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KTP laser fine fenestra stapedotomy with vein graft interposition in the surgical management of otosclerosis

R.J. Salib J. Oates
Department of Otolaryngology/Head and Neck Surgery, Queen’s Hospital, Belvedere Road, Burton-Upon-Trent, Staffordshire, DE13 0RB, U.K.

Correspondence to: R.J. Salib, Infection, Inflammation and Repair, Respiratory Cell and Molecular Biology, Mail Point 810, Southampton General Hospital, Tremona Road, Southampton, SO16 6YD Email: rjs4@soton.ac.uk

Keywords: Otosclerosis, surgery, stapedotomy, laser, management Surg J R Coll Surg Edinb Irel., 1 October 2003, 269-272

Otosclerosis is an hereditary disease of bone derived from the embryonic otic capsule. The exact aetiopathogenesis remains unclear. It can be associated with significant disability due to hearing impairment. Medical and surgical treatments, with varying degrees of effectiveness and complication rates, are available. The surgical method for the correction of the conductive hearing loss associated with otosclerosis continues to undergo technical refinement with the aim of improving results and minimising complications. The surgical technique of fine fenestra stapedotomy is well established. Here, we describe a new modification of this technique involving the use of a KTP laser. Based on the retrospective review of the results and complication rates of over 200 consecutive cases, we would like to recommend the technique of KTP laser fine fenestra stapedotomy in the surgical management of otosclerosis

INTRODUCTION
The first attempt at stapes mobilisation dates back over 100 years. The first stapedectomy operation is credited to Jack of Boston, Massachusetts in 1893. Subsequently, surgical treatment switched to lateral semicircular canal fenestration operations in an attempt to restore free movement of the inner ear fluids in response to sound stimuli. The drawbacks of these operations included the need for a staged procedure, poor results due to diminished cochlear function and condeming the patient to a mastoid cavity with the potential for chronic discharge.

Shea introduced the modern operation of stapedectomy in 1958.¹ After removal of the stapes, he used a vein graft to cover the oval window and interposed a polyethylene tube prosthesis between the graft and the incus.1 Since this period, there has been a substantial increase in the literature describing different techniques. In the 1960s and 1970s, different types of prostheses were introduced. The 1980s saw the emergence of the stapedotomy approach and in the last 15 years attention has been focused on the laser stapedotomy.² The advantages of stapedotomy over stapedectomy in terms of producing less postoperative hearing loss and dizziness, have been reported in many series.^3-5 In addition, laser stapedotomy has been shown to have advantages over traditional small fenestra stapedotomy technique. By vaporising the posterior crus and fashioning the hole in the footplate, the operation is thought to be less likely to result in trauma to the inner ear.⁶

The following section outlines the Burton experience in stapedial surgery for otosclerosis.

It is based on the protocol and surgical technique employed by the senior author (JO), who has carried out over 200 such procedures with high rates of technical success and few complications.

INDICATIONS
The indications are a conductive deafness, associated with a disability, secondary to otosclerotic fixation of the stapes footplate. The air-bone gap should be at least 15dB with a maximum speech discrimination score in excess of 60%. Patients with hearing thresholds in excess of 100dB and no measurable cochlear reserve on speech discrimination, may be suitable for operative intervention to enable them to utilise a hearing aid, which previously would have been of little benefit. Tympanometry should be normal (Type A) with absent stapedial reflexes. Alternative treatment options including amplification using air conduction aids, bone-anchored hearing aids are fully discussed with the patient during the initial 45 minute consultation. The senior author (JO) counsels patients based on his personal surgical experience. Based on his series of over 200 consecutive stapedotomies, patients are advised of a 1-2% risk of severe sensorineural hearing loss. The chances of improving hearing is quoted at 95% with a true hearing benefit (i.e. symmetrical hearing), based on the Glasgow Benefit Plot, of 76%.7 The possibility of post-operative tinnitus, vertigo and facial nerve weakness are also mentioned but not discussed in great detail as they are rare occurrences. During the same consultation, the nature of the surgery is discussed in detail. The discussion is augmented using computerised video clips and slides. Patients are also encouraged to conduct their own research into the subject, including an internet search, prior to making their final decision. The senior author (JO), routinely performs second side surgery providing the following conditions are satisfied:

• The first procedure was not associated with any permanent intra- or post-operative complication

• A satisfactory result was obtained on the first side with complete or over-closure of the air-bone gap

CONTRAINDICATIONS
These may be general relating to the patient’s medical condition, fitness for anaesthesia and pregnancy. Specific contraindications include poor Eustachian tube function, active ear infection, the only-hearing ear, active otosclerosis with positive Schwartze sign and Meniere’s disease. Per-operative findings, including vascular and facial nerve anomalies compromising adequate surgical access may necessitate abandonment of the procedure.

