Postencephalitic parkinsonism

This code describes a form of parkinsonism that develops as a sequela of encephalitis. It presents with symptoms characteristic of Parkinson's disease, such as bradykinesia, rigidity, tremor, and postural instability, but is directly attributable to a prior inflammatory brain infection.

Use this code when documentation clearly indicates parkinsonian symptoms arising after a confirmed or suspected episode of encephalitis. This diagnosis is typically made after excluding other causes of parkinsonism, such as idiopathic Parkinson's disease or drug-induced parkinsonism.

• Ensure documentation explicitly links the parkinsonism to a prior encephalitic event.
• Do not confuse with idiopathic Parkinson's disease (G20) or secondary parkinsonism due to other causes.
• Code any associated neurological deficits or sequelae of the encephalitis separately, if applicable.