2023 ICD-10-CM Diagnosis Code G91


    2016 2017 2018 2019 2020 2021 2022 2023 Non-Billable/Non-Specific Code
  • G91 should not be used for reimbursement purposes as there are multiple codes below it that contain a greater level of detail.
  • The 2023 edition of ICD-10-CM G91 became effective on October 1, 2022.
  • This is the American ICD-10-CM version of G91 - other international versions of ICD-10 G91 may differ.
Type 1 Excludes
Type 1 Excludes Help
A type 1 excludes note is a pure excludes. It means "not coded here". A type 1 excludes note indicates that the code excluded should never be used at the same time as G91. A type 1 excludes note is for used for when two conditions cannot occur together, such as a congenital form versus an acquired form of the same condition.
  • Arnold-Chiari syndrome with hydrocephalus (
    ICD-10-CM Diagnosis Code Q07
    • Q07 Other congenital malformations of nervous sys...
      • Q07.0 Arnold-Chiari syndrome
        • Q07.00 Arnold-Chiari syndrome without spina bifida o...
        • Q07.01 …… with spina bifida
        • Q07.02 …… with hydrocephalus
        • Q07.03 Arnold-Chiari syndrome with spina bifida and ...
      • Q07.8 Other specified congenital malformations of n...
      • Q07.9 Congenital malformation of nervous system, un...
  • congenital hydrocephalus (
    ICD-10-CM Diagnosis Code Q03
    • Q03 Congenital hydrocephalus
      • Q03.0 Malformations of aqueduct of Sylvius
      • Q03.1 Atresia of foramina of Magendie and Luschka
      • Q03.8 Other congenital hydrocephalus
      • Q03.9 Congenital hydrocephalus, unspecified
  • spina bifida with hydrocephalus (
    ICD-10-CM Diagnosis Code Q05
    • Q05 Spina bifida
      • Q05.0 Cervical spina bifida with hydrocephalus
      • Q05.1 Thoracic spina bifida with hydrocephalus
      • Q05.2 Lumbar spina bifida with hydrocephalus
      • Q05.3 Sacral spina bifida with hydrocephalus
      • Q05.4 Unspecified spina bifida with hydrocephalus
      • Q05.5 Cervical spina bifida without hydrocephalus
      • Q05.6 Thoracic spina bifida without hydrocephalus
      • Q05.7 Lumbar spina bifida without hydrocephalus
      • Q05.8 Sacral spina bifida without hydrocephalus
      • Q05.9 Spina bifida, unspecified
Includes Help
"Includes" further defines, or give examples of, the content of the code or category.
  • acquired hydrocephalus
The following code(s) above G91 contain annotation back-references
Annotation Back-References
In this context, annotation back-references refer to codes that contain:
  • Applicable To annotations, or
  • Code Also annotations, or
  • Code First annotations, or
  • Excludes1 annotations, or
  • Excludes2 annotations, or
  • Includes annotations, or
  • Note annotations, or
  • Use Additional annotations
that may be applicable to G91:
  • G00-G99
    2023 ICD-10-CM Range G00-G99

    Diseases of the nervous system

    Type 2 Excludes
    • 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)
    Diseases of the nervous system
Clinical Information
  • (hye-dro-sef-uh-lus) the abnormal buildup of cerebrospinal fluid in the ventricles of the brain.
  • A disorder characterized by an abnormal increase of cerebrospinal fluid in the ventricles of the brain.
  • Excessive accumulation of cerebrospinal fluid within the cranium which may be a congenital or acquired disorder; hydrocephalus ex-vacuo refers to ventricular dilation that occurs as a result of brain substance loss from cerebral infarction and other conditions.
  • Excessive accumulation of cerebrospinal fluid within the cranium which may be associated with dilation of cerebral ventricles, intracranial hypertension; headache; lethargy; urinary incontinence; and ataxia.
  • Excessive gathering of cerebrospinal fluid within the head bone
  • Hydrocephalus is the buildup of too much cerebrospinal fluid in the brain. Normally, this fluid cushions your brain. When you have too much, though, it puts harmful pressure on your brain.there are two kinds of hydrocephalus. Congenital hydrocephalus is present at birth. Causes include genetic problems and problems with how the fetus develops. An unusually large head is the main sign of congenital hydrocephalus. Acquired hydrocephalus can occur at any age. Causes can include head injuries, strokes, infections, tumors and bleeding in the brain. Symptoms of acquired hydrocephalus can include
    • headache
    • vomiting and nausea
    • blurry vision
    • balance problems
    • bladder control problems
    • thinking and memory problems
    hydrocephalus can permanently damage the brain, causing problems with physical and mental development. If untreated, it is usually fatal. With treatment, many people lead normal lives with few limitations. Treatment usually involves surgery to insert a shunt. Medicine and rehabilitation therapy can also help.
  • Hydrocephalus that results from head trauma, brain tumors, intracranial hemorrhage, or meningitis.
  • The abnormal buildup of cerebrospinal fluid in the ventricles of the brain.
Code History
  • 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
  • 2022 (effective 10/1/2021): No change
  • 2023 (effective 10/1/2022): No change
Code annotations containing back-references to G91:
  • Type 1 Excludes: Q03
    ICD-10-CM Diagnosis Code Q03

    Congenital hydrocephalus

      2016 2017 2018 2019 2020 2021 2022 2023 Non-Billable/Non-Specific Code
    • hydrocephalus in newborn
    Type 1 Excludes
    • Arnold-Chiari syndrome, type II (Q07.0-)
    • acquired hydrocephalus (G91.-)
    • hydrocephalus due to congenital toxoplasmosis (P37.1)
    • hydrocephalus with spina bifida (Q05.0-Q05.4)
ICD-10-CM Codes Adjacent To G91
G90.519 Complex regional pain syndrome I of unspecified upper limb
G90.52 Complex regional pain syndrome I of lower limb
G90.521 Complex regional pain syndrome I of right lower limb
G90.522 Complex regional pain syndrome I of left lower limb
G90.523 …… bilateral
G90.529 Complex regional pain syndrome I of unspecified lower limb
G90.59 Complex regional pain syndrome I of other specified site
G90.8 Other disorders of autonomic nervous system
G90.9 Disorder of the autonomic nervous system, unspecified
G90.A Postural orthostatic tachycardia syndrome [POTS]
G91 Hydrocephalus
G91.0 Communicating hydrocephalus
G91.1 Obstructive hydrocephalus
G91.2 (Idiopathic) normal pressure hydrocephalus
G91.3 Post-traumatic hydrocephalus, unspecified
G91.4 Hydrocephalus in diseases classified elsewhere
G91.8 Other hydrocephalus
G91.9 Hydrocephalus, unspecified
G92 Toxic encephalopathy
G92.0 Immune effector cell-associated neurotoxicity syndrome
G92.00 …… grade unspecified

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