Tuesday, March 29, 2011

Modified septoplasty

Introduction:


Septoplasty is the commonly performed surgical procedure these days. It has been evolving for more than a century. It was in the early part of 20th century Freer and Killian first reported this procedure. The technique developed by them involved removal of the complete nasal septum (SMR). It was left to Cottle to fine tune their procedure of submucosal resection of nasal septum. During initial stages due to fear of complications and constraints of illumination septal deviations involving the anterior and middle portions alone were corrected adequately. Posterior deviations were left unattended. With the advent of excellent equipments like the nasal endoscope the whole of the nasal septum can be visualised and this led to removal of excess septal cartilage leading to complications like septal perforation, flappy nasal mucosa and nasal deformities like saddle nose etc. Inspite of being nearly a century old procedure the concepts governing septal surgery has undergone very few modifications. Metzenbaum recognized the importance of caudal portion of nasal septum and was instrumental in devising the first principles of septoplasty. His swinging door technique is still being followed with minor modifications in the septoplasty procedure performed even now.


Modified septoplasty procedure:
Wang etal suggested certain modifications in the currently performed septoplasty procedures. These modifications were aimed at:


1. Ability to deal with all types of septal deviations
2. Preservation of cartilagenous support framework
3. Avoidance of complications


Before suggesting these modifications they conducted extensive studies on the biomechanics of septal deviation. In their study they identified three key stress lines in the nasal septum. These stress lines are:


1. At the junction between the caudal septal cartilage and the medial crus of the alar cartilage. This often causes anterior deviation.
2. Between the quadrangular cartilage and the perpendicular plate of ethmoid. This often leads to superior deviation.
3. Between the quadrangular cartilage and vomer bone, palatine process of maxilla and nasal crest of palatine bone. Deviations in this area leads to inferior deviation.


The reasons for these stress lines can be accounted if the theory of differential septal ossification is considered to be the cause for septal deviation.









Diagram illustrating the three stress lines of nasal septum


During the development of nasal septum uneven ossification of the various parts of the septum can occur. The developing nasal septum is supposed to contain a membranous component anteriorly and cartilagenous and osseous component posteriorly. The posterior portion of nasal septum ossifies and forms perpendicular plate of ethmoid, nasal crests of palatine and maxillary bones and the vomer. Studies have shown that the septal cartilage is still in the process of continuous growth even after full maturation of maxilla and palatine bones. Due to the space constraint the growing cartilagenous portion of the nasal septum buckles.

In the modified procedure of septoplasty suggested by Wang etal the septum is surgically accessed via the standard Hemitransfixation incision. The septal cartilage is freed from its anterior, posterior and inferior attachements. Only the superior attachment is intact ensuring that the septal cartilage does'nt fall off. The cartilage can be shortened in order to fit in to the space. The shortening of the cartilage causes the septum to straighten. Since cartilage is fractured in order to correct the deviation healing takes a little longer. Splinting of the nasal septum is a must atleast for 10 days for optimal wound healing to occur.

Advantages of this modified procedure:

  1. It maintains the thickness and rigidity of the nasal septum
  2. Avoids synechiae formation
  3. Prevents depression of nasal tip and pyramid
  4. It reduces the incidence of septal perforation.
  5. This procedure can safely be performed in adolescents also.

Sunday, March 27, 2011

Drugs used in otology and their formulations


Introduction: Various drugs and formulations are used in otological practice. Some of them may be of questionable value from the therapeutic stand point, still it is worthwhile knowing about these formulations. Topical otological preparations are so unique they need to be studied in detail.

Advantages of topical drug use in otology:
  1. The drug can be administered right where it is needed
  2. First pass metabolism doesnt come into play
  3. Drug is delivered in a targetted manner, in adequate doses. Toxicity is not common
  4. Chronic inflammatory diseases of middle ear cavity causes a certain amount of fibrosis preventing adequate concentrations of systemically administered drug reaching it.

Ear drops are solutions / suspensions of medicines in solvents like water, glycerol, diluted alcohol, or propylene glycol. These solutions can be instilled into the ear. For these ear drops to be effective sufficient contact time should be provided.

