It seems that though the HSM is in general a fantasy character the screenwriters (like in many other K-dramas) have done some research in medical & psychological fields.
1. Insular cortex surgery. Really, the insular cortex is thought to be a substrate for empathy (ability to understand and share the feelings of others). Less insular cortex activation means difficulties in understanding your own emotional and bodily states (alexithymia) and other people’s emotions.
Insular cortex surgery (removing a lesion -- a damaged or abnormal area) is used for treating childhood epilepsy. Serious insular cortex damage can cause a lot of problems with sensory perceptions and emotions.
But hypersensitivity to sounds (hyperacusis) is never treated by brain surgeries.
So, what the show runners have done here is replacing the ML's ugly epilepsy with its seizures with more beautiful hyperacusis.
2. Acute stress disorder (an immediate response to a terrifying, traumatic event like sudden death of a loved one etc.). The word was never pronounced but this is it.
In eps. 14-15 the ML is showing many standard symptoms of the ASD: narrowing the field of consciousness (when he can’t cope with driving), distressing nightmares and flashbacks (when he sees her dead in a nightmare), avoidance of shocking memories (when he closes the picture of her dead body), angry outbursts (when he roars at her father at the farewell ceremony, when he hits the table when interrogating Yoon promising to catch the bastard), physical symptoms such as difficult breathing.
Kudos to the actor, this shock and pain was very well shown.
Acute stress disorder may be followed then by the more or less strong post-traumatic stress disorder but the show runners seem to have mercy to our poor male lead and show little recovery.
