What are the differential diagnoses for a patient presenting with abnormal body movement on one side?

Differential Diagnoses for Unilateral Abnormal Body Movements in a 32-Year-Old Female

The most critical immediate consideration is acute ischemic stroke, which requires emergent evaluation and potential thrombolytic therapy within hours of symptom onset to prevent permanent disability. 1

Immediate Life-Threatening Considerations

Acute Stroke

• Sudden onset of weakness, abnormal movements, or numbness affecting one side of the body is a cardinal sign of stroke and requires immediate activation of emergency medical services 1
• The Cincinnati Prehospital Stroke Scale identifies three key findings: facial droop (asymmetric facial movement), arm drift (one arm drifts downward when both extended), and abnormal speech 1
• If any single abnormality is present on examination, the probability of stroke is 72% 1
• Time-sensitive intervention with IV tPA within 3 hours (up to 4.5 hours in selected patients) can produce a 12% absolute increase in patients achieving minimal or no disability, with a number needed to treat of 8.3 1
• Symptomatic intracerebral hemorrhage occurs in 6% of tPA-treated patients versus 0.6% with placebo, but overall mortality remains similar (17% versus 21%) 1

Seizure Activity

• Focal seizures affecting one area of the brain can present as jerking of only one extremity or one side of the body, with or without altered consciousness 1
• Some focal seizures progress to generalized seizures 1
• Activate emergency services for first-time seizure, seizures lasting >5 minutes, or failure to return to baseline within 5-10 minutes after seizure activity stops 1

Movement Disorder Differentials

Post-Stroke Movement Disorders

• Dystonia is the most common delayed movement disorder after hemorrhagic stroke (45.5% of cases), while parkinsonism (17.4%) and chorea (17.4%) are most common after ischemic stroke 2
• Posterolateral thalamus is the most frequently affected region (22.5% of cases), with dystonia being the most commonly reported movement disorder overall (23.2%) 2
• Strokes in the caudate and putamen result in dystonia in one-third of cases; globus pallidus strokes lead to parkinsonism in nearly 40% 2
• Chorea appears earliest (within hours), while dystonia and tremor manifest months after stroke 2
• Hemorrhagic strokes are responsible for most delayed-onset movement disorders (>6 months), particularly in younger individuals with dystonia 2

Primary Movement Disorders

Hemidystonia:

• Sustained or intermittent muscle contractions causing twisting, repetitive movements, or abnormal postures affecting one side 3
• Can be primary (idiopathic) or secondary to structural brain lesions 3
• Craniofacial region frequently affected with multiple concurrent movement disorders (32% of cases) 4

Hemichorea:

• Irregular, unpredictable, brief, jerky movements affecting one side of the body 3, 5
• Can result from basal ganglia lesions, particularly involving the caudate and putamen 2
• May be associated with metabolic disturbances, autoimmune conditions, or structural lesions 5

Hemiparkinsonism:

• Unilateral bradykinesia, rigidity, and resting tremor 3, 5
• Parkinsonian tremor is typically present at rest (4-6 Hz) and reduced by voluntary movement 6
• In younger patients (age 32), consider secondary causes including Wilson disease, drug-induced parkinsonism, or structural lesions 5

Hemitremor:

• Rhythmic oscillatory movements affecting one side 3
• Essential tremor typically affects upper extremities asymmetrically and is present during movement and maintained posture 6
• Reduced by alcohol consumption in essential tremor 6

Autoimmune/Inflammatory Causes

Anti-IgLON5 Disease:

• 87% of patients have at least one movement disorder at diagnosis, with a median of 3 concurrent movement disorders per patient 4
• Most frequent abnormal movements: gait/balance disturbances (72%), chorea (33%), bradykinesia (28%), dystonia (26%) 4
• Associated features include sleep alterations (87%), bulbar dysfunction (74%), and cognitive impairment (53%) 4
• Consider when multiple movement disorders occur with sleep disturbances, swallowing difficulties, or cognitive changes 4
• Immunotherapy results in sustained improvement in only 13% of cases 4

Drug-Induced Movement Disorders

Tardive Dyskinesia:

