![]() ![]() Yet, into this bottleneck extra vascular AICA anomalies in the CPA can nudge and impose, “suspected of causing hearing loss, tinnitus, and vertigo” due to “the complex interaction between the vascular loop and eighth cranial nerve, in which the loop exerts pressure on the nerve, and the nerve compromises inner ear circulation.” The Traffic Jam: Injuries But No Fatalities Talk about a traffic jam! No room left at all now. Speaking of extras, the facial nerve also goes through that corridor, though it’s not shown in figure 1. That doesn’t leave much room for error or extras. The connecting corridor - called the internal auditory meatus - protects the blood and nerve supplies while linking the ear and vestibular system to the brain. In actuality, all three pass through a short ( about 1 mm) narrow little corridor ( about 3.5 mm) that nature drilled into the temporal bone before entering the brain proper in what’s called the cerebellopontine angle (CPA). That’s just a visual so you can see how they lie inside the skull. In Figure 1, the artery and two nerve branches appear wrapped in a little cylinder. The result is the same if the blood supply is compromised due to injury, space occupying lesion, disease, or anatomical anomaly. Notice how it “shares” a narrow passage way with the vestibular and acoustic branches of the VIII cranial nerve. Figure 1 shows the system with the blood supply shown in red. We mention that artery because it is the blood supply for the inner ear, which includes hearing and vestibular (balance) systems. Vascular loops are anatomical anomalies of the anterior inferior cerebellar artery (AICA). Blood supply to peripheral auditory-vestibular system. Vascular loops can mimic symptoms of acoustic neuroma and that’s the topic of today’s post. The MRI found no evidence of a tumor but surprisingly identified a “vascular loop” occupying some of the space reserved for the VIII nerve to emerge from the inner ear and enter the brain. An acoustic neuroma is a benign, small, slow-growing tumor on the VIII cranial nerve–technically called a vestibular schwannoma. Last August, a post in this section described unusual findings in a patient with unilateral sensorineural hearing loss and retrocochlear findings who was referred for MRI to rule out acoustic neuroma. Vascular Loops and Unilateral Hearing Loss ![]()
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