TECHNIQUE OF LASER FINE FENESTRA STAPEDOTOMY WITH VEIN GRAFT INTERPOSITION
This surgical technique was originally described by Causse and Causse in 1984.⁸ They then described performing a 0.8mm stapedotomy at the posterior third of the footplate by means of a 0.7 mm diamond drill. They used a large 6mm square vein graft interposition technique utilising a Teflon piston with 0.4 mm shaft. Rigorous inflation of the middle ear using Politzer manoeuvres was performed as early as 24 hours post-operatively. The authors felt that this procedure had certain specific advantages, namely:

• A 0.8mm stapedotomy was an ideal size to avoid a persistent air-bone gap for low tones as well as preserving the high tones

• Otosclerotic foci are located in the anterior part of the footplate. Hence, by performing the stapedotomy in the posterior part of the footplate, these foci were not disturbed with the ensuing risk of enzymatic reactivation

• The use of a vein graft conferred certain advantages by providing added protection against bleeding into the vestibule; reducing the risk of the piston being driven too far into the vestibule; reducing the risk of post-operative infection spreading to the membranous labyrinth; and avoiding the risk of a fistula.⁹

The description of the surgical technique that follows is that employed by the senior author (JO). It is based on the technique described above with a few modifications including the use of a laser.

The operation is performed under hypotensive general anaesthesia delivered by an anaesthetist with specific experience in middle ear surgery anaesthesia requirements. In particular, reversal of the general anaesthetic should not be associated with coughing or straining which could cause a rise in intracranial pressure with possible sequelae such as a perilymph leak or even dislodgement of the prosthesis. To this end, a laryngeal mask is employed to protect the airway, ventilate the patient and deliver anaesthetic agents.

Where possible, the vein graft is harvested from the dorsum of the contralateral hand. Following ligation of the ends of the vein, the donor site is closed using a Prolene^® 5-0 pull-out subcuticular suture secured with Steristrips^®. A light pressure dressing is then applied to the dorsum of the hand.

The harvested vein is then split and prepared, endothelial side up, as a 5mm disc with a central dimple on a metal block. The ear is prepared with a solution of aqueous povidone/iodine and the operation performed under strict aseptic conditions. We normally use a permeatal approach unless the external canal is excessively narrow in which case an endaural approach is employed. The description which follows is that of the permeatal approach. Infiltration with local anaesthetic (2% xylocaine/1: 80,000 adrenaline) is performed at the cartilaginous-bony junction in the postero-superior part of the canal wall skin. The infiltration must be performed gently in order to avoid raising blebs in the canal wall skin which make elevation of the tympanomeatal flap difficult and increase the likelihood of tears occurring. A circumferential incision is then made at the limit of the aural speculum. The speculum thus compresses the canal wall skin and minimises bleeding. The tympanomeatal flap, based posterosuperiorly and hinging anteriorly (1 o’clock to 4 o’clock on the left, and 8 o’clock to 11 o’clock on the right), is reflected forward. The chorda tympani is identified and, following opening of its canal with a strong hook, is displaced inferiorly without damaging it. Curetting of the scutum is performed until a good view of the stapedius tendon, the tip of the pyramid and the stapes suprastructure is obtained. Gentle palpation of the stapes suprastructure is performed to confirm fixation of the footplate. The movement of the rest of the ossicular chain is assessed by gently rocking the malleus and noting movement at the incudostapedial joint. The stapedial tendon, posterior and anterior crura are vapourised (Figure 1), in that order, using the potassium titanyl phosphate (KTP) laser (1 Watt, continuous setting). It is vital to ensure that the tip of the laser probe is pointing away from the facial nerve at all times. The incudostapedial joint is separated using an angled joint knife (Figure 2) and the stapes suprastructure removed (Figure 3). The distance between the under-surface of the incus and the footplate is then measured to ascertain the length of prosthesis required. A Causse^® Teflon prosthesis (Figure 4) is prepared and trimmed to size using a wedged measuring block. The shaft of a straight hook is used to expand the loop in order to disrupt its memory and prevent it from self-closure.

