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 6-year-old is brought to clinic by his father ahead of an operation planned for later in the year. The referral came through the school: his teacher has noticed that he always takes the same seat at one end of the front row, and that he turns his head whenever the classroom gets loud. His father would like to know whether hearing is behind any of that before decisions get made. He is otherwise a healthy boy who has hit every developmental milestone, with speech and language exactly where they should be.
Clue 2
The audiogram is the first surprise. Pure-tone testing gives air and bone conduction thresholds of 5 to 10 dB HL right across 250 to 8000 Hz, in both ears, with no air-bone gap on either side. Whatever is going on, his hearing is measurably normal — and it was worth measuring rather than assuming, on both sides.
Clue 3
The reason for the referral is visible from across the room and has been there since the day he was born. The external ear on the right is small and malformed: the helix and antihelix are simply not there, and what remains is a rudimentary concha and a lobule. The ear on the left is entirely normally formed.
Clue 4
What matters next is what lies behind the malformed part. The right ear canal is open and of normal calibre — comfortably wider than 4 mm, so neither narrowed nor closed off — and the eardrum can be followed round its whole circumference and looks entirely normal. Tympanometry is type A on both sides, with normal middle-ear pressure and compliance.
Clue 5
Imaging done for the surgical planning confirms it from the inside. High-resolution scanning of the temporal bones shows a normally formed canal on the right, a well-aerated middle ear of normal dimensions, and an intact chain of malleus, incus and stapes, with no atresia plate anywhere. The rest of the examination is equally quiet: no facial asymmetry, no small or receding jaw, no eye anomaly, no vertebral abnormality, and nobody else in the family affected.
Diagnosis
The finding here is visible from the doorway, so the interesting work is not spotting it but deciding what it does and does not mean. The right external ear has been small and malformed since birth — no helix, no antihelix, just a rudimentary concha and a lobule — while the left is normal. That is the diagnosis, and it sits on a graded spectrum running from slight diminution of the ear to its complete absence. It is one of the commoner congenital differences of the head and neck, affecting 1.8 to 3.5 per 10,000 births in the United States, one-sided in 77 to 93 percent of cases, right-sided about 60 percent of the time and about two and a half times commoner in boys, all of which this child matches. The part worth getting right is the separation from closure of the ear canal, which is the condition that most often travels with it. The two are genuinely different structures, and here the canal is open and of normal calibre — comfortably wider than 4 mm — with the eardrum visible round its whole circumference, and the scan confirms a normally formed canal, an aerated middle ear and an intact ossicular chain with no atresia plate. That distinction is not academic. A closed or nearly closed canal produces a hearing loss of 40 to 60 dB, close to the ceiling for a purely conductive problem, and it is closure that most often accompanies the two most severe grades of the malformation. His audiogram shows the consequence of having an open canal: thresholds of 5 to 10 dB HL in both ears with no air-bone gap. So the honest answer to his father is that the ear looks different but hears normally, and the classroom seat is a habit rather than a deficit. Two practice points sit underneath this. The good ear was measured rather than assumed, which is the rule for any one-sided problem, and the imaging was deliberately deferred until school age and an actual surgical plan, rather than being done in infancy when it would have added radiation without changing anything.
The explanation and decisive case findings were checked against the source below.
Open the clinical referenceFor education and entertainment only. This fictional case is not medical advice and does not replace supervised clinical training, diagnosis, or treatment.
