Megalencephaly

This code represents a neurological condition characterized by an abnormally large brain size, often leading to an enlarged head circumference. It can be a primary condition or secondary to other disorders, and may or may not be associated with intellectual disability or other neurological deficits.

Use this code when documentation clearly indicates a diagnosis of megalencephaly, often supported by imaging studies (e.g., MRI, CT scan) showing increased brain volume. This diagnosis is typically made by a neurologist or geneticist based on clinical examination and diagnostic testing.

• Differentiate from hydrocephalus, which also causes an enlarged head but is due to excess cerebrospinal fluid, not brain tissue.
• Always look for and code any underlying conditions or associated neurological manifestations, such as intellectual disabilities or seizures.
• Ensure the provider's documentation specifies "megalencephaly" and not just "macrocephaly," as macrocephaly can have other causes.