Some surgeons prefer a turban-style head drape. Figure 41-2 depicts the method used to create a turban from a drape. Patients undergoing local anesthesia may wear pajama-type bottoms or underpants to the OR in some facilities. Patients having general anesthesia should wear only a gown.

Equipment and instrumentation

Illumination is provided by the overhead spotlight, the operating microscope, the endoscope, or the surgeon’s fiberoptic headlight. Some surgeons want the room darkened during endoscopy. Various types of fiberoptic endoscopes with appropriate accessories are used. The diameter of aspirating tubes and forceps is small enough to pass through small lumens, and the length is long enough to extend beyond the end of the scope. The lighting mechanism and all accessories should be checked for working order before the patient is brought to the room.

Suction should be available at all times and should include several patent cannulas. The degree of suction should be variable and usually includes a thumb hole for intermittent release of the vacuum. Cannulas with very fine suction tips should be irrigated frequently to avoid blockage. Fine suction tips are equipped with stylets for clearing the lumens.

Suction irrigators are used with sinus endoscopes. Irrigation equipment and solution at body temperature should be available to remove bone dust, clean burrs, and rinse suction apparatus. Warm solutions would cause vasodilation, with the potential for obscured vision by venous bleeding.

Special care with electric appliances is indicated. Bipolar and monopolar electrosurgery are used to control bleeding. Many ENT surgeons use Coblation technology, which is a form of high-frequency bipolar energy in a conductive medium, usually saline. The target tissue is removed using a lower temperature than traditional electrosurgery devices.

Compressed air or nitrogen drills with a foot-pedal control are used on bone, such as the mastoid area. Only the operator should activate the foot pedal. A number of drills for extremely fine work, such as stapes sculpturing, are powered by small electric motors fitted into a handpiece. The tip of the drill is cooled by small drips of irrigation solution during use.

Instrumentation is varied to suit the area. It includes very delicate, small endoscopic and microsurgical implements in addition to various sized bone instruments because of the extensive involvement of cartilage and bone in the facial structures and skull. These areas have relatively little soft tissue. Many instruments are angled with small jaws to permit insertion without obscuring visualization.

Lasers may be used. Carbon dioxide (CO₂) lasers are used to vaporize tissue. Argon lasers coagulate tissue by heat generation. Potassium titanyl phosphate (KTP) lasers coagulate to shrink or debulk tissues. Neodymium:yttrium-aluminum-garnet (Nd:YAG) lasers cut and coagulate to minimize bleeding. Appropriate ebonized or dulled instrumentation and attachments must be available for each type of laser.

Laser surgery is usually done in conjunction with the operating microscope or endoscope. Microsurgical techniques are used because they facilitate distinction between normal and diseased tissue and allow more accurate dissection. All safety precautions are taken to avoid ignition and injury when a laser is used. Team members must wear protective eyewear of the correct optical density for type of laser in use.

Cryosurgery may be used to destroy tissue in accessible areas, especially those that bleed profusely if incised.

Hemostasis and drugs on the sterile field

One or two drops of blood can obscure a microsurgical field. Hemostatic aids and sponges should be ready at all times. Gelfoam pledgets soaked in 1:1000 epinephrine are commonly used. Soaked pledgets are kept in a labeled Petri dish and passed only with forceps. Press the saturated pledget against the side of the dish to wring out some of the moisture before passing to the surgeon.

Various solutions and medications are on the sterile field, for example, cocaine, lidocaine, and epinephrine. Each container and delivery device should be clearly labeled for distinction between irrigation solutions and drugs. Unused drugs are discarded in the presence of another team member after the case is completed. The amount of unused cocaine should be documented before discarding.

Sponges and compressed patties are relatively small and are a distinct hazard when blood soaked because they can occlude an airway. All items used in the OR are counted or accounted for in their entirety at the end of the procedure.

