPS I)

Applicable to

• Reflex sympathetic dystrophy

Excludes1 (never code together)

• causalgia of lower limb (G57.7-)
• causalgia of upper limb (G56.4-)
• complex regional pain syndrome II of lower limb (G57.7-)
• complex regional pain syndrome II of upper limb (G56.4-)

MS-DRG index

Defines the logic of DRG(s) 073-074 in MDC 01.

Approximate ICD-9-CM (GEMs)

• 337.22 Reflex sympathetic dystrophy of the lower limb (approximate)

Code annotations containing back-references to G90.521

Back-references to G90.52

• Type 1 Excludes: G56.4 Causalgia of upper limb ("complex regional pain syndrome I of lower limb (G90.52-)")
• Type 1 Excludes: G56.4 Causalgia of upper limb ("reflex sympathetic dystrophy of lower limb (G90.52-)")
• Type 1 Excludes: G57.7 Causalgia of lower limb ("complex regional pain syndrome I of lower limb (G90.52-)")
• Type 1 Excludes: G57.7 Causalgia of lower limb ("reflex sympathetic dystrophy of lower limb (G90.52-)")

Back-references to G90.5

• Type 1 Excludes: G89.2 Chronic pain, not elsewhere classified ("reflex sympathetic dystrophy (G90.5-)")
• Type 1 Excludes: M89.0 Algoneurodystrophy ("reflex sympathetic dystrophy (G90.5-)")

Nearby codes

• G90.511 Complex regional pain syndrome I of right upper limb
• G90.512 Complex regional pain syndrome I of left upper limb
• G90.513 Complex regional pain syndrome I of upper limb, bilateral
• G90.519 Complex regional pain syndrome I of unspecified upper limb
• G90.52 Complex regional pain syndrome I of lower limb
• G90.521 Complex regional pain syndrome I of right lower limb (this code)
• G90.522 Complex regional pain syndrome I of left lower limb
• G90.523 Complex regional pain syndrome I of lower limb, bilateral
• G90.529 Complex regional pain syndrome I of unspecified lower limb
• G90.59 Complex regional pain syndrome I of other specified site
• G90.8 Other disorders of autonomic nervous system