Indications for use of topical ear drops:

  1. Bacterial / fungal infections of external auditory canal
  2. Chronic suppurative otitis media with a large drum perforation
  3. To liquefy accumulated wax in the external auditory canal
  4. Myringitis granulosa

If drops are to reach the middle ear in adequate concentration the ear drum perforation should be fairly large. The method of administration of ear drops to reach the middle ear cavity is known as the displacement method. In this method the external ear is made dependent by turning the head to the opposite side, with the chin touching the shoulder. The external auditory canal is filled with ear drops. Pressure is applied to the external ear by alternate pressing of the tragus. This maneuver displaces the air from the middle ear cavity which is duly filled up by the ear drops.


Difference between solution and solvent ear drops:

Solution usually consists of a drug which is dissolved in a solvent where as suspension consists of an insoluble drug distributed in a liquid medium. Some of the ear drops can be used as eye drops also. To facilitate such multi usage certain adjuvant drugs are added to the drops in addition to the active drug. Commonly used adjuvants in such drops which can be used as eye and ear drops include:

  1. 0.01% Benzalkonium chloride – This acts as an antifungal agent
  2. Sodium metabisulphite – This agent acts as a buffer maintaining the pH of the solution. This strict maintenance of pH prevents easy degradation of the active drug molecule present in the drops. It also minimizes the irritation caused due to application of the drops. It also retards the oxidation of the active drug there by prolonging the effect of the active drug.
  3. Disodium edetate – This is another adjuvant commonly used. It also acts as an excellent buffering agent. This adjuvant drug increases the bactericidal and antifungal activity of Benzalkonium chloride.
  4. Steroids – Beclamethazone is the commonly used steroid adjuvant drug in the ear drops for its antiinflammatory effect.

Some of the local drug preparations to be used in the external auditory canal may be in the form of creams / ointments. These ointments usually contain antibiotics and antiinflammatory agents in a suitable base like liquid paraffin, wool fat, yellow soft paraffin. Ointments usually have paraffin base. Ointaments are very useful in managing dry scaly skin conditions of external auditory canal. Ointment preparations with Lanolin as the base (wool fat) should be marked clearly on the tube because some patients may develop hypersensitivity reaction to this component of the medicine.

Acetic acid ear drops – Acetic acid in concentration of 2% is an excellent antibacterial and antifungal agent. Acetic acid ear drops can be used to treat mild otitis externa. This is commonly used in paediatric age group.

Aluminium acetate ear drops: This is an astringent drug which can be administered as ear drops or by dipping a cotton wick in the drug and inserting the same into the external auditory canal. Astringent belongs to a group of medicine that causes shrinkage of tissue on local application. Shrinkage of tissue is caused due to the hydroscopic effect of the drug. Hence it can be used to reduce oedema involving the external auditory canal. If this drug needs to be used for its astringent effect then it should be administered using a cotton wick. This drug is known to cause deposition of aluminium acetate crystals in the external auditory canal. Hence periodic cleansing of the ear is a must when this drug is used. This drug can be safely used even in pregnant mothers. In fact this is safest drug that can be administered during pergnancy.

Boric acid ear drops: Formerly this drug was used for their bacteriostatic and antifungal efects. It can be used in varying concentrations. Maxium concentration that can be safely used is 5%. This drug gets absorbed via the inflammed skin leading on to systemic toxicity due to the drug.

Antibiotic & steroid ear drops:
Betnesol / prednisolone sodium phosphate can be administered along with antibiotics like gentamycin / neomycin / quinolenes. When used in combination with these antibiotics they faciliate better effects due to their antiinflammatory effects.

Clotrimazole ear drops:
Clotrimazole is a broad spectrum antifungal agent. This drug inhibits ergosterol synthesis by the fungal cell wall. This destroys the fungus. Fungal infections involving the external auditory canal can also be caused due to inappropriate use of steroid ear drops. Administration of clotrimazole can cause burning sensation in the external auditory canal. Patient should be advised to tolerate it.

