Nervous System & Special Senses

Acute dystonia and tardive dyskinesia from antipsychotics

Clinical Overview and When to Suspect Antipsychotic-Induced Movement Disorders

— Acute dystonia: sustained, often painful muscle contractions producing twisting postures, occurring within hours to 5 days of starting or dose-escalating a high-potency antipsychotic.

— Tardive dyskinesia: involuntary, repetitive, choreoathetoid or stereotyped movements (orobuccolingual, truncal, limb) emerging after ≥3 months of cumulative exposure (≥1 month if age >60).

— Acute dystonia → abrupt nigrostriatal dopamine blockade with cholinergic imbalance.

— TD → chronic D2 blockade producing receptor upregulation/supersensitivity and likely GABAergic striatal dysfunction.

— Metoclopramide (black-box warning for TD), prochlorperazine, promethazine in ED and oncology settings.

— Atypicals (risperidone > others) still cause both syndromes, just less often than typicals.

Board pearl: Always ask about antiemetics and GI motility agents in any patient with new abnormal movements — Step 3 loves the elderly woman on chronic metoclopramide for diabetic gastroparesis who develops TD. Clozapine and quetiapine carry the lowest risk of both syndromes and are preferred when antipsychotic continuation is necessary in TD.

Acute dystonia and tardive dyskinesia (TD) are two distinct extrapyramidal syndromes (EPS) on opposite ends of the temporal spectrum after dopamine D2 receptor blockade.

Mechanism is shared at the root (D2 antagonism in nigrostriatal pathway) but pathophysiology diverges:

Suspect acute dystonia in any young male within days of haloperidol, fluphenazine, prochlorperazine (antiemetic!), or metoclopramide exposure presenting with neck twisting, jaw locking, tongue protrusion, eye deviation, or stridor.

Suspect TD in a chronic schizophrenia or bipolar patient on long-term antipsychotics with new lip smacking, tongue rolling, grimacing, or piano-playing finger movements — often noticed by family before the patient.

High-yield triggers beyond psychiatry:

Presentation Patterns and Key History

— Torticollis/retrocollis — neck twisted laterally or hyperextended.

— Oculogyric crisis — forced sustained upward/lateral eye deviation, often with anxiety and autonomic arousal; classic boards image.

— Buccolingual crisis — tongue protrusion, trismus, dysarthria.

— Laryngospasm/pharyngeal dystonia — stridor, dyspnea, dysphagia → airway emergency.

— Opisthotonos — generalized truncal extension, mimics tetanus or seizure.

— Orobuccolingual: lip smacking, puckering, chewing, tongue writhing ("fly-catcher" tongue).

— Limb: choreoathetoid finger/toe movements, piano-playing fingers.

— Truncal: pelvic thrusting, rocking, respiratory dyskinesia (irregular grunting breaths).

— Movements disappear during sleep, worsen with stress, and patients are often unaware.

— Drug timeline: every antipsychotic and antiemetic in the last 6 months with start dates and dose changes.

— Risk factors for acute dystonia: young (<30), male, African ancestry, high-potency typicals (haloperidol, fluphenazine), recent dose increase, cocaine use, prior dystonic reaction.

— Risk factors for TD: age >55, female, postmenopausal, diabetes, mood disorder, prior acute EPS, longer cumulative exposure, intermittent dosing, smoking, alcohol use disorder.

Key distinction: Acute dystonia is sustained and painful; TD is rhythmic, repetitive, and painless. If the movement hurts and started this week, think dystonia. If it's been smoldering for months and the patient doesn't notice, think TD. Tardive dystonia (a TD subtype) blurs this — fixed dystonic posturing after months of exposure, often refractory and disabling.

Acute dystonia phenotypes (memorize the anatomy):

TD phenotypes:

Key history elements:

Ask about dental work, ill-fitting dentures, and stroke to avoid mislabeling focal dyskinesias as TD.

Physical Exam Findings and Severity Assessment

— Sustained involuntary muscle contraction in a specific body region; movements are not suppressible and worsen with attempted relaxation.

— Check airway: voice quality, stridor, oxygen saturation, ability to handle secretions — laryngeal dystonia is a true airway emergency.

— Vitals: tachycardia and hypertension from pain/anxiety are common; fever should prompt NMS workup.

— Neuro: mental status intact, no rigidity outside the affected muscle group, reflexes normal — distinguishes from NMS and serotonin syndrome.

— Structured 12-item exam scoring facial/oral, extremity, trunk movements 0–4, plus global severity, incapacitation, and patient awareness.

— Perform with patient seated, then standing, then with activation maneuvers (finger tapping, walking) which unmask movements.

— Have patient open mouth, protrude tongue, tap thumb to each finger — orobuccolingual TD often emerges only during these tasks.

— AIMS ≥2 in two body areas or ≥3 in one area supports clinically significant TD.

