1. ICD-10-CM Codes
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2. G00-G99 Diseases of the nervous system
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3. G30-G32 Other degenerative diseases of the nervous system
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4. G31- Other degenerative diseases of nervous system, not elsewhere classified
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5. 2021 ICD-10-CM Diagnosis Code G31.9

2021 ICD-10-CM Diagnosis Code G31.9

Degenerative disease of nervous system, unspecified

2016 2017 2018 2019 2020 2021 Billable/Specific Code

• G31.9 is a billable/specific ICD-10-CM code that can be used to indicate a diagnosis for reimbursement purposes.
• The 2021 edition of ICD-10-CM G31.9 became effective on October 1, 2020.
• This is the American ICD-10-CM version of G31.9 - other international versions of ICD-10 G31.9 may differ.

• Acquired cerebral atrophy
• Cerebellar paraneoplastic degeneration
• Cerebral atrophy, acquired
• Cerebral degeneration in childhood
• Degenerative brain disorder
• Paraneoplastic cerebellar degeneration

• A disorder of the central nervous system characterized by gradual and progressive loss of neural tissue and neurologic function.
• Hereditary and sporadic conditions which are characterized by progressive nervous system dysfunction. These disorders are often associated with atrophy of the affected central or peripheral nervous system structures.
• Neurologic disorders characterized by progressive nervous system dysfunction and loss of neural tissue.

• 056 Degenerative nervous system disorders with mcc
• 057 Degenerative nervous system disorders without mcc

Convert G31.9 to ICD-9-CM

• 2016 (effective 10/1/2015): New code (first year of non-draft ICD-10-CM)
• 2017 (effective 10/1/2016): No change
• 2018 (effective 10/1/2017): No change
• 2019 (effective 10/1/2018): No change
• 2020 (effective 10/1/2019): No change
• 2021 (effective 10/1/2020): No change

• Type 1 Excludes: G31.84
  ICD-10-CM Diagnosis Code G31.84

  Mild cognitive impairment, so stated

  2016 2017 2018 2019 2020 2021 Billable/Specific Code

  Applicable To

  • Mild neurocognitive disorder

  Type 1 Excludes

  • age related cognitive decline (R41.81)
  • altered mental status (R41.82)
  • cerebral degeneration (G31.9)
  • change in mental status (R41.82)
  • cognitive deficits following (sequelae of) cerebral hemorrhage or infarction (I69.01-, I69.11-, I69.21-, I69.31-, I69.81-, I69.91-)
  • cognitive impairment due to intracranial or head injury (S06.-)
  • dementia (F01.-, F02.-, F03)
  • mild memory disturbance (F06.8)
  • neurologic neglect syndrome (R41.4)
  • personality change, nonpsychotic (F68.8)
• Use Additional: G31
  ICD-10-CM Diagnosis Code G31

  Other degenerative diseases of nervous system, not elsewhere classified

  2016 2017 2018 2019 2020 2021 Non-Billable/Non-Specific Code

  Type 2 Excludes

  • Reye's syndrome (G93.7)

  Use Additional

  • For codes G31.0-G31.83, G31.85-G31.9, use additional code to identify:
  • dementia with behavioral disturbance (F02.81)
  • dementia without behavioral disturbance (F02.80)

• Atrophy, atrophic (of)
  • brain (cortex) (progressive) G31.9
• Degeneration, degenerative
  • brain (cortical) (progressive) G31.9
    • childhood G31.9
  • cerebellar NOS G31.9
  • nervous system G31.9
• Hemiatrophy R68.89
  ICD-10-CM Diagnosis Code R68.89

  Other general symptoms and signs

  2016 2017 2018 2019 2020 2021 Billable/Specific Code
  • cerebellar G31.9

Reimbursement claims with a date of service on or after October 1, 2015 require the use of ICD-10-CM codes.