Ceruminolytic ear drops:
These are the most commonly used ear drops. Drugs belonging to this group include oil / aqueous preparations. These drugs are known to soften the wax facilitating its removal by aural syringing. 0.9% sodium choloride solution can be used as ceruminolytic agent. 5% sodabicarb solution can also be used as ceruminolytic agent.
Olive oil / coconut oil / liquid paraffin can also be used as ceruminolytic agents.
Organic solvents like chlorbutanol / paradichlorobenzene can also be used as solvents, but may cause irritation to meatal skin.

Indications for administration for systemic antibiotics:

  1. Acute otitis media
  2. Furunculosis of external auditory canal
  3. Perichondritis of pinna
  4. Acute mastoiditis
  5. Malignant otitis externa

Drugs administered systemically include:

  1. Amoxycillin
  2. Flucloxacillin
  3. Ciprofloxacillin
  4. Penicillins

Drugs used in the management of vertigo:

Betahistine can be used in the management vertigo associated with meniere's disease. This drug reduces the endolymph pressure by improving microvascular circulation in the striavascularis of the cochlea. It also reduces the vertigenous sensation by inhibiting the firing rate of vestibular nuclei. Betahistine is known to reduce vertigo / tinnitus but does little to improve hearing. It is usually prescribed in doses of 16 mg thrice a day.
This drug should be used with caution in patients with bronchial asthma / peptic ulcer.

Dopamine antagonists: Prochlorperazine belongs to this group. Goes by the popular name Stemetil. It is a dopamine antagonist acting by blocking the chemoreceptor trigger zone. It is less sedating with fewer antimuscarinic effects.

Antihistamines: Drugs belonging to this group acts on H1 receptor at the level of chemoreceptor trigger zone thereby blocking the vomiting centre. Examples of drugs belonging to this group are cinnarizine and cyclizine. Cinnarizine can be used as prophylaxis for migraine in doses of 30 mg three times a day. Cyclizine is useful only during acute attacks and is given in doses of 50 mg thrice a day.

Diuretics in the management of meniere's disease: Thiazides and acetazolamide can be used in the management of acute symptoms of Meniere's disease. The cause decompression of the endolymphatic sac due to their diuretic effects.

Steroids in the treatment of sudden sensorineural hearing loss: Steroids have been used in the management of sudden sensorineural hearing loss with varying degress of success. Dosage regimen is as follows:
Prednisalone
60 mg on day I
50 mg on day II
40 mg for following three days
30 mg for subsequent three days

Use of antiviral drugs in otology:

Acyclovir is the classic example of drug belonging to this group. It can be administered in patients with Herpes Zoster oticus. It acts by inhibiting nucleic acid synthesis. It is administered orally in doses of 800 mg five times a day for 5 days. If administered within 72 hours after development of rash it reduces post herpetic neuralgia.





Use of sodium fluroide in otosclerosis:
sodium fluroide is used tto slow down the development of sensorineural hearing loss in a patient with otospongiosis. It acts due to its enzyme inhibiting activity there by preventing osteoclastic bone resorption. Usually it is administered in doses of 40 mg per day for a period of 3-6 weeks. This drug is really useful in patients with cochlear otosclerosis. It has propensity to cause gastric irritation and renal damage.

Friday, March 25, 2011

Wednesday, March 23, 2011

Canine fossa trephination

Introduction:


The key to any successful Endoscopic sinus surgery lies in clearing the residual disease from the maxillary sinus cavity. The diseased mucosa of the maxillary sinus cavity could cause formation of pus, eosinophilic fungal debris, polyps etc. These disorders dont reverse after performing a wide middle meatal antrostomy. They need to be cleaned out physically which can be rather difficult via the middle meatus as the anterior wall of the maxillary sinus and the high lateral walls are virtually not reacheable via the natural ostium. It is hence advisable to remove as much as diseased mucosa from the maxillary sinus in order to facilitate the rapid return of the sinus mucosa to normal. This is where maxillary sinus trephination has a role to play.


