2Otoendoscopy and Otomicroscopy of the Diseased Ear

FWhy look before you operate

Every ossiculoplasty begins long before the patient is anaesthetised, at the moment the surgeon first brings a magnified light into the ear canal. The unaided eye and a head-mirror can tell you that a drum is perforated or that an ear is discharging, but they cannot tell you whya chain has failed or what reconstruction the middle ear will accept. Magnified examination — under the operating microscope, the rigid endoscope, or both — is the single richest source of that information, and it is available in the clinic, before any incision, at almost no cost and no risk. A careful preview frames the entire operative plan: whether disease must be cleared before the chain is rebuilt, whether reconstruction can be done in one stage or must be staged, and what prostheses to have on the trolley.

The diseased ear hides its troubles. A drum can look almost intact while behind it the long process of the incus has dissolved to a thread; a shallow attic dimple can be the visible mouth of an invasive cholesteatoma; a chalky plaque can mark a chain silently cemented to its canal. The examiner’s task is to read these surface signs and infer the hidden state of the middle ear cleft. Done well, this magnified inspection previews what will be met at tympanotomy and converts surprises into expectations. Done poorly, it leaves the surgeon improvising in a bloody field with the wrong prostheses unopened on the back table. The purpose of this module is to make that preview deliberate: to set out what the microscope and endoscope each show, what the cardinal signs of the diseased ear mean, and how those signs translate into a reconstruction strategy.

FTwo instruments, two lines of sight

Otomicroscopy, performed with the binocular operating microscope down an aural speculum, has long been the reference standard for inspecting the external canal and tympanic membrane. Its strengths are real and worth naming: it gives a true stereoscopic, three-dimensional image, it leaves both hands free so the examiner can clean wax, lift a crust, or suction debris while looking, and it is the instrument the surgeon already uses at every stage of the operation. Its limitation is geometric. The microscope sees only in a straight line: anything behind a bony overhang — the scutum over the attic, the bulge of the facial canal, the lip of a retraction pocket — falls outside its view, and no amount of repositioning the speculum can make light bend around a corner.

Otoendoscopywith rigid 0° and angled (30° or 45°) endoscopes answers exactly that limitation. The endoscope is introduced transcanal, and its angled tip and wide field look around cornersinto the very recesses the microscope misses: the epitympanum above the scutum, the facial recess, the protympanum and eustachian-tube orifice, the hypotympanum, and — most importantly — the sinus tympani of the posterior retrotympanum [1999, 2010]. The price is twofold: the standard endoscope gives a monocular, two-dimensional image, so depth must be inferred, and it occupies one hand, leaving only the other to work. The two instruments are therefore complementary rather than rivals: the microscope for stereoscopic, two-handed work in the line of sight; the endoscope for a wide, around-the-corner survey of the hidden anatomy [2010].

The practical consequence for the trainee is to treat the two as a sequence, not a choice. Begin under the microscope to clean the canal and define the drum in three dimensions; then, when an attic pocket, a posterior recess, or a suspected residuum cannot be brought into the straight line of sight, reach for the angled endoscope to inspect what the microscope cannot reach. In modern practice this same logic carries into the operation, where intraoperative endoscopy is used to check the recesses for residual disease after microscopic clearance.

TReading the diseased drum

A disciplined examination interrogates the tympanic membrane region by region. Start with the obvious: the size, site, and margins of any perforation. A dry, central perforation of the pars tensa with a healthy, glistening promontory visible through it is the picture of quiescent mucosal (tubotympanic) chronic otitis media — a comparatively favourable field. A marginal perforation, by contrast, reaching the bony annulus, removes the barrier that normally keeps squamous epithelium out of the middle ear and carries a higher risk of cholesteatoma.

Then read the membrane itself. Retraction— a drum drawn medially by chronic negative pressure — is the cardinal sign of eustachian-tube dysfunction and the seedbed of cholesteatoma. Retraction of the pars flaccida (the attic) is especially significant because pockets there tend to accumulate keratin and progress to attic cholesteatoma. Tympanosclerosis, seen as chalky white plaques in the drum or submucosa, records previous inflammation and warns that the ossicular chain may be tethered or frankly fixed, so that an air-bone gap may reflect fixation rather than discontinuity. Finally, note mucosal status: boggy oedema, polyps, or granulation tissue with otorrhoea signals an active, inflamed, poorly aerated middle ear — the very environment that predicts fibrosis, prosthesis displacement, and extrusion after reconstruction [2001]. Subtle clues matter too: a sunken pars tensa, a blunted anterior sulcus, or generalised atelectasis all point to reduced middle-ear volume and negative pressure that can compromise a prosthesis postoperatively.

