Clinical case review
Review the complete Audiology case, its five progressive clues, the diagnosis, and the clinical reasoning behind the answer.
Want to test yourself first? Play the original case before reading the clues and explanation below.
WhatsTheDx publishes a new Audiology case every day. Five clues, one diagnosis, and no account needed to play.
Play today's Audiology caseThese are the case findings in their original reveal order, moving from the broader presentation to the most discriminating evidence.
Clue 1
A 34-year-old joiner has spent seven weeks with his left ear stopped up. Voices on that side arrive flattened and far away, as though the room were reaching him through a closed door, and underneath it sits a ring that never lets up. In seven weeks it has not shifted by a hair.
Clue 2
Seven weeks ago a car came through a junction into his driver’s door. His head hit the door pillar, and at the roadside blood ran out of that same left ear. He was admitted overnight, and the hearing has been wrong ever since.
Clue 3
The notes from that night describe a bruise spreading over the mastoid process behind the left ear and blood sitting behind the eardrum. Seven weeks on, both have gone. Today the canal is clear — no wax, no debris, no stepoff or laceration — and the drum itself is intact, translucent and moving normally on insufflation. His face is symmetrical when he smiles and screws his eyes shut, and there is no clear or bloody fluid from the ear and none from the nose. Nothing is plugging the ear, and nothing is torn.
Clue 4
A 512 Hz fork on the upper incisors lateralises to the left — the bad side — and behind that ear the tone is louder on the bone than in the air held 2 to 3 cm from the meatus. That is a conduction problem, not a cochlear one. Formal audiometry, deliberately held back several weeks so that the swelling and the blood behind the drum had completely resolved, agrees: a wide air-bone gap on the left with bone-conduction thresholds sitting in the normal range, and a normal right ear. Then the tympanogram lands, and it is the surprise — a normal peak at a normal equivalent ear canal volume on both sides. The middle ear is aerated, the drum is sound, and the gap is still there.
Clue 5
Non-contrast high-resolution imaging at a maximum 1.5-mm slice thickness finds it. A non-displaced fracture line enters through the mastoid air cells behind the ear and runs forward across the roof of the middle ear. The dense capsule around the cochlea and labyrinth is not crossed anywhere along its length — which is exactly why bone conduction came back normal. Injuries that leave that capsule intact make up as much as 95% of these, and they take their hearing loss from hemotympanum or a disrupted ossicular chain. The blood behind the drum is long gone; the gap that is left belongs to the ossicles.
Diagnosis
This is a temporal bone fracture. The first thing the diagnosis tells you is what the head absorbed: the petrous pyramid is the densest bone in the body, and a minimum impact force of 6,000 to 8,000 Newtons is needed to fracture it — which is why more than half of these injuries in adults follow motor vehicle crashes. The signs were all present on the night: blood from the ear, and bruising spreading over the mastoid process, Battle’s sign. Seven weeks later those have faded and what remains is a conductive hearing loss that has not moved. That interval is not incidental. Formal audiometry is deliberately deferred several weeks postinjury so that oedema and hemotympanum have completely resolved, which is exactly why the tympanogram can peak normally at a normal equivalent ear canal volume while a wide air-bone gap persists: fluid and perforation are both off the table, and the fault is mechanical, behind an intact drum. Non-contrast high-resolution CT at a maximum 1.5-mm slice thickness — the gold standard — shows the fracture line, and more importantly shows what it misses. Modern classification turns on otic capsule involvement rather than the old longitudinal/transverse split, which was abandoned because most of these fractures are oblique and fit neither category, despite longitudinal historically making up 70-90% of reported cases. Otic capsule-sparing fractures are up to 95% of the total and produce mixed or conductive loss through hemotympanum or ossicular chain disruption; otic capsule-violating fractures are strongly associated with sensorineural loss and carry facial nerve palsy in about 48% of cases, against 7-12% overall. With the hemotympanum long gone, a persistent conductive loss is an indication for surgical exploration with ossiculoplasty.
The explanation and decisive case findings were checked against the source below.
Open the clinical referenceEditorial policy and correctionsFor education and entertainment only. This fictional case is not medical advice and does not replace supervised clinical training, diagnosis, or treatment.