Tissue grafts and implants

Handle tissue grafts only with forceps, taking care not to crush the tissue. Tissue grafts must be kept from drying out before use. A convenient method is to place the graft on a moist cellulose sponge in a sterile, covered Petri dish. Some surgeons intentionally dry a temporalis fascia graft to facilitate handling. This type of graft, as well as cartilage, may be flattened and thinned in a small sterile press.

Ear

Anatomy of the ear

The structures of the outer and inner ear (Fig. 41-3, A and B) are concerned with two functions:

FIG. 41-3 A, Anatomy of the outer ear. B, Anatomy of the inner ear.

1. Hearing (i.e., receiving sound, amplifying it, and transmitting it to the brain for interpretation)

2. Maintaining body equilibrium

Anatomically, the ear is divided into three parts: external, middle, and inner.

External ear

The external, or outer, ear consists of the auricle, or pinna, composed of cartilage except for the lobe; skin; and the external auditory canal. The meatus of the auricle leads, via the ear canal, to the tympanic membrane or eardrum. This membrane separates the external and the middle ear. A color change of the translucent eardrum, visible through a speculum, may be indicative of middle ear disease. The outermost lining of the tympanic membrane is derived from tissue of the ear canal. The inner lining is continuous with the middle ear mucosa. The eardrum protects the middle ear but may be perforated by injury or pressure built up in the middle ear by infection.

Middle ear

The middle ear consists of the tympanic cavity, a closed chamber that lies between the tympanic membrane and the inner ear. Within this cavity are the three smallest bones in the body—an ossicular chain comprising the malleus, incus, and stapes. They resemble a hammer, anvil, and stirrups, respectively. The malleus, which is attached to the eardrum, joins the incus, the extremity of which articulates with the stapes, the innermost bone. The footplate of the stapes fits in the oval (vestibular) window, an opening in the wall of the inner ear.

The bones of the ossicular chain must be able to move mechanically to conduct sound from the eardrum to the inner ear. The round (cochlear) window, also between the middle and the inner ear, equalizes pressure that enters through the oval window.

The middle ear opens into the nasopharynx by way of the eustachian tube. Normally closed during swallowing or yawning, the eustachian tube aerates the middle ear cavity. This mechanism is essential for adequate hearing.

Posteriorly the middle ear exits to the mastoid process. This inferior projection of the temporal bone is a honeycomb of air cells lined with mucous membrane. Because the antrum of the mastoid process connects with it, middle ear infection may produce mastoiditis. The middle ear is situated in the tympanic portion of the temporal bone; the inner ear is situated in the petrous portion, which integrates with the base of the skull. The tympanic portion also forms part of the ear canal.

Inner ear

The end organs of hearing and equilibrium are situated in the inner ear. The two main sections—cochlear and vestibular—have distinct, although coordinated, functions. The cochlea, a bony spiral, relates to hearing. The vestibular labyrinth, which is composed of three semicircular canals, relates to equilibrium. These structures house two separate fluids—endolymph and perilymph—which nourish and protect the hearing receptors.

The neuroepithelium of the organ of Corti, the end organ of hearing, holds thousands of minute hair cells, which respond to sound waves that enter the cochlea via the oval window. The neuroepithelium of the vestibular portion also contains hair cells. Rapid head motion produces current in the endolymph that may result in nausea or vertigo. The eighth cranial (vestibulocochlear) nerve governs reflexes to muscles to maintain equilibrium and controls hearing.

Proximal structures

The middle and the inner ear are adjacent to many important structures. The seventh cranial (facial) nerve is enclosed in a bony canal running through the tympanic cavity and mastoid bone. The meninges of the temporal lobe of the brain are also near the middle ear and the mastoid. Facial paralysis, meningitis, and intracranial infection, such as brain abscess, are potential complications of ear infection.

The major blood vessels are the internal carotid artery and internal jugular vein, as well as the lateral sinus. Thrombosis and infection of the lateral sinus of the dura mater are potentially lethal complications of otitis media, with or without mastoiditis.

