What is the most likely diagnosis for a 27-year-old man experiencing weekly episodes of staring and jaw movements, with a history of social withdrawal, circumstantial speech, and intense discussion of moral, religious, and philosophical issues, with no evidence of paranoia, hallucinations, or abnormal physical and laboratory findings, including a normal computed tomography (CT) scan of the head?

Differential Diagnosis

• Single most likely diagnosis + E) Temporal lobe epilepsy: The patient's "weird spells" characterized by staring into the distance and jaw movements, occurring at least once weekly since the age of 13, are suggestive of complex partial seizures, which are often associated with temporal lobe epilepsy. The absence of abnormalities on physical and neurologic examinations, as well as normal laboratory studies and a CT scan of the head, does not rule out this diagnosis, as some cases of temporal lobe epilepsy may not have visible structural abnormalities on imaging.
• Other Likely diagnoses + D) Schizophrenia, paranoid type: Although the patient does not exhibit paranoia or hallucinations, his intense and circumstantial speech, preoccupation with moral, religious, and philosophical issues, and social withdrawal (living at home, spending most time in his room) could be indicative of a thought disorder. However, the lack of clear hallucinations or delusions makes this diagnosis less likely than temporal lobe epilepsy. + C) Bipolar disorder, manic: The patient's intense speech and circumstantial thinking could be suggestive of a manic episode. However, there is no clear indication of elevated mood, decreased need for sleep, or other manic symptoms, making this diagnosis less likely.
• Do Not Miss (ddxs that may not be likely, but would be deadly if missed.) + None of the options provided fit perfectly into this category, as they are either more likely (temporal lobe epilepsy) or less severe (agoraphobia, attention-deficit/hyperactivity disorder). However, it's crucial to consider and rule out any condition that could lead to significant morbidity or mortality, such as untreated epilepsy, which can lead to status epilepticus or sudden unexpected death in epilepsy (SUDEP).
• Rare diagnoses + A) Agoraphobia: While the patient is socially withdrawn, there is no clear indication of fear or anxiety related to being in public places or situations from which escape might be difficult, making agoraphobia an unlikely diagnosis. + B) Attention-deficit/hyperactivity disorder: The patient's history of "barely graduating" from high school and current social withdrawal could suggest attentional issues, but there is no clear evidence of inattention, hyperactivity, or impulsivity, which are core symptoms of ADHD.