2027 ICD-10-CM Diagnosis Code G71.19Other specified myotonic disorders

ICD-10-CM Codes›G00–G99›G70-G73›G71

ICD-10-CM G71.19
CMSSource: CMS FY 2027 ICD-10-CM dataset · Effective Oct 1, 2026 – Sep 30, 2027

G71.19 is a billable ICD-10-CM diagnosis code for other specified myotonic disorders. It is valid on HIPAA claims for fiscal year 2027 (October 1, 2026 through September 30, 2027) and groups to MS-DRG 91 through 93. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Myopathies.

G71.19 does not risk-adjust for Medicare Advantage under the CMS-HCC V28 model. It still risk-adjusts in the ESRD (V21) category 75 for payment year 2027.

Code Identity

ICD-10-CM Code
G71.19
Billable Status
Yes — Valid for Submission
Code Describes
Other specified myotonic disorders
Short Description
Other specified myotonic disorders
Same as the full description in the CMS dataset.
Parent Code
G71.1
Myotonic disorders

Code Classification

ChapterG00–G99Diseases of the nervous system
SectionG70-G73Diseases of myoneural junction and muscle
CategoryG71Primary disorders of muscles
This CodeG71.19Other specified myotonic disorders

Medicare Risk Adjustment (HCC)Billing

G71.19 does not risk-adjust for Medicare Advantage under the CMS-HCC V28 model, but it maps to payment categories in the other CMS models shown below.

CMS-HCC V28 (Medicare Advantage Payment Model)
Not mapped
no payment category in the model that pays 100% of MA risk scores
Prior Model (CMS-HCC V24)
Not mapped under V24
this diagnosis newly risk-adjusts under the V28 model
Other CMS Models
ESRD (V21): HCC 75
ESRD V21 weights: 0.059 dialysis, 0.284–0.323 functioning graft
Part D (RxHCC)
Not mapped
G71.19 does not risk-adjust in the RxHCC prescription drug model

Source: CMS Payment Year 2027 risk adjustment mappings and model software. Weights are relative factors, not dollar amounts; a beneficiary's total RAF also includes demographics and interactions. Browse all CMS-HCC categories.

Approximate SynonymsGuidance

Alternate terms and clinical phrases that map to this code.

  • Autosomal recessive axonal neuropathy with neuromyotonia
  • Cataract in systemic disorders
  • Eye closing finding
  • Eye closure myotonia
  • Infantile myotonia
  • Isaacs syndrome
  • Movement of eyelid - finding
  • Myotonia fluctuans
  • Myotonia permanens
  • Myotonic cataract
  • Myotonic disorder
  • Myotonic warm-up phenomenon
  • Myotonic warm-up phenomenon - hand grip
  • Neuromyotonia
  • Non dystrophic myotonia
  • Paradoxical myotonia
  • Paramyotonia congenita
  • Percussion myotonia
  • Peripheral axonal neuropathy
  • Potassium aggravated myotonia
  • Pseudomyotonia
  • Rippling muscle disease
  • Rippling muscle disease with myasthenia gravis

Instructional NotesGuidance

Instructions from the official ICD-10-CM Tabular List that apply to G71.19: its own notes plus those printed at G71 and Chapter 6. A note printed at a category, block or chapter applies to every code under it.

Applicable To

Conditions this code is used for: synonyms of the title or, for "other specified" codes, the conditions assigned to it. The list is not exhaustive.

  • Myotonia fluctuans
  • Myotonia permanens
  • Neuromyotonia [Isaacs]
  • Paramyotonia congenita (of von Eulenburg)
  • Pseudomyotonia
  • Symptomatic myotonia

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 G71 Primary disorders of muscles applies to 28 codes
  • arthrogryposis multiplex congenita (Q74.3)
  • metabolic disorders (E70-E88)
  • myositis (M60.-)
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 G71.19, its category, or a range that includes it.

Excludes1 1

These codes carry an Excludes1 note naming G71.19: they are not reported together with it, unless the two conditions are unrelated.

  • G72.3 Periodic paralysis
    paramyotonia congenita (of von Eulenburg) (G71.19)

Excludes2 1

These codes carry an Excludes2 note naming G71.19: its condition is not part of those codes, and both may be reported when the patient has both.

  • Block M60-M63 Disorders of muscles
    muscular dystrophies and myopathies (G71-G72) names G71-G72, which includes this code

Code First 2

These codes say to code first a condition named in the note, and G71.19 is one of the conditions named.

  • H28 Cataract in diseases classified elsewhere
    myotonia (G71.1-) names G71.1-, which includes this code
  • M62.84 Sarcopenia
    primary disorders of muscles (G71.-) names G71.-, 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 NVS018
Myopathies
Default principal diagnosis: inpatient Yes · outpatient Yes

Clinical InformationClinical

  • Isaacs Syndrome

    a rare neuromuscular disorder with onset usually in late childhood or early adulthood, characterized by intermittent or continuous widespread involuntary muscle contractions; fasciculation; hyporeflexia; muscle cramp; muscle weakness; hyperhidrosis; tachycardia; and myokymia. involvement of pharyngeal or laryngeal muscles may interfere with speech and breathing. the continuous motor activity persists during sleep and general anesthesia (distinguishing this condition from stiff-person syndrome). familial and acquired (primarily autoimmune) forms have been reported. (from ann ny acad sci 1998 may 13;841:482-496; adams et al., principles of neurology, 6th ed, p1491)

Patient EducationClinical

Neuromuscular Disorders

Neuromuscular disorders affect your neuromuscular system. They can cause problems with:

Read the full article at MedlinePlus

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

Convert G71.19 to ICD-9-CMHistory

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

ICD-9-CM
359.29 Myotonic disorder NEC
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 G71.19Overview

What is the ICD-10 code for other specified myotonic disorders?

The ICD-10-CM code for other specified myotonic disorders is G71.19 (sometimes written as G7119). It is billable on HIPAA-covered claims from October 1, 2026 through September 30, 2027.

Is G71.19 (Myotonic disorders) a billable code?

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

What MS-DRG does G71.19 group to?

When other specified myotonic disorders is the principal diagnosis on an inpatient stay, it groups to MS-DRG 91, 92, 93, with relative weights from 0.7783 to 1.7050 depending on complications. Higher weights mean higher Medicare reimbursement.

What is the ICD-9 equivalent of G71.19?

Under the General Equivalence Mappings, other specified myotonic disorders converts to ICD-9-CM 359.29 (myotonic disorder NEC). The mapping is a direct match.

Does G71.19 risk-adjust for Medicare Advantage payment?

Not for Medicare Advantage: G71.19 maps to no category in the CMS-HCC V28 model. It still risk-adjusts in the ESRD (V21) category 75 (Polyneuropathy).