Physiology of hearing

Sound or pressure waves enter the auricle. They pass along the ear canal to the tympanic membrane. The vibration of the waves is transmitted across the middle ear sequentially by the ossicles. Amplification of sound is enhanced to some extent by mechanical action of the ossicles but mainly by aerial ratio. A large volume of sound wave pressure from the tympanic membrane funnels to a small reactive area, the stapedial footplate, intensifying sound. At the footplate of the stapes, sound pressure is transferred to the inner ear via the oval window. The hair cells of the organ of Corti are set in motion by disturbance of the inner ear fluids as sound wave pressure moves from the oval to the round window. Mechanical energy is converted to electrical potential, which is delivered to the brain along the eighth cranial nerve. The brain interprets the impulse (sound) as hearing.

Pathology of hearing

Hearing affects the quality and quantity of interpersonal interactions. It is a major sense for communicating within one’s environment.⁵ Loss of hearing therefore affects social relationships. The type of deafness or hearing loss in varying degrees may result from the following:

1. Disease, such as otosclerosis, in which changes in the bony capsule of the labyrinth occur. Otosclerotic bone invades the stapedial footplate, resulting in its fixation and ultimate inability to vibrate in the oval window. Hearing loss is gradual but progressive. This type of deficiency can be surgically corrected when auditory nerve endings are not destroyed.

2. Trauma, such as a perforated eardrum, requiring repair to restore function and aerial ratio.

3. Infection, usually controlled by antibiotics. Although it is more common in children, infection may also occur in adults. It may cause accumulation of fluid in the middle ear. Mastoiditis results from extension of otitis media.

a. Serous otitis media may result from obstruction of the pharyngeal orifice of the eustachian tube. If blocked, for example, by hypertrophied adenoid tissue, infection, or allergic swelling, the eustachian tube is unable to equalize pressure because air cannot enter the middle ear from the pharynx. The vacuum or negative pressure thus created causes serum to be drawn into the tympanic cavity from blood vessels in the middle ear mucosa. Recurrent otitis media may require drainage of purulent exudate if conservative treatment fails.

b. Acute otitis media may require drainage of purulent exudate if conservative treatment fails.

c. Chronic otitis media with or without mastoiditis may follow recurrent otitis media with tympanic membrane perforation. It can produce a chronically draining ear.

Differential diagnosis

Measurements that compare bone conduction with air conduction are important in differential diagnosis. Bone conduction refers to hearing as transmitted through the skull; air conduction refers to transmission of sound waves from the tympanic membrane to the inner ear via air. Hearing loss caused by a defect in the external or middle ear, referred to as conductive loss, is a mechanical obstruction of air conduction that usually can be helped by surgical intervention. When the decrement is in the inner ear, referred to as perceptive or sensorineural loss, damage to nerve tissue and/or sensory paths to the brain is not benefited by a surgical procedure. Cochlear nerve endings are the main component of sensorineural hearing (Fig. 41-4).

FIG. 41-4 Cross-section of cochlear labyrinth with sensory neural mechanism.

Auditory acuity and function are measured by various tests. The audiogram is one measurement tool. Computer-averaged tomography is used to measure and analyze electrical impulses, known as auditory brainstem responses, from the brain and cortical auditory pathway. An acoustic reflex latency test of the stapedius reflex provides information about hearing sensitivity. Auditory brainstem evoked potentials assess the patient’s hearing threshold.

Surgical procedures of the ear

Current techniques, instrumentation, lasers, and the operating microscope have enhanced the capability of otologists.

