Posttraumatic Stress Disorder (PTSD)
The most likely diagnosis is Posttraumatic Stress Disorder (PTSD), not Acute Stress Disorder, because the symptoms have persisted for 5 weeks—well beyond the 1-month cutoff that distinguishes these two conditions.
Diagnostic Reasoning Based on Timeline
The critical distinguishing factor here is the duration of symptoms:
- Acute Stress Disorder (ASD) requires symptoms occurring between 3 days to 1 month after traumatic exposure 1
- PTSD requires symptoms that persist for ≥1 month (or ≥3 months in some definitions) after the trauma 1
Since this patient's symptoms have been persistent for 5 weeks (35 days), the timeframe has exceeded the maximum duration for ASD and now meets criteria for PTSD 1.
Symptom Profile Consistent with PTSD
The patient's presentation includes classic PTSD symptom clusters 1:
- Intrusive symptoms: Intrusive flashbacks (reexperiencing the traumatic event) 1
- Dissociative symptoms: Numbness and derealization (loss of awareness of present surroundings, feeling that things are unreal) 1
- Significant distress: The symptoms are causing marked functional impairment 1
These symptoms align with the DSM-5 criteria for PTSD, which include intrusion, avoidance, negative alterations in cognitions and mood, and increased arousal that persist for at least 1 month and result in significant impairment 1.
Why Not the Other Diagnoses?
Acute Stress Disorder is ruled out because the 1-month window has passed. ASD specifically captures the acute phase (3 days to 1 month post-trauma), and this patient is now at 5 weeks 1.
Panic Disorder is not appropriate because the symptoms are clearly trauma-linked and include dissociative and intrusive reexperiencing phenomena, not just discrete panic attacks with autonomic arousal 1.
Phobia is incorrect because the patient is experiencing intrusive flashbacks and dissociation related to a specific traumatic event, not an irrational fear of a specific object or situation that leads to avoidance behavior 1.
Clinical Pitfall to Avoid
A common error is assuming that because dissociative symptoms (numbness, derealization) are prominent, the diagnosis must be ASD, since ASD criteria emphasize dissociation 2. However, the temporal criterion takes precedence—once symptoms persist beyond 1 month, the diagnosis shifts to PTSD regardless of symptom profile 1. Dissociative symptoms can and do occur in PTSD 1.
Immediate Clinical Implications
This patient requires prompt intervention, as PTSD at 5 weeks indicates risk for chronic symptoms 3, 4. Early cognitive-behavioral therapy has demonstrated efficacy in preventing chronic PTSD when initiated in the acute phase 3. The presence of dissociative symptoms (derealization, numbness) may predict more severe or prolonged course 5, 2.