Laser stapedotomy

What the laser does

Stapedotomy is the operation for otosclerosis in which the arch of the fixed stapes is removed, a small opening (the fenestra, about 0.4–0.7 mm across) is made in the footplate, and a piston-shaped prosthesis is placed through it and attached to the incus. Laser stapedotomy is the same operation, with the same prosthesis, recovery and risks; some steps are simply done with laser light instead of fine instruments:

• Dividing the stapes tendon, the tiny tendon of the stapedius muscle.
• Vaporising the crura, the two thin legs of the stapes arch, so that the arch comes away with little force on the footplate.
• Making the fenestra, with one or several pulses, instead of with a micro-drill or a hand perforator.

Some surgeons use the laser for every step, some only for the footplate, many not at all; a thick footplate often needs a combination.

The reason is mechanical. The footplate is a thin plate of bone over the inner-ear fluid; pressing or drilling on it can crack or loosen it, and a loose (“floating”) footplate can sink towards the inner ear. A laser does not touch the bone: it is a no-touch technique.

Why the wavelength matters

A laser produces light of a single wavelength, and what it does depends on what absorbs it. Beneath the bony footplate lies perilymph, the inner-ear fluid, which is mostly water, and close beneath that the balance organs. The ideal laser would remove a small disc of bone and leave no heat, pressure or sound in the fluid. None is ideal.

• CO2 (far infrared): very strongly absorbed by water, so its energy is taken up in a thin surface layer. Delivered through the operating microscope or a flexible fibre. Widely used.
• KTP and argon (visible green and blue-green light): absorbed little by water and well by pigmented tissue; fibre-delivered. Little heating of the fluid, but light passing through the opening is not stopped by water.
• Diode (near infrared): compact, relatively inexpensive, fibre-delivered. At 980 nm, water absorption is relatively low and pigment absorption high. At 1,470 nm, water absorption is high: in the Utrecht inner-ear model this diode produced vapour bubbles, pressure waves and heating beneath the footplate, particularly with overlapping pulses, and the authors advised using a laser with less potential harm.
• Thulium (about 2 µm): strongly absorbed by water, fibre-delivered. Advised against, for the reasons below.
• Er:YAG (mid infrared): intensely absorbed by water and efficient on bone, but it works by tiny explosive vaporisation, which produces sound and pressure waves.

Strong water absorption keeps energy near the surface but can boil perilymph into vapour bubbles; weak absorption spares the fluid from heat but lets light travel further. Each wavelength is a trade-off that had to be measured.

Laser or drill: what the trials show

The opening can be made with a laser, a micro-drill (a tiny motorised burr) or a hand perforator (a fine pick). Most comparisons are non-randomised.

• A systematic review by the author’s Utrecht group screened 383 articles and analysed eight studies (999 operations), all with a moderate risk of bias. It found no consistent difference in air-bone gap closure or in dizziness immediately after surgery. Footplate fractures and inner-ear hearing loss appeared more frequent with conventional instruments, and on that basis the authors preferred the laser for first operations.
• A randomised comparison of 336 operations, CO2 laser against micro-drill, followed bone conduction (the inner-ear hearing) from day two to six months. Both showed a small, temporary dip, most marked at 4 kHz and recovering within weeks, with no significant difference between them.
• Between lasers, a second review found only two analysable studies: slightly better gap closure with CO2 than with KTP, of unclear clinical relevance, and a result favouring CO2 over Er:YAG. The evidence was judged insufficient to say which laser to use.

This matches the stapedotomy page: no large, consistent difference in hearing outcome, and possibly fewer mechanical complications with a laser, on evidence at risk of bias. A tool the surgeon knows well counts for more than the tool itself.

What the laser may offer, and what it can cost

What is claimed for the laser:

• No pressure on the footplate, so less risk of cracking it or setting it floating.
• Less noise than a drill. In the Utrecht model the KTP, CO2 and thulium lasers were each significantly quieter than a micro-burr.
• Gentle work around scar in revision surgery: many surgeons divide adhesions around an old prosthesis with a laser rather than pulling on them.

The case for caution is that light is energy, delivered just in front of the inner ear: heat, vapour bubbles and sound can each reach the perilymph. In guinea pigs, opening the cochlea with each of four lasers (thulium, KTP, CO2 and diode) reduced its response to sound, more at high frequencies. That was an animal model, not a human stapedotomy, but a laser is not automatically gentle.

These are reasons to choose a laser carefully and use the least energy that works. In the clinical comparisons, inner-ear loss was not more frequent with a laser; hearing preservation depends on the whole operation.

