Acute peripheral vestibulopathy, of which the chief complaint is positional vertigo, comprises benign paroxysmal positional vertigo (BPPV), labyrinthitis, labyrinthine fistula, and cerebellopontine angle tumors. Since the typical presentation of labyrinthine fistulas may be sensorineural hearing loss, positional vertigo, or disequilibrium, it is often difficult to distinguish from BPPV or Meniere's disease. Herein we report a 61-year-old female patient with typical symptoms and signs attributable to geotropic type variant of the lateral semicircular canal BPPV on the left side, who eventually was confirmed as having a labyrinthine fistula from chronic otitis media with cholesteatoma on the left side. This is another case where, even in the presence of isolated vertigo showing typical findings of acute peripheral vestibulopathy, other otologic symptoms and signs must not be overlooked.
The most common peripheral vestibulopathies diagnosed from positional vertigo may include benign paroxysmal positional vertigo (BPPV), labyrinthitis, and acute vestibular neuritis, and less commonly labyrinthine fistula or cerebellopontine angle tumors.
A 61-year-old female patient was admitted to the emergency unit with the complaint of 2 days' dizziness of whirling nature accompanied by nausea and vomiting. The patient had medical history of hypertension and diabetes mellitus. Bedside neurologic examination revealed otherwise nonspecific. Brain diffusion weighted image (DWI) for the differential diagnosis of a central pathology was normal. On otoscopic examinations, normal right tympanic membrane was seen, but purulent ear discharge was filling the left external ear canal. The patient had been feeling a loss of hearing in her left ear for quite a long time and had been visiting a local otorhinolaryngologic clinic for several months diagnosed and treated for chronic external otitis in the left ear. The patient showed spontaneous, right-beating horizontal nystagmus (6.36 d/s). There was no gaze-evoked nystagmus, and head thrust test was normal. Left-beating horizontal nystagmus (9.70 d/s) was noted after head shaking. Dix-Hallpike test to either side provoked geotropic horizontal nystagmus, but the nystagmus was stronger on the left side (21.23 d/s on the left side compared to 15.00 d/s on the right) and so was the degree of symptoms. Geotropic direction-changing horizontal nystagmus was demonstrated on both sides during the supine roll test. The intensity of the nystagmus on both sides was comparable showing 17.71 d/s on the right side and 17.03 d/s on the left side. The latency and duration of positional nystagmus were 2 and 29 seconds, respectively on the right side, and 3 and 30 seconds, respectively on the left side. On the head bending nystagmus or lying-down nystagmus test, left-beating horizontal nystagmus (7.00 d/s) on the head bending nystagmus test and right-beating horizontal nystagmus (14.93 d/s) on the lying-down nystagmus test was demonstrated, respectively (
At the next follow-up visit, the patient still complained of a positional vertigo aggravated on a leftward head turn, despite the therapeutic maneuver. A neurootologic examination revealed weak spontaneous, right-beating horizontal nystagmus. After head shaking, the horizontal nystagmus was seen to beat to the left. The patient was negative for positional nystagmus from the Dix-Hallpike test and supine roll test, but left-beating horizontal nystagmus on the head bending nystagmus test and right-beating horizontal nystagmus on the lying-down nystagmus test was demonstrated, respectively. From these atypical nystagmus patterns, a thorough examination of the ear was undertaken, where keratinous debris and inflammatory polyps were hidden behind the purulent material blocking the left external auditory canal. The keratinous debris was cleared and polypoid tissues were removed for tissue pathology, after which the patient was sent for the TBCT. On the TBCT, the left middle ear cavity was mostly occupied with soft tissue eroding all the ossicles as well as the bone overlying the lateral semicircular canal and the tegmen tympani (
Under the diagnosis of left cholesteatomatous chronic otitis media with the complication of labyrinthine fistula, the patient was admitted to the hospital. The patient was instructed an absolute bed rest in a 30 degree head elevated position. A brain-blood-barrier-penetrating intravenous antibiotic and osmotic laxative were prescribed. Pure tone audiometry, taken on the day of admission, showed normal air-conduction threshold of 18 dB HL for the right ear, and a mixed hearing loss with an air-conduction threshold of 78 dB HL for the left ear (
Labyrinthine fistula is an aberrant connection between the perilymph-filled inner ear and air-filled middle ear, of which the perilymph leak results in pathology of the vestibule and the cochlea.
