What is the differential diagnosis of catatonia and are there any scales used to measure its severity?

Differential Diagnosis of Catatonia

Catatonia is a syndrome of psychomotor disturbances that must be distinguished from neuroleptic malignant syndrome (NMS), serotonin syndrome, drug-induced parkinsonism, and malignant hyperthermia—conditions that share overlapping features but require different management approaches. 1

Key Differential Diagnoses

Neuroleptic Malignant Syndrome (NMS)

• Clinical overlap with catatonia: Both present with rigidity, mutism, and altered mental status, making differentiation challenging 1
• Distinguishing features of NMS: History of recent antipsychotic exposure (within 3 days) or dopamine agonist withdrawal, hyperthermia (>100.4°F), lead pipe rigidity, autonomic instability (blood pressure fluctuations ≥20 mm Hg diastolic or ≥25 mm Hg systolic within 24 hours, diaphoresis, urinary incontinence), and elevated creatine kinase (≥4 times upper limit of normal) 1
• Critical distinction: NMS typically develops after antipsychotic initiation or dose increase, while catatonia can occur independently of medication exposure 1

Serotonin Syndrome

• Differentiating features: Myoclonus (present in 57% of cases), hyperreflexia, and clonus are highly diagnostic for serotonin syndrome and rarely seen in catatonia 1
• Medication history: Recent use of serotonergic agents (SSRIs, SNRIs, MAOIs, tramadol, linezolid) within 5 weeks 1
• Modified Dunkley criteria: Diagnosis requires serotonergic drug exposure plus either tremor with hyperreflexia, spontaneous clonus, or ocular/inducible clonus with agitation or diaphoresis 1

Drug-Induced Parkinsonism

• Overlapping symptoms: Bradykinesia, tremors, and rigidity can mimic catatonic stupor 1
• Key distinction: Parkinsonism typically develops gradually over weeks with antipsychotic use, lacks the waxy flexibility and posturing characteristic of catatonia, and responds to anticholinergic agents 1

Malignant Hyperthermia

• Context-specific: Occurs exclusively during or immediately after anesthesia exposure (particularly volatile anesthetics and succinylcholine) 1
• Rapid onset: Develops within minutes to hours of anesthetic exposure, unlike the days-to-weeks course of catatonia 1

Psychiatric Conditions

• Severe depression with psychomotor retardation: Lacks the full spectrum of catatonic signs (catalepsy, waxy flexibility, echolalia, echopraxia) 1
• Acute psychosis: May have disorganized behavior but typically lacks the characteristic motor signs of catatonia 1
• OCD with severe compulsions: Can present with repetitive behaviors that superficially resemble stereotypies, but these are driven by obsessional content rather than true catatonic phenomena 2

Medical Conditions

• CNS infections (meningitis, encephalitis): Fever, headache, nuchal rigidity, and CSF abnormalities distinguish these from primary catatonia 1
• Seizures/postictal states: EEG abnormalities and temporal relationship to seizure activity 1
• CNS tumors with elevated intracranial pressure: Neuroimaging reveals structural lesions 1

Scales for Measuring Catatonia

Bush-Francis Catatonia Rating Scale (BFCRS)

• Most widely used instrument for identifying and quantifying catatonia severity 3, 4
• Screening version: 14 items assessing core catatonic signs (stupor, catalepsy, waxy flexibility, mutism, negativism, posturing, mannerisms, stereotypies, agitation, grimacing, echolalia, echopraxia, verbigeration, rigidity) 3
• Severity scale: 23 items providing detailed assessment of symptom intensity 4

Abnormal Involuntary Movement Scale (AIMS)

• Primary use: Monitoring for tardive dyskinesia in patients on antipsychotics, but can help differentiate drug-induced movement disorders from catatonia 1
• Recommended frequency: Assessment every 3 to 6 months during neuroleptic therapy 1

Clinical Pitfalls to Avoid

Misattributing catatonic symptoms to medication side effects: Parkinsonism from antipsychotics can be mistaken for catatonia, leading to inappropriate treatment escalation rather than dose reduction 1. The presence of waxy flexibility, posturing, and echolalia/echopraxia strongly favors catatonia over drug-induced parkinsonism.

Delaying treatment while pursuing extensive differential: Malignant catatonia with autonomic instability and fever is life-threatening and requires immediate benzodiazepine trial or ECT, even before completing full workup 1, 5, 3. A positive lorazepam challenge test (improvement after 1-2 mg IV/IM lorazepam) both confirms diagnosis and initiates treatment.

Missing catatonia in medical settings: Catatonia occurs in 3.3% of medical inpatients but remains underrecognized, particularly when presenting with delirium or in ICU settings 3. Systematic screening with the BFCRS in patients with unexplained stupor or rigidity improves detection.