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 also another form: objective tinnitus. Objective tinnitus is also often called 'somatosounds' and is sometimes audible to external listeners during clinical examination, unlike subjective tinnitus, which is only heard by the patient themselves.

These somatosounds can originate from various structures in the head and neck region, for example from muscles (myoclonic 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 in detail here.

Myoclonic tinnitus

Myoclonic tinnitus occurs due to a problem with various 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 by, among other things, 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 detected, but it can be caused by reduced functioning of a particular structure in the region of the palatal muscles. Diagnosis is often made through endoscopic examination of the palatal muscles, electromyography (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 stapes muscle in the middle ear, which are connected to the hearing bones and provide movement of these bones and protection against loud sounds. There can be various causes underlying this abnormal muscle contraction: trauma, anxiety, vascular problems, and infections are some examples. To diagnose this form of tinnitus, otoendoscopic examination (an observation of the eardrum using an otoscope), tympanometry (measurement of the eardrum), stapedial reflex measurement (test to measure the response of the stapes muscle in the middle ear), and possibly an MRI to detect demyelinating conditions can be used.⁴

Vascular tinnitus

Vascular tinnitus is de vaakst voorkomende vorm van
pulsatiele tinnitus, especially when this pulse is synchronous with the heartbeat. The sound originates from arterial or venous blood flow and is caused by turbulence in the blood flow, which can create a vibration of the vessel walls that will be detected as pulsatile tinnitus. This can also be observed, for example, in patients with high blood pressure. To diagnose the symptoms, otoscopy and a complete head and neck examination are often performed. Audiometry and tympanometry are also performed, and an ABR, an objective hearing and auditory nerve test, can also be done. Furthermore, blood work and imaging are often done to get a better picture 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 hearing of one's own voice and breathing), fullness in the ear, and often tinnitus as well. This type of tinnitus, and thus the underlying cause, can be determined through audiometry and physical clinical examination.⁶

Again, with each type of objective tinnitus, a good understanding of the patient's symptoms is of great importance in achieving a correct diagnosis, and subsequently treatment as well. A detailed medical history and performing the correct examinations is therefore crucial to make a good distinction between subjective and objective tinnitus and to determine the correct subtype.