Nasal Stents

Are they really useful?

Dr. T. Balasubramanian

Role of stents in ESS

By

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

Introduction:

Formation of synechiae constitutes one of the common complications following ESS.

Conservative estimates place about 10 % of all patients who have undergone ESS as prone for

synechiae. Dissection in the frontal sinus area is more prone for synechiae formation because

of the difficult access. Dissection in this area is troublesome due to the difficult angle

involved. True cutting instruments which cause little tissue damage have difficulty in

reaching this area. Using powered shavers and debriders in this area has also not managed to

reduce the risk of synechiae. Stents have been used with varying degree of success in

preventing postop complications following ESS.

Functions of Stents following ESS:

1. The primary function of stent is to separate two edges of raw wound thus preventing

the formation of fibrous band / synechiae. This is classically seen when there is lateralization

of middle turbinate following ESS. Lateralization of middle turbinate can potentially

obstruct middle meatus drainage. This can effectively be prevented by placing a stent

between the middle turbinate and the lateral nasal wall.

2. Stents can potentially take up space which would otherwise be occupied by mucous/

clot. Presence of clot can lead to epithelial migration and synechiae formation.

3. Patients in whom stents have been placed have very little crust formation, hence

frequent wound debridement is not needed.

4. Stents also serve as occlusal dressing facilitating better & faster wound healing.

Occlusal dressings have known to reduce tissue necrosis.

Types of nasal stents:

1. Middle meatal stent

2. Frontal sinus stent

3. Drug containing stents

Middle meatal stents:

Role of middle meatal stents include:

1. Decrease synechiae formation

2. To prevent lateralization of middle turbinate

3. Since it fills up the ethmoid sinuses it effectively prevents clots, mucous or fibrin.

Stents of middle meatus is also known as spacers. Common spacers of middle meatus are

made of glove fingers filled with polyvinyl acetyl sponge which are sutured together and tied

with silk. Since this spacer is smooth it does not adhere to the surrounding tissue, thus serves

as an occlusive dressing.

Foam made of biodegradable synthetic material like polyurethane can also be used to stent

the middle meatus after surgery. This material is suitable for patients who does not tolerate

other types of middle meatal stents.

Shikani stent:

This stent was designed by Dr. Alan Shikani of John Hopkin's university. It is a silicone stent

with two flanges – one triangular which is used to separate the middle turbinate from the

lateral nasal wall and the other smaller flange is used to secure the stent in the maxillary

sinus. This stent can safely be left in place for more than 2 weeks. It is also safe for use in

paediatric populations.

Image showing shikani stent

Diagramatic representation of Shikani stent in position

This stent is available in three different sizes.

Advantages of Shikani stent:

1. It prevents lateralization of middle turbinate

2. It maintains the patency of the maxillary sinus ostium

3. It maintains the patency of middle meatus

4. It prevents synechea formation

5. Promotes mucosal healing

6. Post op nasal packing is not necessary

7. Can easily be removed without anesthesia (office procedure)

Doyle spacers:

This splint was first developed by Doyle. This splint is very easy to introduce and remove. It

prevents synechiae formation. After placement this splint can be sutured to the nasal septum.

Figure showing Doyle spacers

Two different types of Doyle's spacers are available (one for the right nasal cavity and the

other for the left nasal cavity)

While using Doyle's spacers the trough should be placed along the free edge of middle

turbinate so that both surfaces of middle turbinate is effectively splinted.

Image showing Doyle's spacer in position

Frontal sinus stents / spacers:

The subject of stents / spacers in this area is highly controversial. Due to the inherent

difficulties involved in surgeries of this area very little data is available for critical analysis.

Initially surgeons were using rigid tubes made of various materials to stent this area. These

tubes failed in the long run.

Neel (1976) by his famous canine experiments demonstrated that stenting the frontal sinus

with thin silastic sheets resulted in less fibrosis, less osteoblastic activity and better healing

when compared to the use of rubber tube stents.

