Otitis media and externa

Otitis externa exists in two types. A patient may have: (1) An infected hair follicle near the entrance of his meatus (a staphylococcal boil), which is very painful, because the skin here is tightly bound down to the perichondrium of the elastic cartilage of his ear. His boil is always near the entrance to his meatus, because there are no hair follicles to become infected in the deeper bony part. (2) A diffuse inflammation of his whole ear canal resembling eczema. The common causes are: (a) excessive self-cleaning of the ear, (b) ''stress' and (c) excessive humidity.

Acute otitis media is typically a disease of children. A child presents with acute earache, and fever; if he is very young, he may vomit, or have fits. At first, the margin of his drum and the handle of his malleus are red; later, his entire drum is red and bulges, so that it obscures his malleus. A few hours later his drum may burst, and give him instant relief. Otitis media is most common in children under one, and is often recurrent. Haemophilus influenzae or Streptococcus pneumoniae are usually responsible. Antibiotics are effective, if you give them in good doses promptly. There is no need to continue them beyond 48 hours.

Chronic otitis media is usually the result of failure to treat the acute stage. It too exists in two types.

The tubotympanic type is much more common, and is also known as the mucosal or ''safe' type, because it rarely leads to serious complications. The patient has a profuse mucopurulent discharge from his ear, without a very bad smell; he has a central perforation of his drum (a hole surrounded on all sides by drum), and moderate deafness. This type is the result of a low resistance to infection, due to poor health and nutrition.

The attic, bony type is also known as the ''unsafe' type, because it is more likely to lead to complications if the disease becomes advanced. A cyst lined with epidermis develops in the upper part of the patient's middle ear, and fills with scales to form a ''cholesteatoma'. This is surrounded by inflammatory tissue, and may erode through the bony walls of his middle ear and create a pathway for infection. He has a perforation on the edge of his drum, in its pars flaccida, or in its posterosuperior region. He has a small volume of very smelly discharge, and is usually severely, but variably, deaf. This type is common in India and South East Asia, but is less common elsewhere. Erosion and infection may spread: (1) Into his labyrinth, causing giddiness. (2) Through the roof of his middle ear, causing an extradural or subdural abscess in his temporal lobe, or in his posterior fossa. (3) To his lateral sinus, which may thrombose, and make him very ill with a high fever. (4) To his meninges; this is uncommon because infection is usually well localized. (5) To involve his facial nerve. Refer all these complications; he needs expert surgery, including a mastoidectomy, perhaps with tympanoplasty,, to preserve his hearing, and perhaps his life.

OTITIS THE DIFFERENTIAL DIAGNOSIS of acute otitis media is mainly otitis externa (particularly a boil in the ear), and in young children, ''teething'.

Suggesting otitis externa[md]the patient is an adult with normal hearing (unlike otitis media), no fever or only a low fever, less malaise and prostration than with otitis media. He has pain when his pinna and canal are moved. He may also have a swollen, tender node just behind his ear. Don't confuse this with the tender bone of mastoiditis.

OTITIS EXTERNA If he has a boil in his ear, give him a strong analgesic, and a high dose of an intravenous or intramuscular antibiotic, effective against penicillin-resistant staphylococci. Apply an ear wick of magnesium sulphate or glycerine and ichthammol.

CAUTION ! (1) Don't incise a boil unless it is clearly fluctuant, because there is a danger of perichondritis and collapse of his pinna. (2) A boil in the ear is very painful, so don't forget the analgesics.

If he has the diffuse form of otitis externa, keep his ear clean. Syringe it, and be sure to mop it dry afterwards. Give him antiseptic steroid ear drops. If he is a ''self-cleaner', treat the condition that is causing him to touch his ear, and persuade him to leave it alone.

If it is subacute or chronic, clean his ear with boracic or 50% spirit drops. If he also has a low-grade skin infection, give him a broad spectrum antibiotic systemically.

ACUTE OTITIS MEDIA TREATMENT. Give antibiotics early. Give him a high dose of ampicillin or amoxycillin for 2 days. Or, less satisfactorily, give him penicillin. Aim for good compliance over this short period. If he is very unwell, give the antibiotic intramuscularly. Avoid chloramphenicol as a first choice, and use erythromycin only if he is allergic to penicillin. Relieve his pain, and apply local heat to his ear (the mother of one contributor, who had otitis media as a child, used to wrap a hot baked potato in a woolly sock and apply this to his ear[md]marvellous!). As soon as he is well, and his drum is no longer bulging, stop the antibiotics.

If his pain and fever continue, and his drum is still bulging after 24 hours of treatment, the organism is probably insensitive to the antibiotic you are giving him, or you are not giving him enough. Change the antibiotic or increase the dose.

