RES is a clinical diagnosis for which there is no specific diagnostic test. One hundred cases have been reported in the literature so far, with an estimated male-to-female ratio of 1:1.25 and a median age at onset of 44 years (with a wide range of ages: 4 to 92 years) . Lance  was the first to describe RES in the literature in a 1996 report of 12 patients with recurrent RES. Pain in RES varies from mild to severe [3, 4]. Its duration may be seconds  or hours . The frequency of episodes may be several times per day, or there may be year-long remission periods . Raieli and colleagues  reported that unilateral or bilateral 30- to 60-minute episodes can occur in isolation and be associated with migraine (before, during or after). In 10% of the cases they reported, red ears preceded onset of a painful migraine attack. In their series of 96 children admitted with headache, who ranged from 6 to 18 years of age, 55 (57%) had migraine, and RES was found in 16 migraine cases. RES did not occur in the other headache groups. It was associated with severe pain in 62.5% and neurovegetative symptomatology (nausea, vomiting, phonophobia and/or photophobia) in 50% .
Episodes have been reported to occur spontaneously or to be triggered by heat ; by entering a hot room ; by touch [2, 5]; by neck movement [2, 5]; by sneezing, coughing, hair-brushing, physical exercise, chewing, and stress ; and by exposure to cold and lying on the affected side .
There are various views regarding the pathophysiology of this condition. Lance  suggested that the syndrome is induced in patients with cervical disorders, predominantly C3 root discharge causing antidromic release of vasodilator peptides (peripheral mechanism). He proposed that the primary mechanism is activation of the trigeminovascular system. He pointed out, and Hirsch  reiterated, that parasympathetic vasodilatation is greater in the nose and cheek than in the ear; therefore, red ears must be mediated primarily by inhibition of sympathetic vasoconstriction or activation of sympathetic vasodilatation. Thus, the presence of RES suggests an underlying dysregulation of sympathetic outflow. Purdy  noted that, in RES, there is pain in and around the ear associated with autonomic phenomena, including erythema of the ear ipsilateral to the pain. He suggested that the condition be labeled auriculoautonomic cephalalgia or be placed in the trigeminal autonomic cephalgia group. Several authors, including Kumar and colleagues , have used brainstem trigeminovascular activation to explain RES associated with migraine. Lambru and colleagues suggested that it is possible that trigeminoautonomic parasympathetic activation occurs with sympathetic deficit. The imbalance between parasympathetic and sympathetic systems thus may facilitate inhibition of sympathetic tone of the ear. Sympathetic dysregulation, not parasympathetic activation as formerly believed, may be the predominant mechanism of RES .
Another group  has suggested that RES is an auricular form of erythromelalgia with similar burning pain, erythema and increased skin temperature. Erythromelalgia is a condition affecting hands and feet that might be caused by sensory and sympathetic nerve dysfunction.
RES has been associated with various conditions, including upper cervical pathology (arachnoiditis, facet joint spondylosis and cervical root traction), glossopharyngeal and trigeminal neuralgia, temporomandibular joint (TMJ) dysfunction and thalamic syndrome . Associations have been reported with primary headache disorders, including migraine, chronic paroxysmal hemicranias , hemicrania continua and the short-lasting unilateral neuralgiform headache with conjunctival injection . Other cases are idiopathic. Donnet and Valade proposed two types of RES: (1) a primary form that occurs in young people and is associated with migraine and (2) a secondary form that occurs in older adults and is associated with cervical disorder or trigeminal autonomic cephalalgia phenomenon .
Various treatments for RES have been used with varying success. Among the 12 patients Lance described, one improved with methysergide therapy. One experienced partial symptomatic relief with indometacin, and others with propranolol, application of a cold pack, amitriptyline, or imipramine .
Inconsistent results have been reported following treatment with non-steroidal anti-inflammatory drugs , topical anesthetics, cooling the ear , verapamil and gabapentin  and greater auricular nerve blockade with a combination of local anesthetics and steroids. Some authors have reported relief over an eight-week period, and others have noted no benefit [2, 13]. Bender  suggested that in primary or idiopathic cases, treatment of the coexisting headache disorder with drugs such as propranolol, amitriptyline, imipramine and flunarizine helps to resolve these cases to varying degrees. Secondary forms may be more resistant to treatment . In one review, secondary cases appeared to have a greater response to treatment than idiopathic cases . In secondary cases, such as those associated with TMJ dysfunction, a dental plate was reported to be useful in relieving symptoms [2, 9]. In cases associated with chronic paroxysmal hemicrania, indometacin was found to be effective [3, 16].
Transient unilateral sensation of aural fullness with tinnitus was described in one of Lance’s original cases  and blockage without tinnitus in 2 further cases of chronic paroxysmal hemicrania . Aural fullness was present in our case on the first presentation; additional subjective hearing loss in background noise without evidence of hearing loss on audiometry was possibly due to central auditory pathway changes.
Various triggers of RES have been identified; however, we found no reports of dietary triggers that provoke RES. Alcohol and spicy foods are known to cause bilateral facial flushing. Gustatory flushing is mediated by an autonomic neural reflex involving the trigeminal nerve. The presence of a dietary trigger that causes neurological symptoms suggests a migrainous etiology, as such triggers in migraine are well-known and avoidance is a therapeutic mainstay. The non-concentrate orange juice that our patient consumed is a well-known brand in the United Kingdom. There is a possibility that ethyl butyrate (also known as butyric acid ethyl ester), which is often used in flavoring extracts, could be the culprit rather than the orange juice itself. In our patient, dietary, stressor and lifestyle modifications were sufficient to relieve her physical symptoms and psychological distress. We advocate examining a patient’s lifestyle and encouraging the patient to keep a symptom diary to identify environmental factors that provoke RES. Clinicians should be made aware of the likelihood of migraine pathogenesis in primary RES and the range of management options available (non-pharmacological lifestyle changes as well as prophylaxis).
RES is a little known condition with much variation in individual patients’ symptoms and variable responses to proposed treatments. It may go unrecognized and can cause the patient undue anxiety. Often patients feel ignored without a firm diagnosis or management. Patients may present repeatedly to emergency departments, general practices or various specialist departments (ear, nose and throat; dermatology; neurology; audiovestibular medicine; and/or audiology) before being diagnosed. Raised awareness of this disorder with prompt diagnosis has cost benefits by reducing the number of primary and secondary care presentations, decreasing psychological distress and speeding return to usual daily activities.