ICD-10-CM Use Additional Code Notes · Chapter 6 · FY 2027 G00-G99

Use Additional Code Notes in Chapter 6: Diseases of the nervous system ICD-10-CM

A Use Additional Code note means a second code should be added, after this one, to fully describe the condition. In Chapter 6 (G00-G99), notes printed in the chapter name other codes 150 times, and Use Additional Code Notes anywhere in the Tabular List name the chapter’s codes 35 times, covering 19 distinct codes, categories and ranges. Switch views to read the list either way.

✓ From the official FY 2027 ICD-10-CM Tabular ListDefinitions follow the Official Guidelines, Section I.A
150
References in Its Notes
35
References to Its Codes
19
Chapter Codes Named
G00-G99
Chapter 6
Chapter 6

Use Additional Code Notes by the code that carries the note

38 of 38 shown
  • G00.2 Streptococcal meningitis
  • G00.3 Staphylococcal meningitis
  • G00.8 Other bacterial meningitis
    • code to further identify organism (B96.-)
  • G04.02 Postimmunization acute disseminated encephalitis, myelitis and encephalomyelitis
  • G04.32 Postimmunization acute necrotizing hemorrhagic encephalopathy
  • G06 Intracranial and intraspinal abscess and granuloma applies to 3 codes
    • code (B95-B97) to identify infectious agent.
  • G10 Huntington's disease
  • G20 Parkinson's disease applies to 5 codes
  • G21.0 Malignant neuroleptic syndrome
  • G21.11 Neuroleptic induced parkinsonism
  • G21.19 Other drug induced secondary parkinsonism
    • code for adverse effect, if applicable, to identify drug (T36-T50 with fifth or sixth character 5)
  • G24.0 Drug induced dystonia applies to 3 codes
    • code for adverse effect, if applicable, to identify drug (T36-T50 with fifth or sixth character 5)
  • G25.1 Drug-induced tremor
    • code for adverse effect, if applicable, to identify drug (T36-T50 with fifth or sixth character 5)
  • G25.3 Myoclonus
    • code for adverse effect, if applicable, to identify drug (T36-T50 with fifth or sixth character 5)
  • G25.4 Drug-induced chorea
    • code for adverse effect, if applicable, to identify drug (T36-T50 with fifth or sixth character 5)
  • G25.61 Drug induced tics
    • code for adverse effect, if applicable, to identify drug (T36-T50 with fifth or sixth character 5)
  • G25.7 Other and unspecified drug induced movement disorders applies to 3 codes
    • code for adverse effect, if applicable, to identify drug (T36-T50 with fifth or sixth character 5)
  • G30 Alzheimer's disease applies to 4 codes
  • G31 Other degenerative diseases of nervous system, not elsewhere classified applies to 14 codes
  • G31.09 Other frontotemporal neurocognitive disorder
    • code, if applicable, to identify mild neurocognitive disorders due to known physiological condition (F06.7-)
  • G31.83 Neurocognitive disorder with Lewy bodies
    • code, if applicable, to identify mild neurocognitive disorders due to known physiological condition (F06.7-)
  • G31.84 Mild cognitive impairment of uncertain or unknown etiology
    • alcohol abuse and dependence (F10.-)
    • exposure to environmental tobacco smoke (Z77.22)
    • history of tobacco dependence (Z87.891)
    • hypertension (I10-I1A)
    • occupational exposure to environmental tobacco smoke (Z57.31)
    • tobacco dependence (F17.-)
    • tobacco use (Z72.0)
  • G40.42 Cyclin-Dependent Kinase-Like 5 Deficiency Disorder
    • cortical blindness (H47.61-)
    • global developmental delay (F88)
  • G40.5 Epileptic seizures related to external causes applies to 2 codes
    • code for adverse effect, if applicable, to identify drug (T36-T50 with fifth or sixth character 5)
  • G43 Migraine applies to 48 codes
    • code for adverse effect, if applicable, to identify drug (T36-T50 with fifth or sixth character 5)
  • G44.4 Drug-induced headache, not elsewhere classified applies to 2 codes
    • code for adverse effect, if applicable, to identify drug (T36-T50 with fifth or sixth character 5)
  • G61.1 Serum neuropathy
    • code for adverse effect, if applicable, to identify serum (T50.-)
  • G62.0 Drug-induced polyneuropathy
    • code for adverse effect, if applicable, to identify drug (T36-T50 with fifth or sixth character 5)
  • G62.82 Radiation-induced polyneuropathy
  • G71.14 Drug induced myotonia
    • code for adverse effect, if applicable, to identify drug (T36-T50 with fifth or sixth character 5)
  • G72.0 Drug-induced myopathy
    • code for adverse effect, if applicable, to identify drug (T36-T50 with fifth or sixth character 5)
  • G72.1 Alcoholic myopathy
    • code to identify alcoholism (F10.-)
  • G90.4 Autonomic dysreflexia
    • fecal impaction (K56.41)
    • pressure ulcer (pressure area) (L89.-)
    • urinary tract infection (N39.0)
  • G90.81 Serotonin syndrome
    • linezolid (T36.8X5)
    • monoamine oxidase inhibitors (T43.1X5)
    • selective serotonin and norepinephrine reuptake inhibitors [SSNRI] (T43.215)
    • selective serotonin reuptake inhibitors [SSRI] (T43.225)
    • disseminated intravascular coagulation (D65)
    • hypertensive crisis (I16.-)
    • metabolic acidosis (E87.2-)
    • shock, not elsewhere classified (R57.-)
    • toxic encephalopathy (G92.-)
    • ventricular tachycardia (I47.2-)
  • G92.8 Other toxic encephalopathy
    • code for adverse effect, if applicable, to identify drug (T36-T50 with fifth or sixth character 5)
  • G92.9 Unspecified toxic encephalopathy
    • code for adverse effect, if applicable, to identify drug (T36-T50 with fifth or sixth character 5)
  • G93.3 Postviral and related fatigue syndromes applies to 3 codes
    • code, if applicable, for post COVID-19 condition, unspecified (U09.9)
  • G93.7 Reye's syndrome
    • code for adverse effect due to salicylates, if applicable (T39.0-, with sixth character 5)

The first view lists notes printed in this chapter (a note on a category or block applies to every code beneath it). The second lists codes of this chapter named by Use Additional Code Notes anywhere in the Tabular List, including notes in other chapters.

Questions About Use Additional Code Notes

What does a Use Additional Code note mean?

A Use Additional Code note tells you to add a second code, reported after the code that carries the note, to describe the condition completely. In an etiology/manifestation pair it sits at the etiology code and points to the manifestation (Section I.A.13). The FY 2027 Tabular List has 1,491 of them; 1,174 name other codes, with 1,438 references to 389 distinct codes, categories and ranges.

Where does the additional code go?

After the code carrying the note. For etiology/manifestation pairs the Guidelines are explicit: the etiology is sequenced first, followed by the manifestation code.

Related References

ICD-10-CM Official GuidelinesICD-10-CM Code LookupICD-10-CM Codes ListCode Lists by Tag

Source: FY 2027 ICD-10-CM Tabular List (CMS and NCHS) and the ICD-10-CM Official Guidelines for Coding and Reporting FY 2027, Section I.A. ICD List is not affiliated with CMS or NCHS.