If acute otitis media fails to resolve after 5 days of antibiotic treatment, change to another one. If this fails, stop: don't persist with antibiotics indefinitely. Some surgeons incise the drum (see below) when pain has not improved after 3 days of antibiotic treatment.

If you see a child after his drum has already perforated, and is discharging, culture the discharge and give him penicillin for a week. If necessary, change the antibiotic when the result becomes available. Teach his parents, or a nurse, to dry-mop the discharge with cotton wool (''Primary Child Care' Section 17.5). If this is not done often enough, otitis externa and a persistent discharge may follow. Monitor his hearing. If it does not return to normal, refer him. In the developed world, where otitis media is normally treated early, a persistent discharge after acute otitis media already suggests mastoiditis. It may not do so elsewhere.

If his mother has difficulty getting cotton wool to swab his ear, ask her to put a toilet paper wick (assuming she has any) into it for a minute, three times, and to repeat this three times a day.

CAUTION ! Don't attempt myringotomy (incising the drum)[md]it is not for the occasional operator, because you can easily dislocate the incudo-stapedial joint. The only absolute indication for it is acute otitis media, with a facial palsy (see below).

CHRONIC OTITIS MEDIA DIAGNOSIS. This is the patient with a perforated ear- drum which discharges continuously or intermittently, and who may or may not give a history of a previous acute attack. Smell the discharge. An offensive, thick, pasty discharge is characteristic of a cholesteatoma, and thus of serious disease. His prognosis, and the urgency of referral, depend on where the perforation is in his drum, rather than on how big it is.

If the perforation does not extend to the edge of his drum, and does not involve its pars flaccida (the superior part of his drum), it is central and is not dangerous, because a cholesteatoma is rare. He complains of increasing deafness, recurrent discharge, and occasionally earache, but pain is rare. Referral is less urgent. Teach him the importance of a careful aural toilet.

If the perforation extends to the edge of his drum, and particularly if it involves the pars flaccida, it is marginal and is dangerous, because it implies bone destruction. A cholesteatoma is common. Try to refer him.

TREATMENT FOR CHRONIC OTITIS MEDIA. Mop out his ear canal, and try to see the peforation. If there is much discharge, rinse out his ear with warm sterile water or saline; mop his ear dry, and you will then be able to examine it. You can syringe a discharging ear, but it is probably wise not to syringe one with a cholesteatoma. Try to keep his ear mopped dry with cotton wool, in the hope that the perforation in his drum will heal. Spirit drops may dry it out.

He may develop any of the many complications listed under ''Difficulties with chronic otitis media' below.

DIFFICULTIES [s7]WITH ACUTE OTITIS MEDIA If he has SEVERE EARACHE, WITH A NORMAL DRUM, suspect referred pain from dental caries, or an impacted wisdom tooth. If these are not responsible, suspect referred pain from his pharynx, or his temporomandibular joints. If an adult has earache, a normal drum, and an enlarged node in his neck, suspect that he has carcinoma of his pharynx (32.28), or larynx.

If you see a FLUID LEVEL or BUBBLES in a child's ear, with an indrawn drum, he has SEROUS OTITIS MEDIA (secretory otitis media). This may be the result of obstruction of his Eustachian tube by enlarged adenoids, and is common in children recovering from otitis media, or it may occur spontaneously. He usually has no pain, and little hearing loss. If there are bubbles or a fluid level, enough air remains to maintain his hearing; with all the air gone, deafness is more marked. Middle ear effusions usually resolve spontaneously, so wait several weeks if necessary. If his effusion persists, it may it may alter his behaviour, and impair his speech, even if it does not cause marked hearing impairment. If his school behaviour or progress is poor, or the acquisition of speech is affected, consider referring him for myringotomy, perhaps with the insertion of a grommet for ventilation.

If he has acute otitis media, and develops a FACIAL PALSY, myringotomy is essential. Refer him. Distinguish this from herpes zoster of the geniculate ganglion, which is excruciatingly painful, and is accompanied by vesicles in his meatus and on his drum.

If he has TENDERNESS, redness, and swelling over his mastoid process, he has ACUTE MASTOIDITIS. This is usually accompanied by persistent fever, and a red, bulging drum, with pus discharging through a perforation. Tenderness is acute high on the mastoid proces. Note that a meatal boil (furuncle) may also produce postauricular swelling, due to the infection of an adjacent lymph node. If he is an infant, acute mastoiditis causes a swelling above and behind his ear, displacing it outwards and downwards. If he has a boil in his meatus, the swelling is evenly distributed up and down his postauricular groove, displacing his ear outwards, but not downwards.

If AN ADULT DEVELOPS SEROUS OTITIS MEDIA for the first time, consider the possibility of obstruction of his Eustachian tube by a nasopharyngeal tumour.