• Repetitive but non-rhythmic involuntary movements at normal movement speed 6
• Post-neuroleptic dyskinesias are usually permanent and do not disappear when the causative medication is stopped 6
• Obtain detailed medication history including antipsychotics, antiemetics (metoclopramide), and other dopamine-blocking agents 5

Acute Dystonic Reaction:

• Can occur within hours to days of starting dopamine-blocking medications 5
• Typically affects craniofacial muscles but can be hemidystonic 5

Diagnostic Approach Algorithm

Step 1: Determine Acuity and Time Course

• If sudden onset (minutes to hours): Assume stroke until proven otherwise 1
  • Activate emergency services immediately 1
  • Perform Cincinnati Prehospital Stroke Scale: facial droop, arm drift, speech abnormalities 1
  • Obtain time of symptom onset for potential thrombolytic therapy 1
  • Emergent neuroimaging (MRI preferred over CT) to exclude hemorrhage and identify ischemic changes 1

Step 2: Characterize Movement Phenomenology

• Determine dominant movement disorder type 3:
  • Dystonia: sustained muscle contractions, twisting postures
  • Chorea: irregular, brief, jerky movements
  • Tremor: rhythmic oscillations
  • Parkinsonism: bradykinesia, rigidity, rest tremor
  • Myoclonus: sudden, brief, shock-like jerks

Step 3: Assess for Associated Features

• Neurological examination 1:

  • Motor strength testing: Grade 0 (no movement) requires immediate physician notification 7
  • Sensory examination for unilateral deficits 1
  • Cranial nerve examination for facial asymmetry, gaze abnormalities 1
  • Cerebellar testing for ataxia 1
  • Cognitive assessment for orientation, language, attention 1

• Non-neurological features 4:

  • Sleep disturbances (suggest autoimmune etiology)
  • Bulbar symptoms (dysphagia, dysarthria)
  • Cognitive changes
  • Psychiatric symptoms

Step 4: Obtain Targeted History

• Medication history: antipsychotics, antiemetics, dopaminergic agents 8, 6, 5
• Vascular risk factors: hypertension, diabetes, smoking, hyperlipidemia 1
• Family history: essential tremor, Huntington disease, Wilson disease 5
• Onset pattern: sudden (stroke, seizure), subacute (autoimmune), gradual (neurodegenerative) 3, 2

Step 5: Neuroimaging Strategy

• MRI brain with and without contrast is the preferred initial structural imaging 1
  • Evaluate for stroke patterns: cortical/subcortical infarcts, hemorrhage 2
  • Assess basal ganglia: signal abnormalities in caudate, putamen, globus pallidus, thalamus 1, 2
  • Look for patterns of atrophy or abnormal substance deposition 1
  • Exclude structural lesions, tumors, vascular malformations 1

Step 6: Additional Investigations Based on Dominant Phenotype

• If stroke suspected: Complete stroke workup including vascular imaging, cardiac evaluation, hypercoagulable studies 1
• If autoimmune suspected: Anti-IgLON5 antibodies, other paraneoplastic/autoimmune panels 4
• If young-onset parkinsonism: Wilson disease screening (ceruloplasmin, 24-hour urine copper), genetic testing 5
• If drug-induced suspected: Trial of medication discontinuation or dose reduction 6, 5

Critical Pitfalls to Avoid

• Do not delay stroke evaluation in young patients: Stroke can occur at any age, and the 32-year-old demographic does not exclude this diagnosis 1
• Do not confuse absence of voluntary movement (motor grade 0) with flaccidity: Grade 0 specifically refers to no active motion regardless of tone 7
• Do not assume single etiology: 87% of patients with anti-IgLON5 disease have multiple concurrent movement disorders 4
• Do not overlook medication history: Both prescription and over-the-counter dopamine-blocking agents can cause movement disorders 8, 6, 5
• Do not rely solely on visual estimation of motor function: Use standardized assessment scales for reproducibility 7
• Do not dismiss sleep or bulbar symptoms: These associated features significantly narrow the differential toward autoimmune etiologies 4