ICD-10-CM 2027
ICD-10 code for myotonia
From the official ICD-10-CM alphabetic index entry “Myotonia (acquisita) (intermittens)”. Page updated September 29, 2026.
About coding myotonia
The ICD-10-CM code for myotonia is M62.89 (Other specified disorders of muscle). The official index lists 9 more specific codes, so check the documentation for details such as type, cause, site or severity before settling on M62.89.
Within M62.8, choose M62.89 (Other specified disorders of muscle) only when documentation doesn't support a more specific option: muscle weakness (generalized) (M62.81), Rhabdomyolysis (M62.82), muscle spasm (M62.83), Sarcopenia (M62.84) and dysfunction of the multifidus muscles, lumbar region (M62.85).
It is not a CC or MCC, so as a secondary diagnosis it doesn't change the MS-DRG severity level.
In MS-DRG v44.0, it is part of the grouping logic for DRG 557 (Tendonitis, Myositis and Bursitis with MCC, relative weight 1.489) and DRG 558 (Tendonitis, Myositis and Bursitis without MCC, relative weight 0.8875), in MDC 08 (Diseases and Disorders of the Musculoskeletal System and Connective Tissue), as a principal or secondary diagnosis. The DRG a claim lands in depends on the principal diagnosis, procedures and any CC/MCC secondary diagnoses.
More specific myotonia codes (official index)
- atrophica G71.11 — Myotonic muscular dystrophy
- chondrodystrophic G71.13 — Myotonic chondrodystrophy
- congenita (acetazolamide responsive) (dominant) (recessive) G71.12 — Myotonia congenita
- drug-induced G71.14 — Drug induced myotonia
- dystrophica G71.11 — Myotonic muscular dystrophy
- fluctuans G71.19 — Other specified myotonic disorders
- levior G71.12 — Myotonia congenita
- permanens G71.19 — Other specified myotonic disorders
- symptomatic G71.19 — Other specified myotonic disorders
Common questions about myotonia ICD-10 codes
What is the ICD-10 code for myotonia?
- M62.89 — Other specified disorders of muscle. More specific codes apply when the documentation supports them: G71.11, G71.13, G71.12, G71.14 and others below.
What is the ICD-10 code for atrophica myotonia?
- G71.11 — Myotonic muscular dystrophy.
What is the ICD-10 code for chondrodystrophic myotonia?
- G71.13 — Myotonic chondrodystrophy.
What is the ICD-10 code for congenita myotonia?
- G71.12 — Myotonia congenita.
What is the ICD-10 code for drug-induced myotonia?
- G71.14 — Drug induced myotonia.
What is the ICD-10 code for dystrophica myotonia?
- G71.11 — Myotonic muscular dystrophy.
What is the ICD-10 code for fluctuans myotonia?
- G71.19 — Other specified myotonic disorders.
Is M62.89 billable?
- Yes. M62.89 is a billable/specific ICD-10-CM code valid for FY2027 (October 1, 2026 – September 30, 2027).
Can M62.89 be used as a principal diagnosis?
- Yes. The Medicare Code Editor doesn't restrict M62.89 as a principal diagnosis.
Is M62.89 a CC or MCC?
- No. M62.89 is neither a CC nor an MCC under MS-DRG v44.0.