12-phase flow (12)

1. 1FRAME
   Differentiate posterior-circulation stroke from vestibular neuritis in continuous-vertigo-with-nystagmus patient; CT misses ~80% of acute posterior strokes — HINTS is the diagnostic battery (Kattah Stroke 2009 PMID 19762709)
   advance: AVS syndrome recognised; not positional / episodic
2. 2ENTRY
   Confirm AVS: continuous vertigo + n/v + gait unsteadiness + nystagmus × ≥24 h; rule out BPPV (positional brief <1 min) via Dix-Hallpike (Hotson/Baloh NEJM 1998 PMID 9725927; GRACE-3 PMID 37166022)
   inputs: vertigo_tempo_continuous_vs_positional, duration_hours_or_days
   advance: AVS confirmed
3. 3CONTEXT
   Capture age, vascular risk factors, recent neck trauma, alcohol/thiamine status, ototoxic / anticonvulsant medications; reproductive-age / pregnant women — Wernicke if hyperemesis (GRACE-3 PMID 37166022)
   inputs: age, sbp, vascular_risk_factors, recent_neck_trauma_or_chiropractic, medications_ototoxic_or_anticonvulsant
   advance: Pre-test probability mapped
4. 4RED_FLAGS
   Severe headache or neck pain (vertebral artery dissection), sudden SNHL (AICA stroke), drop attacks / visual loss / dysarthria / dysphagia (posterior TIA), anticoagulation, age>60 + vascular risk → low threshold for MRI / CTA (Newman-Toker Acad Emerg Med 2013 PMID 24127701)
   advance: Red flags scored
5. 5INITIAL_WORKUP
   HINTS exam (HIT + nystagmus pattern + test of skew) ± hearing finger-rub for HINTS-plus; Dix-Hallpike if any positional component; CBC, BMP, glucose, ECG (AF screen) (Kattah Stroke 2009 PMID 19762709; Newman-Toker Acad Emerg Med 2013 PMID 24127701; GRACE-3 PMID 37166022)
   inputs: horizontal_head_impulse_test, nystagmus_pattern, test_of_skew_alternate_cover, hearing_examination_finger_rub_or_audiogram, gait_unsteadiness_grade, dix_hallpike_maneuver
   actions: workup.vertigo, panel.cbc, panel.cardiac
   advance: HINTS pattern classified central vs peripheral
6. 6BRANCHING_WORKUP
   If any central HINTS feature OR HINTS-plus positive OR uninterpretable exam OR red flag → MRI brain with DWI within 48 h; CTA/MRA vertebrobasilar if neck pain or dissection suspicion; do NOT use non-contrast CT alone — sensitivity ~20% for acute posterior stroke (Kattah Stroke 2009 PMID 19762709; GRACE-3 PMID 37166022 — explicit recommendation against CT)
   actions: protocol.stroke
   advance: Central pattern → neuro-imaging escalated; peripheral pattern → vestibular-neuritis pathway
7. 7DIFFERENTIAL
   AVS vs BPPV (positional, brief) vs vestibular migraine (recurrent episodic, headache history, photophobia) vs Meniere (episodic + low-tone SNHL + tinnitus) vs Wernicke (thiamine empirically) vs MS / cerebellitis vs functional (PPPD) — episodic vs continuous-with-nystagmus is the key tempo split (Tarnutzer CMAJ 2011 PMID 21576300; Hotson/Baloh NEJM 1998 PMID 9725927)
   inputs: alcohol_thiamine_status
   advance: Phenotype assigned
8. 8RISK_STRATIFICATION
   Central HINTS pattern or HINTS-plus = stroke pathway; severity by NIHSS + posterior-circulation deficits; peripheral pattern + benign trajectory + age <50 + no vascular risk = vestibular neuritis low-risk (Kattah Stroke 2009 PMID 19762709)
   advance: Central vs peripheral risk tier assigned
9. 9TREATMENT
   Step 1 — Central pattern → activate stroke pathway per neuro.ischaemic-stroke.v1 (tPA window / thrombectomy DAWN/DEFUSE-3); Step 2 — Peripheral pattern (vestibular neuritis) → short-course methylprednisolone (Strupp NEJM 2004 PMID 15269315 — taper from 100 mg PO daily × 22 d; valacyclovir adds no benefit), early vestibular rehab within 3 d, brief vestibular suppressant (meclizine 25-50 mg PO TID ≤3 d only — chronic use delays compensation), antiemetic (ondansetron 4 mg PO/IV q8h PRN or prochlorperazine 5-10 mg PO/IV); Step 3 — BPPV → Epley canalith-repositioning (GRACE-3 PMID 37166022); Step 4 — Meniere → salt restriction + diuretic ± intratympanic steroid (separate engine); Step 5 — Wernicke suspected → thiamine 500 mg IV TID before glucose
   inputs: sbp, creatinine
   advance: Treatment ladder initiated
10. 10DISPOSITION
    Central pattern → admit / stroke-unit / ICU per stroke pathway; peripheral pattern + benign trajectory + reliable follow-up → discharge home with vestibular-rehab + ENT/neurology follow-up; uninterpretable HINTS or HINTS-plus equivocal → admit for MRI-DWI (Newman-Toker Acad Emerg Med 2013 PMID 24127701; GRACE-3 PMID 37166022)
    advance: Disposition decision documented
11. 11MONITORING
    Inpatient (if central): daily neuro-checks + NIHSS; outpatient (if peripheral): symptom-trajectory check at 48-72 h; ENT / audiology if hearing involvement; vestibular-rehab adherence (Strupp NEJM 2004 PMID 15269315; GRACE-3 PMID 37166022)
    advance: Monitoring plan documented
12. 12FOLLOWUP
    Vestibular-rehab 4-6 wk; ENT for persistent vertigo / hearing loss / Meniere features; neurology for recurrent vertigo with red flags / migraine features / suspected demyelination; fall-risk assessment + home-safety in elderly; driving counselling per jurisdiction (GRACE-3 PMID 37166022; Hotson/Baloh NEJM 1998 PMID 9725927)
    advance: Long-term follow-up scheduled