Keywords
labyrinth - trauma - tympanic membrane rupture - perilymph - stapes surgery
Introduction
Traumatic perilymphatic fistula is not a rare event with regards to sport activities
or traffic accident. However, iatrogenic damage to the inner ear can occur following
the common use of grommets and ventilation tube insertion. Here, we describe how early
surgical management may help recover the inner ear function, despite severe damage
to this fragile structure.
Review of Literature with Differential Diagnosis
Review of Literature with Differential Diagnosis
A perilymph fistula is an abnormal communication between inner ear perilymphatic spaces
to the aerated middle ear. A wide variety of signs and symptoms as well as numerous
etiologies are associated with perilymph fistula, from congenital malformations to
accidental or iatrogenic trauma to the inner ear.[1]
[2]
[3] During the past 30 years, several cases of traumatic perilymphatic fistula have
been reported. Those include cases associated with ear cleansing, surgeries, trauma,
and blast.[2]
[3]
[4]
[5]
[6]
[7]
[8]
[9]
[10]
[11] Traumatic perilymph fistula following penetrating intravestibular ventilation tube
has yet to be reported.
Case Report
A 62-year-old woman with a past history of chronic otitis underwent a tube placement
for a right-sided posterior retraction pocket. Immediately after the procedure, she
developed severe vertigo associated with nausea and vomiting. She was discharged with
antivomiting medication, which was said to be a normal postoperative event. Four days
later she was admitted in emergency for acute vertigo. Clinical evaluation revealed
right index finger deviation and left beating nystagmus with hearing loss. Otoscopy
showed the tube in place. A temporal bone computed tomography (CT) scan was performed
and showed the transtympanic ventilation tube associated with middle ear effusion,
but bony components within the vestibule were missed ([Fig. 1]). She was admitted in the otolaryngology department and managed medically. Her condition
improved, and she was discharged 3 days later.
Fig. 1 High-resolution temporal computed tomography (with 0.6-mm slice thickness) in axial
(A) and coronal reconstruction (B). The middle ear is filled with fluid; the ossicular
chain is not recognizable. There is no pneumolabyrinth, but careful examination may
have revealed high-density components within the vestibule (A, arrow). The tube is
seen in the external canal (B, arrowhead).
One week later, she was referred to our tertiary referral center complaining of progressive
right-sided hearing loss associated with severe vertigo. She presented with right-sided
vestibular impairment and positive Hennebert sign on the right ear. On otoscopic examination,
she had tympanic membrane retraction with the ventilation tube inserted in the posterosuperior
quadrant with pulsating waterlike fluid leaking through the tube. The audiometry showed
a right-sided, severe mixed hearing loss ([Fig. 2]). A new high-resolution temporal bone CT scan clearly showed a right pneumolabyrinth
within the vestibule and the semicircular canals, sparing the cochlea, associated
with the ventilation tube penetrating the vestibule through the oval window ([Figs. 3] and [4]). She was diagnosed with right iatrogenic stapes trauma with perilymph fistula and
urgently taken to the operating room. The long process of the incus as well as the
stapes posterior crura and the posterior and inferior part of the footplate were fractured.
The rest of the footplate was intact. The tube was penetrating the vestibule in the
posterior and superior part of the stapes footplate. The tube was gently removed,
and the vestibule was refilled with saline solution. The vestibule was sealed with
perichondrium and maintained with fibrin glue; the whole montage was stabilized using
a Silastic (Dow Corning, USA) sheet positioned from the facial canal to the promontory.
The tympanic membrane was repaired using underlay tympanoplasty with cartilage. The
ossicular chain was not reconstructed.
Fig. 2 Right-ear pure tone audiogram performed 1 week after discharge from postemergency
hospitalization showing severe mixed hearing loss. Dotted line: bone conduction; plain
line: air conduction.
Fig. 3 Second computed tomography scan. The presence of air within the inner ear space (arrowhead)
permits the visualization of the tube that penetrates into the vestibule (arrow).