General considerations

1. Local anesthesia may be used for a minor procedure on the external ear, but general anesthesia generally is used to avoid patient movement while the surgeon is manipulating delicate structures in the middle or inner ear.

a. Inhalation anesthesia may be given by facemask for a short procedure, with the anesthesia provider seated at the head of the OR bed.

b. The anesthesia provider sits alongside the OR bed with the patient facing him or her when the patient is intubated for a major procedure.

c. Hypotensive anesthesia may be employed to create a bloodless field, especially during microsurgery.

d. Nitrous oxide is discontinued before placement of a graft in the middle ear to minimize the risk for increased pressure in the inner ear.

e. General anesthesia may be supplemented with a local agent in some procedures, often with epinephrine to control bleeding.

2. The patient’s head is turned with the affected side up and stabilized in a donut. The pinna on the unaffected side should be protected from pressure.

3. Lint-free drapes are preferred. It is mandatory that gloves be free of powder and lint. The formation of a powder granuloma in the oval window can cause irreversible sensorineural hearing loss.

4. The operating microscope is used for many otologic procedures.

a. The surgeon sits at the head of the OR bed to use the microscope.

b. Microinstruments should be carefully handled before, during, and after use.

5. Compressed absorbent patties (cottonoids) moistened with normal saline solution, rather than gauze sponges, are frequently used. They must be counted.

6. Hemostasis may be achieved with epinephrine, absorbable hemostatic sponges or oxidized cellulose, laser, and bone wax.

7. Prosthetic devices should be available in an assortment of types and sizes. Tissue allografts may be used.

8. A nerve stimulator may be used to identify facial, acoustic, cochlear, and/or vestibular nerve branches. Evoked potential audiometry also may be used to monitor the seventh and eighth cranial nerves.

9. Bone instruments, including powered drills, are used for opening the temporal bone.

10. CO₂, Nd:YAG, argon, and KTP lasers are used during otologic procedures to control bleeding, divide nerves, and/or vaporize tissues.

11. Pressure dressings are usually applied. Some surgeons place 1 drop of phenylephrine (Neo-Synephrine) in the ear canal postoperatively.

External ear procedures

Removal of a foreign body.

Removing a foreign body from the outer canal is performed most frequently in children. The object is washed out or removed to prevent purulent infection. A plant seed or vegetable foreign body, such as a pea, is not irrigated, because it may swell in the ear and increase the difficulty of removal.

General anesthesia sometimes may be required. Trauma should be minimal during removal of a foreign body to prevent stenosis of the canal or perforation through the eardrum.

Drainage of a hematoma.

Usually a result of injury, a hematoma is drained to avoid infection with subsequent chondritis and deformity of the auricle.

Excision of a tumor.

The extent of the surgical procedure to excise a tumor, either benign or malignant, depends on the size and type of tumor. The skin of the pinna is vulnerable to actinic (chemical) changes caused by radiant energy during exposure to the sun. Basal cell lesions do not metastasize, but squamous cell carcinoma often does. Primary cancer may be excised by a wide or wedge excision with primary closure or a wide excision with a skin graft. If the lesion is extensive, partial or total pinnectomy may be necessary. The area can be skin-grafted and reconstructed cosmetically with a prosthesis. Radical temporal bone resection is indicated if the bone (canal) is involved. Neck dissection may be indicated if nodal metastases are present.

Middle ear procedures

Mastoidectomy.

Mastoidectomy, the eradication of mastoid air cells, may be indicated to relieve complications of acute or chronic mastoiditis. Mastoidectomy is more commonly performed in conjunction with a reconstructive procedure (see “Tympanomastoid Reconstruction”). A cholesteatoma can form after repeated infections (Fig. 41-5).

FIG. 41-5 A, Mastoid air cells and cholesteatoma. B, Mastoid bone with air cells and cholesteatoma removed.

Simple mastoidectomy.

The mastoid process is opened behind the ear. Air cells are removed by drilling through bone with small burrs, without involving the middle ear or external canal.

Modified radical mastoidectomy.

Simple mastoidectomy and removal of the posterior wall of the ear canal provide drainage from the mastoid into the canal. The tympanic membrane and middle ear ossicles are preserved.

Radical mastoidectomy.

