Labyrinthine infarction

Douglas J Lanska MD FAAN MS MSPH (Dr. Lanska of the Great Lakes VA Healthcare System and the University of Wisconsin School of Medicine and Public Health has no relevant financial relationships to disclose.)
Originally released August 15, 2000; last updated January 29, 2017; expires January 29, 2020

This article includes discussion of labyrinthine infarction and labyrinthine ischemia. The foregoing terms may include synonyms, similar disorders, variations in usage, and abbreviations.

Overview

The author explains the clinical presentation, pathophysiology, prevention, diagnostic work-up, and management of labyrinthine infarction. Although a variety of conditions can cause labyrinthine ischemia, labyrinthine infarction most commonly occurs in the setting of thromboembolic disease of the anterior inferior cerebellar artery or the basilar artery, and almost all of these cases present with acute prolonged vertigo and vestibular dysfunction of peripheral, central, or combined origin. Unlike labyrinthine dysfunction from a viral cause, the most common pattern of dysfunction with labyrinthine infarction includes a combined loss of auditory and vestibular function. Canal paresis associated with posterior circulation ischemic stroke, usually within the territory of the anterior inferior cerebellar artery, typically normalizes within 5 years.

Key points

 

• The clinical manifestations of ischemia of the inner ear can include acute vertigo, nausea and vomiting, imbalance, unilateral deafness, tinnitus, and canal paresis.

 

• A variety of conditions can cause labyrinthine ischemia, including thromboemboli of the posterior circulation, fat emboli, thromboangiitis obliterans, migrainous infarction, decompression illness, hyperlipidemia, macroglobulinemia, sickle cell disease, leukemia, polycythemia vera, and other causes of hypercoagulation or hyperviscosity.

 

• Most commonly, labyrinthine infarction occurs in the setting of thromboembolic disease of the anterior inferior cerebellar artery or the basilar artery.

 

• Unlike labyrinthine dysfunction from a viral cause, the most common pattern of dysfunction with labyrinthine infarction includes a combined loss of auditory and vestibular function.

 

• If neurologic symptoms are absent, it is more likely that viral labyrinthitis is the cause of acute audiovestibular symptoms, especially in the absence of abnormal findings on imaging.

 

• Although acute unilateral hearing loss and hypofunction of the vestibulo-ocular reflex typically indicate labyrinthine dysfunction, cerebellar findings should not be overlooked, including direction-changing positional nystagmus, which suggests dysfunction of the posterior cerebellar vermis.

 

• Small infarcts of the brainstem or cerebellum can produce vertigo without other localizing neurologic symptoms: roughly 1 in 10 patients with an isolated cerebellar infarction present with vertigo, nystagmus, and postural unsteadiness mimicking acute peripheral vestibular disorders.

 

• The blood supply to the inner ear flows through only 1 main blood vessel, the internal auditory artery (or labyrinthine artery), which typically originates from the anterior inferior cerebellar artery.

Historical note and terminology

A series of important experimental studies in animals in the 1950s established that (1) cochlear function is extremely sensitive to anoxia, and electrical activity deteriorates within 60 seconds of interruption of blood flow; (2) cochlear function may return to normal if blood flow is restored within 8 minutes of complete obstruction but not if blood flow is interrupted for more than 30 minutes; (3) permanent obstruction of either the inferior cochlear vein or the internal auditory artery produces rapid loss of function and histologic changes; (4) external hair cells and the ganglion cells of the cochlea are particularly vulnerable to arterial obstruction, whereas the vestibular end organs are relatively resistant; (5) venous obstruction produces early epithelial edema, followed by hemorrhage into the epithelium and perilymphatic and endolymphatic spaces, hair cell damage with secondary ganglion cell degeneration, and later fibrosis and ossification; (6) arterial obstruction produces more rapid and severe damage than venous obstruction; (7) arterial obstruction produces early histologic changes in hair cells within 30 minutes, followed in a few hours by extensive necrosis including the supporting cells without hemorrhage and ultimately severe fibrosis and ossification by 6 months; (8) several patterns of end-organ involvement were observed with arterial obstruction corresponding to different arterial distributions within the inner ear; and (9) patterns of end-organ damage with arterial obstruction included involvement of all cochlear and vestibular end organs, involvement of the cochlea, saccule, and the posterior canal ampulla, or involvement of the utricle, part of the saccule, and the anterior and horizontal canal ampullae, but without cochlear involvement (Fernandez 1955; Kimura and Perlman 1956a; Kimura and Perlman 1956b; Kimura and Perlman 1958a; Kimura and Perlman 1958b; Perlman and Kimura 1957; Perlman and Fernandez 1959).

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