Freeman stents:

This stent is used after surgeries involving frontal sinus outflow tract. This stent is made of

silicone tubing and one end is biflanged. This flange helps in preventing early extrusion of the

stent. The material used (silicone) is virtually inert and does not irritate the mucosa of frontal

sinus outflow tract. This stent can easily be retained in position for more than 3 months. This

stent is available in two sizes (14 f and 16 f). This stent can easily be inserted via an external

incision or endoscopically through the nose using the specially designed introducer available

with the pack.

Figure showing Freeman frontal sinus stent. Note their flanged edges.

Image showing Freeman kit containing the stent along with introducer

Rains frontal sinus stents:

This is the first self retaining stent designed specifically for frontal sinuses. Major purpose of

this stent is to maintain the frontal sinus drainage pathway following surgery. It ensures that

there is no excessive narrowing of this area develops following surgery. A somewhat larger

Rain stent can be used after frontal sinus trephening. This helps in regular visualization of

frontal sinus using 2.7 nasal endoscope. This stent is made of medical grade silicone rubber.

On insertion the bulb of the stent expands to retain the stent in position. After the frontal

sinus drainage pathway has re-epithelialized the stent can easily be removed in the

consulation room itself without anesthesia.

Indications for frontal sinus stenting:

1. A post op diameter of frontal sinus outflow tract less than 5 mm is an indication for

stenting

2. Extensive demucosalization of the frontal sinus out flow tract is an absolute indication

for stenting

3. Exposure of bone in the frontal sinus outflow tract following surgery is an indication

for stenting

4. Extensive polyposis involving the frontal sinus outflow tract

5. Surgeries involving frontal sinus malignancies

Figure showing Rain's frontal sinus stent

Rains stent is available in two sizes ( 4mm and 6 mm).

Silastic sheet tubes (customized):

These tubes are usually prepared using thin silastic sheets (0.01 – 0.04mm). Major advantage

of these stents is that they can be customized according to the anatomical needs of the patient.

These thin sheets can ideally be used under following settings:

1. In patients whom more than 40% of mucosa over frontal sinus outflow tract has been

denuded.

2. Following frontal sinus obliteration surgical procedures

3. It can also be used to line the frontal sinus when large segment of frontal sinus mucosa

has been debrided as in the case of tumor surgeries.

The major advantage of using silastic sheet is that they confirm to the shape of frontal sinus

ostium and forms a scaffolding over which mucosal regrowth can occur. These stents can be

safely retained in place for more than 6 months. These stents also help in atraumatic suction

clearance of frontal outflow tract area. Thicker silastic sheets can be used to stent post op

area following Draff III procedure.

Medicated nasal stents:

Stents can be used as a reliable local drug delivery vehicle. These stents serve dual purpose.

Drugs that can be incorporated and delivered via these stents include: steroids, antibiotics and

anitneoplastic drugs. Stents impregnated with corticosteroids helps in reduction of local

mucosal oedema, reduces scar tissue formation and keeps the mucosal edges apart.

Commonly used steroid stents release about 60 micrograms of steroid per day.

Relieva Stratus Spacer:

This is one type of medicated spacer. It is available in two types, i.e. For ethmoid sinus and

for frontal sinus. These spacers are catheter based self retaining implantable device.

Ethmoidal spacers are used commonly to moisten the ethmoid air cells. The terminal ends of

these spacers are radio opaque. These spacers are supplied with deployment guide tool which

faciliates easy insertion. These spacers are provided with drug reservoirs. Drugs from the

reservoir permeates gradually into the area of insertion.

Figure showing Relieva Stratus ethmoid sinus Spacer

It is advisable to stent all patients who undergo revision endoscopic sinus surgery.

Absorbable nasal stents:

These stents are biodegradable and need not be removed after placement. These stents are

usually made of hyaluronic acid which is a naturally occuring component of extracellular

matrix. These stents help to keep the surgical site moist, prevents adhesions and on top of it

all need not be removed.

Gelatin film stents:

Multilayerd Gelatin film can be introduced in the middle meatus after surgery. Major

advantage of this stenting material is that it is cheap and easily available. Stenting of middle

meatus after surgery effectively prevents middle turbinate from lateralizing and obstructing

the drainage pathway of anterior group of sinuses.