2027 ICD-10-CM Diagnosis Code G58.9Mononeuropathy, unspecified

ICD-10-CM Codes›G00–G99›G50-G59›G58

ICD-10-CM G58.9
CMSSource: CMS FY 2027 ICD-10-CM dataset · Effective Oct 1, 2026 – Sep 30, 2027

G58.9 is a billable ICD-10-CM diagnosis code for mononeuropathy, unspecified. It is valid on HIPAA claims for fiscal year 2027 (October 1, 2026 through September 30, 2027) and groups to MS-DRG 73 through 74. Coders also document this condition as ischemic neuropathy. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Nerve and nerve root disorders.

Code Identity

ICD-10-CM Code
G58.9
Billable Status
Yes — Valid for Submission
Code Describes
Mononeuropathy, unspecified
Short Description
Mononeuropathy, unspecified
Same as the full description in the CMS dataset.
Parent Code
G58
Other mononeuropathies

Code Classification

ChapterG00–G99Diseases of the nervous system
SectionG50-G59Nerve, nerve root and plexus disorders
CategoryG58Other mononeuropathies
This CodeG58.9Mononeuropathy, unspecified

Approximate SynonymsGuidance

Alternate terms and clinical phrases that map to this code.

  • Ischemic neuropathy
  • Mononeuritis
  • Mononeuropathy
  • Nerve entrapment due to scar
  • Nerve palsy
  • Peripheral nerve thickening
  • Polyneuropathy and mononeuropathy

Instructional NotesGuidance

Instructions from the official ICD-10-CM Tabular List that apply to G58.9: its own notes plus those printed at block G50-G59 and Chapter 6. A note printed at a category, block or chapter applies to every code under it.

Excludes1

Not coded here: the excluded code is never reported together with this one, unless the two conditions are unrelated.

From Block G50-G59 Nerve, nerve root and plexus disorders applies to 106 codes
  • 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: the excluded condition is not part of this code, but a patient may have both, so both codes may be reported.

From Chapter 6 (G00-G99) Diseases of the nervous system applies to 700 codes
  • 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)

Source: CMS ICD-10-CM Tabular List. How to read instructional notes.

Referenced in Other NotesGuidance

Instructional notes printed at other codes that name G58.9, its category, or a range that includes it.

Excludes1 1

These codes carry an Excludes1 note naming G58.9: they are not reported together with it, unless the two conditions are unrelated.

  • M79.2 Neuralgia and neuritis, unspecified
    mononeuropathies (G56-G58) names G56-G58, which includes this code

Index to Diseases and InjuriesGuidance

Alphabetical index entries that point to this code.

Clinical ClassificationClinical

AHRQ’s CCSR groups this code into broader clinical categories.

CCSR NVS017
Nerve and nerve root disorders
Default principal diagnosis: inpatient Yes · outpatient Yes

Clinical InformationClinical

  • Mononeuropathies

    disease or trauma involving a single peripheral nerve in isolation, or out of proportion to evidence of diffuse peripheral nerve dysfunction. mononeuropathy multiplex refers to a condition characterized by multiple isolated nerve injuries. mononeuropathies may result from a wide variety of causes, including ischemia; traumatic injury; compression; connective tissue diseases; cumulative trauma disorders; and other conditions.

Patient EducationClinical

Peripheral Nerve Disorders

Nerves are like wires that carry messages back and forth between your brain and your body. Your peripheral nerves branch off from your brain and spinal cord and connect to all parts of your body, including your muscles and organs.

The full article covers:

  • What are peripheral nerves?
  • What are peripheral nerve disorders?
  • What causes peripheral nerve disorders?
  • What are the symptoms of peripheral nerve disorders?
  • How are peripheral nerve disorders diagnosed?
  • What are the treatments for peripheral nerve disorders?
  • Can peripheral nerve disorders be prevented?

Read the full article at MedlinePlus

Courtesy of MedlinePlus, a service of the U.S. National Library of Medicine.

Convert G58.9 to ICD-9-CMHistory

The closest ICD-9-CM equivalents under the General Equivalence Mappings.

ICD-9-CM
355.9 Mononeuritis NOS
Approximate The match is approximate rather than exact.

Code HistoryHistory

FY 2016AddedAdded to the ICD-10-CM code setEffective October 1, 2015, the first year of ICD-10-CM.
FY 2017–2026No changes
FY 2027CurrentCurrent code set, no changesEffective October 1, 2026 through September 30, 2027.

Questions About G58.9Overview

What is the ICD-10 code for mononeuropathy, unspecified?

The ICD-10-CM code for mononeuropathy, unspecified is G58.9 (sometimes written as G589). It is billable on HIPAA-covered claims from October 1, 2026 through September 30, 2027.

Is G58.9 (Other mononeuropathies) a billable code?

Yes. This is a billable ICD-10-CM code, specific enough to report mononeuropathy, unspecified on HIPAA-covered claims from October 1, 2026 through September 30, 2027.

What MS-DRG does G58.9 group to?

When mononeuropathy, unspecified is the principal diagnosis on an inpatient stay, it groups to MS-DRG 74, 73, with relative weights from 1.0172 to 1.5773 depending on complications. Higher weights mean higher Medicare reimbursement.

Can G58.9 be reported with M79.2?

Not as a rule. The Excludes1 note at block G50-G59, which applies to G58.9, lists "neuralgia NOS (M79.2)". An Excludes1 note means the excluded code is never reported together with this one; the only exception is when the two conditions are unrelated to each other (Official Guidelines, Section I.A.12.a).

What is the ICD-9 equivalent of G58.9?

Under the General Equivalence Mappings, mononeuropathy, unspecified converts to ICD-9-CM 355.9 (mononeuritis NOS). The mapping is approximate, so confirm the match fits the documentation.