If your workers delivering primary care are NOT ALLOWED TO USE ANTIBIOTICS, and so cannot use them to treat otitis media, instruct them like this. Clean the ear, syringe it with a rubber rat-tailed syringe, using water or, better, 30% spirit in saline. Then insert drops of 50% spirit. With the ear held uppermost for 2 minutes, insert 2 or 3 drops twice daily after cleaning. Although attic disease and a cholesteatoma should not be syringed, the risks in the routine use of this treatment are small.

DIFFICULTIES [s7]WITH CHRONIC OTITIS MEDIA If he has a TENDER SWELLING OVER HIS MASTOID, he has ACUTE-ON-CHRONIC MASTOIDITIS, and needs a radical mastoidectomy. If you cannot refer him for this, do a cortical one (25.4). Temporary drainage may be lifesaving, and allow you more time to refer him.

If he has chronic otitis media, and has earache, this is ominous. Pus is gathering under pressure somewhere, and, unless it is released, it may track internally, with serious results. If he also has fever, he needs referral for a radical mastoidectomy soon, even if he has no signs of other complications. Antibiotics alone will cure none of the complications; but always start them before you refer him.

If he has earache and fever with bilateral chronic discharge, the side with the ache is the side on which he has acute-on-chronic mastoiditis.

If PERMANENT DEAFNESS develops as the result of bilateral chronic otitis media, he will need a hearing aid.

If he has chronic otitis media and develops a FACIAL PALSY, a cholesteatoma is invading his facial nerve. Refer him for radical mastoidectomy.

If he has a chronically discharging ear and suffers from SEVERE VERTIGO, perhaps with VOMITING, he has LABYRINTHITIS. These symptoms are worse when he moves his head. He usually also has fever and is unwell. Look for a fine horizontal nystagmus, and see if this is made worse when you close his ear canal with your finger, and gently press it (the fistula sign). Admit him, and give him penicillin in high doses, as described below, with chloramphenicol and metronidazole. He needs a radical mastoidectomy, as soon as his labyrinthitis has settled.

If he has a chronically discharging ear which suddenly becomes PAINFUL, and he has HEADACHES, VERTIGO, NECK STIFFNESS, or LOSS OF CONSCIOUSNESS, his condition is serious, because the infection has spread from his middle ear to his dura, meninges, or brain. Admit him, give him penicillin with chloramphenicol and metronidazole, and refer him rapidly.

If he becomes VERY ILL with severe headache, vomiting, and fever, he has MENINGITIS. Neck stiffness, photophobia, and a positive Kernig's sign will soon follow. Confirm the diagnosis by lumbar puncture. Examine his CSF by Gram's method, and culture it.

Either give him 600 mg penicilllin G intramuscularly every 4 hours for 3 days, then 6-hourly. And inject 10 000 units intrathecally every day. And give him chloramphenicol and metronidazole, as in Section 2.9.

Or, if you have no chloramphenicol, combine the penicillin with metronidazole and sulphadiazine 2 g 4-hourly.

Continue these drugs for 2 weeks, but stop the intrathecal penicillin after 3 days. Make sure he has an adequate fluid intake. When his meningitis has settled, he needs a radical, or failing that, a cortical mastoidectomy.

If, in addition to the signs of meningitis (above), he develops NOMINAL APHASIA (difficulty in naming familiar objects), or PYRAMIDAL SIGNS, suspect a BRAIN ABSCESS. Refer him: he is best treated by drainage through a burr hole (a hazardous operation because of the nearness of the sigmoid sinus) and antibiotics, followed by a radical mastoidectomy.

If he has RIGORS, and is comparatively well in between, suspect LATERAL SINUS THROMBOSIS. Do a lumbar puncture, and when the manometer is in place compress his jugular vein, first on one side, and then on the other. If his CSF pressure rises on the normal side, but not on the side on which he has ear symptoms, his lateral sinus is thrombosed on that side (Queckenstedt's test). Give him high doses of penicillin, and refer him.

Fig. 25-2 ANATOMY FOR MASTOIDECTOMY. A, a schematic view of the tympanic antrum with the horizontal semicircular canal in its medial wall. B, the squamous temporal bone, showing the position of the suprameatal (MacEwen's) triangle. C, a diagrammatic view of this triangle bordered by the three tangents, showing the drum lying anteriorly. D, the cavity of the middle ear and its connecting air spaces. E, gouge into the triangle from these directions. F, use a gouge not a chisel. G, a horizontal section through the external auditory meatus, showing the approach to the mastoid. Note that the meatus runs anteromedially.

1, the attic. 2, the antrum. 3, the suprameatal triangle. 4, the posterior extension of the zygomatic process (the suprameatal ridge). 5, the spine of Henle. 6, the handle of the malleus. 7, the facial nerve. 8, the lateral sinus. 9, the lateral semicircular canal. 10, the external auditory canal. 11, the eustachian tube. Kindly contributed by Christopher Holborrow, Ian Kennedy and Patrick Beasley.