Current Concepts Of Functional Endoscopic Sinus Surgery Functional

Functional Endoscopic Sinus Surgery (FESS) is now a well accepted globally as a preferred modality for  treatment of chronic recurrent sinusitis. However, since Paranasal sinuses are surrounded by vital structures such as orbit, skull base and brain  damage to these anatomical structures can lead to  serious  complications.
These serious complications for a benign condition of recurrent sinusitis is not acceptable and thorough knowledge and understanding of the basic concepts for this surgery is  extremely important. Besides,  the surgeon has to get used to operating and orienting through an endoscope which is quite daunting in the initial stages of a learning curve which is a far cry from operating with the head light ! This problem of orientation working through the endoscope is further multiplied by the use of angled scopes such as 30 degree and more so  working with the 70 degree which must be used while working in the frontal recess or dealing with a pathology affecting maxillary sinuses.
 In recent years, as the   Functional Endoscopic Sinus Surgery became more popular world wide, it also transpired that  there was  a significant number of revision operations  performed as a result of patient’s continued symptoms of chronic recurrent sinusitis. Our institution being a secondary and tertiary referral centre it became apparent that revision surgical procedures became a “ normal” practice. The  increasing incidence of revision surgery indicates that there is some problem in understanding of  patho physiology of this relatively newly formed concept of Functional Endoscopic Sinus Surgery (FESS) 
Following  are the examples  some of our revision cases which shows distorted anatomy, significant scarring and residual disease giving rise to  chronic symptoms
Endoscopic view of nasal cavity with a  O degree 4mm ‘scope. 
S- septum,  MT- middle turbinate, LW- lateral wall of the nose, IT- Inferior turbinate, IMA – inferior meatal antrostomy, ST- superior turbinate, SM-superior meatus, P- polyps, MMA- Middle Meatal Antrostomies,  LP- lamina pyparacea

The earlier workers   like   Hejak, Herrmann, Proctor, Naumann of the 19th century  considered  that the most common site of chronic disease is Osteo Meatal Complex (OMC). The “key” areas of the OMC are not seen in the plain X- rays and even minor swelling or obstruction in the middle meatus could be quite significant causing patient’s symptoms. At times sinus symptoms are overshadowed  by  non specific symptoms.

The common symptoms of chronic recurrent sinusitis are as follows

Nasal Symptoms –  such as -nasal obstruction, generalised congestion, Purulent rhinorrhoea, anosmia, hyposmia

Facial symptoms – facial pains and headaches

Pharyngeal symptoms – pots nasal drip,  recurrent pharyngitis and sore throats

Laryngeal symptoms – like recurrent laryngitis with hoarseness, and cough

Chest symptoms – Recurrent chest symptoms and exacerbation of asthma

Ear symptoms – occasionally otitis media as the mucopus running down  over the Eustachian tubes causing chronic mucosal  swelling and blocking E. tubes
Sometimes an acute attack of sinus infection in recurrent sinusitis can result in a serious orbital complication at any age especially in children as demonstrated below with several patients ranging from a 3 year old boy up to an adult.
Note even in a small child  all developing sinuses could be infected and spread of infection to the orbit with potential complication of blindness.

 Note even in a small child  all developing sinuses could be infected and spread of infection to the orbit with potential complication of blindness.

The conventional treatment in the past for the chronic sinusitis prior to the understanding of the muco ciliary mechanism of the sinuses was to create an artificial opening in the inferior meatus in an attempt to drain the maxillary sinuses, namely Inferior meatal antrostomy and Cald Well Luc procedure. However, post operative follow ups of these patients including short and long term revealed that there remains a constant infection of the maxillary sinuses in spite of patent inferior meatal antrostomy as seen in the following illustrations.

Failing   this inferior antrostomies the maxillary sinuses were approached through sublabial incision into the maxillary sinus exposing antero lateral surface  and excise the mucosa of the sinus as described by George Cald Well in 1893, with the hope that this would clear the symptoms of chronic sinusitis but it did not as seen in this CT scan of a patient IMA and Cald Well Luc procedure some 46 yrs ago .Note persistent infection in ethmoid, frontal and maxillary sinuses on the left side.

 

In fact  in the article by Cald Well Luc in New York Medical Journal published in 1893 they   described that the main problem of chronic sinusitis is in fact in the middle meatus where the maxillary sinuses drain through their natural ostia. In other words if the natural maxillary sinus drainage and ventilation is obstructed due to various pathologies in the middle meatus this will in turn will not allow drainage and ventilation of the sinuses during normal breathing process. The natural drainage  the maxillary sinus is always towards the natural ostium of the sinus near the floor of the orbit as shown in this figure of an intraoperative photograph of a left maxillary sinus. The  muco pus is  being driven toward at the natural ostium by mucociliary mechanism

The concept that the middle meatus, the ethmoid sinuses  may be  the prime cause of the problem resulting in lager sinuses to be affected was already thought  by other workers in the past. Since the advent of the better understanding of the muco ciliary mechanism and drainage of the sinuses  through natural ostia by pioneering work of Messerlklinger from Graz university from Austria laid the foundation of functional endoscopic sinus surgery.