— Parkinsonism (also drug-induced): bradykinesia, cogwheel rigidity, resting tremor, masked facies — opposite phenotype to TD.

— Akathisia: subjective inner restlessness with pacing/leg crossing; patient complains, unlike TD where patient is unaware.

— Tardive dystonia: fixed abnormal posture (e.g., retrocollis) rather than choreoathetoid flow.

Step 3 management: Document a baseline AIMS before starting any antipsychotic and repeat every 6 months for first-generation and every 12 months for second-generation agents (every 6 months in high-risk patients: elderly, diabetic, mood disorder). This is a board-favorite quality metric and a frequent gap in real-world care that Step 3 patient-safety questions probe.

Acute dystonia exam:

TD exam — use the AIMS (Abnormal Involuntary Movement Scale):

Differentiating exam pearls:

Diagnostic Workup — Initial Evaluation

— Bedside airway and vital sign assessment first; pulse oximetry continuous if any pharyngeal involvement.

— Fingerstick glucose and basic metabolic panel — hypocalcemia and hypomagnesemia can cause tetany/spasm mimicking dystonia.

— CK if generalized or prolonged contractions → rule out rhabdomyolysis and NMS.

— Temperature — fever + rigidity + altered mental status = stop and evaluate for NMS before treating as simple dystonia.

— Tox screen if stimulant use suspected (cocaine, MDMA can produce dystonic reactions).

— Pregnancy test in reproductive-age women (alters benztropine/diphenhydramine choice considerations).

— Comprehensive medication reconciliation including OTC and antiemetics; calculate cumulative antipsychotic exposure.

— TSH (hyperthyroidism causes chorea), CMP, CBC.

— Ceruloplasmin and 24-hour urine copper if age <40 with new movement disorder → Wilson disease.

— HIV, RPR in appropriate contexts (HIV chorea, neurosyphilis).

— ANA, anti-dsDNA if systemic features suggest lupus chorea.

— Huntington gene testing if family history of chorea or psychiatric illness with dementia.

Board pearl: A young patient on no neuroleptics with new "TD-like" movements demands Wilson disease and Huntington workup before attributing to a brief past metoclopramide exposure. Step 3 punishes anchoring.

Both syndromes are clinical diagnoses — no confirmatory lab or imaging exists. Workup is aimed at excluding mimics and assessing comorbidities that change management.

Acute dystonia — initial workup:

TD — initial workup:

ECG — baseline before any antipsychotic switch; QTc matters because many agents (haloperidol, ziprasidone, IV ondansetron alternatives) prolong it.

Diagnostic Workup — Advanced and Confirmatory Studies

— Movement disorder is asymmetric or focal (TD is typically symmetric; unilateral chorea suggests stroke, tumor, or basal ganglia lesion).

— Atypical features: cognitive decline, ataxia, pyramidal signs, seizures.

— Acute onset without clear drug trigger.

— Look for basal ganglia signal abnormalities (Wilson's, NBIA, anti-NMDA, CO poisoning, hypoxic injury).

— HTT CAG repeat for Huntington when chorea + psychiatric + family history.

— Consider C9orf72, DRPLA, neuroacanthocytosis panels in select cases.

— Movement disorders neurology for diagnostic uncertainty, tardive dystonia, or treatment-refractory TD.

— Psychiatry for antipsychotic optimization and shared decision-making about switching agents.

— AIMS — gold standard for TD severity and treatment response; quantitative score allows tracking VMAT2 inhibitor response.

— DISCUS (Dyskinesia Identification System: Condensed User Scale) — alternative in institutional settings.

— Burke-Fahn-Marsden Dystonia Rating Scale for tardive dystonia.

— Withdrawal-emergent dyskinesia appears within days–weeks of stopping/reducing antipsychotic and typically resolves in 1–3 months — distinguishes from persistent TD which lingers or worsens.

Key distinction: Persistent TD continues >1 month after drug discontinuation; withdrawal dyskinesia resolves within 3 months. The temporal course after dose reduction is itself a diagnostic test — and a Step 3 trap when the stem describes worsening movements after a dose decrease.

Neuroimaging — MRI brain is indicated when:

EEG — only if events are paroxysmal and seizure cannot be excluded (oculogyric crisis is sometimes mistaken for focal seizure).

Genetic testing:

Specialty referrals:

Validated scales for longitudinal tracking:

Drug withdrawal trial is both diagnostic and therapeutic when feasible:

Risk Stratification and Management Logic

— Airway-threatening (laryngeal, pharyngeal, severe oculogyric with autonomic distress) → IV anticholinergic immediately, prepare for airway management, monitored bed.

— Non-airway (isolated torticollis, limb dystonia) → IM anticholinergic or antihistamine, observe 30–60 min, oral taper.

