Terms that appear in Eagle syndrome scan reports, clinic letters and research papers, in plain English.

Atlanto-styloid compression: Narrowing of the internal jugular vein where it passes between the styloid process and the transverse process of the atlas (C1). Also called styloidogenic jugular venous compression.
Atlas (C1): The first vertebra of the neck, which supports the skull. Its transverse processes stick out to each side, close to the styloid process.
Carotid artery: One of the two main arteries supplying the head. Each common carotid artery divides in the neck into an internal branch, which supplies the brain, and an external branch, which supplies the face and scalp.
Carotid sheath: A sleeve of connective tissue in the neck that encloses the carotid artery, the internal jugular vein and the vagus nerve.
Catheter venography: An X-ray test in which a thin tube is passed into the veins and contrast is injected to show them. A pressure sensor on the catheter can measure the pressure on each side of a narrowing (manometry).
Collateral veins: Alternative drainage routes that carry blood around a blocked or narrowed vein. In the neck they include the vertebral venous plexus and veins at the back of the neck.
Cone-beam CT (CBCT): A compact CT scanner used mainly in dentistry and head and neck imaging. It shows bone in three dimensions with a lower radiation dose than conventional CT.
CT (computed tomography): A scan that uses X-rays and a computer to produce cross-sectional images. The standard test for measuring the styloid process.
CT angiography (CTA): A CT scan taken while contrast dye flows through the arteries, showing how the styloid process relates to the carotid arteries.
CT venography (CTV): A CT scan timed to show the veins filled with contrast. Used to look for narrowing of the internal jugular vein.
Digastric muscle: A small muscle under the jaw with two parts. Its back part runs close to the internal jugular vein and can add to compression.
Dissection: A tear in the inner wall of an artery. Blood can collect within the wall and narrow or block the artery, or a clot can form and travel to the brain, causing a stroke.
Dysphagia: Difficulty swallowing.
Elongated styloid process: A styloid process 30 mm or longer, the most widely used cutoff. Elongation is common and on its own does not mean a person has Eagle syndrome.
First bite syndrome: A cramping pain in the cheek or jaw with the first bite of a meal, which eases as eating continues. A recognized, usually temporary effect of surgery near the parotid gland and styloid process.
Glossopharyngeal nerve (cranial nerve IX): The nerve that carries sensation from the back of the tongue, the tonsils and the throat. Irritation of it by the styloid process is thought to cause the sharp throat pain of classic Eagle syndrome.
Glossopharyngeal neuralgia: Brief, severe, electric-shock pain in the throat, tonsil area or ear, caused by irritation of the glossopharyngeal nerve. It can resemble, and be confused with, Eagle syndrome.
Horner syndrome: A drooping upper eyelid, a small pupil and reduced sweating on one side of the face, caused by damage to the sympathetic nerves that run along the carotid artery.
Hyoid bone: A U-shaped bone at the top of the front of the neck, above the voice box. The stylohyoid ligament attaches to its lesser horn.
Idiopathic intracranial hypertension (IIH): Raised pressure of the fluid around the brain without a tumor or other visible cause. Also called pseudotumor cerebri. Narrowing of the veins that drain the brain is common in IIH, and some specialists consider it a cause.
Internal jugular vein: The main vein draining blood from the brain, one on each side of the neck. Near the skull base it passes between the styloid process and the atlas.
Intracranial pressure: The pressure inside the skull. When it is too high, it can cause headache, visual problems and swelling of the optic nerves.
Lidocaine infiltration test: An injection of local anesthetic into the tonsil area near the styloid tip. If the usual pain goes away while the anesthetic works, that supports the styloid process as its source.
Manometry: Measuring pressure directly, here with a catheter inside a vein. A pressure drop across a narrowing shows that it obstructs blood flow.
MR venography (MRV): An MRI scan of the veins. It shows blood flow and collateral veins without radiation, but shows bone less clearly than CT.
Odynophagia: Pain on swallowing.
Ossification: The turning of soft tissue, such as a ligament, into bone.
Otalgia: Ear pain. In Eagle syndrome it is usually referred pain, felt in the ear but coming from the throat.
Panoramic X-ray (orthopantomogram): A dental X-ray showing both jaws in one image. It often shows an elongated styloid process, but misses about a third of them.
Papilledema: Swelling of the optic nerve heads at the back of the eyes, seen through an ophthalmoscope. A sign of raised intracranial pressure.
Pseudo-articulated: An ossified stylohyoid ligament that looks jointed, with a gap between two bony segments. Type II in the Langlais classification.
Pulsatile tinnitus: A rhythmic whooshing or pulsing sound in the ear that keeps time with the heartbeat. It can come from turbulent blood flow in a narrowed vein.
Segmented: An ossified stylohyoid ligament made of several separate bony pieces. Type III in the Langlais classification.
Stenosis: Narrowing of a blood vessel or other passage.
Stylohyoid chain: The styloid process, the stylohyoid ligament and the lesser horn of the hyoid bone, considered together.
Stylohyoid ligament: The ligament that runs from the tip of the styloid process to the hyoid bone. It can calcify or turn to bone, lengthening the styloid in effect.
Styloid process: A thin, pointed spike of bone projecting down and forward from the temporal bone, just below each ear. Three small muscles and two ligaments attach to it.
Styloidectomy: An operation to shorten or remove the styloid process, either through the mouth (transoral) or through a cut in the neck (transcervical).
Stylomastoid foramen: A small opening in the skull just behind the base of the styloid process, through which the facial nerve leaves the skull. Its position explains why surgery near the styloid base carries a small risk of facial weakness.
Tonsillar fossa: The hollow at the side of the throat where the tonsil sits. The tip of an elongated styloid can sometimes be felt through it.
TORS (transoral robotic surgery): Surgery through the mouth using a surgical robot, which gives the surgeon a magnified 3D view.
Transcervical: Through the neck. A transcervical styloidectomy uses a cut in the skin of the upper neck.
Transoral: Through the mouth. A transoral styloidectomy reaches the styloid through the tonsil area, leaving no visible scar.
Transverse process: A bony projection on each side of a vertebra. The transverse processes of the atlas (C1) are unusually wide and sit close to the internal jugular vein.
Vagus nerve (cranial nerve X): A long nerve that runs inside the carotid sheath, between the carotid artery and the jugular vein, and supplies the throat, voice box and internal organs.