Only assign the NIHSS stroke scale score with category
I63 - Cerebral Infarction. The Inpatient ICD-10-CM Coding Guidelines, Coding Clinic 4th Qtr. 2016 page 61, and The AHA’s Coding Handbook FY 2018 all specify to use with category I63. The subcategory, NIHSS score, R29.7-, has an instructional note to code first the type of cerebral infarction (I63-), and does not include hemorrhagic infarctions. The I63 subcategory also has an instruction note to add a code for the NIHSS score, if known, whereas, the subcategory for the hemorrhagic infarctions does not.
FY 2018 Inpatient ICD-10-CM Coding Guidelines
Coding Clinic, 4th Quarter 2016, page 61
The AHA’s Coding Handbook FY 2018