— In high-risk patients (young male starting high-potency typical), some clinicians co-prescribe prophylactic benztropine 1–2 mg BID for the first 1–2 weeks, then taper.

— Better strategy: choose a lower-risk agent (atypical antipsychotic) when clinically appropriate.

1. Confirm diagnosis and rule out mimics (chunks 4–5).

2. Reassess need for antipsychotic. If used off-label (e.g., insomnia, mild anxiety), discontinue.

3. If antipsychotic is necessary, switch from typical to atypical, preferably clozapine or quetiapine (lowest TD propensity); avoid increasing the current dose to suppress movements — this masks but worsens long-term TD.

4. Start a VMAT2 inhibitor (valbenazine or deutetrabenazine) — first-line FDA-approved therapy.

5. Discontinue anticholinergics (benztropine, trihexyphenidyl) — they worsen TD even though they help drug-induced parkinsonism and acute dystonia.

6. Address modifiable risk factors: glycemic control, smoking cessation, alcohol reduction.

Step 3 management: The single most common board error is increasing the antipsychotic to suppress TD or adding benztropine. Both are wrong. Correct moves are switch to clozapine/quetiapine, start VMAT2 inhibitor, stop anticholinergics.

Acute dystonia — emergency triage logic:

Prevention strategy for acute dystonia:

TD management logic — stepwise:

Shared decision-making: discuss that TD may be partially reversible, especially with early VMAT2 therapy, but complete resolution is not guaranteed.

Pharmacotherapy — First-Line Drug Regimens

— Benztropine 1–2 mg IM or IV — onset 15–30 min, repeat in 30 min if no response, max 6 mg/day. Preferred in adults.

— Diphenhydramine 25–50 mg IM or IV — preferred in children and pregnancy; also useful when anticholinergic burden is a concern (less central effect than benztropine at equivalent doses, but still sedating).

— Trihexyphenidyl 2–5 mg PO — for outpatient/mild cases or oral taper after acute resolution.

— Follow with oral benztropine 1–2 mg BID for 3–7 days to prevent recurrence; longer if antipsychotic is continued.

— Refractory dystonia: lorazepam 1–2 mg IV as adjunct (benzodiazepines relax via GABAergic mechanism).

— Valbenazine 40 mg PO daily x 1 week, then 80 mg daily; once-daily dosing, no titration of meaningful complexity.

— Deutetrabenazine start 6 mg BID, titrate weekly by 6 mg/day to max 48 mg/day (24 mg BID); take with food.

— Both deplete presynaptic dopamine by inhibiting VMAT2, reducing dopamine packaging into vesicles.

— Adverse effects: somnolence, QT prolongation (check baseline ECG, avoid in congenital long QT), parkinsonism, depression/suicidality (boxed for tetrabenazine, less so for the newer agents but monitor).

— Contraindications: hepatic impairment (deutetrabenazine), concurrent MAOIs, untreated depression with suicidality.

Board pearl: Anticholinergics treat acute dystonia and drug-induced parkinsonism but worsen TD. Memorize this opposing effect — it's the single highest-yield pharm fact for this topic.

Acute dystonia — first-line agents:

TD — VMAT2 inhibitors (FDA-approved, first-line):

Tetrabenazine — older, requires CYP2D6 genotype-guided dosing at higher doses, more depression risk; rarely first-line now.

Adjunctive/second-line for TD: clonazepam (limited evidence), ginkgo biloba (some RCT support), amantadine (modest).

Expanded Pharmacology and Switching Strategies

— Valbenazine: simpler dosing, once daily, no food requirement, no CYP2D6 genotyping — usually preferred for adherence.

— Deutetrabenazine: deuterated tetrabenazine with longer half-life and smoother profile than tetrabenazine; BID dosing, requires food.

— Both reduce AIMS scores ~30% at 12 weeks; effect persists with continued therapy.

— Monitoring: ECG at baseline and after dose changes if QTc concerns; clinical depression/suicidality screening; AIMS every 3 months initially.

— Clozapine has the strongest evidence for both reducing TD and being usable without worsening it; requires ANC monitoring (weekly x 6 months, biweekly x 6 months, monthly thereafter via REMS).

— Quetiapine is a reasonable second choice with low D2 occupancy.

— Cross-titrate slowly (weeks) to avoid psychiatric decompensation and withdrawal dyskinesia flare.

— Metoclopramide, prochlorperazine, promethazine.

— Anticholinergics (benztropine, trihexyphenidyl, diphenhydramine chronic use, oxybutynin, tricyclics).

— Levodopa and stimulants can unmask dyskinesias.

— Ondansetron (watch QTc), scopolamine patch for motion, dimenhydrinate short-term.

— Avoid metoclopramide entirely; if needed for gastroparesis, limit to <12 weeks per FDA black box.