A radical mastoidectomy is performed for chronic mastoiditis. The middle ear cavity and mastoid antrum are combined into a single cavity for inspection and cleaning. Mastoid air cells are removed. The ossicles and tympanic membrane are partially removed. The stapes and facial nerve are preserved.

Tympanoplasty.

Tympanoplasty, as a general term, refers to any procedure performed to repair defects in the eardrum and/or middle ear structures for the purpose of reconstructing sound conduction paths. The degree of hearing improvement after tympanoplasty is related to the degree of damage. Preferably, the ear should be uninfected at the time of the surgical procedure. If not, infected tissue is debrided. As microsurgical procedures, tympanoplasties are classified into five types:

1. Type I (myringoplasty) is closure of a perforation in the tympanic membrane caused by infection or trauma. The ossicular chain is normal. Autologous fascia or a vein is used to repair the perforation. A vein graft is taken from the patient’s forearm or hand. Fascia, more commonly used as a patch over a perforation, is obtained from the temporalis muscle.

2. Type II is closure of a perforated tympanic membrane with erosion of the malleus. The graft is placed against the incus or remains of the malleus.

3. Type III replaces the tympanic membrane to provide protection for the stapes and round window. The tympanic membrane, malleus, and incus have been destroyed by disease. The stapes is intact and mobile. A homograft of tympanic membrane with attached malleus and incus is placed in contact with the normal stapes, permitting transmission of sound.

4. Type IV is similar to type III except that the head, neck, and crura of the stapes are missing. The mobile footplate may be left exposed with the graft placed around it. The air pocket between the graft and the round window provides sound protection for the round window. To conserve the middle ear hearing mechanism, homograft transplantation of tympanic membrane and ossicles may be used to rebuild the chain.

5. Type V is similar to type IV except that the stapedial footplate is fixed because of otosclerosis (osteospongiosis). A fenestra (small opening) is made in the horizontal semicircular canal. The homograft seals off the middle ear to provide sound protection for the round window.

Reconstruction of the middle ear may be done with a synthetic bioinert material such as high-density polyethylene sponge (Plastipore). Fibrin glue also is used. Partial and total ossicular replacement prostheses have been developed.

Tympanomastoid reconstruction.

Tympanoplasty may be combined with either simple or radical mastoidectomy. The mastoid is drained and cleaned before reconstruction of the eardrum or middle ear ossicles. After incision behind the auricle, the tympanic membrane and tympanic cavity are inspected. The mastoid antrum is entered by drilling through mastoid bone.

Sometimes in chronic otitis media, the mucous membrane of the tympanic cavity is replaced by epithelium from the ear canal as it grows through a perforation in the eardrum. Desquamated skin cells that cannot escape form a ball or cyst, known as a cholesteatoma. If present in the middle ear or mastoid, a cholesteatoma is removed during mastoidectomy and/or tympanoplasty. If left intact, a cholesteatoma can cause permanent hearing loss, balance disturbance, infection, and facial nerve paralysis.

Stapedectomy and stapedotomy.

Conductive hearing loss can result from fixation of the stapes, most often caused by otosclerosis. The surgeon aims to restore vibration from the incus to the mobile oval window membrane to transmit sound. A stapedectomy involves partial or total removal of the stapes.

A partial stapedectomy removes only the fixed footplate (Fig. 41-6); a total stapedectomy removes the entire stapes, including the footplate. A stapedotomy (small opening into the footplate) may be the preferred procedure. The opening is made with a handheld perforator, microsurgical power drill, or laser. An argon, CO₂, or KTP laser may be used for this purpose. A low-wattage lasing beam avoids thermal damage to the perilymph and inner ear structures. After partial or total stapedectomy or stapedotomy, the remaining superstructure is used to reconstruct the sound-conducting mechanism.

FIG. 41-6 Partial stapedectomy. A, Stapes superstructure attached to fixed otosclerotic footplate. B, Footplate removed; superstructure remains.

