Question: When a patient suffers from post-traumatic headache, what is the best ICD-10 code to represent this condition? New Hampshire Subscriber Answer: First, you’ll need to decide whether the headache was unspecified, acute, or chronic. Then you can choose among the following codes to start: 6th character options: You’ll then use a 6th character to indicate whether the headache was intractable (“1”) or not intractable (“9”).