Step 3 management: When a patient on long-term metoclopramide for gastroparesis develops TD, the first step is to stop metoclopramide, then assess persistence at 3 months before committing to chronic VMAT2 therapy — many cases improve substantially after withdrawal alone.

Choosing among VMAT2 inhibitors:

Antipsychotic switching for TD:

Drugs that exacerbate or unmask TD — avoid or minimize:

Antiemetic alternatives in a patient with prior TD or high risk:

Comorbid mood disorder: lithium, lamotrigine, and valproate do not cause TD and can replace antipsychotic mood stabilization where appropriate.

Special Populations — Elderly and Renal/Hepatic Impairment

— Highest risk group for TD — incidence ~5×/year on typicals vs ~1%/year in younger adults.

— Use the lowest effective antipsychotic dose for the shortest duration; revisit indication every 3–6 months.

— Beers Criteria: avoid antipsychotics for behavioral symptoms of dementia unless non-pharmacologic measures fail and patient is a danger — FDA black-box mortality warning in dementia patients.

— Anticholinergics for acute dystonia: avoid benztropine in elderly due to delirium, urinary retention, constipation, falls; use lower-dose diphenhydramine cautiously or lorazepam instead, recognizing fall risk.

— VMAT2 inhibitors: well tolerated in elderly, but watch for orthostasis, somnolence, parkinsonism worsening.

— Deutetrabenazine and tetrabenazine are contraindicated in hepatic impairment.

— Valbenazine: reduce to 40 mg/day in moderate–severe hepatic impairment.

— Most antipsychotics are hepatically metabolized — dose-reduce or avoid in advanced cirrhosis.

— Valbenazine: no adjustment for mild–moderate, avoid in severe renal impairment (CrCl <30).

— Deutetrabenazine: limited renal data, use cautiously.

— Paliperidone (renally cleared) requires dose reduction; risperidone preferred at low doses in CKD.

— Baseline ECG before haloperidol, ziprasidone, IV antipsychotics, and VMAT2 inhibitors.

— Avoid combining with macrolides, fluoroquinolones, ondansetron, methadone when QTc >450 ms.

Board pearl: In a nursing home resident with dementia and agitation, the question "what's the best agent?" almost always has the answer "non-pharmacologic behavioral intervention first" — antipsychotics carry mortality and TD risks that Step 3 expects you to weigh against modest behavioral benefit.

Elderly patients:

Hepatic impairment:

Renal impairment:

QTc considerations in elderly polypharmacy:

Special Populations — Pregnancy, Pediatrics, and Sex-Specific Issues

— Acute dystonia from prochlorperazine or promethazine (common antiemetics in hyperemesis) does occur — treat with diphenhydramine 25–50 mg IV/IM (preferred over benztropine; pregnancy category B-equivalent and long safety record).

— Avoid benztropine in pregnancy when possible (limited data, anticholinergic effects on fetal heart rate and meconium ileus risk near term).

— VMAT2 inhibitors: limited pregnancy data; weigh risks of untreated TD vs unknown fetal effects. Generally hold during pregnancy if TD is mild–moderate.

— Antipsychotic continuation in pregnancy: untreated psychosis carries higher fetal risk than most second-generation antipsychotics; do not abruptly stop. Olanzapine, quetiapine, risperidone have the most reassuring data.

— Neonatal EPS and withdrawal can occur with third-trimester antipsychotic exposure — coordinate delivery with NICU awareness.

— Acute dystonia is disproportionately common in children and adolescents receiving antiemetics (metoclopramide, prochlorperazine) — high index of suspicion in ED.

— Treat with diphenhydramine 1 mg/kg IV/IM (max 50 mg).

— Antipsychotic use in pediatric bipolar, autism irritability, Tourette's — monitor AIMS every 3–6 months; pediatric TD is rare but reported.

— Women, especially postmenopausal, have higher TD risk; estrogen withdrawal may unmask supersensitivity.

— Men have higher acute dystonia risk, especially young men of African ancestry.

Key distinction: In pregnancy with acute dystonia from antiemetics, use diphenhydramine, not benztropine. In pediatric acute dystonia from metoclopramide, also use diphenhydramine, and document the reaction prominently to prevent re-exposure — a frequent Step 3 patient-safety angle.

Pregnancy:

Lactation: most antipsychotics enter breast milk at low levels; clozapine and lithium are exceptions (avoid). Valbenazine/deutetrabenazine — limited data, generally avoid.

Pediatrics:

Sex-specific:

Complications and Adverse Outcomes

— Laryngospasm and asphyxia — rare but lethal; airway dystonia can cause respiratory arrest within minutes.

— Rhabdomyolysis from sustained generalized contraction → AKI; check CK if symptoms persist >30 min or are generalized.

— Fractures and joint dislocation — particularly mandibular dislocation from trismus, vertebral injury from opisthotonos.

— Aspiration pneumonia from pharyngeal dystonia and dysphagia.

