A 28-year-old woman is brought to the emergency department 6 weeks after witnessing her husband's fatal cardiac arrest at home. She was performing CPR when he collapsed. She reports recurrent, intrusive flashbacks of his collapse occurring several times daily, accompanied by intense fear and physiological arousal (palpitations, sweating). She has avoided the bedroom and kitchen where the event occurred, and refuses to be alone. She experiences nightmares 4–5 nights per week and has difficulty concentrating at work. She denies suicidal ideation but reports persistent sadness and loss of interest in activities she previously enjoyed. On mental status examination, she appears tearful, with restricted affect. What is the most likely diagnosis?

Explanation

## Diagnosis: Posttraumatic Stress Disorder (PTSD) ### Key Clinical Features Present **Key Point:** PTSD is diagnosed when trauma-related symptoms persist for ≥1 month following a traumatic event and cause significant functional impairment. This patient demonstrates: - **Timing:** Symptoms began 6 weeks post-trauma (well beyond the 1-month threshold) - **Intrusive symptoms:** Recurrent flashbacks with physiological reactivity (palpitations, sweating) - **Avoidance:** Avoids trauma-related locations (bedroom, kitchen); avoids being alone - **Negative cognitions/mood:** Persistent sadness, anhedonia, restricted affect - **Arousal symptoms:** Nightmares, hypervigilance, difficulty concentrating - **Functional impairment:** Unable to work effectively, withdrawn from activities ### PTSD Diagnostic Criteria (DSM-5) | Criterion | Status in This Patient | |-----------|------------------------| | **Criterion A: Traumatic event** | Witnessed spouse's fatal cardiac arrest ✓ | | **Criterion B: Intrusion symptoms** | Flashbacks, physiological reactivity ✓ | | **Criterion C: Avoidance** | Avoids locations, avoids being alone ✓ | | **Criterion D: Negative mood/cognition** | Persistent sadness, anhedonia, restricted affect ✓ | | **Criterion E: Arousal/reactivity** | Nightmares, difficulty concentrating ✓ | | **Criterion F: Duration ≥1 month** | 6 weeks post-trauma ✓ | | **Criterion G: Functional impairment** | Work dysfunction, social withdrawal ✓ | **High-Yield:** The **duration of ≥1 month** is the critical temporal distinction between acute stress disorder (3 days–1 month) and PTSD (≥1 month). ### Clinical Pearl **Key Point:** Comorbid depression is common in PTSD (up to 50% of cases). The presence of anhedonia and sadness does not exclude PTSD; rather, these are part of the negative mood/cognition cluster of PTSD criteria. ### Mnemonic: PTSD Criteria **REINS** = **R**e-experiencing (flashbacks, nightmares), **E**motional numbing/avoidance, **I**ntrusion symptoms, **N**egative mood and cognitions, **S**leep/arousal disturbance. [cite:DSM-5, American Psychiatric Association]