A 17-year-old girl is brought to the office by her parents for evaluation following the accidental drowning of her younger sister a week ago. The patient, her sister, and 2 friends had gone swimming in the ocean. When the sister became submerged, the patient attempted to rescue her but was overpowered by strong rip currents and was forced to return to shore. The mother is concerned that her daughter seems to be unaware of her sister's death and believes she is "in denial." The patient was unable to answer questions from the police about the drowning and reports she cannot remember any details of what happened that day. Physical examination is unremarkable. On mental status examination, the patient is alert and fully oriented. She becomes upset and confused when the incident is discussed. Which of the following is the most likely diagnosis?

Question

A 17-year-old girl is brought to the office by her parents for evaluation following the accidental drowning of her younger sister a week ago.  The patient, her sister, and 2 friends had gone swimming in the ocean.  When the sister became submerged, the patient attempted to rescue her but was overpowered by strong rip currents and was forced to return to shore.  The mother is concerned that her daughter seems to be unaware of her sister's death and believes she is "in denial."  The patient was unable to answer questions from the police about the drowning and reports she cannot remember any details of what happened that day.  Physical examination is unremarkable.  On mental status examination, the patient is alert and fully oriented.  She becomes upset and confused when the incident is discussed.  Which of the following is the most likely diagnosis?

Quizplus · Accepted Answer

This patient's inability to recall an event that cannot be explained as ordinary forgetfulness is consistent with dissociative amnesia. This disorder typically consists of localized or selective amnesia for a particular event, as in this patient's inability to recall her sister's drowning, but it can also involve more generalized amnesia for personal identity and autobiographical history. Onset is typically sudden and preceded by overwhelming or intolerable events. Definitive diagnosis requires ruling out the effects of a substance (eg, alcohol-induced blackouts, illicit substances, medications) or a neurologic condition (eg, brain trauma). Amnesia involving traumatic events can also occur as a feature of acute or posttraumatic stress disorder (PTSD). (Choice A) Adjustment disorder is characterized by psychologic symptoms that occur in response to an identifiable, non-life threatening psychosocial stressor (eg, relationship conflict, job loss). Adjustment disorder would not explain this patient's sudden amnesia in response to an overwhelming traumatic event. (Choice B) Although complicated grief reaction may include a sense of disbelief, it is a persistent disorder that lasts at least 6-12 months after the loss. It is characterized by intense yearning for the deceased, ruminative thoughts, and dysfunctional behavior. (Choice C) Conversion disorder (functional neurologic symptom disorder) is characterized by motor or sensory neurologic symptoms (eg, weakness, abnormal movements, nonepileptic seizures) that are inconsistent with recognized neurologic disease. Although the onset is typically sudden and may include dissociative symptoms, this patient lacks the motor and sensory symptoms necessary for this diagnosis. (Choice E) Although a history of trauma and amnesia for the traumatic event is also seen in PTSD, this patient lacks other key symptoms of this disorder (eg, hyperarousal, intrusive memories/nightmares/flashbacks, avoidance behaviors). In addition, PTSD is diagnosed only if symptoms last >4 weeks. Educational objective: Dissociative amnesia involves an isolated inability to recall important autobiographical information that is inconsistent with ordinary forgetfulness. It typically occurs abruptly following an overwhelming, traumatic event.

A 17-Year-Old Girl Is Brought to the Office by Her