Fig. 4 Second computed tomography scan, coronal view. The pneumolabyrinth extended into
the vestibule and the superior and lateral canals (arrows) but did not extend into
the cochlea (arrowhead) and might have explained both the conservation of the auditory
function up to the 2 weeks after injury as well as the initial recuperation of hearing
function after the surgery.
In the immediate postoperative period, the patient still presented positional dizziness
as well as a left-sided beating nystagmus. Bone conduction auditory testing at postoperative
day 2 showed marked improvement of the right-side thresholds ([Fig. 5]). The patient was discharged 5 days after surgery. On day 12 after surgery, she
suddenly complained of worsening hearing loss and severe tinnitus. The pure tone average
(PTA) showed complete anacusis on the right ear ([Fig. 5]). No revision surgery was indicated. Treatment with vestibular rehabilitation was
introduced and helped dispel the dizziness within a 6-month period of time.
Fig. 5 Right-ear pure tone audiogram done 4 days (A) and 12 days (B) after surgical intervention.
(A) Note the hearing improvement in bone conduction. (B) Complete anacusis occurred
12 days after the surgery. Dotted line: bone conduction; plain line: air conduction.
Abbreviations: RE, right ear; LE, left ear.
Discussion
Our case is singular for the three following points: the erroneous placement of a
tube under general anesthesia; the missed diagnosis in the emergency setting; and
the relative conservation of the cochlear function despite severe trauma to the labyrinth.
This is, to our knowledge, the first direct penetration of an aeration tube into the
vestibule. We found another case of labyrinthine injury following tube insertion,
due to gradual bony erosion of the osseous labyrinth as a long-term complication.[12]
First, the trauma undoubtedly followed immediate misplacement of the tube, in the
posterosuperior quadrant of the drum. This is clearly a wrong procedure, demonstrating
an insufficient and inappropriate education. Second, the workup performed in the emergency
room was inadequate. Both the clinical history and the CT scan clearly should have
stressed the suspicion of trauma to the inner ear. The presence of a pneumolabyrinth
on a high-resolution CT scan of the temporal bone is pathognomonic of perilymphatic
fistula.[8]
[10]
[11]
[12] This inappropriate diagnosis highlights the necessity of appropriate education in
trauma-related injuries. Education, reconfiguration of trauma services, and better
provision of neurocritical care facilities do improve the quality of care to trauma-related
patients.[13]
[14] Although the initial CT scan was difficult to interpret, the high-density spots
within the vestibule should have drawn attention to a possible severe inner ear trauma
([Fig. 1A]). High-resolution CT scan of temporal bone is mandatory in such a scenario.[5]
[6]
[ 15]
[16]
[17] Finally, it was unexpected that the pneumolabyrinth did not extend into the cochlea
([Fig. 4]), but we think that the preservation of the cochlear fluid explains the conservation
of the sensorineural component of the hearing. The protective role of the valve of
Bast (that closes the utricular duct) explains this unusual situation: decreasing
pressure in the whole endolymphatic system collapses the ductus reuniens and causes
closure of the valve.[18]
[19]
[20]
[21] It is plausible that the reopening of the valve of Bast after the repair of the
fistula may have let the remaining air bubbles t diffuse within the cochlea and induce
total auditory loss.
Final Comments
Tympanic tubes should be inserted in all cases in the infero- or anteroinferior quadrant
of the drum, and this procedure should be performed under local anesthesia. In cases
of suspicion of traumatic damage to the stapes footplate, surgery should be performed
as fast as possible following trauma. Although the outcome of vestibular symptoms
is good, regardless of lesion, severity, or intervention,[3]
[6] hearing outcome is more unpredictable. We agree with Hidaka et al on the following
predictive factors of hearing preservation in a scenario of pneumolabyrinth: (1) early
intervention within 15 days; (2) pneumolabyrinth limited to semicircular canals and
vestibule; (3) existence of stapes lesion.[3] According to Tsubota et al, the value of the bone conduction thresholds should be
considered a significant prognostic factor as well.[6]
