Neuroleptic Malignant Syndrome (NMS) Management

Algorithm Steps

1. ▶

   Start

   Suspected NMS

   Patient on dopamine antagonist with concerning symptoms

   1. ●

      Action

      Recognize Clinical Features

      Classic tetrad (may be incomplete)

      • Hyperthermia (>38°C, often >40°C)
      • Muscular rigidity ('lead-pipe')
      • Altered mental status (confusion → coma)
      • Autonomic instability (tachycardia, labile BP, diaphoresis)
      1. ●

         Action

         Identify Offending Agent

         Recent exposure to dopamine-blocking agent

         • Typical antipsychotics (haloperidol, fluphenazine)
         • Atypical antipsychotics (any)
         • Antiemetics (metoclopramide, prochlorperazine)
         • Dopamine withdrawal (stopping levodopa, amantadine)
         • Onset: hours to weeks after starting/increasing
         1. ⚠

            Warning

            ⚠️ STOP Offending Agent Immediately

            Discontinue ALL dopamine antagonists

            • Stop antipsychotic immediately
            • Stop antiemetics (metoclopramide, etc.)
            • If Parkinson's patient: restart dopamine agonist
            1. ●

               Action

               Order Diagnostic Workup

               Labs and imaging to confirm and monitor

               • CK (often >1000 U/L, may exceed 100,000)
               • CBC with differential (leukocytosis common)
               • BMP (renal function for rhabdomyolysis)
               • LFTs
               • Lactate
               • Myoglobin (urine)
               • Iron studies (low serum iron in NMS)
               1. ◆

                  Decision

                  Assess Severity

                  Determine level of care needed

                  1. ●

                     Action

                     Mild NMS

                     Low-grade fever, mild rigidity, stable vitals

                     • Stop offending agent
                     • Supportive care
                     • IV fluids
                     • Benzodiazepines PRN for rigidity
                     • Close monitoring - can progress
                     1. ◆

                        Decision

                        Response to Treatment?

                        Reassess in 24-48 hours

                        1. ✓

                           Outcome

                           Improving

                           Continue supportive care, wean medications

                           • Continue treatment 10-14 days after resolution
                           • Monitor for complications
                           • Consider psychiatry consult for alternative medications
                           1. ⚠

                              Warning

                              ⚠️ Monitor for Complications

                              Life-threatening complications

                              • Rhabdomyolysis → acute kidney injury
                              • Aspiration pneumonia
                              • Respiratory failure
                              • DIC
                              • Cardiac arrhythmias
                              • Mortality: 5-20%
                              1. ●

                                 Action

                                 Future Antipsychotic Use

                                 Rechallenge considerations

                                 • Wait at least 2 weeks after NMS resolution
                                 • Use different antipsychotic (lower potency)
                                 • Start at low dose, titrate slowly
                                 • Consider clozapine (lowest NMS risk)
                                 • Close monitoring during rechallenge
                        2. ⚠

                           Warning

                           Refractory NMS

                           Consider electroconvulsive therapy (ECT)

                           • ECT effective in refractory cases
                           • Response rate ~73% in case series
                           • Also treats underlying psychiatric condition
                           • Bilateral electrode placement preferred
                  2. ⚠

                     Warning

                     Moderate-Severe NMS

                     High fever, severe rigidity, autonomic instability

                     • ICU admission required
                     • Aggressive IV fluids (rhabdomyolysis)
                     • Active cooling measures
                     • Continuous cardiac monitoring
                     1. ●

                        Action

                        Aggressive Supportive Care

                        Core management for all moderate-severe cases

                        • IV fluids: Aggressive hydration (target UOP >200mL/hr)
                        • Cooling: Ice packs, cooling blankets, cold IV fluids
                        • VTE prophylaxis
                        • Respiratory support (may need intubation)
                        • Benzodiazepines: Lorazepam 1-2mg IV for rigidity/agitation
                        1. ●

                           Action

                           Specific Pharmacotherapy

                           Consider for moderate-severe cases

                           • DANTROLENE: 1-2.5mg/kg IV, repeat q5-10min (max 10mg/kg/day)
                           • - For severe rigidity and hyperthermia
                           • - Reduces muscle contraction
                           • BROMOCRIPTINE: 2.5-5mg PO/NG TID (max 45mg/day)
                           • - Dopamine agonist
                           • - Avoid if unable to protect airway
                           • AMANTADINE: 100mg PO/NG BID-TID alternative