CURRENT STATE OF THE ART TREATMENT OF SINUSITIS AND SINONASAL POLYPOSIS USING THE MICRODEBRIDER

Author: Dr.G.K.Hebbar

Both chronic sinusitis and nasal polyposis have the reputation of being incurable whatever the modality of treatment.  This was true in the early days, but fortunately things are changing today.  The introduction of endoscopes in E.N.T has revolutionized treatment of these conditions.  However, the latest addition to successful treatment of these disorders is the addition of the microdebrider, a powered tool for treating sinus-related disorders.  Here are a few frequently asked questions regarding chronic sinusitis, sino-nasal polyposis, its diagnosis and its current treatment modality.

What are paranasal sinuses (PNS)?

PNS are mucosal lined air filled cavities in the skull bones adjacent to the nasal cavity and also communicating with this cavity.  There are paired and unpaired sinuses. The paired ones are Maxillary sinuses, Ethmoidal sinuses, Frontal sinuses. Spenoidal sinus is unpaired. 

What is Sinusitis?

Sinusitis is the result of infection of these paranasal sinuses. There are two types of sinusitis – Acute and Chronic. Acute sinusitis is characterized by definite tenderness over the affected sinuses and profuse purulent nasal discharge.  The triad of nasal congestion, facial discomfort and nasal discharge most frequently defines chronic sinusitis.  Frequently, not all of the symptoms of chronic sinusitis are present.

How is sinusitis diagnosed?

The diagnosis of Acute sinusitis is fairly easy and a plain X-ray of the paranasal sinuses (PNS) usually confirms the diagnosis.

In contrast to the relative ease of diagnosing acute sinusitis, diagnosis of headache and facial pain associated with chronic sinus disease requires careful history and meticulous evaluation.  General headlight examination of the nose and X-ray of the PNS may be normal.  The severity of the head and facial pain is variable and pain may be absent.  Accurate diagnosis of chronic sinus disease therefore requires a careful history, comprehensive nasal endoscopic examination, and CT scan of the sinus area. Comprehensive nasal endoscopy is performed using surface anaesthesia in the outpatient setting using 0-degree and 30-degree endoscopes.  The entire nasal chambers, its recesses and the area behind the nasal cavity is examined in detail. When chronic sinus disease is suspected a CT scan of the Osteomeatal complex may be performed. The endoscopic findings are then correlated with the CT scan findings and further steps in the treatment of the condition contemplated. 

Fig: Endoscopic view of Sinus Infection 

What are nasal polyps?

Nasal polyps are smooth-surfaced, fleshy masses extending into the nasal cavity.  They may arise from the Maxillary sinuses, wherein they are termed as Antrochoanal polyps (ACP) or they may arise from the ethmoid sinuses, when they are termed as ethmoidal polyps. ACP’s are usually a single mass and unilateral whereas ethmoidal polyps are multiple and found in both the nasal cavities. Nasal polyps are easily diagnosed on general head light ENT examination.  A CT scan confirms the diagnosis and provides more details of the affected sinuses.  It helps in planning the treatment. 

Fig: CT scan of Antral Polyp

What is the treatment modality of Chronic sinusitis and Nasal polyps?

Management of either chronic sinusitis or nasal polyps follow similar principles.  The first step is to identify any reversible process that may affect the mucosa of the nose or PNS.  These are generally some allergens.  Hence antiallergic and decongestant treatment is the first line of therapy.

Chronic sinusitis and nasal polyps have to be tackled surgically.  Earlier, in chronic sinusits, the sinuses were tackled through an external route.  This caused increased morbidity to the patient and the recurrence rate was higher.  Also, in cases of nasal polyps intranasal polypectomy with the aid of a headlight was performed which was associated with a very high recurrence rate.  Today, with the introduction of rigid endoscopes the entire modality of treatment for sinus diseases and nasal polyps has been revolutionized.

What is Functional Endoscopic Sinus Surgery (FESS)?

The introduction of high-quality nasal endoscopes has markedly improved intraoperative visualization by the intranasal route.  Trauma to normal structures, and hence postoperative morbidity is minimized and precise meticulous surgery to restore physiologic routes of drainage and re-establish ventilation is possible. This is in stark contrast to non-endoscopic intranasal procedures where there is a lot of blood loss and damage to the normal structures causing a lot of scar tissue and poor functional results.  Since the FESS techniques have been standardized external approaches to the sinuses are rarely done these days.  Practically however, the limited field of view may create disorientation unless the surgeon has developed an intimate knowledge of the anatomy.  Hence the surgeon needs to be trained specifically in endoscope and instrument handling techniques in such confined spaces.  FESS techniques have proven to be far superior to other conventional modalities of treatment followed earlier.  In most cases patients are discharged the next day and need absolutely no bed rest.  Most of them report for work within forty-eight hours after surgery.  

Fig: Video-Endoscopic Sinus Surgery in progress

What is a microdebrider?

The microdebrider is a powered rotary shaving device with continuous suction used during FESS.  It is made up of a cannula connected to a hand piece, which in turn is connected to a motor with foot control and a suction device.  The cannula is made up of two parts, an outer blunt tip with a lateral port and an oscillating inner cannula with a similar lateral port has serrated blade which cuts and extracts soft tissue as it is suctioned through the side port of the cannula.  The blunt tip of the outer cannula protects vital structures within the sinuses and only the soft tissues that are sucked into the lateral port is cut and extracted.  Hence this device is built for safety. 

What are the advantages of the microdebrider in FESS?

Endoscopes have markedly improved visualization for sinus surgery, but expanding concepts of FESS have outpaced available operative instrumentation.  The surgical techniques are continually improving, but the basic concepts of the newer instruments have changed very little.  With currently available FESS instruments, surgeons often find that they cannot do the precise and delicate surgery demanded by the functional approach.  Consequently, the goals of meticulous cutting, a near bloodless field, unimpaired vision, and continuous removal of resected tissue remains elusive.  The instruments used so far are “grabbing” tools that grab and tear normal tissues along with the diseased tissues.  This grab and tear approach predisposes to increased bleeding, which is the archenemy of the FES surgeon, because it leads to decreased visibility, the cornerstone of complications.  The lack of continuous suction at the operative site is a technical limitation that compounds the stress for the surgeon and increases the inherent risk for the patient.

The microdebrider facilitates preservation of mucosa and vital structures by resecting only diseased, obstructive tissue with very limited blood loss.  Simultaneous continuous suction at the operative site is a marked benefit of this instrument, which helps overcome the well recognized problem of blood pooling that increases the potential for operative morbidity.  Since the normal tissues are not disturbed the healing time is cut by half.  There is no scar tissue formation and the function of the sinuses and the nasal cavities are restored to normal in a short time after surgery.

Nasal polypectomies are performed in a more precise manner with very little blood loss.  Because the blood loss is minimal and the operative field clear removal of the disease is complete.  Hence the recurrence rate is low when compared to conventional polypectomies.

The microdebrider has shown itself to be a safe and effective instrument for routine and complicated FESS.  It is increasingly replacing conventional instruments in FES surgery the world over.