— Psychological trauma and nonadherence — patients who experience oculogyric or laryngeal crises often refuse all future antipsychotics; document the reaction and counsel about alternative agents to preserve future treatment options.

— Irreversibility — ~50% persist indefinitely after antipsychotic discontinuation; tardive dystonia is more often permanent than orobuccolingual TD.

— Functional impairment: dysphagia and weight loss from oromandibular dyskinesia, dental damage, speech impairment, social isolation, employment loss.

— Respiratory dyskinesia — irregular breathing, dyspnea, recurrent aspiration; often misdiagnosed as anxiety or COPD.

— Falls from truncal/limb instability, especially in elderly.

— Suicide risk — TD-related disability and stigma contribute to depression and suicidality; screen regularly.

— Drug-induced parkinsonism, depression, somnolence, akathisia, QT prolongation.

— Don't trade TD for disabling parkinsonism — reduce dose if rigidity/bradykinesia emerges.

— A patient on antipsychotic can have acute dystonia + drug-induced parkinsonism + akathisia + TD simultaneously — each requires different management.

Board pearl: Respiratory dyskinesia in a patient with chronic schizophrenia presenting with "anxiety" and irregular breathing is a classic missed diagnosis — pulse oximetry is normal, lung exam is clear, and the diaphragm is dyskinetic. Look at the abdomen and chest wall for irregular involuntary breathing.

Acute dystonia complications:

TD complications:

VMAT2 inhibitor adverse effects:

Overlap syndromes to recognize:

When to Escalate Care

— Airway involvement (stridor, laryngospasm, severe pharyngeal dystonia, hypoxia) → call airway team, prepare for intubation, give IV anticholinergic immediately, monitored bed or ICU.

— Failure to respond to two doses of IM/IV anticholinergic within 30 min → escalate to IV lorazepam, consider neurology consult, and reconsider diagnosis (NMS, serotonin syndrome, status dystonicus, seizure).

— Fever, rigidity beyond focal dystonia, altered mental status, autonomic instability → stop antipsychotic, evaluate for NMS, ICU-level care, dantrolene/bromocriptine.

— Severe or rapidly progressive TD despite drug switch → movement disorders neurology referral.

— Tardive dystonia with disabling fixed posturing → consider botulinum toxin injection for focal dystonia or deep brain stimulation (GPi) for refractory generalized cases.

— Respiratory or swallowing dyskinesia with weight loss or aspiration → SLP evaluation, nutritional support, urgent treatment escalation.

— Suicidality related to TD distress → psychiatric admission consideration.

1. Move clock 5 min: ABC assessment, continuous pulse ox, oxygen.

2. Order: benztropine 2 mg IV STAT, IV access, ECG, CBC, BMP, CK, temperature.

3. Reassess at 15 min; if persistent, repeat benztropine or give diphenhydramine 50 mg IV; consult anesthesia for airway.

4. Stop offending antipsychotic; document allergy/adverse reaction.

5. Disposition: monitored bed x 24 hours, then transition to oral benztropine taper.

CCS pearl: On the CCS, document the offending agent in the medication allergy/adverse reaction list before discharge — failure to do so is a common scoring gap and a real-world safety lapse.

Acute dystonia — emergency escalation:

Status dystonicus — generalized severe sustained dystonia with rhabdomyolysis, hyperthermia, respiratory compromise; ICU admission, sedation, neuromuscular blockade if needed, neurology and movement disorders consult, MRI brain.

TD — when to escalate:

CCS sequence for acute laryngeal dystonia:

Key Differentials — Other Drug-Induced Movement Disorders

— Bradykinesia, cogwheel rigidity, resting tremor, masked facies — looks like idiopathic Parkinson's but symmetric and temporally related to antipsychotic.

— Onset days to weeks after initiation; reversible over weeks–months after withdrawal.

— Treatment: reduce dose, switch to lower-D2 agent, add benztropine or amantadine (the opposite of TD management).

— Subjective inner restlessness, inability to sit still, pacing, leg crossing/uncrossing.

— Patient complains of restlessness; in TD, patient is unaware of movements.

— Onset hours–days; can be acute or tardive.

— Treatment: reduce antipsychotic dose, propranolol 10–30 mg TID (first-line), benzodiazepines, mirtazapine; anticholinergics are NOT effective.

— Tetrad: hyperthermia, lead-pipe rigidity, autonomic instability, altered mental status.

— Elevated CK (often >1000), leukocytosis, hyperkalemia.

— Onset over days; medical emergency — stop antipsychotic, supportive care, dantrolene, bromocriptine, ICU.

— Differs from acute dystonia by global rigidity, fever, and AMS.

Key distinction: Akathisia → propranolol/benzo; dystonia → anticholinergic; parkinsonism → anticholinergic or amantadine; TD → VMAT2 + stop anticholinergic. Memorize this four-way table — it's the highest-yield content on antipsychotic adverse effects for Step 3.

