ICD-10 Code G92.04 – Immune effector cell-associated neurotoxicity syndrome, grade 4 (2026): Diagnosis, Symptoms & Billing Guide
2026 ICD-10-CM Diagnosis Code G92.04 – Immune effector cell-associated neurotoxicity syndrome, grade 4
What it is
This code identifies the most severe grade of immune effector cell-associated neurotoxicity syndrome (ICANS). It is used when neurologic toxicity follows immune effector cell therapy and is documented as grade 4.
Clinical signs
Grade 4 ICANS reflects critical neurologic impairment, such as profound encephalopathy, coma, or inability to arouse the patient. Clinical features vary; refer to documentation and the grading system used by the treating team.
When to use this code
Use this code when the provider clearly documents ICANS as grade 4 after immune effector cell treatment, such as CAR-T therapy. Code it only when the severity grade is stated in the record or can be confirmed from documented criteria. If the grade is not specified, check documentation rather than assuming the highest level.
Do not use for
Do not use this code for nonspecific altered mental status, delirium, or encephalopathy without a documented link to immune effector cell therapy. Do not assign it when a different ICANS grade is recorded.
Coding tip
Verify the therapy type, timing, and documented ICANS grade before coding G92.04.