Denominator for the measure reads:
◾OR: "Occurrence A of Symptom, Active: Neurologic Symptoms of Stroke (start datetime)"
◾OR: "Occurrence A of Symptom, Active: Baseline State (stop datetime)"
◾ <= 120 minute(s) starts before start of "Occurrence A of Encounter, Performed: Emergency Department Visit (facility location arrival datetime)"

Numerator for the measure reads:
◦AND: ◾OR: "Medication, Administered: Thrombolytic (t-PA) Therapy" <= 180 minute(s) starts after start of "Occurrence A of Symptom, Active: Baseline State (stop datetime)"
◾OR: "Medication, Administered: Thrombolytic (t-PA) Therapy" <= 180 minute(s) starts after start of "Occurrence A of Symptom, Active: Neurologic Symptoms of Stroke (start datetime)"

In both Numerator and denominator the component, "starts after start of "Occurrence A of Symptom, Active: Neurologic Symptoms of Stroke (start datetime)" " that uses value set "Neurologic Symptoms of Stroke SNOMED-CT Value Set (2.16.840.1.113883.3.117.1.7.1.399)"

The Value set actually codify actual symptoms of stroke, like numbness,pain etc... and not the date component when actual onset date / start date. We have most of our clients documenting all the symptoms finding and the time of onset as two separate components pretty much same like they want to document Last known well - baseline state using "Baseline State SNOMED-CT Value Set (2.16.840.1.113883.3.117.1.7.1.417)"... the date - time documentation for when symptom of stroke discovered.
This data element is very infeasible, as when user documents the symptoms - the symptoms are already set in past mostly few hours already. User does not document each symptom and its time as a pair but set of symptoms and the date of first symptom onset as second documentation data point. Because of these issues, provider organizations have to design all kinds of inconvenient workarounds to try to get this information recorded by someone in a discrete format. This difficulty can be completely eliminated by changing this data element like "Baseline State SNOMED-CT Value Set (2.16.840.1.113883.3.117.1.7.1.417)"