Encephalitis, myelitis and encephalomyelitis in diseases classified elsewhere (G05) ICD-10-CM
The G05 code range covers encephalitis, myelitis and encephalomyelitis in diseases classified elsewhere with 3 ICD-10-CM diagnosis codes. 2 of them are billable and valid for claim submission in fiscal year 2026, and the category headers group them but cannot themselves be billed.
Code First
Certain conditions have both an underlying etiology and multiple body system manifestations due to the underlying etiology. For such conditions, the ICD-10-CM has a coding convention that requires the underlying condition be sequenced first followed by the manifestation. Wherever such a combination exists, there is a "use additional code" note at the etiology code, and a "code first" note at the manifestation code. These instructional notes indicate the proper sequencing order of the codes, etiology followed by manifestation.
- underlying disease, such as:
- congenital toxoplasmosis encephalitis, myelitis and encephalomyelitis P37.1
- cytomegaloviral encephalitis, myelitis and encephalomyelitis B25.8
- encephalitis, myelitis and encephalomyelitis in systemic lupus erythematosus M32.19
- eosinophilic meningoencephalitis B83.2
- human immunodeficiency virus [HIV] disease B20
- poliovirus A80
- suppurative otitis media H66.01 H66.4
- systemic lupus erythematosus M32.19
- trichinellosis B75
Type 1 Excludes
A type 1 excludes note is a pure excludes note. It means "NOT CODED HERE!" An Excludes1 note indicates that the code excluded should never be used at the same time as the code above the Excludes1 note. An Excludes1 is used when two conditions cannot occur together, such as a congenital form versus an acquired form of the same condition.
- adenoviral encephalitis, myelitis and encephalomyelitis A85.1
- encephalitis, myelitis and encephalomyelitis in measles B05.0
- enteroviral encephalitis, myelitis and encephalomyelitis A85.0
- herpesviral [herpes simplex] encephalitis, myelitis and encephalomyelitis B00.4
- listerial encephalitis, myelitis and encephalomyelitis A32.12
- meningococcal encephalitis, myelitis and encephalomyelitis A39.81
- mumps encephalitis, myelitis and encephalomyelitis B26.2
- postchickenpox encephalitis, myelitis and encephalomyelitis B01.1
- rubella encephalitis, myelitis and encephalomyelitis B06.01
- toxoplasmosis encephalitis, myelitis and encephalomyelitis B58.2
- zoster encephalitis, myelitis and encephalomyelitis B02.0
Codes in the G05 Range 3 codes · 2 billable
Clinical Terms in This Code Range
Definitions from the National Library of Medicine for conditions coded in the G05 range.
Cerebral Phaeohyphomycosis
CNS infections caused by neurotropic dematiaceous fungi that contain melanin in their cell walls. The infections often result in BRAIN ABSCESS; ENCEPHALITIS; and MENINGITIS in patients who are often immunocompetent. The common causative fungi include members Cladophialophora bantiana, Exophiala dermatitidis, Rhinocladiella mackenziei, and Ochroconis gallopavum. R. mackenziei infection is seen almost exclusively in patients from the MIDDLE EAST.
Dengue
An acute febrile disease transmitted by the bite of AEDES mosquitoes infected with DENGUE VIRUS. It is self-limiting and characterized by fever, myalgia, headache, and rash. SEVERE DENGUE is a more virulent form of dengue.
Dengue Vaccines
Vaccines or candidate vaccines used to prevent infection with DENGUE VIRUS. These include live-attenuated, subunit, DNA, and inactivated vaccines.
Dengue Virus
A species of the genus FLAVIVIRUS which causes an acute febrile and sometimes hemorrhagic disease in man. Dengue is mosquito-borne and four serotypes are known.
Flavivirus
A genus of FLAVIVIRIDAE containing several subgroups and many species. Most are arboviruses transmitted by mosquitoes or ticks. The type species is YELLOW FEVER VIRUS.
Limbic Encephalitis
A paraneoplastic syndrome marked by degeneration of neurons in the LIMBIC SYSTEM. Clinical features include HALLUCINATIONS, loss of EPISODIC MEMORY; ANOSMIA; AGEUSIA; TEMPORAL LOBE EPILEPSY; DEMENTIA; and affective disturbance (depression). Circulating anti-neuronal antibodies (e.g., anti-Hu; anti-Yo; anti-Ri; and anti-Ma2) and small cell lung carcinomas or testicular carcinoma are frequently associated with this syndrome.
Lyme Neuroborreliosis
Nervous system infections caused by tick-borne spirochetes of the BORRELIA BURGDORFERI GROUP. The disease may affect elements of the central or peripheral nervous system in isolation or in combination. Common clinical manifestations include a lymphocytic meningitis, cranial neuropathy (most often a facial neuropathy), POLYRADICULOPATHY, and a mild loss of memory and other cognitive functions. Less often more extensive inflammation involving the central nervous system (encephalomyelitis) may occur. In the peripheral nervous system, B. burgdorferi infection is associated with mononeuritis multiplex and polyradiculoneuritis. (From J Neurol Sci 1998 Jan 8;153(2):182-91)
Phaeohyphomycosis
OPPORTUNISTIC INFECTIONS caused by the dematiaceous (darkly pigmented) MITOSPORIC FUNGI of ALTERNARIA, Bipolaris, CLADOSPORIUM, Curvularia, and EXOPHIALA. These fungi have pigmented HYPHAE due to MELANIN in the cell wall. The initial subcutaneous cyst from the infection can become systemic and spread rapidly to renal, pulmonary and cerebral systems (see CEREBRAL PHAEOHYPHOMYCOSIS) in an IMMUNOCOMPROMISED HOST.
Severe Dengue
A virulent form of dengue characterized by THROMBOCYTOPENIA and an increase in vascular permeability (grades I and II) and distinguished by a positive pain test (e.g., TOURNIQUET PAIN TEST). When accompanied by SHOCK (grades III and IV), it is called dengue shock syndrome.
About the G05 Code Range
The ICD-10 code section G05 covers encephalitis, myelitis, and encephalomyelitis when these conditions occur as complications or manifestations of other underlying diseases. These codes specifically identify brain and spinal cord inflammations linked to infections, autoimmune disorders, or other systemic illnesses classified elsewhere.
Within this section, G05.3 is used for encephalitis and encephalomyelitis caused by various infections and immune-related conditions, including HIV/AIDS-associated encephalitis, fungal, bacterial, or viral infections like Lassa virus encephalitis and tick-borne encephalitic disorders. This code helps medical coders capture brain inflammations tied to specific infectious agents or paraneoplastic syndromes. Meanwhile, G05.4 classifies myelitis related to systemic diseases or infections such as multiple sclerosis, lupus, Lyme neuroborreliosis, and various fungal or protozoal infections affecting the spinal cord. Knowing the specific ICD-10 code for encephalitis or myelitis in diseases classified elsewhere enables precise documentation of neurological inflammations secondary to diverse causes, aiding targeted treatment and accurate medical records.
Questions About This Page
How many billable codes are in the G05 range?
Of the 3 codes in this range, 2 are billable and valid for claim submission from October 1, 2025 through September 30, 2026. Category header codes group them but cannot be reported on claims.
What does the G05 range classify?
The range classifies encephalitis, myelitis and encephalomyelitis in diseases classified elsewhere. Each code links to its own reference page with billing status, MS-DRG grouping, coding notes, and clinical information.
Related References
Source: CMS FY 2026 ICD-10-CM Tabular List and order file, effective October 1, 2025 through September 30, 2026.
