Otalgia

Otalgia is defined as ear pain. Two separate and distinct types of otalgia exist. Pain that originates within the ear is primary otalgia; pain that originates outside the ear is referred otalgia.

Typical sources of primary otalgia are external otitis, otitis media, mastoiditis, and auricular infections. Most physicians are well trained in the diagnosis of these conditions. When an ear is draining and accompanied by tympanic membrane perforation, simply looking in the ear and noting the pathology can make the diagnosis. When the tympanic membrane appears normal, however, the diagnosis becomes more difficult.

Referred otalgia is a topic unto itself. Although many entities can cause referred otalgia, their relationship to ear pain must be identified. A categorical discussion of the workup, treatment, prognosis, demographics, and other issues is impossible because the various pathologies responsible for creating referred otalgia are so diverse.

By definition, referred otalgia is the sensation of ear pain originating from a source outside the ear.

To better understand referred otalgia, the physician first must understand the anatomic distribution of nerves associated with the ear. Irritation of these nerves, as well as irritation of distant branches of these nerves, can cause the perception of pain within the ear.

Pathophysiology: The sensory innervation of the ear is served by the auriculotemporal branch of the fifth cranial nerve, trigeminal nerve (CN V), the first and second cervical nerves, the tympanic (Jacobson) branch of the glossopharyngeal nerve, the auricular (Arnold) branch of the vagus nerve, and the sensory branches of the facial nerve. Neuroanatomically, the sensation of otalgia is thought to center in the spinal tract nucleus of CN V. Not surprisingly, fibers from CNs V, VII, IX, and X and cervical nerves 1, 2, and 3 have been found to enter this spinal tract nucleus caudally near the medulla. Hence, noxious stimulation of any branch of the aforementioned nerves may be interpreted as otalgia.

Causes: Dental disorders are the most common cause of referred pain to the ear. Of this group of disorders, temporomandibular dysfunctions account for the majority of patients. The auriculotemporal branch of the trigeminal nerve mediate pain, which is often perceived deep within the ear.

Within the oral cavity, the sensory innervation becomes quite complex. The tongue receives fibers from the glossopharyngeal nerve, the facial nerve, the trigeminal nerve and the vagus nerve posteriorly. All these nerves have distributions in the ear as well.

Sinusitis is another very common source of ear pain. The neural pathway is along V2, and the auriculotemporal nerve of V3, of CN V. Because the trigeminal nerve supplies the nasal cavity, patients with inflammatory mucosal contact points and nasal obstruction may develop symptoms in their ears.

Neck problems can also refer pain to the ears. These disorders include cervical osteoarthritis, cervical myofascial pain syndrome, and traumatic injuries. The cervical spine is sensitive and well supplied by the cervical nerve roots. Muscular pain from the trapezius or sternocleidomastoid may project postauricularly to the mastoid and occipital area.

Sensory branches of the vagus and glossopharyngeal nerves supply mucosal areas in the upper aerodigestive tract such as the nasopharynx, oropharynx, laryngopharynx, and larynx. The vagus continues caudally and supplies sensory enervation to the bronchus, esophagus, and heart as well. Irritative lesions at any of these sites may lead to secondary otalgia.

Tonsillitis and pharyngitis are very common causes of earaches in children. Less commonly, laryngitis, laryngeal tumors, esophagitis, and even angina pectoris may manifest as otalgia.

Sometimes, pain may be from irritation of the nerves themselves without an inciting source. These disorders are termed neuralgias. Neuralgias are typified by lancinating pain in the distribution of the involved nerve.

Source: http://www.emedicine.com/ent/topic199.htm

Contributed by John Lee