Assign WFNS from a reliable clinical examination at a named timepoint. Preserve confounders and never turn a CT pattern or a poor clinical grade into an automatic treatment or futility decision.
{
"categories": [
{
"outcome_code": "1",
"gcs_total": "15",
"major_focal_neurologic_deficit": "absent"
},
{
"outcome_code": "2",
"gcs_total": "13_to_14",
"major_focal_neurologic_deficit": "absent"
},
{
"outcome_code": "3",
"gcs_total": "13_to_14",
"major_focal_neurologic_deficit": "present"
},
{
"outcome_code": "4",
"gcs_total": "7_to_12",
"major_focal_neurologic_deficit": "present_or_absent"
},
{
"outcome_code": "5",
"gcs_total": "3_to_6",
"major_focal_neurologic_deficit": "present_or_absent"
}
],
"applicability": {
"intended_use": "Standardized bedside communication of clinical severity in a patient with subarachnoid hemorrhage, classically aneurysmal SAH.",
"classification_unit": "one_patient_at_one_explicit_clinical_timepoint_after_initial_resuscitation",
"required_inputs": [
"reliable_Glasgow_Coma_Scale_total_and_components",
"presence_or_absence_of_major_focal_neurologic_deficit",
"assessment_timepoint",
"confounder_status"
],
"outside_scope": [
"grading_from_CT_alone",
"quantifying_subarachnoid_blood_burden",
"diagnosing_the_aneurysm",
"predicting_delayed_cerebral_ischemia_from_grade_alone",
"automatic_treatment_or_futility_decision"
]
},
"assignment_algorithm": [
"Stabilize airway, breathing and circulation and identify immediately reversible examination confounders.",
"Record eye, verbal and motor GCS components plus the total at a named timepoint; do not infer a score hidden by sedation or paralysis.",
"Record whether a major focal neurologic deficit such as aphasia or hemiparesis is present when the examination can establish it.",
"Map GCS 15 without a major deficit to 1; GCS 13-14 without versus with a major deficit to 2 versus 3; GCS 7-12 to 4; and GCS 3-6 to 5.",
"If reliability is materially limited, return the observed facts and a provisional or unassignable state rather than manufacturing a definitive grade."
],
"decisive_boundaries": {
"grade_1_versus_2": "GCS 15 is grade 1 only when a major focal deficit is absent; GCS 14 is already within grade 2 or 3.",
"grade_2_versus_3": "Both grades use GCS 13-14. Absence of a major focal deficit is grade 2 and presence is grade 3; never invert this axis.",
"grade_3_versus_4": "GCS 13 remains grade 2 or 3 according to deficit; GCS 12 is grade 4 regardless of deficit.",
"grade_4_versus_5": "GCS 7 is grade 4 and GCS 6 is grade 5; focal-deficit status does not move either band."
},
"examination_reliability_gate": {
"confounders_to_record": [
"sedatives_or_anesthetics",
"endotracheal_intubation_limiting_verbal_score",
"neuromuscular_blockade",
"postictal_state_or_ongoing_seizure",
"hydrocephalus",
"hypoxia_or_hypotension",
"metabolic_or_temperature_derangement",
"language_or_preexisting_neurologic_limit"
],
"intubated_verbal_component": "Use the locally declared GCS convention and expose the verbal limitation; do not silently assign a normal verbal score.",
"timepoint_rule": "A grade before resuscitation, after resuscitation, after cerebrospinal-fluid diversion and after sedation are different observations. Preserve the timepoint and any change rather than overwriting the trajectory.",
"focal_deficit_rule": "Do not declare absence of a major deficit when coma, paralysis or an otherwise unreliable examination prevents testing."
},
"imaging_and_system_boundaries": {
"CT": "CT establishes hemorrhage distribution and complications but cannot provide the clinical GCS-plus-deficit WFNS grade.",
"original_Fisher_or_modified_Fisher": "These are CT blood-distribution frameworks and must be calculated separately from their own imaging inputs; no numeric crosswalk to WFNS is valid.",
"Hunt_Hess": "Hunt-Hess uses different clinical descriptors. A historical correspondence is not a one-to-one conversion and must not replace direct grading.",
"aneurysm_status": "WFNS does not identify aneurysm site, rupture source, rebleeding, hydrocephalus, vasospasm or delayed cerebral ischemia; return those as separate facts."
},
"current_management_boundary": {
"all_grades": "Activate specialized aneurysmal-SAH care, identify and secure the ruptured aneurysm as early as feasible, preferably within 24 hours when appropriate, and apply current neurocritical-care guidance. The WFNS numeral is communication context rather than an order.",
"poor_grade": "Grades 4-5 do not establish futility or justify withholding aneurysm treatment. Resuscitation, reversible causes, age, comorbidities, hemorrhage pattern, brain injury, patient values and multidisciplinary judgment determine candidacy and timing.",
"prohibited_legacy_inference": "Do not reproduce the historical rule that grades above 3 should simply wait for surgery; contemporary care evaluates early aneurysm securing across grades."
},
"risk_interpretation": {
"population_gradient": "Higher grades are associated with worse outcomes in groups, but the scale is not a calibrated patient-level probability model.",
"confounding": "Sedation, intubation, hydrocephalus, seizures, resuscitation state and timing can shift the observed grade and materially bias prognosis.",
"prohibited_inferences": [
"individual_mortality_percentage",
"individual_functional_outcome_percentage",
"treatment_benefit_from_grade_alone",
"neurologic_futility"
]
},
"agent_output_contract": [
"Return the examination timepoint and reliability before the grade.",
"Return the exact GCS components and total plus major focal-deficit status.",
"Name the decisive boundary, especially the grade 2 versus 3 deficit split.",
"Keep CT blood burden, aneurysm status, hydrocephalus and complications as separate outputs.",
"Separate population-level severity context from individualized prognosis and treatment."
],
"missing_input_behavior": [
"Without a reliable GCS total and components, do not assign a definitive WFNS grade.",
"With GCS 13-14 but unknown deficit status, return a grade 2-or-3 conditional range and request a reliable focal examination.",
"If a query supplies CT findings only, route to the appropriate CT hemorrhage framework and explicitly withhold WFNS.",
"If the examination changes after resuscitation or cerebrospinal-fluid diversion, retain both grades with their timepoints."
],
"supporting_sources": [
{
"role": "primary_scale",
"citation": "Drake et al. J Neurosurg. 1988;68:985-986",
"doi": "10.3171/jns.1988.68.6.0985",
"pmid": "3131498"
},
{
"role": "current_US_care_context",
"citation": "Hoh et al. Stroke. 2023;54:e314-e370",
"doi": "10.1161/STR.0000000000000436"
},
{
"role": "current_European_care_context",
"citation": "Vergouwen et al. Eur Stroke J. 2026",
"doi": "10.1093/esj/aakag043",
"pmcid": "PMC13151661"
}
],
"source_locator": "Drake et al. 1988, DOI 10.3171/jns.1988.68.6.0985, original table; Rosen and Macdonald 2013, PMC3621041, Table 3; Hoh et al. 2023, DOI 10.1161/STR.0000000000000436, aneurysm-treatment timing; Vergouwen et al. 2026, PMC13151661, current multidisciplinary aSAH care."
}