What finding is most significant in diagnosing trigeminal neuralgia?

Intermittent sharp pain triggered by touch is the most significant finding in diagnosing trigeminal neuralgia. This condition is characterized by episodes of intense, sudden, and severe facial pain that can be precipitated by minimal stimuli, such as light touch, chewing, or even a breeze. The nature of the pain—typically described as sharp, stabbing, or electric shock-like—along with the specific triggers, helps differentiate trigeminal neuralgia from other types of facial pain or headaches.

The other options, while they may indicate other conditions, do not align with the hallmark symptoms of trigeminal neuralgia. For instance, facial swelling may suggest an inflammatory or infectious process in the area, but it is not a symptom characteristic of trigeminal neuralgia. Consistent headaches could relate to a variety of headache disorders, and morning joint pain is not relevant in this context, as it pertains more to conditions like arthritis. Thus, the distinguishing feature of sharp, trigger-sensitive pain is crucial for the diagnosis of trigeminal neuralgia.