A 32-year-old woman from Mumbai is brought to the emergency department by her family with acute onset of bizarre behaviour. For the past 3 days, she has been speaking in a disorganized manner, laughing at inappropriate times, and refusing to eat or bathe. She sits motionless for hours with her arms held in unusual postures that she maintains even when moved by others. Her family reports no prior psychiatric history, and she denies any substance use. Urine drug screen is negative. Blood glucose is 110 mg/dL, and thyroid function tests are normal. On examination, she exhibits waxy flexibility and mutism. What is the most likely diagnosis?

Explanation

## Diagnostic Reasoning **Key Point:** Catatonia is a psychomotor syndrome characterized by abnormal motor behavior, mutism, and negativism. When catatonia occurs in the context of psychotic symptoms (disorganized speech, inappropriate affect) without a clear medical or substance-related cause, catatonic schizophrenia is the diagnosis. ### Clinical Features of Catatonia Present in This Case | Catatonic Feature | Present in Patient | Clinical Significance | |-------------------|-------------------|----------------------| | **Waxy flexibility** | Yes | Limbs move passively and maintain posture | | **Mutism** | Yes | Absence of speech | | **Posturing** | Yes | Spontaneous assumption of unusual postures | | **Negativism** | Implied (refusing food/bathing) | Resistance to instructions | | **Psychomotor retardation** | Yes (sitting motionless) | Decreased spontaneous activity | ### Psychotic Features 1. **Disorganized speech** — incoherent, tangential language 2. **Inappropriate affect** — laughing at inappropriate times (incongruent with mood) 3. **Behavioral disorganization** — refusal to eat/bathe, bizarre behavior ### Exclusion of Medical/Substance Causes - **Urine drug screen:** Negative (rules out substance-induced psychosis or catatonia) - **Blood glucose:** Normal (rules out hypoglycemia/hyperglycemia) - **Thyroid function tests:** Normal (rules out thyroid-related psychosis or catatonia) - **No prior psychiatric history:** Suggests acute onset, typical of first-episode schizophrenia **High-Yield:** Catatonic schizophrenia is now classified under "Schizophrenia with catatonic features" in DSM-5, but the clinical presentation and diagnostic approach remain the same. Catatonia can occur in schizophrenia, mood disorders, medical conditions, and substance use — the key is to exclude medical and substance causes first. **Clinical Pearl:** Waxy flexibility (cerea flexibilitas) is pathognomonic for catatonia and is rarely seen in other psychiatric or neurological conditions. When combined with mutism, posturing, and psychotic symptoms, it strongly suggests catatonic schizophrenia. **Mnemonic: CATATONIA** — Features to assess - **C**atatepsy (waxy flexibility, posturing) - **A**kinesia (decreased spontaneous movement) - **T**urbulence (agitation, excitement) - **A**ffect (inappropriate, blunted) - **T**owering (mutism, negativism) - **O**bstruction (refusal of care) - **N**egativism (resistance) - **I**ncontinence (may occur) - **A**bnormal speech (disorganized, echolalia) ## Differential Diagnosis Analysis ```mermaid flowchart TD A["Acute psychotic presentation with catatonic features"]:::outcome --> B{"Medical/substance cause?"}:::decision B -->|"Yes: labs abnormal, drug screen positive"| C["Treat underlying cause"]:::action B -->|"No: labs normal, drug screen negative"| D{"Catatonic features present?"}:::decision D -->|"Yes: waxy flexibility, mutism, posturing"| E{"Psychotic symptoms?"}:::decision D -->|"No: no catatonia"| F["Other psychiatric disorder"]:::outcome E -->|"Yes: disorganized speech, delusions, inappropriate affect"| G["Catatonic Schizophrenia"]:::action E -->|"No: catatonia only"| H["Catatonia (other cause)"]:::outcome ``` **Why Catatonic Schizophrenia Is Correct:** The patient presents with: 1. Clear catatonic features (waxy flexibility, mutism, posturing, negativism, psychomotor retardation) 2. Psychotic symptoms (disorganized speech, inappropriate affect, bizarre behavior) 3. Acute onset (3 days) 4. Exclusion of medical causes (normal labs, negative drug screen) 5. No prior psychiatric history (first episode) This constellation meets criteria for schizophrenia with catatonic features.