mrcpsych-1643

A 42-year-old woman arrives at the emergency department complaining of sensations in her head that she describes as similar to ‘electric shocks’. She has a history of anxiety and depression and has been taking venlafaxine for the past two months, but has a track record of not taking her medication regularly. Apart from that, she is in good health. Her vital signs show a slightly elevated blood pressure, and her routine blood tests and 12-lead ECG are normal. What is the probable cause of her symptoms?