There are 2 types of RES: primary (idiopathic) RES and secondary RES. Primary RES occurs independently or alongside primary headaches like migraines or trigeminal autonomic cephalalgias. Primary RES is more common in children and adolescents.
While the exact pathophysiology of primary RES is not fully understood, it is believed to be driven by trigeminal-autonomic reflex dysfunction, with inhibition of sympathetic vasoconstriction resulting in vasodilation and the characteristic symptoms of burning and redness.
Secondary RES occurs due to an underlying condition, most commonly an upper cervical spine lesion or temporomandibular joint dysfunction. Other less common causes include thalamic syndrome, Chiari 1 malformation, and neurovascular compression of the C3 nerve root by the vertebral artery. Secondary RES is more frequently observed in adults. The leading theory for secondary RES is that underlying pathology leads to peripheral nerve irritation that results in the release of vasodilator substances, causing symptoms of redness, burning, and pain.
RES is a diagnosis of exclusion. The mandatory clinical features include redness and pain in one or both ears.
In 2013, Lambru, Miller, and Matharu proposed the following diagnostic criteria:
- At least 20 attacks fulfilling criteria 2-5.
- Episodes of external ear pain lasting up to 4 hours.
- The ear pain has at least 2 of the following characteristics:
- Burning quality
- Unilateral location
- Mild-to-moderate severity
- Triggered by cutaneous or thermal stimulation of the ear
- The ear pain is accompanied by ipsilateral redness of the external ear.
- Attacks occur with a frequency of 1 or more per day, although cases with lower frequency may occur.
- Not attributed to another disorder.