Drug-induced parkinsonism (DIP):

Akathisia:

Neuroleptic malignant syndrome (NMS):

Tardive akathisia, tardive tourettism, tardive myoclonus — less common late-emergent syndromes after chronic D2 blockade.

Withdrawal-emergent dyskinesia — chorea after antipsychotic discontinuation or dose reduction; resolves within 1–3 months and distinguishes from persistent TD.

Serotonin syndrome — clonus (lower > upper), hyperreflexia, agitation, autonomic instability; SSRI/MAOI/tramadol/linezolid context. Differs by hyperreflexia and clonus (NMS has rigidity without clonus).

Key Differentials — Non-Pharmacologic Movement Disorders

— Autosomal dominant CAG repeat in HTT (>39 repeats).

— Triad: chorea, psychiatric (depression, irritability, psychosis), cognitive decline.

— Family history of suicide and dementia in middle age.

— Distinguished from TD by family history, cognitive decline, caudate atrophy on MRI, and absence of antipsychotic exposure.

— Treated with VMAT2 inhibitors (same drugs as TD) plus psychiatric care.

— AR ATP7B mutation, copper accumulation.

— Onset typically <40; tremor, dystonia, dysarthria, parkinsonism, Kayser-Fleischer rings, hepatic dysfunction, psychiatric symptoms.

— Low ceruloplasmin, high 24-hr urine copper, elevated LFTs.

— Treated with penicillamine, trientine, zinc.

Board pearl: A young patient with chorea, hepatitis, and psychiatric symptoms — think Wilson before TD, even if there's a brief antipsychotic history. Step 3 likes to embed Wilson in a "TD" stem because both can present with movement plus psychiatric features.

Huntington disease:

Wilson disease:

Sydenham chorea: post-streptococcal autoimmune chorea in children; resolves with time and antistreptococcal therapy.

Chorea gravidarum: pregnancy-related chorea, often in patients with prior Sydenham or SLE; resolves postpartum.

SLE chorea / antiphospholipid syndrome chorea: ANA, anti-dsDNA, antiphospholipid antibodies; treat underlying disease.

Hyperthyroidism: chorea, fine tremor, tachycardia, weight loss; check TSH.

Stroke or basal ganglia lesion: hemiballismus from subthalamic nucleus infarct; unilateral, abrupt onset, MRI confirms.

Tourette syndrome: stereotyped motor and vocal tics; onset <18, waxes/wanes, premonitory urge, partially suppressible — TD lacks suppressibility and premonitory urge.

Essential tremor, dystonic tremor, functional movement disorder — distinct phenomenology.

Long-Term Plan, Secondary Prevention, and Discharge Medications

— Discontinue or substitute the offending agent; if antipsychotic must continue, switch to a lower-potency or atypical option (quetiapine, olanzapine, aripiprazole) and titrate slowly.

— Oral benztropine 1–2 mg BID for 1–2 weeks to prevent recurrence, then taper.

— Document the reaction in the medication allergy list with the specific drug, dose, and reaction type.

— Patient education: warning signs of recurrence, when to seek emergency care, list of drugs to avoid (prochlorperazine, metoclopramide, haloperidol).

— Long-term VMAT2 inhibitor therapy if movements are clinically significant or distressing.

— Reassess antipsychotic indication every 6 months; minimum effective dose, consider gradual taper if psychiatrically stable.

— Discontinue all anticholinergics unless required for concurrent acute dystonia/parkinsonism.

— Address modifiable risk factors: glycemic control (diabetes worsens TD), smoking cessation, alcohol moderation.

— Consider clozapine if psychiatric illness requires ongoing antipsychotic — strongest evidence for safe long-term use in TD.

— Annual influenza, COVID boosters, pneumococcal per age/risk, shingles ≥50.

— Metabolic monitoring on antipsychotics: weight, BMI, waist circumference, fasting glucose/HbA1c, lipid panel, BP at baseline, 12 weeks, then annually.

— Primary care for cardiometabolic monitoring (antipsychotics drive obesity, diabetes, dyslipidemia).

— Psychiatry for medication management and AIMS monitoring.

— Neurology for refractory or atypical movement disorders.

Step 3 management: At every visit for a patient on chronic antipsychotic, document AIMS, current indication, lowest effective dose review, and metabolic parameters. These four items are the longitudinal quality bundle Step 3 expects.

After acute dystonia:

After TD diagnosis:

Vaccinations and preventive care in chronic mental illness:

Care coordination:

Follow-Up, Monitoring, and Counseling

— Outpatient visit within 1–2 weeks to confirm resolution, review oral anticholinergic taper, and finalize antipsychotic plan.

— Reinforce the drug avoidance list and provide a written wallet card.

— AIMS every 3 months during VMAT2 titration and first year of therapy.

