Alphabetic Index FY2027

G56.42

Causalgia of left upper limb

FY2027Chapter 6: Diseases of the nervous system/G50–G59 Nerve, nerve root and plexus disorders

BillableComplete code, valid to report
Care settingsHome Health Primary · Neuro Rehabilitation

G56.42 (also written G5642) is a billable ICD-10-CM diagnosis code for causalgia of left upper limb. It is part of the FY2027 code set, effective October 1, 2026. It is one of the 28 codes in category G56 (Mononeuropathies of upper limb). Its coding notes include 11 Excludes1 entries and 8 Excludes2 entries.

Excludes1

Not coded here. The listed conditions generally should not be reported together.

Inherited from G56.4 Causalgia of upper limb
  • 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-)
Inherited from G56 Mononeuropathies of upper limb
  • current traumatic nerve disorder - see nerve injury by body region
Also from chapter/block level (5 notes)
Inherited from G50–G59 Nerve, nerve root and plexus disorders
  • current traumatic nerve, nerve root and plexus disorders - see Injury, nerve by body region
  • neuralgia NOS (M79.2)
  • neuritis NOS (M79.2)
  • peripheral neuritis in pregnancy (O26.82-)
  • radiculitis NOS (M54.1-)

Excludes2

Not included here. Both codes may be reported if the patient has both conditions.

Also from chapter/block level (8 notes)
Inherited from Chapter 6 Diseases of the nervous system
  • certain conditions originating in the perinatal period (P04-P96)
  • certain infectious and parasitic diseases (A00-B99)
  • complications of pregnancy, childbirth and the puerperium (O00-O9A)
  • congenital malformations, deformations, and chromosomal abnormalities (Q00-Q99)
  • endocrine, nutritional and metabolic diseases (E00-E88)
  • injury, poisoning and certain other consequences of external causes (S00-T88)
  • neoplasms (C00-D49)
  • symptoms, signs and abnormal clinical and laboratory findings, not elsewhere classified (R00-R94)

Care settings

How CMS programs treat this code. These are CMS claim edits and list entries, not coverage or eligibility rules.

Home Health Primary

Accepted as the primary (principal) diagnosis on a home health claim. The Home Health Grouper assigns it to the Neuro Rehabilitation clinical group.

Source: CMS Home Health Grouper Software v07.2.26, effective October 1, 2026