In this case, we initially suspected the patient to have a central pathology because of the inverted head shaking nystagmus beating to the opposite direction from the spontaneous nystagmus. However, no central lesions were observed on the brain DWI. On both the Dix-Hallpike test and supine roll test in the emergency unit, substantial geotropic direction-changing horizontal nystagmus was provoked. Head bending nystagmus was beating to the left, and lying-down nystagmus was to the right. These findings, collectively, added on the findings of purulent otorrhea with a history of recent treatment of external otitis, misled to an initial presumptive diagnosis of the left lateral semicircular canal BPPV and external otitis. Although the nystagmus was more intense on the right supine roll compared to the left, the difference was not significant, and the symptoms were similar between both sides. Moreover, the head bending nystagmus was seen to beat to the left, leading to the impression of the lateral semicircular canal BPPV on the left side rather than the right.
The nature of the nystagmus pattern in this patient with labyrinthine fistula mimicking the typical positioning nystagmus of the left semicircular canal BPPV requires some explanation. Subtle movements of the cholesteatoma following positional changes of the head may affect pressure changes in the area of the fistula, which in turn influence the change in the direction of the endolymphatic flow. When the head was turned 90 degrees to the left during the initial examination in the emergency unit, the cholesteatoma might have leaned closer to the left semicircular canal creating a positive pressure on the membranous labyrinth. Hence, a utriculopetal endolymphatic flow causing a utriculopetal deviation of the cupula in turn, leads to an excitatory stimuli creating a left-beating geotropic horizontal nystagmus in accordance with Ewald's second law (
Most acutely vertiginous patients are easily diagnosed with otologic pathologies such as BPPV, Meniere's disease or acute vestibular neuritis based upon patient's symptoms and simple audio-vestibular workups. But we experienced a misdiagnosed dizzy patient by paying less attention to physical findings and being presumptive on initial video-oculographic results. Since the fistula test is of little value in the diagnosis of labyrinthine fistula, negative test results might have added to the missed initial diagnosis.
Results of video-oculographic recordings. A: Geotropic positional nystagmus appears when the head is turned to the right in the supine position. B: Geotropic positional nystagmus appears when the head is turned to the left in the supine position. C: Left horizontal nystagmus appears when the head bent 30 degrees forward in the neutral sitting position. D: Right horizontal nystagmus appears when the patient lies supine with the head flexed 30 degrees forward.
Axial and coronal scans of temporal bone computed tomography (TBCT). Axial (A) and coronal (B) views of TBCT reveals a soft tissue density in the left middle ear cavity. Erosion of the lateral semicircular canal by assumed cholesteatoma can be seen in the left temporal bone (white arrows).
Pure tone audiometry. A: On the first day of outpatient visit, pure tone audiometry shows conductive hearing loss in the left ear. B: Three months after operation, pure tone audiometry shows a substantial improvement in the left ear.
Hypothesis of directional changing positional nystagmus. Cholesteatoma causes an erosive loss of the endochondral bone overlying the labyrinth. A: When the head turns to the left side in the supine position, cholesteatoma may become more attached to left horizontal semicircular canal. It may evoke mass-induced positive pressure (straight arrow) of the membranous labyrinth, which causes utriculopetal flow of endolymphatic fluid. It may cause utriculopetal deviation of the cupula leading to an excitatory stimuli. B: When the head turns to the right side in the supine position, cholesteatoma may be detached to left horizontal semicircular canal. It can evoke a slight leakage of perilymphatic fluid based on the Pascal's principle, which causes utriculofugal flow of endolymphatic fluid. It may causes utriculofugal deviation of the cupula leading to an inhibitory stimuli. *slit leakage of perilymphatic fluid. Curved arrow: direction of endolymphatic flow, white arrowhead: lesion side, black arrowhead: patient's nose. C: cholesteatoma.