Abstract
Perilymphatic fistula is usually associated with sudden or fluctuating sensorineural hearing loss. We present a case of whiplash injury in a patient who showed conductive hearing loss at low frequencies due to a perilymphatic fistula occurring in the round window. Although no middle ear pathology was found, the symptoms and laboratory findings were mimicking the so called “third mobile window” phenomenon, but without the presence of inner ear dehiscence. Following early surgical exploration with patching of the round window the hearing was restored and the patient was free of symptoms.
1
Introduction
Perilymphatic fistula (PLF) is a condition where there is an abnormal communication between the middle and inner ear, which allows the escape of perilymphatic fluid into the middle ear. Most PLFs are located in the round or oval window as a rupture in the membranous labyrinth . Causes of PLF could be iatrogenic (e.g. after stapedectomy), erosive (cholesteatoma, tumor), congenital or traumatic ; in traumatic cases, the mechanisms involved are usually abrupt change of cerebrospinal fluid pressure (physical exertion, e.g. heavy lifting, delivery, bending over) or middle ear pressure (barotraumas, nose blowing, sneezing, ear slap) . Perilymphatic fistula secondary to head trauma is relatively uncommon, especially without temporal bone fracture .
It has been reported that traumatic PLF is usually associated with sudden or fluctuating sensorineural hearing loss . We present a case with PLF in the round window who showed an air–bone gap at low frequencies, compatible with a conductive hearing loss.
2
Case report
A 40-year-old woman presented to the ENT clinic because this morning, as she was holding her baby in the arms, this baby suddenly had lifted his head hitting with force the underside of the mother’s jaw. Then, the mother described that she saw everything black for a few seconds, but being conscious to leave her baby on the ground. She noted an immediate marked aural fullness and tinnitus on the left associated with unsteadiness.
A bedside ENT examination revealed lateralization to the left ear on Weber’s test and the Rinne test was negative on the left side; the eardrum was intact on both sides. The nose pinched Valsalva was positive eliciting a left beating nystagmus with dizziness and transient loss of balance; otherwise, on Frenzel glasses no spontaneous nystagmus was found. The patient also reported that she could hear her own footsteps and a tuning fork placed on the medial malleolus of her left ankle was heard loudly in the left ear.
Tympanogram was normal and acoustic reflexes were present on both ears. A pure tone audiogram showed a low-frequency conductive hearing loss in the left with air–bone gap reaching 40 dB and negative bone-conduction thresholds (− 10 to − 5 dB) at 250 and 500 Hz ( Fig. 1 A ); at 2000 and 4000 Hz a slight sensorineural hearing loss was noted. The vestibular evoked myogenic potentials (VEMPs) testing showed a lowered threshold (100 dB SPL) on the left side. A CT scan of the temporal bones excluded temporal bone fracture, ossicular fracture or dislocation, or effusion in the tympanic cavity.
