Vascular Loops and Neuro-Otologic Symptoms: Is There Any Correlation?

doi:10.4236/ijohns.2013.26051

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International Journal of Otolaryngology and Head & Neck Surgery, 2013, 2, 245-247

Published Online November 2013 (http://www.scirp.org/journal/ijohns)

http://dx.doi.org/10.4236/ijohns.2013.26051

Open Access IJOHNS

Vascular Loops and Neuro-Otologic Symptoms :

Is Ther e Any Correlation?

Amaya Roldán-Fidalgo*, Antonio Rodríguez-Valiente, Francisco Martín González, Mayte Pinilla,

Almudena Trinidad, Beatriz Brea Álvarez

Department of Otorhinolaryngology and Neuroradiology, Puerta de Hierro University Hospital, Madrid, Spain

Email: *[email protected], [email protected], [email protected], pin[email protected], [email protected],

[email protected]

Received September 25, 2013; revised October 20, 2013; accepted November 2, 2013

License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

ABSTRACT

Objective: To determine the relationship between vascular loops in the internal auditory canal and otologic symptoms.

Methods: We performed a retrospective study, with a systematic review of the literature and analyzed the magnetic

resonances imaging (MRI) of 91 patients attended in the ENT department since April to June 2013, in order to correlate

radiological findings with otologic symptoms. Results: Vascular loops were seen in the internal auditory canal of pa-

tients without clinical symptoms; however an association was found between the presence of vascular compression of

the eighth nerve displayed on MRI and the presence of sensorineural hearing loss and tinnitus. No association was

found between vertigo and vascular loops. Conclusion: The presence of vascular loops in the internal auditory canal

may be an incidental finding in MRIs of patients without clinical symptoms. However, in patients with tinnitus or sen-

sorineural hearing loss that is unexplained by other clinical pathologies, these may be correlated with the existence of

vascular loops which compress the eighth cranial nerve or contact the bone wall of the internal auditory canal. Further

studies involving a larger number of patients are required to accurately evaluate the association between these symp-

toms and vascular loops.

Keywords: Vascular Loop; Arterial Loop; Internal Auditory Canal; Tinnitus; Deafness; Vertigo

1. Introduction

The presence of vascular loops in the internal auditory

canal (IAC), formed by the anterior inferior cerebellar

artery (AICA), is a common finding in the systematic

study of MRIs [1,2]. Controversial results have been re-

ported in the literature about the relationship between

vascular compression of the vestibular nerve trunks and

neuro-otologic symptoms, and some authors have sug-

gested that compression of the nerve might be the origin

of otherwise unexplained as hearing loss, tinnitus, neu-

rological symptoms and vertigo [3-10].

In order to determinate the relationship between vas-

cular loops and otologic symptoms, we performed a ret-

rospective study in patients attended in the ENT depart-

ment.

2. Materials and Methods

We performed a retrospective study with a systematic

review of the literature and we studied the MRIs of 91

patients attended in our ENT department over a three

months period (April to June 2013), looking for the

presence of vascular loops in the internal auditory canal.

In patients with vascular loops in the MRI we collected

data related to neuro-otologic symptoms (hearing loss,

tinnitus, vertigo and hemifacial spasm) from their medi-

cal history. All patients had been performed a complete

otoneurological examination with otoscopy, audiometry

and videonystagmography.

3. Results

A total of 91 MRIs of patients attended in our ENT de-

partment were analyzed, 20 MRIs displayed vascular

loops in the IAC.

We collected data from the medical history of the 20

patients with vascular loop in the MRI, related to neuro-

otologic symtoms. We found 12 patients with otologic

symptoms, three patients with IAC vascular loops in the

*Corresponding author.

A. ROLDÁN-FIDALGO ET AL.

246

asymptomatic ear, and five patients without clinical

symptoms.

Out of 12 patients with otologic symptoms, a vascular

compression of the eighth cranial nerve on MRI (Figure

1(a)) was presented in six patients, four patient reported

sensorineural hearing loss, and two patients continuous

tinnitus. A vascular loop in con tact with the bone wall of

the internal auditory canal (Figure 1(b)) was presented

in six patients; all of th em reported the presence of tinni-

tus resistant to standard medical treatment (Table 1).

None of the patients had vertigo or hemifacial spasm.