— AIMS every 6 months for stable patients on first-generation antipsychotics or in high-risk groups.

— AIMS every 12 months for stable patients on second-generation antipsychotics.

— Document AIMS score, body areas affected, global severity, patient awareness, and functional impact.

— Baseline and periodic ECG (QTc) if QT-prolonging comorbidities or comedications.

— Depression and suicidality screening (PHQ-9) at each visit.

— Liver function tests for deutetrabenazine; avoid in hepatic impairment.

— Watch for parkinsonism, sedation, akathisia as VMAT2 adverse effects — dose-reduce if disabling.

— Baseline, 12 weeks, then annually: weight, BMI, fasting glucose or HbA1c, lipid panel, BP.

— Waist circumference and personal/family history of diabetes, dyslipidemia, CVD at baseline.

— TD movements disappear during sleep and worsen with stress — normalize this for patients and families.

— Avoid metoclopramide and prochlorperazine lifelong; use ondansetron for nausea.

— Alcohol and smoking worsen TD risk.

— Adherence to VMAT2 inhibitor is critical — abrupt discontinuation causes rebound movements.

— Driving safety: somnolence from VMAT2 and antipsychotics; counsel about impairment.

Board pearl: Counseling that TD movements stop during sleep reassures patients who fear a progressive neurodegenerative disease — and is a Step 3 vignette giveaway to distinguish TD from Huntington (Huntington chorea also decreases in sleep but other features differ) or essential tremor (action-related, absent at rest).

Acute dystonia follow-up:

TD monitoring cadence:

VMAT2 monitoring:

Antipsychotic metabolic monitoring (ADA/APA consensus):

Counseling points:

Ethical, Legal, and Patient Safety Considerations

— Discuss TD risk explicitly before starting any antipsychotic — incidence ~5%/year on typicals, ~1–3%/year on atypicals; cumulative lifetime risk is substantial.

— Document the discussion of EPS, TD, metabolic syndrome, NMS, mortality in dementia, and alternative treatments.

— Patients with psychosis lacking decisional capacity: pursue substituted judgment via surrogate or court-appointed guardian; document capacity assessment.

— For involuntary medication in committed patients, follow state-specific procedures (often requires court hearing — Rivers v. Katz, Rogers v. Commissioner).

— Adverse drug reactions, especially TD attributable to metoclopramide (black-box warning), should be reported to FDA MedWatch.

— Document in the medication allergy/adverse reaction field, not just progress notes, to prevent reordering by other clinicians.

— At hospital discharge, reconcile every antipsychotic and antiemetic; communicate TD diagnosis explicitly to the receiving primary care and psychiatry providers.

— Avoid initiating prochlorperazine or metoclopramide for nausea in a patient with documented TD or prior acute dystonia — medication reconciliation is a top patient-safety gap.

— Antipsychotics used for insomnia, anxiety, dementia agitation carry TD risk without strong evidence — particularly ethically problematic; FDA black-box mortality warning in dementia.

— Reassess off-label indications at every visit; document risk–benefit reasoning.

— Patient may refuse antipsychotic forever after a dystonic reaction — respect autonomy while offering alternative agents and addressing fears.

Step 3 management: When a nursing home resident with dementia develops TD on chronic risperidone prescribed for "agitation," the correct ethical-legal step is to document the indication, attempt non-pharmacologic alternatives, discuss with surrogate, and taper the antipsychotic — not to add a VMAT2 inhibitor on top while continuing the offending agent.

Informed consent for antipsychotic initiation:

Mandatory documentation and reporting:

Transition-of-care safety:

Off-label prescribing:

Capacity in the setting of acute dystonia:

Tort and malpractice: failure to monitor with AIMS, failure to disclose TD risk, and continued antipsychotic use after onset of TD without consideration of alternatives are recurring litigation patterns.

High-Yield Associations and Rapid-Fire Facts

— Acute dystonia: haloperidol, fluphenazine, prochlorperazine, metoclopramide.

— TD: same list plus chronic exposure to any D2 antagonist; metoclopramide has FDA black-box warning limiting use to <12 weeks.

— Acute dystonia: young, male, African ancestry, high-potency typical, recent dose increase, prior dystonia, cocaine.

— TD: elderly, female, postmenopausal, diabetes, mood disorder, prior EPS, longer cumulative exposure, intermittent dosing, smoking.

— Acute dystonia → benztropine or diphenhydramine.

— Akathisia → propranolol or benzodiazepine.

— Drug-induced parkinsonism → benztropine, amantadine, or dose reduction.

— TD → VMAT2 inhibitor (valbenazine, deutetrabenazine); stop anticholinergics; switch to clozapine/quetiapine.

— NMS → stop drug, dantrolene, bromocriptine, supportive care, ICU.

— Acute dystonia: hours–5 days.

— Akathisia: hours–days.

