2027 ICD-10-CM Diagnosis Code G51.9Disorder of facial nerve, unspecified

ICD-10-CM Codes›G00–G99›G50-G59›G51

ICD-10-CM G51.9
CMSSource: CMS FY 2027 ICD-10-CM dataset · Effective Oct 1, 2026 – Sep 30, 2027

G51.9 is a billable ICD-10-CM diagnosis code for disorder of facial nerve, 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 disorder of left facial nerve. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Nerve and nerve root disorders.

Code Identity

ICD-10-CM Code
G51.9
Billable Status
Yes — Valid for Submission
Code Describes
Disorder of facial nerve, unspecified
Short Description
Disorder of facial nerve, unspecified
Same as the full description in the CMS dataset.
Parent Code
G51
Facial nerve disorders

Code Classification

ChapterG00–G99Diseases of the nervous system
SectionG50-G59Nerve, nerve root and plexus disorders
CategoryG51Facial nerve disorders
This CodeG51.9Disorder of facial nerve, unspecified

Approximate SynonymsGuidance

Alternate terms and clinical phrases that map to this code.

  • Disorder of left facial nerve
  • Disorder of right facial nerve
  • Facial nerve disorder
  • Facial nerve motor disorder
  • Facial nerve sensory disorder
  • Seventh cranial nerve autonomic disorder

Instructional NotesGuidance

Instructions from the official ICD-10-CM Tabular List that apply to G51.9: its own notes plus those printed at G51, block G50-G59, and Chapter 6. A note printed at a category, block or chapter applies to every code under it.

Includes

Further defines, or gives examples of, the content of the category.

From G51 Facial nerve disorders applies to 10 codes
  • disorders of 7th cranial nerve

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.

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

  • Facial Nerve Diseases

    diseases of the facial nerve or nuclei. pontine disorders may affect the facial nuclei or nerve fascicle. the nerve may be involved intracranially, along its course through the petrous portion of the temporal bone, or along its extracranial course. clinical manifestations include facial muscle weakness, loss of taste from the anterior tongue, hyperacusis, and decreased lacrimation.

Patient EducationClinical

Facial Injuries and Disorders

Face injuries and disorders can cause pain and affect how you look. In severe cases, they can affect sight, speech, breathing and your ability to swallow. Fractures (broken bones), especially in the bones of your nose, cheekbone and jaw, are common facial injuries.

Read the full article at MedlinePlus

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

Convert G51.9 to ICD-9-CMHistory

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

ICD-9-CM
351.9 Facial nerve dis NOS
Exact Match The mapping is direct, with no qualifiers.

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 G51.9Overview

What is the ICD-10 code for disorder of facial nerve, unspecified?

The ICD-10-CM code for disorder of facial nerve, unspecified is G51.9 (sometimes written as G519). It is billable on HIPAA-covered claims from October 1, 2026 through September 30, 2027.

Is G51.9 (Facial nerve disorders) a billable code?

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

What MS-DRG does G51.9 group to?

When disorder of facial nerve, 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 G51.9 be reported with M79.2?

Not as a rule. The Excludes1 note at block G50-G59, which applies to G51.9, 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 G51.9?

Under the General Equivalence Mappings, disorder of facial nerve, unspecified converts to ICD-9-CM 351.9 (facial nerve dis NOS). The mapping is a direct match.