4. Discussion

There is an apparent discrepancy between the frequent

finding of vascular loops penetrating the internal auditory

canal in anatomic studies (12% by post-mortem dissec-

tions [2], 7% by computed tomography cisternography

[11], 14% - 34% by magnetic resonance imaging (MRI)

[12,13] in the normal population), and the infrequency of

ear symptoms associated with the presence of the loops.

Some explanations of this discrepancy include the de-

velopment of symptoms when the artery elongates (con-

genital or acquired), hardens (arteriosclerosis), or be-

comes fixed to the nerve (arachnoid adhesions) and com-

presses it [14]. The space available for the facial, vesti-

bulocochlear nerve and AICA loop in the internal audi-

tory meatus is minimum [15], creating an anatomic sus-

ceptibility of the n erve to vascular compression dysfu nc-

tion.

Auditory symptoms may be due to a complex interac-

tion between the seventh or eighth cranial nerve and the

vascular loop, in which the loop compresses the nerve

and the nerve compromises circulation to the inner ear.

The findings of a cochlear type of hearing loss, excellent

speech discrimination and normal caloric test results

should raise the suspicion of a vascular loop [16]. A loop

in contact with the vascular wall might cause pulsatile

tinnitus by direct transmission of pulsations to the coch-

lea via the internal auditory canal (bone conduction

mechanism) [17-21]. The compression of facial nerve is

frequently, and cause hemifacial spasm [22]. The com-

pression of the auditory and vestibular nerve trunks by

vascular loops might cause sensorineural hearing loss,

tinnitus and vertigo [2 -4].

In the present study none of the 91 patients with vas-

cular loop in the IAC presented vertigo or hemifacial

spasm.

The presence of pulsatile tinnitus (50%) and sen-

sorineural hearing loss (33%) were the conditions most

frequently encountered among the patient group studied

(Table 1).

De Riddet et al. [18] and Nowe et al. [23] found that

subjects with pulsatile tinnitus were 80 times more lik ely

to have a contacting vascular loop than patients with non-

(a) (b)

Figure 1. (a) Vascular loop adjacent to the eighth cranial

nerve, in a patient with sensorineural hearing loss in the

right ear; (b) MRI with a vascular loop in contact with the

internal auditory canal in a patient with pulsatile synchro-

nous tinnitus.

Table 1. Distribution of otologic symptoms in the patients

with vascular loop in the magnetic resonance imaging.

SYMPTOMS

VASCULAR LOOP IN

THE INTERNAL

AUDITORY CANALSensorineural

hearing loss Continuous

tinnitus Pulsatile

tinnitus

Compression of the eight

nerve 4 2 -

Contact the bone wall- - 6

pulsatile tinnitus.

Chadha and Weiner [1] suggested that the presence of

unilateral hearing loss were twice more likely to have

vascular loops in the symptomatic ear than in the as-

ymptomatic ear.

In selected cases, when a vascular loop is found to be

in contact with the affected cranial nerve, and no other

cause is identified, it would seem reasonable to consider

invasive neurosurgical micro-vascular decompression

with mixed results [1,24-26]. Shredded Teflon is place in

the internal auditory canal between the cochlea and the

intrameatal vascular loop [1]. The objective is to create a

sound barrier between the walls of the internal auditory

canal an d th e lo op , an d b e tw een the lo op and th e co ch le a,

without causing too much compression on the cochlear

nerve. None patients attended in our ENT department

required neurosurgical micro-vascular decompression

due to medical control of symptoms.

5. Conclusions

In patients without associated with neuro-otologic symp-

toms, the presence of vascular loops in the internal audi-

tory canal may be an incidental finding in MRIs, how-

ever, in patients with pulsatile or continuous tinnitus, or

sensorineural hearing loss, vertigo, which is unexplained

by other clinical pathologies, it may be correlated with

the existence of vascular loops which compress the eigh th

Open Access IJOHNS

A. ROLDÁN-FIDALGO ET AL.

Open Access IJOHNS

247

cranial nerve, or facial nerve in case of hemifacial spasm,

or contact the bone wall of the internal auditory canal.

As a result of the limited number of cases and small

amount of literature found, further multicentre studies

involving a larger number of patients would be advisable

to correlate otologic symptoms with the presence of vas-

cular loops in the internal auditory canal and thereby

accurately evaluate the association between these symp-

toms and vascular loops.

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