The previous workers in this field  such as Hyjeck 1926  wrote that 

According to my experience the cause of stenosis in cases of acute inflammation most frequently lies in the nose itself and is due to oedematous swelling——–

In chronic cases the stenosis is mostly in the middle meatus
In 1926- The concept of middle meatal antrostomies was put forward  by Seibenmann and Kubo because of long term patency

In 1935 king demonstrated the flow of mucus towards natural ostium in spite of inferior meatal antrostomy being present.

Proctor 1966 showed that 
The ethmoid sinuses are usually the key to any problem involving infectous sinusitis——–infection generally begins there and persistence infection there is usually the reason for the failure of therapy directed to any other sinuses.

In 1972- It was Messerklinger laid the foundation of the concept of MMA on the basis of muco ciliary pathways and with  the advent of multiangle endoscopes, better light illumination and interpretations of detailed surgical anatomy on imaging techniques, these combined understanding enhanced the scope of functional endocopic sinus surgery as we know today.
In fact George Cald well who described the operation in  New York medical journal in 1893 showed that this semilunar fold (ie, hiatus semilunaris) acts as an imperfect valve to the maxillary sinus and incidentally guides fluid from higher cells  in to the maxillary antrum as I have repeatedly demonstrated on the cadaver. For this reason the diagnosis of empyema of the antrum is NOT sufficient until the frontal and anterior ethmoids cells have been excluded.

Further more he maintains that the Antrum may be the receptacle (not the origin) of pus or become involved secondarily.
The concept of ethmoids are the main culprit for the infection in the  larger sinuses can be seen and exemplified by the a clinical case  below.

A 9 year old  girl was seen with left subperiosteal abscess and an attempt was made to drain the abscess from the maxillary sinus with an indwelling tube in the sinus for repeated washouts. However,   patient still on I/V antibiotics deteriorated and was referred to us. The CT images of the first day shows that the ethmoids showed haziness but the maxillary sinus was clear. It was only in a subsequent day or two that the maxillary sinus became infected when attempt was made to drain it.
By the time it was seen by us the infection had already spread in to the left posterior ethmoid and sphenoid.
An endoscopic approach was used to drain the abscess and remove the disease  from left anterior, posterior ethmoid and sphenoid sinus. 

 A rapid recovery soon followed on the following day and the patient was normal in 5 days 

In fact  in the article by Cald Well Luc in New York Medical Journal published in 1893 they   described that the main problem of chronic sinusitis is in fact in the middle meatus where the maxillary sinuses drain through their natural ostia. In other words if the natural maxillary sinus drainage and ventilation is obstructed due to various pathologies in the middle meatus this will in turn will not allow drainage and ventilation of the sinuses during normal breathing process. The natural drainage  the maxillary sinus is always towards the natural ostium of the sinus near the floor of the orbit as shown in this figure of an intraoperative photograph of a left maxillary sinus. The  muco pus is  being driven toward at the natural ostium by mucociliary mechanism

Pattern of mucociliary pathways from the anterior and posterior group of sinuses.
 The anterior group of sinuses ie,anterior ethmoids, bulla ethmoidaes, frontal sinuses and maxillary sinuses drain into  the hiatus semilunaris of the middle meatus. Where as the postetior group is, posterior ethmoid in to the superior meatus  and sphenoid drain in to the spheno ethmoidal recess. These  are pre-determined muco ciliary pathways and cannot be altered. By careful and diligent examination of the nasal cavity one can diagnose the pathology   in the sinuses.

The ventilation of the sinuses through the natural os of the sinuses have been studied by Aust and Drettner in August 1974 in 25 healthy subjects and concluded that

  1. The oxygen exchange is directly proportional functional size  of the ostium, ie, only a small change in the diameter of the Os  eg, a mucosal thickening  has a  dramatic effect on exchange of oxygen in maxillary sinuses
  2. It is inversely proportional to the size of the maxillary sinuses
  3. Oxygen exchange through the natural Os is twice as  fast as during nasal respiration as during mouth breathing with nostrils closed

We studied mucociliary clearance in patients before and after functional endoscopic sinus surgery in 1997 and showed conclusively that this improves significantly  following  restoring natural drainage and ventilation of the sinuses. We practised pre operative instillation of the solution in cadaver, a  a drop of gention violet (shown in the illustration) to get the “feel” of the procedure. 

A standard solution of  25 % saccharine  was instilled  in to the maxillary sinus through the fontanel  following a surface  anaesthetic of the lateral wall of the nose and patient was observed till he/she experiences a sweet taste in the back of the mouth. The post operative introduction of the solution  in the maxillary sinus was easy through the middle meatal antrostomy. The details of the study  with statistical analysis were published in Ear, Nose and Throat Journal in the  year  1997, volume 76, no.12, 884-886