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    v1.0.28
    OpenPayerBilling CodesOther disorders of the nervous systemICD-10-CM g91-hydrocephalus
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    ICD-10-CM Code For Hydrocephalus: Group Overview

    The International Classification of Diseases, Tenth Revision, Clinical Modification (ICD-10-CM) code group G91 includes diagnoses of hydrocephalus, encompassing congenital, acquired, communicating, and noncommunicating forms that affect cerebrospinal fluid circulation and ventricular size. These ICD-10-CM diagnosis codes are used to document clinical scenarios such as ventricular enlargement due to impaired cerebrospinal fluid flow, normal pressure hydrocephalus with gait and cognitive changes, or hydrocephalus secondary to hemorrhage, tumor, infection, or trauma, capturing disease severity and neurologic involvement. Accurate coding within the ICD-10-CM G91 group supports proper claim adjudication and complete clinical documentation for appropriate reimbursement.

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    ICD-10-CM G91: Hydrocephalus Overview

    The diagnoses in the ICD-10-CM G91 group represent hydrocephalus, a disorder of cerebrospinal fluid dynamics leading to ventricular enlargement and increased intracranial pressure. These codes target conditions affecting the central nervous system and its cerebrospinal fluid pathways. Accurate coding is important for reflecting clinical severity and supporting appropriate reimbursement.

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    When to Use

    Use a code from this group when documentation indicates hydrocephalus as a primary diagnosis or secondary condition that affects clinical management or resource utilization. Select the code that best reflects the type (communicating versus noncommunicating), acuity, and underlying cause when specified in the clinical record.

    ICD-10-CM Codes

    7 rows

    ICD-10-CM CodeDescription
    G91.0Communicating hydrocephalus
    G91.1Obstructive hydrocephalus
    G91.2(Idiopathic) normal pressure hydrocephalus
    G91.3Post-traumatic hydrocephalus, unspecified
    G91.4Hydrocephalus in diseases classified elsewhere
    G91.8Other hydrocephalus
    G91.9Hydrocephalus, unspecified

    DRG Codes

    2 rows

    DRG CodeDescription
    056Degenerative Nervous System Disorders with MCC
    057Degenerative Nervous System Disorders without MCC

    Typical Clinical Scenarios

    • An adult patient presents to the emergency department with rapidly worsening headache, nausea, altered mental status, and papilledema after a recent subarachnoid hemorrhage; neuroimaging shows acute enlargement of the ventricular system consistent with communicating hydrocephalus causing increased intracranial pressure. A diagnosis from this group is assigned to describe the acute hydrocephalic process requiring urgent neurosurgical evaluation. Typical codes: G91.0, G91.2
    • An older outpatient with progressive gait disturbance, urinary incontinence, and cognitive decline over months is referred for neurologic evaluation; brain MRI demonstrates ventricular enlargement out of proportion to cortical atrophy, consistent with normal pressure hydrocephalus. A diagnosis from this group is used to capture the chronic, idiopathic ventricular enlargement as the primary neurologic condition driving management and possible CSF diversion consideration. Typical codes: G91.3, G91.9
    • A patient with a history of ventriculoperitoneal shunt placement for prior hydrocephalus presents with low-grade fever, abdominal pain, and signs of shunt malfunction with imaging showing proximal catheter obstruction and ventricular enlargement; coding identifies the hydrocephalus as a postoperative/comorbid complication related to the shunt and guides tracking of shunt-related disorders. Typical codes: G91.4, G91.8

    Related Codes

    G90-DISORDERS-OF-AUTONOMIC-NERVOUS-SYSTEM

    ICD-10-CM Code For Disorders Of Autonomic Nervous System: Group Overview

    G92-TOXIC-ENCEPHALOPATHY

    ICD-10-CM Code For Toxic Encephalopathy: Group Overview

    G93-OTHER-DISORDERS-OF-BRAIN

    ICD-10-CM Code For Other Disorders Of Brain: Group Overview

    G94-OTHER-DISORDERS-OF-BRAIN

    ICD-10-CM Code For Other Disorders Of Brain In Diseases Classified Elsewhere: Group Overview

    G95-OTHER-AND-UNSPECIFIED-SPINAL-CORD

    ICD-10-CM Code For Other And Unspecified Diseases Of Spinal Cord: Group Overview

    G96-OTHER-DISORDERS-OF-CENTRAL-NERVOUS-SYSTEM

    ICD-10-CM Code For Other Disorders Of Central Nervous System: Group Overview

    G97-INTRAOPERATIVE-AND-POSTPROCEDURAL-NERVOUS-SYSTEM

    ICD-10-CM Code For Intraoperative And Postprocedural Complications Of Nervous System: Group Overview

    G98-OTHER-NERVOUS-SYSTEM-DISORDERS

    ICD-10-CM Code For Other Disorders Of Nervous System Not Elsewhere Classified: Group Overview

    G99-OTHER-DISORDERS-OF-NERVOUS-SYSTEM

    ICD-10-CM Code For Other Disorders Of Nervous System In Diseases Classified Elsewhere: Group Overview

    Frequently Asked Questions

    References

    1. 1.CPT® Codes and Descriptions. AAPC. Retrieved Aug 11, 2026.Maintains the CPT code set's official descriptions and guidelines, licensed from the American Medical Association, used as the definitional source for CPT codes on this page.
    2. 2.HCPCS Quarterly Update. Centers for Medicare & Medicaid Services (CMS). Retrieved Aug 11, 2026.CMS's quarterly release of HCPCS Level II codes and short/long descriptors, the source for HCPCS code definitions and update history.
    3. 3.ICD-10-CM Full Code List. Centers for Medicare & Medicaid Services (CMS). Retrieved Aug 11, 2026.CMS's complete ICD-10-CM diagnosis code list, used to cross-reference diagnosis codes associated with this procedure or service.
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