What are Cerebral Atrophy ICD-10-CM Codes?
There is no single ICD-10-CM diagnosis code labeled explicitly as “cerebral atrophy,” but several codes describe this degenerative condition of the nervous system. In ICD-10 coding, cerebral atrophy—whether localized or generalized brain atrophy—is typically documented through the underlying disease process, such as traumatic brain injury, cerebrovascular diseases, or neurodegenerative disorders.
Two primary ICD-10-CM codes frequently used to describe brain degeneration or cerebral cortex shrinkage include:
- G31.9 – Degenerative disease of nervous system, unspecified
This code applies to cases of progressive loss of brain tissue when no other specified degenerative diseases can be identified. It is often used in cases where there is mild cognitive impairment or senile degeneration of the brain, but no clear cause is found.
Healthcare professionals should use more specific codes when the underlying disease process is known. When the underlying cause of cerebral atrophy is known, ICD-10-CM guidelines recommend using a more specific diagnosis code. The following nervous system not elsewhere classified and neurodegenerative disease codes are valid and billable in 2025:
- G46.4 – Cerebellar stroke syndrome
This ICD-10-CM code is used when a cerebrovascular event leads to dysfunction in the cerebellum, potentially causing secondary brain atrophy over time. - S06.2X0A – Diffuse traumatic brain injury without loss of consciousness, initial encounter
Represents early-stage care for traumatic brain injury, a condition known to result in central nervous system damage and eventual cerebral degeneration. - G80.9 – Cerebral palsy, unspecified
A developmental and motor disorder associated with degeneration of brain structures, including the cerebral cortex and spinal cord, that can contribute to circumscribed brain atrophy. - A85.8 – Other specified viral encephalitis
Encephalitis, or inflammation of the brain, can cause acute or long-term degenerative diseases of the nervous system, sometimes leading to senile degeneration or dementia. - G10 – Huntington’s disease
A hereditary degenerative disorder affecting motor control and cognition, commonly associated with progressive cerebral atrophy and other degenerative diseases of nervous system. - G30.9 – Alzheimer’s disease, unspecified
This dementia-related ICD-10 code documents late-onset Alzheimer’s or unspecified types, which are known for causing brain shrinkage, memory decline, and senility NOS.