Measles complicated by encephalitis

This code signifies a severe neurological complication arising from a measles infection, specifically inflammation of the brain parenchyma. It indicates that the patient's measles has progressed to involve the central nervous system, leading to encephalitis.

Apply this code when documentation clearly states a diagnosis of measles with associated encephalitis. This typically occurs in cases where a patient presenting with measles symptoms subsequently develops neurological signs such as altered mental status, seizures, or focal neurological deficits, and encephalitis is confirmed through clinical evaluation, imaging, or CSF analysis.

• Always ensure documentation explicitly links the encephalitis to the measles infection.
• Do not use this code for post-infectious encephalomyelitis (PIM) or subacute sclerosing panencephalitis (SSPE), which have distinct ICD-10-CM codes.
• Sequence this code as the primary diagnosis if the encephalitis is the reason for the encounter, or as a secondary diagnosis if another condition is the primary focus but measles encephalitis is a significant co-morbidity.