What causes catatonia and how is it differentiated from delirium?

Causes and Differentiation of Catatonia from Delirium

Causes of Catatonia

Catatonia arises from a diverse array of psychiatric, neurological, and medical conditions, with mood disorders (particularly severe bipolar depression), psychotic disorders, and neurological diseases being the most common culprits. 1, 2

Primary Psychiatric Causes

• Severe depressive episodes in bipolar disorder are especially prone to progressing to catatonia, particularly when characterized by psychomotor retardation, hypersomnia, and psychotic features 2
• Psychotic disorders including schizophrenia are common psychiatric associations 1

Secondary Medical and Neurological Causes

• Viral encephalitis and meningitis represent the most common organic causes, especially in children and adolescents 2
• Seizure disorders including epilepsy can precipitate catatonia 2
• CNS structural lesions such as brain tumors, congenital malformations, and cerebral venous sinus thrombosis 2
• Endocrinopathies, particularly thyroid disorders 2
• Infectious etiologies including HIV-related syndromes 2
• Metabolic disorders such as Wilson's disease and lipid storage disorders (Gaucher's disease) 2
• Movement disorders including Huntington's disease and other choreiform conditions 2

Iatrogenic and Substance-Related Causes

• Neuroleptic malignant syndrome from antipsychotic medications 3, 2
• Stimulant medications and corticosteroids 2
• Substances of abuse including amphetamines and cocaine 2

Pathophysiological Mechanisms

• Dysfunction in cortico-cortical and cortico-subcortical pathways involving the basal ganglia appears central to catatonia pathogenesis 1
• Prenatal viral exposure may increase risk for later psychotic disorders with catatonic features 1

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Differentiating Catatonia from Delirium

The critical distinction lies in recognizing that catatonia is primarily a psychomotor syndrome with preserved or only mildly altered consciousness, while delirium is fundamentally a disorder of attention and consciousness with acute onset and fluctuating course. 3, 4

Core Diagnostic Features of Delirium

• Acute onset and fluctuating course (develops over hours to days, worsens in evening "sundowning") 4
• Inattention as the cardinal feature - inability to focus, sustain, or shift attention 3, 4
• Altered level of consciousness - ranging from hyperalert to stuporous 4
• Disorganized thinking - incoherent speech, rambling, illogical flow of ideas 3, 4
• Symptoms fluctuate substantially throughout the day with possible lucid intervals 3, 4

Core Diagnostic Features of Catatonia

• Psychomotor abnormalities including immobility, posturing, waxy flexibility, stereotypies, mannerisms, and echophenomena 5
• Mutism or minimal verbal output 6
• Negativism - opposition or lack of response to external stimuli 5
• Stupor - lack of psychomotor activity with reduced responsiveness, but consciousness is typically preserved or only mildly impaired 7
• Symptoms are generally more stable throughout the day compared to delirium's fluctuations 4

Key Differentiating Clinical Features

Level of Consciousness:

• Delirium: Markedly altered, fluctuating awareness 4
• Catatonia: Awareness and consciousness frequently intact or only mildly impaired 3, 7

Attention:

• Delirium: Profound inattention is mandatory for diagnosis 4
• Catatonia: Attention may be difficult to assess due to mutism/immobility, but not the primary deficit 7

Temporal Course:

• Delirium: Acute onset with marked fluctuations during the day 4
• Catatonia: More stable presentation without characteristic diurnal fluctuations 7

Motor Features:

• Delirium: Hyperactive (agitation) or hypoactive (lethargy), but lacks the specific catatonic signs 3, 4
• Catatonia: Specific motor signs including waxy flexibility, posturing, catalepsy, stereotypies, and echophenomena 5

Response to Testing:

• Delirium: Fails attention tests (reciting months backward, digit span) 4
• Catatonia: May not engage with testing due to negativism/mutism, but when consciousness is assessed, it is relatively preserved 7

Critical Clinical Pitfall: Co-occurrence

A major diagnostic challenge is that catatonia and delirium can co-occur in 8-26% of cases, particularly in medical settings. 8, 9 This overlap creates diagnostic confusion because:

• Both can present with altered mental status and behavioral changes 7
• Catatonic patients may appear incoherent and thus meet some delirium criteria 7
• 93% of hospitalized patients with catatonia also meet criteria for delirium 9
• The DSM-5 exclusion criteria stating catatonia cannot occur in delirium is increasingly questioned by clinical evidence 8, 7, 9

Practical Assessment Approach

When evaluating altered mental status, systematically assess for both conditions:

1. First, assess for delirium using the Confusion Assessment Method (CAM), which requires: acute onset/fluctuating course + inattention + (altered consciousness OR disorganized thinking) 4

2. Then, specifically screen for catatonia using the Bush-Francis Catatonia Screening Instrument, looking for ≥2 signs (or ≥4 for higher specificity): immobility, mutism, staring, posturing, grimacing, echopraxia/echolalia, stereotypy, mannerisms, verbigeration, rigidity, negativism, waxy flexibility 8, 9

3. Obtain collateral history to establish baseline cognitive function and timeline of symptom onset 4

4. Look for neurological red flags suggesting catatonia: new-onset catatonia warrants workup for encephalitis, seizures, or structural CNS disease 7

Diagnostic Testing Considerations

Clonus and hyperreflexia are highly diagnostic for serotonin syndrome (which can mimic catatonia), not for catatonia itself 3

Myoclonus is characteristic of serotonin syndrome (57% of cases), helping differentiate from catatonia 3

Treatment Response as Diagnostic Tool

A lorazepam challenge test can help differentiate:

• Catatonia typically responds to benzodiazepines (60% response rate in pure catatonia) 8
• Pure delirium does not respond to lorazepam in the same manner 8
• However, only 11% of patients with co-occurring catatonia-delirium respond to lorazepam, suggesting the combination requires different management 8
• When catatonia and delirium coexist, 43-57% show some improvement with benzodiazepines 9

Management Implications

For catatonia (with or without delirium):

• Consider lorazepam or electroconvulsive therapy even in medical catatonia 7
• Use neuroleptics with extreme caution due to risk of neuroleptic malignant syndrome 7

For delirium:

• Treat underlying medical cause 3
• Non-pharmacological approaches first 3
• Benzodiazepines for agitation if needed 3

Critical warning: Patients with both catatonia and delirium have worse outcomes, longer hospital stays, and increased complications, requiring aggressive identification and treatment of underlying causes 5