— Drug-induced parkinsonism: days–weeks.

— NMS: 1–3 days, can occur anytime.

— TD: ≥3 months (≥1 month if >60).

— VMAT2 inhibitors deplete presynaptic dopamine, serotonin, norepinephrine packaging — hence the depression and parkinsonism side effects.

— Anticholinergics worsen TD because striatal cholinergic interneurons normally oppose dopaminergic supersensitivity.

Board pearl: The opposing effect of anticholinergics — helpful in acute dystonia and parkinsonism, harmful in TD — appears in roughly every other Step 3 question on antipsychotic adverse effects. Internalize it.

Highest-risk drugs:

Lowest-risk antipsychotics: clozapine (lowest) > quetiapine > aripiprazole (partial agonist, but can still cause TD and akathisia).

Risk factor mnemonics:

Treatment cheat sheet:

Onset timing:

Monitoring scale: AIMS for TD; Burke-Fahn-Marsden for dystonia; Barnes Akathisia Rating Scale for akathisia.

Pharmacology:

Board Question Stem Patterns

— 22-year-old male given prochlorperazine for migraine; 4 hours later returns with painful neck deviation and tongue protrusion.

— Answer: IM/IV diphenhydramine or benztropine; discontinue prochlorperazine; document.

— 68-year-old with diabetic gastroparesis on metoclopramide x 2 years develops lip smacking and tongue rolling noted by daughter.

— Answer: discontinue metoclopramide, reassess in 3 months; if persistent, start VMAT2 inhibitor.

— Question asks the next step in management; distractors include increasing haloperidol, adding benztropine.

— Answer: switch to clozapine or quetiapine; start valbenazine; stop benztropine.

— Answer: HTT gene testing — Huntington, not TD, even if there's brief antipsychotic exposure.

— Answer: NMS, not acute dystonia; stop haloperidol, supportive care, consider dantrolene/bromocriptine, ICU.

— Answer: IV diphenhydramine (preferred in pregnancy over benztropine).

— Quality measure question: continue current AIMS monitoring every 6–12 months, document indication, minimum effective dose.

— Patient complains of inner restlessness, pacing → akathisia → propranolol.

— Patient unaware of lip smacking observed by family → TD → VMAT2.

Key distinction: When the stem emphasizes patient unawareness, think TD. When the stem emphasizes patient distress and restlessness, think akathisia. When the stem emphasizes pain and twisting, think acute dystonia. This phenomenology triage solves most Step 3 antipsychotic adverse effect questions.

Pattern 1 — Young ED patient with neck twisting after antiemetic:

Pattern 2 — Elderly woman on chronic metoclopramide with new lip movements:

Pattern 3 — Schizophrenia patient on haloperidol with worsening orobuccolingual movements:

Pattern 4 — Patient with chorea, depression, and family history of similar illness:

Pattern 5 — Hospitalized patient on IV haloperidol develops fever, rigidity, AMS:

Pattern 6 — Pregnant patient with hyperemesis given promethazine, develops oculogyric crisis:

Pattern 7 — Stable schizophrenia patient on risperidone, AIMS unchanged x 2 years:

Pattern 8 — Restlessness vs TD:

One-Line Recap

Acute dystonia is an early, painful, focal contraction reversed with anticholinergics or antihistamines, while tardive dyskinesia is a late, painless, repetitive choreoathetoid movement disorder that is worsened by anticholinergics and treated with VMAT2 inhibitors plus a switch to clozapine or quetiapine.

Board pearl: If you remember nothing else: anticholinergics for acute dystonia, VMAT2 inhibitors for TD, propranolol for akathisia, stop the drug for NMS — this four-way matrix solves the majority of Step 3 antipsychotic movement-disorder vignettes.

Recognize the timeline: dystonia in hours–days, parkinsonism in weeks, NMS anytime, TD after ≥3 months (≥1 month if >60) of D2 blockade — temporal pattern alone often makes the diagnosis on Step 3.

Treat by mechanism: dystonia and parkinsonism reflect cholinergic excess relative to dopamine → anticholinergics help; TD reflects D2 supersensitivity → anticholinergics worsen it, and VMAT2 inhibitors (valbenazine, deutetrabenazine) deplete presynaptic dopamine to rebalance the system.

Always reconsider the antipsychotic itself: stop or substitute when possible, switch to clozapine or quetiapine when antipsychotic must continue, eliminate metoclopramide and prochlorperazine in patients with prior reactions or TD, and document the adverse reaction in the allergy field to prevent re-exposure across the care continuum.

Monitor longitudinally: baseline and serial AIMS every 6–12 months, metabolic parameters annually, capacity and consent documentation for every antipsychotic initiation, and reassessment of the indication at every visit — especially for off-label use in dementia, insomnia, or anxiety where the FDA black-box mortality and TD risks outweigh modest benefits.