By Anaïs Behaeghel
In the previous article in this series, subjective tinnitus was discussed. This is the most common form of tinnitus, but there is another form: objective tinnitus. Objective tinnitus is also often called 'somatosounds' and is sometimes audible to external observers during clinical examination, in contrast to subjective tinnitus, which is only audible to the patient themselves.
These somatosounds can originate from different structures in the head-neck region, for example from muscles (mycological tinnitus), blood flow in blood vessels (vascular tinnitus) or a problem with the Eustachian tube (also called patulous Eustachian tube).1 Objective tinnitus is often characterized by a pulsatile and low-frequency tinnitus sound. The types of objective tinnitus can be subdivided into different categories, which are discussed extensively here.
Myoclonic tinnitus
Myoclonic tinnitus occurs due to a problem with different types of muscles, including the muscles of the soft palate in the mouth (also called palatal myoclonic tinnitus) and muscles in the middle ear (also called middle ear myoclonic tinnitus).2
Palatal myoclonic tinnitus is characterized by an irregular, intermittent clicking sound. This is a rare form of myoclonic tinnitus in which the palatal muscles in the mouth contract voluntarily or involuntarily. A first form of palatal myoclonic tinnitus is a symptomatic form, which can be caused, among other things, by a problem with blood flow in the region of the palatal muscles. A second form, the essential form, is more common, and in this case no underlying conditions are identified, but it can be caused by reduced function of a specific structure in the region of the palatal muscles. Diagnosis is often made by means of endoscopic examination of the palatal muscles, electromyogram (an examination of muscle activity), imaging and neurological examination.3
Middle ear myoclonic tinnitus is characterized as a soft buzzing or crackling sound and is rather rare. The sound is caused by an abnormal contraction of the tensor tympani muscle or the stapedius muscle in the middle ear, which are connected to the ossicles and are responsible for movement of these bones and protection against loud sounds. Various causes can underlie this abnormal muscle contraction: trauma, anxiety, vascular problems and infections are some examples here. To diagnose this form of tinnitus, otoendoscopic examination (observation of the eardrum using an otoscope), tympanometry (measurement of the eardrum), stapedial reflex measurement (test to measure the response of the stapedius muscle in the middle ear) and possibly an MRI to detect demyelinating diseases can be used.4
Vascular tinnitus
Vascular tinnitus is the most common form of pulsatile tinnitus, and especially when this pulse is synchronized with the heartbeat. The sound originates from arterial or venous blood flow and is caused by turbulence in the blood flow, which can cause vibration of the vessel walls that will be detected as pulsatile tinnitus. This can, for example, also be observed in patients with high blood pressure. To diagnose the symptoms, otoscopy and a complete head-neck examination are often performed. Audiometry and tympanometry are also performed, and ABR, an objective test of hearing and the auditory nerve, can also be done. Further, blood tests are often taken and imaging is performed for a better understanding of the underlying cause of the tinnitus complaints.5
Patulous Eustachian tube
Patulous Eustachian tube is a condition of the Eustachian tube, also known as the connection between the middle ear and the nasopharynx, characterized by various symptoms, including autophony (the disturbing perception of one's own voice and breathing), fullness in the ear and also often tinnitus. This type of tinnitus, and thus the underlying cause, can be determined by means of audiometry and physical clinical examination.6
Again, for each type of objective tinnitus, good understanding of the patient's complaints is of great importance in order to reach a correct diagnosis, and subsequently also treatment. A detailed history and the performance of the correct examinations are therefore crucial to make a good distinction between subjective and objective tinnitus and to determine the correct subtype.
1 Park, S. N. (2016). Objective tinnitus. Hanyang Medical Reviews, 36(2), 99. https://doi.org/10.7599/hmr.2016.36.2.99
2 Park, S. N. (2016). Objective tinnitus. Hanyang Medical Reviews, 36(2), 99. https://doi.org/10.7599/hmr.2016.36.2.99
3 Park, S. N. (2016). Objective tinnitus. Hanyang Medical Reviews, 36(2), 99. https://doi.org/10.7599/hmr.2016.36.2.99
4 Park, S. N. (2016). Objective tinnitus. Hanyang Medical Reviews, 36(2), 99. https://doi.org/10.7599/hmr.2016.36.2.99
5 Park, S. N. (2016). Objective tinnitus. Hanyang Medical Reviews, 36(2), 99. https://doi.org/10.7599/hmr.2016.36.2.99
6 Park, S. N. (2016). Objective tinnitus. Hanyang Medical Reviews, 36(2), 99. https://doi.org/10.7599/hmr.2016.36.2.99