Neuroimaging clinics of North America
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Neuroimaging Clin. N. Am. · May 2016
ReviewVenous Abnormalities Leading to Tinnitus: Imaging Evaluation.
Venous anomalies are the most commonly identified abnormality by imaging in the work-up for pulse synchronous tinnitus. Potential diagnoses include idiopathic intracranial hypertension, sigmoid sinus wall anomalies, transverse and sigmoid sinus stenosis, jugular bulb anomalies, and prominent posterior fossa emissary veins. These causes are discussed in detail along with the association between sigmoid sinus wall anomalies and idiopathic intracranial hypertension.
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Tinnitus is a common symptom that usually originates in the middle ear. Vascular causes of pulsatile tinnitus are categorized by the location of the source of the noise within the cerebral-cervical vasculature: arterial, arteriovenous, and venous. Arterial stenosis secondary to atherosclerotic disease or dissection, arterial anatomic variants at the skull base, and vascular skull base tumors are some of the more common causes of arterial and arteriovenous pulsatile tinnitus. Noninvasive imaging is indicated to evaluate for possible causes of pulsatile tinnitus, and should be followed by catheter angiography if there is a strong clinical suspicion for a dural arteriovenous fistula.
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Tinnitus is a consequence of changes in auditory and nonauditory neural networks following damage to the cochlea. Homeostatic compensatory mechanisms occur after hearing loss and these mechanisms alter the balance of excitatory and inhibitory neurotransmitters. ⋯ When auditory network dysfunction is coupled with limbic-gating dysfunction, an otherwise meaningless auditory percept such as tinnitus may acquire negative emotional features. The development of effective treatment options is enhanced by the understanding of the neural networks underpinning tinnitus.
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Surgery for tinnitus can be divided into procedures directed specifically at elimination of tinnitus versus those directed at an independent primary otopathology whose symptoms include tinnitus. For the latter, although there may be an independent primary goal for which the surgery is undertaken, tinnitus may be expected to improve secondarily. This article will address both tinnitus-specific and tinnitus non-specific procedures for objective and subjective causes.
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Although tinnitus may originate in damage to the peripheral auditory apparatus, its perception and distressing symptomatology are consequences of alterations to auditory, sensory, and limbic neural networks. This has been described in several studies, some using advanced structural MR imaging techniques such as diffusion tensor imaging. ⋯ New MR imaging techniques enabling detailed depiction of the labyrinth may be useful when diagnosis of Meniere disease is equivocal. Advances in computed tomography and MR imaging have enabled noninvasive diagnosis of dural arteriovenous fistulae.