THunting cholesteatoma in the hidden recesses

Cholesteatoma is the disease that most often forces the hand in ossiculoplasty, both because its enzymatic and inflammatory activity destroys the incus and stapes superstructure and because reconstructing into an ear that still harbours it invites residual disease around the prosthesis. The whole point of magnified examination is to find it — ideally before operating, and certainly before deciding to reconstruct. The cardinal sign is white, flaky keratin debris collecting in a retraction pocket whose self-cleaning base cannot be confirmed. When that pocket lies in the attic, behind the scutum, the microscope shows only its mouth; the angled endoscope is the instrument that looks up and over the bony rim to see whether the fundus is clean or packed with matrix [2010].

The most treacherous territory is the posterior retrotympanum, and within it the sinus tympani— a recess that runs medial to the facial nerve and pyramidal eminence, deep and variable in extent, and largely shielded from any straight line of sight. Endoscopic anatomical studies have shown just how variable its depth is and why it is so hard to clear, and it is consistently the commonest hidden site of residual cholesteatoma after microscopic surgery [2010]. Inspecting it — and the facial recess lateral to the nerve — is a textbook indication for the angled endoscope, whether in the clinic to gauge disease extent or intraoperatively to check for residuum once the microscope has done its work. Comparative work bears this out: in children, transcanal totally endoscopic surgery cleared cholesteatoma confined to the middle ear and attic at least as completely as the two-handed postauricular microscopic approach, with no advantage demonstrated for the microscope in these limited-disease ears[2020]. The reading from the literature is consistent — the endoscope’s value is access to recesses the microscope cannot survey.

TInferring ossicular erosion

Much ossicular pathology is confirmed only by palpation at tympanotomy, but the experienced examiner can infer a great deal from the surface. Through a translucent or retracted drum, a foreshortened or medialised malleus handle may be visible, hinting at retraction or fixation; an absent or eroded long process of the incus may be glimpsed where the lenticular region should meet the stapes; and in total discontinuity the promontory may be seen barethrough the membrane. These signs gain their full meaning only when correlated with the audiogram. The classic pairing — an intact drum, a type A tympanogram, and a large (often 50–60 dB) air-bone gap — points to ossicular discontinuity, most often at the eroded incudostapedial junction. A similar gap behind a perforation but with an immobile chain on pneumatic testing suggests fixation instead. The incus, with its slender, poorly perfused long process, is the ossicle the reconstructive surgeon meets in trouble most often.

The examiner should also gauge the two anchors on which every reconstruction depends: the malleus handle and the stapes superstructure. Whether each is present, eroded, or absent — the very axes of the Austin classification — determines whether the chain will be bridged with cement or an interposition, spanned with a partial prosthesis (PORP) to a surviving stapes arch, or replaced down to the footplate with a total prosthesis (TORP) [1971]. None of this can be settled with certainty before the ear is open, but a thoughtful magnified examination, read alongside audiometry and high-resolution CT, lets the surgeon walk into theatre expecting the right problem and equipped for it.

CFrom preview to a surgical plan

The clinician’s job is to convert what the magnified examination shows into decisions. Three of those decisions dominate. First, disease control versus reconstruction. If examination reveals active cholesteatoma — keratin in an attic pocket, an uncleared sinus tympani, granulation with foul otorrhoea — the governing priority is a safe, dry ear, not a closed air-bone gap. Reconstructing the chain into active disease courts residual cholesteatoma around the prosthesis and a high extrusion rate, so eradication comes first and the ossiculoplasty is commonly staged, with a planned second look and reconstruction months later once the ear is proven disease-free.

Second, single-stage versus staged reconstruction.A dry, well-aerated ear with healthy mucosa and a contained, fully cleared lesion may permit reconstruction at the same sitting; an inflamed, poorly aerated ear, or one where disease clearance leaves doubt, argues for delay. This is precisely where the magnified preview earns its keep, because the mucosal and aeration findings it reveals — oedema, atelectasis, negative pressure, the state of the remaining ossicles — are the same variables that prognostic staging systems such as the OOPS index weight when they predict hearing outcome[2001]. Third, prosthesis selection.The inferred status of the malleus handle and stapes superstructure tells the surgeon which rung of the reconstructive ladder is likely — cement or interposition for a short incus defect, a PORP onto an intact stapes arch, a TORP onto a bare mobile footplate — so the right implants are on the trolley before the drum is raised [1971].

The overarching lesson is one of correlation. No single instrument is sufficient: the microscope and endoscope are complementary, and both are read against the audiogram and the CT scan. A magnified examination that is merely glanced at yields a perforation and little else; a magnified examination that is interrogated— pocket by pocket, recess by recess, sign by sign — previews the operation, sets its sequence, and tells the surgeon what to carry into theatre. That preview is the foundation on which every subsequent decision in ossiculoplasty is built.