@Oman first welcome and I hope you really choose the method of operation wisely as intraoral operation is sometimes riskier than transcervical as all the cranial nerves are not fully visible through that method. Also, the recovery could be longer and getting all the styloid and calcified stylohyoid ligament could be difficulty. The transcervical approach is the best choice as it is difficulty to remove calcified stylohyoid ligament through intraoral approach. The transcervical approach is also widely performed nowadays so I would choose that over the intraoral one.
Anyways, your case reminded me of research paper I posted in here a while back (see below) where a 51 year old lady had 3 teeth removed and had sinus surgery as she thought it could relieve the pain. So Eagle syndrome is known to send people off to wrong path for years before it gets diagnosed since it mimics a whole host of other diseases. I call it the great imitator.
Here is her clinical finding before the operation which relieved her oral pain.
Clinical findings
The patient reported a foreign-body sensation in the oropharyngeal region, and painful chewing and swallowing, mostly with solid foods, which had worsened over time. The pain was experienced almost every day, sometimes spontaneously, and it was enhanced by rotation of the head to the left. It could also be elicited by palpation of the tonsillar fossa. The pain was described as “aching during mouth opening” and “dull as a pharyngitis,” and was associated with a noise in the ispilateral ear. Pain quality was assessed by the DN4 questionnaire for neuropathic pain [7], which revealed only mechanical allodynia. The severity of the pain was rated 5/10 using the Numeric Pain Rating Scale (NPRS), and was partially relieved by acetaminophen (1000 mg, p.o., t.i.d.).
Orofacial evaluation according to DC recommendations [8] revealed a slight tumefaction at the left angle of the mandible without any modification in the appearance of the skin. Digital palpation revealed painful left masseter, mylohyoid muscle and the posterior part of the digastric muscles. Ear and nose examination was unremarkable. A left deviation of the mandibula during mouth opening was also observed. Intraoral examination revealed an asymmetry at the level of the palatine tonsils. The ipsilateral (left) tonsil seemed bent inside, and palpation of the oropharynx highlighted the left voluminous styloid process visible on orthopantomogram (see below).