 Piece of vein graft interposition: |
A large piece of vein graft helps
to prevent excessive movement and penetration of the piston into the vestibule,
as well as to reconstruct an annular ligament function important for preserving
proper impedance relationships.Place the piece of vein graft adventitial or "sticky" side down on the footplate. The part of the piece of vein graft lying between the piston and the fenestra gives dissipation force and push-pull effect (elasticity) to the system. This new annular ligament avoids a loss of sound conduction due to an acoustic bridge (Fig.18 a, b, c). |
The piece of vein graft rests with the external aspect on the stapes footplate. The oval fossa and its portion located between the piston and the edge of the stapedotomy hole endow resistance and elasticity to transmission. |
 Piston placement: |
|
The piston is 0.4 mm diameter. Thus the part of the
vein graft sitting between the fenestra and the piston will be 0.2 mm thick,
as it is the usual thickness of an annular ligament of a stapes footplate,
for impedance relationship reasons. In case of excessive tympanic membrane
retraction, the piston may bend decreasing execessive fluid pressure risk.
The loop of the piston, being of Teflon, is gentle onto the long process
of the incus as opposed e.g. to a wire loop. The position of the loop may
be adjusted on the long process of the incus in order that the piston shaft
be perpendicular to the hole. Avoiding sudden excessive penetration of the
shaft is important at the time of the positioning. The contrary may result
in a barotrauma-like phenomenon. The upper loop of the piston is opened
by placing cup forceps within the loop of the piston and spreading the
jaws of the instrument several times. A sharp pick may also be used in order
to break part of the memory of the teflon loop. The loop will remain open
for a few minutes allowing the placement of the piston before the "memory"
of the teflon closes it again. The piston is carried into the ear with a
suction tube, and placed using the suction tube with a curved needle. The
loop is gently crimped around the incus using cup forceps (Fig.19 a, b, c). |
 Fig.19 a : The loop of the piston is opened. |
 Fig.19 b : Suction tube and curved needle place the loop on the long process of the incus. |
|
Fig.19 c : The loop of the piston is closed with cup forceps. |
 Stapes tendon |
|
Trying to preserve the stapes tendon may result into too difficult
or hazardous surgery. It is possible to reestablish a stapedial reflex
at the end of the operation. The stapes tendon is sectioned with a hook
rather than with scissors as near as possible to the head of the stapes
at the beginning of surgery and a Polycel device, which can slid on the
piston shaft, is placed (Fig.20). |
| Fig.20 : A: Causse Polycel device (Xomed-Treace ®) B: Stapes tendon. C: Pyramid of the stapes tendon. D: Fragment of connective tissue |
|
Polycel has been chosen as, in case of calcification of the tendon at
any rate, the piston will maintain a normal function ; the vibration of
the teflon piston will not be altered. Polycel is very light. It is very
easily glued by the fragment of perivenous connective tissue placed between
the Polycel device and the tendon (Fig.21
a). |
 |
Fig.21 a The tendon is glued to the Polycel platform. |
|
We advise placing the fragment of connective tissue as a matter of fact
between the Polycel device and the pyramid, as it will enable the tendon
to continue to be efficient in spite of very early contraction of this tendon
(Fig.21 b). |
 |
Fig.21 b |
|
Such a reconstruction of the stapes tendon is not always possible. But,
when it is possible, it will protect the patient against acoustic trauma.
It will also make for better speech discrimination when the patient speaks,
since the stapes tendon contracts as soon as the subject begins to speak,
in order to decrease the perception of mid and low tones and let the high
pitched frequencies, which are more difficult to hear, be comparatively
amplified. |
 Bending test: |
|
Proper placement of the piston is confirmed by the "bending test".
For an optimal verification,this test must be achieved before the placement
of the Polycel device. A small pick is used to apply lateral pressure to
the piston. If the piston bends slightly, the position is good. If the piston
actually moves, it is not seated well in the stapedotomy fenestra (Fig.22 a and b). |
 |
Fig.22 a and b : The piston shaft is seated well. (b), The piston shaft is not inserted in the stapedotomy hole or may be too short. |
 Postoperative care: |
|
The patient lies toward the operated ear, as
the new annular ligament around the piston is water proof. |
Middle ear inflation
Bone conduction audiogram | RESULTS |
|
(Otosclerosis) Ref: Otosclerosis update book for Paris congress - September 1994 |
| n = 26 330 | Total number |
| n = 22 901 | Total number using Jean-Bernard CAUSSE technique |
| Average improvement of air conduction = 37dB (500 Hz, 1 KHz and 2 KHz) | |
| Long term success : 22 714 (99,18%) | |
| Gap | { | > 10 dB : 41 (0,17%) |
| = préop.: 37 (0,16%) | ||
| > préop.: 17 (0,07%) | ||
| Partial cochlear deterioration |
{ | following week: 23 (0,10%) |
| following years: 17 (0,07%) | ||
| Total deafness | { | following week: 3 (0,01%) |
| following years: 5 (0,02%) | ||
|
SURGICAL TECHNIQUE of Jean-Bernard CAUSSE |
The vibration of the inner ear fluids is molecular size only. That is
the reason why pressure and volume are most responsible of the energy in
the inner ear :E = P.V.
Impedance transfer is the vibrating surface ratio in-between that of the
tympanic membrane and that applied to the fluids. Consequently, if the area
of vibration applied to the inner ear fluids is too small, there is a poor
hearing on the low and mid speech frequencies.
Otosclerotic foci invade the annular ligament; this elastic band of 0.2mm
loses its elasticity. The annular ligament is a "shock absorber"
protecting the inner ear against acoustic trauma and baro-trauma. It is
necessary to rebuild very efficiently this shock absorber action in order
to protect the patients against acoustic trauma and baro-trauma. This technique
allows an efficient reconstruction of the annular ligament. Politzerisation
after surgery, avoiding fibrous tissue in the middle ear, is allowed by
this technique. The patient will be allowed to scuba-dive and to take the
plane without any risk.
The stapes reflex reconstruction is also a protection against acoustic trauma
and baro-trauma. The attachment of the stapes tendon to the posterior crus
is much higher than the pyramidal process. The shape of the joint of the
footplate is very specific to help the footplate to be fixed as soon as
the tendon contracts. Not to keep the tendon intact, but to lower the tendon
and to attach it to the shaft of the prosthesis to get the tendon perpendicular
to the piston is thus necessary. When the tendon will contract, the stapes
tendon will not push the piston into the vestibule. The piston will be blocked
on the edge of the stapedotomy. |
