Objective tinnitus is a physical sound that emanates from the body, such as pulsing blood flow through the great vessels in the neck or tetanic contractions of the stapedius muscle on the tympanic membrane. With a stethoscope, microphone, or just the unaided ear, an observer can sometimes hear an objective tinnitus. Objective sounds in the head are relatively rare. In objective tinnitus, etiologies can be separated in terms of whether the tinnitus is pulsatile or nonpulsatile. Pulsatile tinnitus has a rhythmic/repeating periodicity. Pulsatile tinnitus can have a musculoskeletal, vascular, or respiratory etiology. Most of the cases of objective tinnitus are local in origin, such as musculoskeletal activity from the stapedius muscle, tensor tympani muscle spasms in the middle ear, or myoclonus of the palate (Table 1). Vascular causes such as arteriovenous shunts, glomus tumors, high-riding dehiscent jugular bulbs, aberrant carotid arteries, persistent stapedial arteries, and microvascular compression can cause pulsatile tinnitus through a structural mechanism. Another rare condition that results in pulsating noises in the head is pseudotumor cerebri, which results from intracranial hypertension; this is discussed in detail in Chapter 24. However, systemic disorders can present with a pulsing sound through generation of high-speed vascular flow with audible turbulence. Hyperdynamic states such as pregnancy (2), anemia [(1), p. 257], hypertension, and hyperthyroidism [(3), p. 13] cause tinnitus. Another local cause of pulsatile tinnitus may be airflow through a patulous eustachian tube (Table 1). Objective nonpulsatile tinnitus may be recordable but may not necessarily have a rhythmic/repeating periodicity. Etiologies of objective nonpulsatile tinnitus include temporomandibular joint dysfunction, spontaneous otoacoustic emissions, and superior/posterior canal dehiscence syndrome (Table 2). These are all local causes of an objective sound.
TABLE 1 Etiologies of Objective Pulsatile Tinnitus
Musculoskeletal Stapedial muscle spasm Tensor tympani muscle spasm Palatal myoclonus
Arteriovenous shunts Congenital AVM Posttraumatic AVM Glomus tumors
Hyperdynamic cardiovascular system Pseudotumor cerebri Pregnancy Anemia
Arterial Aberrant carotid artery Carotid stenosis Persistent stapedial artery
High-riding dehiscent jugular bulb Sigmoid/transverse sinus obstruction
Patulous eustachian tube
Note: Systemic disorders are highlighted in bold type. Abbreviation: AVM, arteriovenous malformations. Source: From Ref. 1.
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