An incision is made deep in the canal near but not in the eardrum. The eardrum is folded over, giving access to the middle ear. The stapes is disconnected from the incus, fractured by fine microinstruments, and removed. The oval window is sealed by a graft of vein, perichondrium, fascia, fat, or an absorbable hemostatic sponge over the oval window. A prosthesis is inserted and connected to the incus and to the graft, thus restoring sound conduction. Prostheses are made of various inert materials such as polyethylene, stainless steel, or tantalum.

By performing the microsurgical procedure with the patient under local anesthesia, the surgeon can reposition the eardrum and use his or her voice to test whether the patient’s hearing is improved. Otosclerosis usually involves both ears, but stapedectomy is performed on only one ear at a time.

Stapes mobilization.

The stapes is manipulated at the footplate to restore normal function. A break through an otosclerotic lesion is achieved by means of transcrural pressure or direct application of chisels and picks to the footplate. A mobile, unaffected portion of a functioning stapes remains. Various techniques are used, with or without the use of prosthetic devices. The advantage of the procedure is that the preserved stapedial footplate provides natural protection for the inner ear. The disadvantage is that frequently a continuing otosclerotic process causes the footplate to become refixed. Therefore stapedectomy is more popular because it produces long-lasting results.

Stapes procedures are performed under direct vision with the operating microscope. The procedures do not disturb the integrity or position of the eardrum.

Removal of middle ear vascular tumors.

The argon laser is absorbed by red pigment. Therefore, it is suited for removal of small vascular tumors in the middle ear, such as glomus tympanicum tumors. The argon laser acts by photocoagulation.

Inner ear procedures

Endolymphatic sac shunt.

The endolymphatic sac is an appendage of the membranous inner ear located in the posterior fossa, anterior to the lateral sinus and posterior to the semicircular canals. An excessive accumulation of endolymph in this sac causes the episodic vertigo (dizziness), tinnitus (ear ringing), and sensorineural hearing loss of Ménière’s disease. Through a simple mastoidectomy approach, the sac is opened and the inner ear is drained into either the subarachnoid space or the mastoid. A shunt tube is inserted to maintain drainage.

Labyrinthectomy.

In labyrinthectomy the vestibular labyrinth is removed from the inner ear to correct incapacitating vertigo. This results in loss of vestibular function and hearing.

Vestibular neurectomy.

A middle fossa approach to the internal auditory canal for vestibular neurectomy combines otologic and neurosurgical procedures. Through a temporal bone craniotomy incision, dura of the floor of the middle fossa is elevated to expose structures in the superior portion of the internal auditory canal. The superior and inferior vestibular nerves, which control equilibrium, are sectioned to control intractable vertigo. The cochlear nerve, the hearing portion of the eighth cranial nerve, is not damaged, thus preserving hearing. A graft of temporalis muscle is placed over the exposed internal auditory canal to prevent leakage of cerebrospinal fluid.

Removal of an acoustic neuroma.

Acoustic neuroma resection may be performed by an otologist and/or a neurosurgeon, depending on its location and the extent of neurologic involvement. An acoustic neuroma is a slow-growing, encapsulated, benign tumor of the eighth cranial (acoustic) nerve. It originates in the neural sheath in the internal auditory canal but grows to involve nerve fibers in the posterior fossa. Initially the patient experiences unilateral hearing loss and disturbances, especially tinnitus, and equilibrium problems such as mild vertigo.

The syndrome may resemble Ménière’s disease or an expanding intracranial tumor. Early differential diagnosis is enhanced by brainstem evoked response audiometry, vertebral angiography, and small-volume air-contrast computed tomography (CT).

A small neuroma, confined to the internal auditory canal, may be resected by the otologist using a microsurgical technique through a middle fossa approach to preserve hearing. If a translabyrinthine approach is used to gain access to the internal auditory canal posterior to the inner ear structures, the patient will have total hearing loss after the surgical procedure. Acoustic neuromas extending into the cranial cavity are resected by the neurosurgeon. The CO₂ laser may be used to excise acoustic neuromas through a transmastoid or craniotomy approach. Cerebrospinal fluid leak and meningitis are complications of the craniotomy approach.

