Pharmacology

A 22-year-old woman is admitted to the hospital because of right-hand anaesthesia, that developed after an argument with her brother. She is in good spirits and seems unconcerned about her problem. There is no history of physical trauma. The neurologic examination is negative EXCEPT for reduced sensitivity to pain in a glove-like distribution over the right hand. Her entire family is in attendance and is expressing great concern and attentiveness. She ignores her brother and seems unaware of the chronic jealousy and rivalry described by her family. The most likely diagnosis is