Neurosurgery Coding Alert

Do you know what KCNQ2-related epilepsy is?

ICD-10 just settled on its list of new, revised, and deleted codes for 2025, and it has several additions that will be relevant to your practice. ICD-10 2025 released almost 300 additions, deletions, and revisions for the next copy of the code book.

Do this: Get used to these codes before you have to start using them by looking at them early. Remember, you are supposed to use the 2025 ICD-10 code list on October 1, 2024.

Check out the codes that will affect your coding come October.

ICD-10 Reveals New Epilepsy Group

There will be a whole new set of epilepsy codes in the G40.8- (Other encephalitis, myelitis and encephalomyelitis) section of ICD-10. The new codes are:

• G40.84 (KCNQ2-related epilepsy)
• G40.841 (KCNQ2-related epilepsy, not intractable, with status epilepticus)
• G40.842 (KCNQ2-related epilepsy, not intractable, without status epilepticus)
• G40.843 (KCNQ2-related epilepsy, intractable, with status epilepticus)
• G40.844 (KCNQ2-related epilepsy, intractable, without status epilepticus)

Condition description: KCNQ2-related epilepsy results from mutations in the KCNQ2 gene, which regulates neuronal excitability. This condition is able to manifest itself as various epilepsy types. Symptoms of KCNQ-2-related epilepsy include developmental delays, intellectual disability, and movement disorders.

For patients suffering KCNQ-related epilepsy, the seizures usually start in the first days or weeks of their lives. The seizures they suffer vary, but are often tonic or tonic-clonic seizures. KCNQ2-related epilepsy is typically diagnosed via genetic testing to identify the KCNQ2 gene. There is no cure for KCNQ2-related epilepsy, treatment often includes anti-seizure medications, ketogenic diet, or specialized therapies.

Several Codes Converted to Parents

There are also several ICD-10 codes that were converted to “parent” codes, which will spawn new codes that are under the parent code’s heading.

Example: One of the codes that ICD-10 converted to parent was G90.8 (Other disorders of autonomic nervous system). Starting on October 1, the code will expand to require a 5th character (G90.8-). The new codes beneath G90.8- (the “children”) are:

• G90.81 (Serotonin syndrome)
• G90.89 (Other disorders of autonomic nervous system)

Impact: This move gives a specific ICD-10 code to serotonin syndrome, which you would code as G90.8 currently. Serotonin syndrome is a potentially serious condition that occurs when there’s an excess buildup of serotonin in the central nervous system. The buildup often occurs because of certain medications the patient is taking, drug interactions, or overdose of serotonergic medication.

The next code that will covert to parent in October is M51.36 (Other intervertebral disc degeneration, lumbar region). When the code becomes M51.36-, these will be your 6th character options:

• M51.360 (Other intervertebral disc degeneration, lumbar region with discogenic back pain only)
• M51.361 (Other intervertebral disc degeneration, lumbar region with lower extremity pain only)
• M51.362 (Other intervertebral disc degeneration, lumbar region with discogenic back pain and lower extremity pain)
• M51.369 (Other intervertebral disc degeneration, lumbar region without mention of lumbar back pain or lower extremity pain)

Impact: This move will make M51.36 a code set that includes descriptions indicating the absence/presence of lower extremity pain, discogenic back pain, and lumbar back pain.

Finally, ICD-10 also converted M51.37 (Other intervertebral disc degeneration, lumbosacral region) to parent for 2025. When this code starts requiring a 6th character, these will be your options:

• M51.370 (Other intervertebral disc degeneration, lumbosacral region with discogenic back pain only)
• M51.371 (Other intervertebral disc degeneration, lumbosacral region with lower extremity pain only)
• M51.372 (Other intervertebral disc degeneration, lumbosacral region with discogenic back pain and lower extremity pain)
• M51.379 (Other intervertebral disc degeneration, lumbosacral region without mention of lumbar back pain or lower extremity pain)

Impact: Much like M51.36, the expansion of M51.37 will result in a code set that includes descriptions indicating the absence/presence of lower extremity pain, discogenic back pain, and lumbar back pain.

Remember to Note These Standalone Codes

There are also a set of new codes that don’t come in a group, as the ones above do. These codes are:

• G93.45 (Developmental and epileptic encephalopathy)
• M62.85 (Dysfunction of the multifidus muscles, lumbar region)
• Z15.1(Genetic susceptibility to epilepsy and neurodevel­opmental disorders)

Impact: The addition of G93.45 will give coders another more specific coding option in the G93.4- (Other and unspecified encephalopathy). The M62.85 code will serve a similar function, expanding specific coding options in the M62.8- (Other specified disorders of muscle) code set. The Z15.1 code will give you another three-character option between Z15.0- (Genetic susceptibility to malignant neoplasm) and Z15.8- (Genetic susceptibility to other disease).

Chris Boucher, MS, CPC, Senior Development Editor, AAPC