A 28-year-old male from Jharkhand with P. falciparum malaria is started on artemether IV 120 mg stat, then 60 mg daily. On day 3 of treatment, he develops sudden-onset vertigo, nystagmus, and ataxia. Neurological exam confirms cerebellar signs. Parasitemia has cleared. What is the most likely diagnosis and what is the appropriate management?

Explanation

## Clinical Presentation Analysis **Key Point:** Neurological symptoms appearing **after parasitemia clearance** and **during artemether therapy** suggest **post-artesunate neurological syndrome (PANS)**, NOT cerebral malaria. **High-Yield:** Cerebral malaria presents with altered consciousness, seizures, or coma **while parasites are still present**. Neurological deterioration after parasite clearance is characteristic of PANS. ## Post-Artesunate Neurological Syndrome (PANS) ### Epidemiology & Timing - Occurs in ~0.5–1.5% of severe malaria patients treated with IV artesunate or artemether - Symptoms emerge **2–7 days after parasite clearance** (median day 3–4) - More common with artemether than artesunate; rare with oral artemisinin derivatives - Risk factors: high initial parasitemia, severe malaria, delayed treatment ### Clinical Features - **Cerebellar syndrome:** ataxia, nystagmus, dysarthria, vertigo - **Brainstem signs:** pupillary abnormalities, vertical gaze palsy - **Pyramidal signs:** hyperreflexia, extensor plantar response - **Consciousness:** usually preserved (unlike cerebral malaria) ### Pathophysiology Likely due to **immune-mediated inflammation** triggered by rapid parasite clearance and antigen release, possibly involving artemisinin-derived metabolites and microglial activation. ## Management of PANS ```mermaid flowchart TD A[Severe malaria on IV artemether/artesunate]:::outcome --> B[Parasitemia clears by day 2–3]:::outcome B --> C[Neurological symptoms emerge<br/>ataxia, nystagmus, vertigo]:::urgent C --> D{Diagnosis: PANS}:::decision D --> E[STOP IV artemether immediately]:::urgent E --> F[Switch to oral artemisinin derivative<br/>artemether, artemisinin, or artesunate]:::action F --> G[Supportive care:<br/>airway, fluids, seizure prophylaxis]:::action G --> H[Consider corticosteroids<br/>if severe/progressive]:::action H --> I[Most recover fully within days–weeks]:::outcome ``` ## Why NOT Continue or Escalate Artemether **Warning:** Continuing IV artemether or increasing the dose will worsen neurotoxicity. The problem is NOT inadequate parasite killing (parasites are already cleared) but artemether-induced inflammation. ## Comparison: Cerebral Malaria vs PANS | Feature | Cerebral Malaria | PANS | | --- | --- | --- | | **Timing** | During acute parasitemia | After parasite clearance (day 2–7) | | **Parasitemia** | High, ongoing | Cleared or minimal | | **Consciousness** | Altered (coma, confusion) | Usually preserved | | **Seizures** | Common | Uncommon | | **Cerebellar signs** | Rare | Common (ataxia, nystagmus) | | **Management** | Continue/escalate artemether | **Stop artemether, switch to oral** | | **Prognosis** | High mortality if untreated | Usually self-limited, good recovery | ## Recommended Switch **Clinical Pearl:** After stopping IV artemether, switch to: - **Oral artemether** 4 mg/kg/day, OR - **Oral artemisinin** 2 mg/kg/day, OR - **Oral artesunate** 2 mg/kg/day (if available) These oral formulations have lower neurotoxicity risk and are adequate for post-parasitemia maintenance therapy. ## Why Other Options Are Wrong - **Continue/increase artemether + add quinine:** Cerebral malaria is ruled out (parasites cleared, consciousness intact). Continuing artemether will worsen PANS. Quinine adds no benefit. - **Continue artemether + dexamethasone:** While corticosteroids may be considered in severe PANS, the first step is to **stop the offending drug**. Dexamethasone alone without discontinuing artemether is inadequate. - **Reduce dose + antihistamine:** PANS is not a simple allergic or dose-dependent side effect; it is immune-mediated. Dose reduction without switching agents is insufficient.