Figure 2: Separation of the incudostapedial joint using a triangular joint knife

Figure 4: Two different types of stapedotomy pistons. From top to bottom, the Richards^® fluoroplastic bucket handle prosthesis with stainless bail and the Causse^® fluoroplastic loop piston

A ‘rosette’ is formed on the footplate (Figure 5) using the KTP laser (1 Watt, continuous setting) and a 0.8mm stapedotomy completed with a diamond dust burr (Figure 6). The vein graft is positioned over the footplate (Figure 7) with the aid of a regulated positive/ negative pressure suction mechanism, specially designed by the senior author (JO) and operated by a foot pedal. The same suction mechanism is then used to introduce the prosthesis and position it alongside the long process of the incus. The open loop should point towards the proximal end of the incus. The prosthesis is then rotated into place with the aid of two 900 angled hooks. It is crimped around the long process with the vein graft thus interposed between its tip and the vestibule (Figure 8). The ‘bending sign’ is demonstrated by gently pressing the shaft of the prosthesis to ensure adequate penetration into the stapedotomy. The chorda tympani is repositioned to improve the blood supply to the distal part of the incus. The flap is then replaced and held in position with Gel-foam^® and a light Terra-cortril^® dressing in the external canal.

Figure 7: Vein graft in position completely covering oval fossa and its immediate surrounds

Figure 8: Stapedotomy piston in position having been crimped around long process of the incus

The remaining vein graft can be used if necessary as an underlay graft to seal any inadvertent tears in the tympanic membrane. Ondansetron and co-amoxiclav (cefuroxime in the case of penicillin allergy) are given per-operatively. Post-operatively, the patient is kept in for one to two nights. Antibiotics are continued for four days post-operatively. Upon discharge, patients are instructed to avoid blowing the nose and to sneeze with their mouths open for the first two weeks. Flying is allowed after three weeks. We do not routinely practice Politzerisation. The ear pack and hand suture are removed one week post-operatively.

In the absence of any complications and on confirmation of a successful closure of the air-bone gap, patients are usually followed up at three weeks, six months, one year and then at yearly intervals thereafter for four years, following which they are discharged.

DISCUSSION
There is currently no universally accepted technique for stapes surgery, and each of the major techniques, including total and partial stapedectomy and fine fenestra stapedotomy, are likely to produce excellent results in the hands of experienced operators. Technical modifications and refinements of stapes surgery, such as the one described here, will no doubt continue in the future, but there will never be a substitute for the knowledge and skill of the surgeon.¹⁰

After all, it is not the instruments or techniques that ensure success, but rather the minds and hands in control of the instruments.¹¹ The surgical technique of fine fenestra stapedotomy is well-established. We have described a new modification of this technique involving the use of a KTP laser. We find the technique both reliable and safe to perform. On the wider front, our experience adds weight to the case for the routine use of the laser as a safe and effective surgical tool in modern otological practice.

ACKNOWLEDGEMENTS
We would like to thank our colleague Dr. Robert Vincent, M.D., at the Jean Causse Ear Clinic, Traverse de Béziers, Colombiers, France, for his help with preparation of the illustrations.

REFERENCES
1. Shea JJ. Fenestration of the oval window. Ann Otol Rhinol Laryngol 1958; 67: 932-951.
2. Lippy WH, Berenholz LP, Burkey JM. Otosclerosis in the 1960s, 1970s, 1980s and 1990s. Laryngoscope 1999; 109: 1307-1309.
3. Fisch U. Stapedotomy vs. stapedectomy. Am J Otol 1982; 4: 112-117.
4. Causse J. Stapedotomy techniques and results. Am J Otol 1985; 6: 68-71.
5. Marquet J. Stapedotomy technique and results. Am J Otol 1985; 6: 63-67.
6. Shabana YK, Allam H, Pederson CB. Laser stapedotomy. J Laryngol Otol 1999; 113: 413-416.
7. Browning GG, Gatehouse S, Swan RC. The Glasgow Benefit Plot: a new method for reporting benefits from middle ear surgery. Laryngoscope 1991; 101: 180-185.
8. Causse JB, Causse JR. Technique for otosclerosis. Am J Otol 1984; 5: 392-396.
9. Causse JB, Causse JR, Parahy C. Stapedotomy technique and results. Am J Otol 1985; 6: 68-71.
10. Lundy LB. Otosclerosis update. Otolaryngol Clin North Am 1996; 29: 257-263.
11. House HP, Kwartler JA. Total stapedectomy. In: Brackman DE, Shelton C, Arriaga MA, eds. Otologic Surgery. Philadelphia: WB Saunders, 1994.

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