Optimal location for Canine fossa traphination:


Anatomical studies have shown that the best place to insert the trocar in the canine fossa is at the junction of the mid pupillary line and a horizontal line drawn through the floor of the nasal vestibule. At this site a 5mm hole can very easily be drilled thorough which a 4 mm nasal endoscope can easily be passed.



Illustration showing the exact location for placing the trocar in the canine fossa




Indications for canine fossa trephining:

  1. Grade III maxillary sinus disease that cannot be addressed adequately via the enlarged natural ostium
  2. Presence of excessive polypoidal mucosa within the maxillary sinus
  3. Presence of mucopyoceles
  4. Presence of a large antrochoanal polyp

Before proceeding with canine fossa trephining a large middle meatal antrostomy should be performed. A 70 degree endoscope can be used to inspect the interiors of the maxillary sinus cavity. This inspection will also help in grading the maxillary sinus disease.

Grade I – Normal or slightly oedematous mucosa
Grade II – Oedematous mucosa with small polypi without eosinophilic mucous
Grade III – Presence of extensive polypi and thick tenacious mucin

Anatomy of the canine fossa:

The canine fossa is the thinnest portion of the anterior wall of the maxillary sinus. Hence it is easy to breach this area and enter into the sinus. Boundaries of the canine fossa include:

  1. Canine eminence formed by the canine tooth – medial
  2. Root of the zygoma – laterally
  3. Alveolar process of maxilla - inferiorly
  4. Infraorbital foramen with the infraorbital nerve superiorly

The trephining of the canine fossa can be performed sublabially. After successful trephination using the trocar has been performed the opening can be widened using a burr. The opening should be wide enough to permit insertion of a 4 mm nasal endoscope. The maxillary sinus can be visualized from both angles i.e via the natural ostium using a 70 degree endoscope and via the opening in the anterior wall of maxilla. One port can also be used to introduce instruments to remove the diseased mucosa and pent up secretions.

Complications: Are very few if anatomy is respected.

  1. Facial numbness
  2. Numbness of upper dentition
  3. Pain over the cheek
  4. Hematoma over cheek

Most of these complications are self limiting and resolve within the first week after surgery.



Middle turbinate Implant

video



Middle turbinate lateralization has been reported as the most common factor associated with the failure of primary endoscopic sinus surgery.  Currently various techniques have been used to prevent lateralisation of middle turbinate like packing the middle meatal area with merocel or resorting to Bolgerisation.  This middle turbinate implant helps in preventing lateralization of middle turbinate following endoscopic sinus surgery.

Tuesday, March 22, 2011

Role of imaging in the diagnosis of parapharyngeal and adjacent neck space lesions


Introduction:
Parapharyngeal space is a suprahyoid neck space. It is surrounded by other important facial spaces. Old text books divided this space into prestyloid and post stymoid compartments. The prestyloid compartment lying infront of the styloid process and the post styloid one lying behind it. Current literature designates post styloid compartment as carotid space and the prestyloid compartment is considered to be the true parapharyngeal space. The parapharyngeal space contains fat. This is clearly visible in imaging and displacement of fat indirectly helps the radiologist to identify and quantify the extent of lesions involving parapharyngeal space. Parapharyngeal space is a hidden area that cannot be easily examined. Lesions of this space present rather late and in advanced stage. A surgeon will have to resort to imaging in order to visualize this area. 

Paraph Imaging

Sunday, March 20, 2011

Labyrinthitis ossificans


Introduction:
The human bony labyrinth is composed of endosteal, enchondral and perisoteal layers. The endosteal layer consists of bone lined with a single layer of cells that have numerous gaps separating them. This layer is significantly thin. The enchondral layer is rather unique in that it reaches the adult size by 23 weeks of gestatation and undergoes minimal remodelling after the age of 2. The periosteal layer is composed of lamellar bone and is capable of bone remodelling and repair.
Labyrinthitis ossificans is the pathologic new bone formation within the lumen of otic capsule. This condition is always associated with profound deafness and loss of vestibular function. Cochlear ossification in this condition doesnot cross the endosteal layer or alter the architecture of the enchondral bone.

