Endoscopic Myringoplasty

By

Dr. T. Balasubramanian M.S. D.L.O.

Synonyms: Myringoplasty, Tympanoplasty, Endoscopic myringoplasty

Definition:  Myringoplasty is a procedure used to seal a perforated tympanic membrane using a graft material.  Formerly an operating microscope was used to perform myringoplasties.  Recently with the common usage of nasal endoscope for nasal surgeries, we have started using it for ear surgeries also.

The aim of this article is to share our experiences on endoscopic myringoplasty.  Endoscopic myringoplasty is performed using a 0 degree rigid endoscope.  In fact we use the 4 mm nasal endoscope itself  for this purpose.  This procedure is always performed transcanally. 

Procedure:
     The surgery is performed under local anesthesia.  Temporalis fascia graft is harvested under local anesthesia conventionally and allowed to dry.  The external auditory canal is then anesthetised using 2 % xylocaine  mixed with 1 in 10,000 adrenaline injection.  About 1/2 cc is infiltrated at 3 - o clock, 6 - o clock, 9 - o clock, and 12 - o clock positions about 3mm from the annulus.  The patient is premedicated with intramuscular injections of 1 ampule fortwin and 1 ampule phenergan.   

     Step I: Freshening the margins of perforation - In this step the margins of the perforation is freshened using a sickle knife of an angled pick.  This step is very important because it breaks the adhesions formed between the squamous margin of the ear drum (outer layer) with that of the middle ear mucosa.  These adhesions if left undisturbed will hinder the take up of the neo tympanic graft.  This procedure will infact widen the already present perforation.  There is nothing to be alarmed about it.

     Step II: This step is otherwise known as elevation of tympano meatal flap.  Using a drum knife a curvilinear incision is made about 3 mm lateral to the annulus.  This incision ideally extends between the 12 - o clock, 3 - o clock, and 6 - o clock positions in the left ear, and 12 - o clock, 9 - o clock and 6 - o clock positions in the right ear.  The skin is slowly elevated away from the bone of the external canal.  Pressure should be applied to the bone while elevation.  This serves two purposes:
1. It prevents excessive bleeding
2. It prevents tearing of the flap
This step ends when the skin flap is raised up to the level of the annulus.

     Step III:  Elevation of the annulus and incising the middle ear mucosa.  In this step the annulus is gradually lifted from its rim.  As soon as the annulus is elevated a sickle knife is used to incise the middle ear mucosal attachement with the tympano meatal flap.  This is a very important step because the inner layer of the remnant ear drum is continuous with the middle ear mucosa.  As soon as the middle ear mucosa is raised, the flap is pushed anteriorly till the handle of the malleus becomes visible.

     Step IV:  Freeing the tympano meatal flap from the handle of malleus.  In this step the tymano meatal flap is freed from the handle of malleus by sharp dissection of the middle ear mucosa.  Sometimes the handle of the malleus may be turned inwards hitching against the promontory.  In this scenario, an attempt is made to lateralise the handle of the malleus.  If it is not possible to lateralise the handle of the malleus, the small deviated tip portion of the handle can be clipped.  The handle of the malleus is freshened and stripped of its mucosal covering. 

     Step V: Placement of graft (underlay technique).  Now a properly dried temporalis fascia graft of appropriate size is introduced through the ear canal.  The graft is gently pushed under the tympano meatal flap which has been elevated.  The graft is insinuated under the handle of malleus.  The tympano meatal flap is repositioned in such a way that it covers the free edge of the graft which has been introduced.  Bits of gelfoam is placed around the edges of the raised flap.  One gel foam bit is placed over the sealed perforation.  This gelfoam has a specific role to play.  Due to the suction effect created it pulls the graft against the edges of the perforation thus perventing medialisation of the graft material.

The following advantages were noted in this procedure:

1.  The quality of image was excellent.
2. Documentation of the procedure became simple
3. The middle ear can be easily examined using an endoscope
4. Almost all cases may be performed transcanally avoiding unnecessary post aural incision and suture.

Disadvantages:

The only disadvantage noted by this author was that both the hands were not free.  One hand must be utilised to stabilise the endoscope.

When compared with conventional microscopic myringoplasy, the author found no difference in the success rates.  Added to this is the convenience and portability of the endoscope. 

The surgical clipping shown here has been recorded while doing endoscopic myringoplasty.