We present two clinical cases to illustrate that we are currently in a position to  accurately locate the site of the lesion in vestibular system diseases thanks to advances  in complementary tests.

• Vestibular syndrome

• Downbeating nystagmus

• Upbeating nystagmus

• vHIT

Carmona S, Grinstein G, Weinschelbaum R, Zalazar G (2018) Topodiagnosis of the Inner Ear: Illustrative Clinical Cases. Ann Otolaryngol Rhinol 5(1): 1201.

HIT: Head Impulse Test; Vhit: Video Head Impulse Test; VNG: Videonystagmography; Y.O.: Years Old MRI: Magnetic Resonance Imaging; VVOR: Visual Vestibulo Ocular Reflex; VOR: VestibuloOcular Reflex; BPPV: Benign Paroxysmal Positional Vertigo

In recent years, we have witnessed a progress in the study of the vestibular system. Thanks to the development of new examination techniques and the improvement of existing ones, we have been able to accurately locate the lesion within this system. We present two clinical cases to illustrate what we have just mentioned.

Case 1

Male, 18 y.o.

Date of consultation: 02/07/17

Patient who presents left ear tinnitus and hearing loss, andanacute vestibular syndrome with permanent vertigo accompanied by neurovegetative symptoms two days before consultation.

During the first 24 hours after onset of symptoms, he presents sudden deafness in the left ear audiogram (Figure 1).

Figure 1: Audiogram with left sudden hearing loss.

Intratympanic dexamethasone is administered, he was medicated with pentoxyphylline and betahistine at another center.

During the first week he continues experiencing dizziness and vertigo that lasts seconds upon positional changes. These symptoms are still present at the moment of the first consultation at our Department.

Cerebellopontine angles and brain MRI show no evidence of disease.

Physical examination: Lateropulsion to the left with Romberg, nystagmus post head shaking to the right, bedside HIT does not show refixation saccade.

02/21/17 - two weeks later

vHIT are performed

vHIT shows drop in the response of the left posterior semicircular canal (Figure 2).

Figure 2: vHIT shows a drop in the response of the left posterior semicircular canalv.

A downbeat nystagmus after 30 seconds latency is observed, with the concomitant vertigo sensation when Dix-Hallpike maneuver to the left with Video Frenzel is performed.

Epley maneuver is performed with good outcome.

03/28/2017 - one month later

Control under Frenzel video without nystamus.

Patient refers an improvement in his symptoms.

He can perform his normal daily activities.

Case 2

Female patient, 53 y.o., who suffers from an acute vestibular syndrome that forces her to stay in bed for 48 hours eleven months before consultation. Since then, and for several weeks, she feels as if “her head goes to the right”. She also experiences instability and positional dizziness.

Current physical examination shows a spontaneous vertical upbeat nystagmus; when fixation is removed (video 1, 2: Postural 0°) the nystagmus accentuates slightly with positional changes (video 3, 4: Postural 30° and left turn and right turn), the rest of the neuro-otologic and neurologic examination was normal, hearing is preserved and symmetric.

Supplementary studies: a brain and ears MRI with Gadolinium was performed with normal results.

vHIT shows a pure drop of the right anterior semicircular canal, with covert saccades, a significantly marked interaural asymmetry (Figure 3),

Figure 3: vHIT shows a pure drop of the right anterior semicircular canal.

optical reflexes including VVOR, VOR and saccades were completely normal.

Audiogram was normal according to age (Figure 4).

Figure 4: Audiogram showing presbycusis.

The combination of vestibular symptoms and sudden hearing loss is not unusual [1], but its mechanism is unclear. Recent inner ear circulation compromise modelsshow that a cochleo-vestibular artery compromise would cause a selective compromise of the posterior semicircular canal and of the acute frequencies (Figure 5) [2].

Figure 5: Model that show that a cochleo-vestibular artery compromise would cause a selective compromise of the posterior semicircular canal and of the acute frequencies.

In the first case, given the patient’s age and the fact that he has no history of vascular diseases, a viral etiology [3] must be considered, since this mechanism can produce anacusia and a selective compromise of the vestibular nerve inferior division which is shown by a drop of the posterior semicircular canal VOR gain with corrective saccades.

The Video Head Impulse Test is a useful tool, associated in this case to the audiometric data for the correct diagnosis of the inner ear sensors

The presence of vertical downbeat nystagmus with latency would suggest an apogeotropic variant of the posterior Figure 4 semicircular canal [4]which is highly probable given the response to Epley maneuver.

Another possibility is a selective damage of the posterior semicircular canal macula.

A central vestibular compromise in the loop that connects the vestibular nuclei with the archicerebellum should always be ruled out in the presence of positional downbeat nystagmus, given the fact that selective inhibition over the anterior semicircular canal is weaker than over the posterior one

Recent publications [4-6]. CITAR EL PAPER NUEVO CON ASPRELLA consider the existence of anterior semicircular canal BPPV highly unlikely, yet, a dysfunctional misbalance between both vertical canals may lead, theoretically speaking, to a downbeat nystagmus which is seen only with a change in position [7].

In the second case, we conclude that the patient suffered from neuritis of the right vestibular nerve superior division with a selective compromise of the anterior semicircular canal.

In this case, the Video Head Impulse Test makes it possible to perform a topodiagnosis consistent with the clinical picture and evolution.

Our greater physiopathological knowledge makes it possible for us to study the inner ear function from a neurophysiological point of view, to rule out a central compromise and to anticipate the evolution of patients with cochleo-vestibular compromise such as the one in this case.

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2. D’Albora R, Civizonas M, Araujo R, Fernández S. Irrigación e inervación del oído interno, su aplicación clínica. Pag 3-12. In Carmona S, Kattah J. Manejo del syndrome vestibular agudo, Akadia editorial, Buenos Aires. 2017.

3. Jeong SH, Kim HJ, Kim JS. Vestibular neuritis. Semin Neurol. 2013; 33: 185-194.

4. Vannucchi P, Pecci R, and Giannoni B. Posterior Semicircular Canal Benign Paroxysmal Positional Vertigo Presenting with Torsional Downbeating Nystagmus: An Apogeotropic Variant. Int J Otol. 2012; 9: 413603.

5. Welgampola MS, Akdal G, Halmagyi GM. Neuro-otology- some recent clinical advances. J Neurol. 2017; 264: 188-203.

6. Carmona S, Zalazar G, Weisnchelbaum R. Down beating Nystagmus in Benign Paroxysmal Positional Vertigo: an Apogeotropic Variant of Posterior Semicircular Canal. Curr Opinion Neurological Sci. 2017; 6: 301-305

7. Carmona S, Goldstein JN, Kattah JC, Kothari S. Online appendix: acute dizziness and vértigo interactive case unknowns. In Newman-Toker DE, Kerber KA, Meurer WJ, Omron R, Edlow JA. Emergency Neurootology: diagnosis and management of acute dizziness and vértigo. Neurologic Clinics. 2015; 33: 577-600.