Causes of labyrinthitis ossificans:

  1. Bacterial meningitis
  2. Vascular obstruction to labyrinthine artery
  3. Temporal bone trauma
  4. Autoimmune inner ear disease
  5. Leukemia
  6. Tumors of temporal bone
  7. Suppurative labyrinthitis following CSOM

Commonly involved portion of cochlea in this condition is scala tympani portion of the basal turn of the cochlea. This is more severe in patients with bacterial meningitis. Infections from inflammed meninges reach the inner ear via the cochlear aqueduct. Usually the cochlear aqueduct drains into the scala tympani close to the round window region. This is the reason why predominant ossification of the inner ear occurs in this area following bacterial meningitis. This creates lot of problem during cochlear implant electrode introduction via the round window. This ossified area should be drilled out with a microdrill inorder to insert the electrode in these patients.

According to Paperella labyrinthitis ossificans can be divided into three stages:

Acute stage – This stage is characterised by pus which fills up the perilymphatic spaces, sparing the endolymphatic space. This is followed by the formation of serofibrinous exudate.

Stage of fibrosis – This stage is characterised by fibroblastic proliferation within the perilymphatic spaces which usually begins two weeks after the onset of infection. This stage is also associated with new bone formation (angiogenesis).

Stage of ossification – This stage is characterised by bone formation and is first observed at the basal turn of the cochlea.

Theories proposed to explain the pathogenesis of labyrinthitis ossificans:

  1. Paperella's theory: This theory was proposed by Paperella and Sigiura in 1967. They hypothesized that bone lining cells of the cochlea are plueripotent stem cells that remain uncomitted till they are stimulated to differentiate into osteoblasts.
  2. Linthicum theory: Linthicum in 1985 said that bone originates from osteoblasts within the otic capsule. He also suggested that ectopic bone forms on the endosteal layer after an inflammatory insult.
  3. Pericyte theory: This theory suggests that pericytes associated with blood vessels that supply the modiolus and spiral ligament have been hypothesized as cells of origin.



Monday, March 14, 2011

Effects of sectioning chorda tympani nerve during middle ear surgery

Introduction:


The chorda tympani nerve is a branch of facial nerve. It derives all its fibers from the nervous intermedius of wrisberg. The chorda tympani nerve contains gustatory fibers from the anterior two thirds of the tongue and parasympathetic fibers to all the salivary glands excepting the parotid. Sectioning the chorda tympani nerve not only affects the taste but also reduces the basal secretion of salivary glands causing xerostomia.


Discussion:


The sublingual and submandibular salivary glands are responsible for about two thirds of the basal saliva production. The parotid gland contributes to just a third of the basal salivary production. Destruction / trauma to chorda tympani nerve on both sides can definitly cause dryness of mouth due to a reduction in the amount of saliva secreted by sublingual and submandibular salivary glands. Usually sectioning of one chorda tympani nerve will go unnoticed. When middle ear surgery is contemplated on both ears then the patient should be warned of the realistic risks of xerostomia. Caution should be exercised in operating on the opposite ear of patients who have already undergone middle ear surgery in the ipsilateral ear.


Hence all otologists should take extra care to preserve this nerve during middle ear surgical procedures.

Sunday, March 06, 2011

Novel way of managing Little's area bleed in the nose


Many a time we would have faced problems cauterizing a Little's area bleed. This is basically due to the use of nasal speculum
which obscures the field and also keeps one hand occupied. Bray in his " How I do it" describes how he put to use the Mallet spint.
Procedure:
A Mallet splint is a common tool used to treat Mallet (Trigger) finger. This splint is available in different sizes. It can be cut and introduced into the anterior nares.
This keeps the nasal cavity open providing a good view of nasal septum area. It also has the advantage of leaving both the surgeon's hand free.
The most proximal part of the Mallet splint is cut and shaped into a "U" shaped splint. This splint can be readily inserted into the nasal cavity.
Since this splint is made of silastic, its memory holds the nasal cavity open.
Since both the hands of surgeon are free the bleeder can easily be cauterized either by electro or chemical cautery.

fingersplint


Stack's splint