For select patients, stereotactic radiosurgery can be performed on an outpatient basis with local anesthesia. Hearing is preserved in 50% of these patients.

Implantation of a cochlear prosthesis.

Cochlear implants have been used for adults since the 1980s, but it was not until the 1990s that they were used for children. Children as young as 1 year old can be candidates for implantation. A cochlear implant can restore perception of sound to patients who have profound sensorineural deafness not responsive to external amplification of a hearing aid. They are indicated for use in patients who have intact eighth cranial nerve function.

The implant is an electronic device that converts sound waves into electrical signals to stimulate cochlear nerve fibers in the absence of functioning hair cells. Several devices are available. All of them have external and internal components (Fig. 41-7). The external part, which is attached behind the ear, has a microphone/transmitter and a speech processor/receiver. The internal part has a receiver/stimulator and electrode/channel that is threaded through the cochlea.

The internal electrode attaches to wires permanently implanted in the cochlea. Through a postauricular incision, a simple mastoidectomy is performed. Under the operating microscope, the facial recess between the posterior canal and the facial nerve is enlarged to expose the chorda tympani nerve and the middle ear. The electrode is securely seated in the mastoid cavity and placed through a recess into the middle ear. It is directed through an opening made in the round window into the scala tympani until it meets resistance. Placement is critical. A plug of fascia from the temporalis muscle is placed around the electrode at the round window to prevent perilymph leakage.

The internal electrode stimulates the auditory nerve to interpret sound. The single-channel model stimulates the nerve randomly so that the patient can discern environmental sounds but not speech. A multichannel electrode enables the patient to distinguish environmental sounds and some speech by differentiating the frequency, volume, and pitch of sound waves. With a single-channel electrode, a ground wire is placed under the temporalis muscle in the mastoid or middle ear. A multichannel electrode does not have a ground wire. The internal receiver is sutured in position over the temporal bone behind the ear.

Electromagnetic components and/or a titanium enclosure for the receiver may act as an electrical ground device. Only bipolar electrosurgery is used if additional surgery is needed after placement of the receiver. Patients with cochlear implants should avoid MRIs because of metal components within the implanted device.

The external microphone/transmitter component of the implant activates the internal receiver/stimulator. Transmission may be percutaneous or transcutaneous. In the percutaneous model, a direct wire to a receiver implanted behind the ear connects the transmitter. In the transcutaneous model, the transmitter converts electrical energy into magnetic currents that pass through intact skin to the receiver. In both models, sound enters the microphone and is transmitted to a speech processor, worn outside the body, where it is encoded into electrical signals or energy and amplified. The coded signals return to the transmitter and are passed to the internal receiver. The patient can adjust amplification of environmental sounds.

Nose

Anatomy of the nose

The supporting structures of the nose consist of two nasal bones and the nasal processes of the maxillary bones superiorly, the lateral cartilages and connective tissue inferiorly, and the septum. The septum, composed of bone posteriorly and cartilage anteriorly, divides the nose into two chambers lined by mucous membrane. The anterior portion, or vestibule, holds the nasal hairs. The external anterior orifices are called nares.

The internal portion of the nose, the nasal cavity (Fig. 41-8) extends to the nasopharynx, the space behind the choanae (funnel-like posterior nasal orifices). The nose communicates with the ear via the eustachian tube. The hard and soft palates divide the nasal and oral cavities. The ethmoid bone separates the nasal and cranial cavities.