Why the thulium laser was advised against

The thulium laser is fibre-delivered and strongly absorbed by water, which made it look attractive. The author’s Utrecht group measured it alongside KTP and CO2 lasers:

• Bubbles and sound. In a laboratory model of the inner ear, thulium produced large vapour bubbles in the vestibule and more sound than the other two lasers.
• Heat. It heated the fluid up to 0.6 mm beneath the footplate; KTP caused the least heating.
• Cochlear function. In the guinea-pig study it caused the largest loss of sensitivity of the four lasers.
• Patients. In a prospective, non-randomised comparison of 194 first stapedotomies, the air-bone gap closed to within 10 dB at three months in 90.0% with thulium and 96.8% with CO2. Four patients in the thulium group had inner-ear hearing loss and three had tinnitus, against none with CO2.

The authors advised against the thulium laser for stapedotomy. The clinical comparison was not randomised, but laboratory, animal and clinical findings pointed the same way.

Not every centre shares this view. An Italian series of 148 patients reported the thulium laser as safe, with the air-bone gap closed to within 10 dB in 87–90% and no signs of inner-ear impairment.

“Laser treatment” for otosclerosis: what it is and is not

Laser treatment of otosclerosis (in French, otospongiose traitement au laser) means this operation. The laser does not treat the otosclerotic bone, stop the condition or make surgery unnecessary; it is an instrument used inside a stapedotomy, and no laser applied from outside the ear frees a fixed stapes. The real decisions come first: hearing aid or stapedotomy?, and how much of the footplate to open (stapedectomy or stapedotomy).

Questions you can ask about the tool

• Which instrument will you use for the opening (laser, micro-drill or perforator), and why?
• If a laser, which type, and how long have you used it?
• What do you do if the footplate is thick or the first opening is incomplete?
• If a thulium laser is proposed: how do you view the published concerns about it?
• What are your own results, for hearing and for inner-ear loss, with this technique?

A good answer gives a reason rather than a brand. The questions about a surgeon’s own figures on the stapedotomy page matter more than any of these.

Sources

• Koenraads SPC, de Boorder T, Grolman W, Kamalski DMA. A 1,470 nm diode laser in stapedotomy: mechanical, thermal, and acoustic effects. Lasers Surg Med. 2017;49(6):619-624. PubMed
• Covelli E, Elfarargy HH, Filippi C, et al. Thulium laser in stapedotomy surgery. Acta Otolaryngol. 2022;142(3-4):234-240. PubMed
• Wegner I, Kamalski DM, Tange RA, et al. Laser versus conventional fenestration in stapedotomy for otosclerosis: a systematic review. Laryngoscope. 2014;124(7):1687-1693. PubMed
• Somers T, Vercruysse JP, Zarowski A, et al. Stapedotomy with microdrill or carbon dioxide laser: influence on inner ear function. Ann Otol Rhinol Laryngol. 2006;115(12):880-885. PubMed
• Kamalski DM, Wegner I, Tange RA, et al. Outcomes of different laser types in laser-assisted stapedotomy: a systematic review. Otol Neurotol. 2014;35(6):1046-1051. PubMed
• Kamalski DM, Verdaasdonk RM, de Boorder T, et al. Comparison of KTP, thulium, and CO2 laser in stapedotomy using specialized visualization techniques: thermal effects. Eur Arch Otorhinolaryngol. 2014;271(6):1477-1483. PubMed
• Kamalski DM, Verdaasdonk RM, de Boorder T, et al. Comparing mechanical effects and sound production of KTP, thulium, and CO2 laser in stapedotomy. Otol Neurotol. 2014;35(7):1156-1162. PubMed
• Kamalski DM, de Boorder T, Bittermann AJ, et al. Capturing thermal, mechanical, and acoustic effects of the diode (980 nm) laser in stapedotomy. Otol Neurotol. 2014;35(6):1070-1076. PubMed
• Kamalski DM, Peters JP, de Boorder T, et al. Influence of laser-assisted cochleostomy on acoustically evoked compound action potentials in the guinea pig. Otol Neurotol. 2014;35(8):1306-1311. PubMed
• Kamalski DM, Vincent R, Wegner I, et al. A nonrandomized comparison of the thulium laser and the CO2 laser in primary stapedotomy for otosclerosis. Otol Neurotol. 2014;35(10):1715-1719. PubMed

This page provides general educational information. It cannot replace an individual assessment, which depends on a full history, examination, audiometry and, where relevant, imaging. If you have sudden hearing loss, severe pain, facial weakness, severe dizziness or discharge with fever, seek medical care promptly.