ICD-10-CM > G00-G99 > G40-G47 > G44 > G44.3 G44.3 Post-traumatic headache Non-Billable/Non-Specific Codes G44.30Post-traumatic headache, unspecifiedG44.301Post-traumatic headache, unspecified, intractableG44.309Post-traumatic headache, unspecified, not intractableG44.31Acute post-traumatic headacheG44.311Acute post-traumatic headache, intractableG44.319Acute post-traumatic headache, not intractableG44.32Chronic post-traumatic headacheG44.321Chronic post-traumatic headache, intractableG44.329Chronic post-traumatic headache, not intractable