The paranasal sinuses are the frontal, maxillary, ethmoid, and sphenoid. Ostia (openings from the sinuses and nasolacrimal ducts) are located in the nasal lateral walls. The ostia provide a drainage system for the sinuses, as well as aerate them. Three turbinate bones (superior, middle, and inferior) are also situated in the lateral walls. These bones are covered with a vascular mucosa. Beneath each turbinate is a corresponding meatus. Tears drain into the nose through the nasolacrimal duct that enters the inferior meatus. Drainage from the paranasal sinuses is passed to the nose through the middle and superior meatus.

External and internal carotid arteries and their branches supply blood to the nasal region. Because of the extensive vascularity, lymphatic supply, and proximity to the brain, infections on or about the face are potentially very dangerous. Microorganisms may readily be carried to the cavernous sinus, or thrombi may form in the cavernous sinus. The sense of smell is derived from the first cranial (olfactory) nerve. The sensory nerve supply of the nasal area is associated with the trigeminal or fifth cranial nerve.

Physiology of the nose

• It provides filtered air to the respiratory system. Fine cilia in the mucous membranes propel mucus toward the nasopharynx. Air is warmed and moistened as it passes to the trachea and lower respiratory tract.

• It contains the end organs for smell in the olfactory epithelium, which differs from other nasal epithelia. When nasal obstruction blocks off the olfactory epithelium, loss of smell (anosmia) results. The senses of smell and taste are closely related.

Surgical procedures of the nose

Nasal procedures are concerned with two factors: adequate ventilation to accessory spaces and adequate drainage from them. Abnormalities in structure, congenital or traumatic, and disease processes hinder function. Corrective procedures are done to relieve obstruction, to ensure drainage, to resect tumors, or to control bleeding (epistaxis).

General considerations

1. CT and rhinoscopy are often performed preoperatively to diagnose the nature and extent of pathologic conditions, especially in the paranasal sinuses.

2. Many nasal procedures are performed with the patient under local anesthesia with or without IV sedation.

a. Topical 4% cocaine may be sprayed on the nasal mucosa or applied with soaked, compressed, absorbent patties (cottonoids) or sponges put in the nostrils. Cocaine produces vasoconstriction, as well as anesthesia. The used patties should be accounted for at the end of the procedure.

b. A local agent, often lidocaine hydrochloride, 1% or 2%, is injected into the middle meatus. Epinephrine usually is used for vasoconstriction to control bleeding.

c. When general anesthesia is indicated, a pack is placed in the pharynx to prevent aspiration of blood after the patient is intubated.

3. Paranasal sinuses and tissues underlying the mucosa are considered sterile. Therefore, instrumentation should be sterile, although the nasal cavity is considered a contaminated area because the instrumentation is entering a vascular bed. Venous drainage could easily carry microorganisms to the cavernous sinus, causing an intracranial infection.

4. CO₂, Nd:YAG, and KTP lasers may be used. Endoscopes also are used. All equipment and accessories should be checked for working order.

5. Nasal packing is inserted at the end of most procedures except endoscopic sinus and laser procedures. A mustache dressing may be placed under the nose to act as a drip pad. Postoperatively the patient should be positioned in a head-up position to minimize bleeding. Ice is placed over the nasal bridge for the first 48 hours. The ice should be used in 20-minute intervals only.

Nasal cavity procedures

The supporting structures surrounding nasal air passages can be injured or displaced. Acute or chronic disease processes can cause dysfunction or obstruction.

Epistaxis.

Most nosebleeds are caused by trauma, usually at Kiesselbach’s plexus of arteries and veins (also known as Little’s area) in the anterior part of the nasal septum (Fig. 41-9). Dehumidified air may cause changes in the mucosa and splitting of tiny vessels. Bleeding may be spontaneous, as in patients with arteriosclerosis, hypertension, or blood dyscrasia. Epistaxis is usually anterior and unilateral. In people with systemic disease, such as leukemia, or with severe fracture, the bleeding is frequently posterior and more severe. Management involves locating the precise bleeding site and promptly instituting appropriate therapy. Severe hemorrhage places the patient in a precarious condition. Hypovolemia should be corrected preoperatively.