Does the location of a vascular loop in the cerebellopontine angle explain pulsatile and non-pulsatile tinnitus?

Abstract

The purpose was to investigate patients with unexplained pulsatile and non-pulsatile tinnitus by means of MR imaging of the cerebellopontine angle (CPA) and to correlate the clinical subtype of tinnitus with the location of a blood vessel (in the internal auditory canal or at the cisternal part of the VIIIth cranial nerve). Clinical presentation of tinnitus and perceptive hearing loss were correlated. In 47 patients with unexplained tinnitus, an MR examination of the CPA was performed. Virtual endoscopy reconstructions were obtained using a 3D axial thin-section high-resolution heavily T2-weighted gradient echo constructive interference in steady state (CISS) data-set. High-resolution T2-weighted CISS images showed a significantly higher number of vascular loops in the internal auditory canal in patients with arterial pulsatile tinnitus compared to patients with non-pulsatile tinnitus (P<0.00001). Virtual endoscopy images were used to investigate vascular contacts at the cisternal part of the VIIIth cranial nerve in patients with low pitch and high pitch non-pulsatile tinnitus. A significantly different distribution of the vascular contacts (P=0.0320) was found. Furthermore, a correlation between the clinical presentation of non-pulsatile tinnitus (high pitch and low pitch) and the perceptive hearing loss was found (P=0.0235). High-resolution heavily T2-weighted CISS images and virtual endoscopy of the CPA can be used to evaluate whether a vascular contact is present in the internal auditory canal or at the cisternal part of the VIIIth cranial nerve and whether the location of the vascular contact correlates with the clinical subtype of tinnitus. Our findings suggest that there is a tonotopical structure of the cisternal part of the VIIIth cranial nerve. A correlation between the clinical presentation of tinnitus and hearing loss was found.

Vascular Loops at the Cerebellopontine Angle: Is There a Correlation with Tinnitus?

“…Similarly, Nowé et al 6 stated that nonpulsatile tinnitus may result from a microvascular compression at the cisternal segment of the eighth CN and showed a correlation between the clinical presentation of nonpulsatile tinnitus (high and low pitch) and perceptive hearing loss. Nowé et al 6 and De Ridder et al 9 found a strong correlation between the presence of vascular loops in the IAC seen on MR imaging and pulsatile tinnitus. They theorized that pulsatile tinnitus is caused by direct transmission of pulsations to the cochlea via a resonance effect in the petrous bone.…”

“…The anatomic course and complex vascular relationships of cisternal and canalicular parts of the eighth CN have been visualized successfully by using the 3D-FIESTA sequence. 6,9,11,14 The neurovascular compression of the eighth CN can produce vertigo, tinnitus, or hearing disturbances or various combinations of them, unlike vascular compression of the trigeminal or facial nerve. This complicated symptomatology makes vascular compression syndromes of the eighth CN difficult to understand.…”

“…[6][7][8][9]16 In their 2 articles involving a retrospective analysis of patients who had undergone surgical decompression, Ryu et al 7,8 proposed the concept of neurovascular compression syndrome of the eighth CN and recommended early decompression before irreversible impairment of the nerve function occurred. Similarly, Nowé et al 6 stated that nonpulsatile tinnitus may result from a microvascular compression at the cisternal segment of the eighth CN and showed a correlation between the clinical presentation of nonpulsatile tinnitus (high and low pitch) and perceptive hearing loss. Nowé et al 6 and De Ridder et al 9 found a strong correlation between the presence of vascular loops in the IAC seen on MR imaging and pulsatile tinnitus.…”

“…4,5 Compression of the eighth cranial nerve (eighth CN) by vascular structures has been proposed as a cause of tinnitus. [6][7][8][9][10] However, controversial results have been reported in the medical literature about the relationship between neurovascular compression of the eighth CN and neuro-otologic symptoms. [11][12][13][14] The purpose of our study was to assess the correlation between the presence of a vascular loop and its contact with the eighth CN in the cerebellopontine angle (CPA) and ipsilateral symptoms of unexplained tinnitus by using a 3D fast imaging employing steady-state acquisition (3D-FIESTA) sequence, which is an MR imaging technique that provides good contrast between CSF, nerves, and vessels.…”

A Compartment-Based Approach for the Imaging Evaluation of Tinnitus

“…However, subjects with pulsatile tinnitus have an 80-fold higher chance of having a contacting vascular loop than patients with nonpulsatile tinnitus. 40,41 The pathophysiologic role of these loops in tinnitus is unclear.…”