How to Use an Otoscope

A. Simon Carney, Registrar in Otolaryngology
John P. Birchall, Professor of Otolarygology
Department of Otolaryngology, Queens Medical Centre
Nottingham NG7 7UH
(Modified slightly from an article that originally appeared in 1995 in the British Student Medical Journal)


Although few medical graduates go on to a career in ear, nose, and throat surgery, most doctors will at some time be required to look at the ears of patients under their care. Unfortunately, otoscopy is often poorly mastered by medical students. Detailed knowledge of pathology is not essential, but if you can recognise the appearance of a normal ear and then develop a simple system to detect any abnormalities that you may not be familiar with, you will not go far wrong.

 

Clinical anatomy

Fig. 1. The pinna - The pinna is composed of elastic cartilage covered with skin. In the middle is the conchal bowl, which funnels down towards the external auditory meatus.

The external ear canal is about 2-5 cm long in adults and extends from the conchal bowl to the tympanic membrane. It is not straight so you need to pull the pinna upwards and backwards to get a better view of the tympanic membrane. The membrane lies at an angle to the canal creating the anteroinferior recess of the canal, where debris or foreign bodies may collect.

 

 

Fig. 2. The tympanic membrane consists of the pars tensa and the pars flaccida (figs 2 and 3 on next page). The malleus handle lies in the middle layer of the pars tensa. At the superior end of the handle is the lateral process of the malleus, the most medial and easily recognisable structure in the drum. The tip of the handle is called the umbo, and a cone of light can usually be seen extending anteroinferiorly from the umbo - the light reflex.

The drum is surrounded by a fibrocartilaginous annulus, and the chorda tympani nerve (the branch of the facial nerve supplying taste to the anterior part of the tongue) crosses the junction between the pars flaccida and pars tensa. You can see the long process of the incus and the stapedius tendon through the posterosuperior quadrant of the drum, the promontory (the bone overlying the basal turn of the cochlea) and the round window niche through the posteroinferior quadrant, and the eustachian tube orifice anterosuperiorly.

 

Using an otoscope

First explain to the patient that you are going to look in the ear and that it may be uncomfortable, although it should not be painful. Choose a speculum size that is appropriate for the patient's canals and fit it to the otoscope. Children have narrower canals and will require a narrower speculum than adults.

Always hold the otoscope in the hand of the same side as the ear you are about to examine.

You can hold the otoscope in either a pencil grip or a hammer grip. The pencil grip allows the side of your hand to rest on the patient's temple, reducing the risk of trauma if the patient suddenly moves his or her head (this is common when examining young children or patients with tender canals). Many students prefer the hammer grip as it initially feels more natural. It is less satisfactory, however, because you have less control, which increases the risk of inflicting pain by pressing the speculum tip on to the skin of the canal wall. We recommend that you persevere with the pencil grip until you find it a more natural poise.

 

Examine the good ear first

Examine the good ear first. This has several advantages: it prevents the spread of infection into an unaffected ear, it usually allows you to see some normal anatomy with which to compare the other side, and also helps stop you relaxing once you have identified one abnormality, failing to see less obvious but often more important findings - a common problem of students. With the light source turned up full, use the otoscope as a torch to examine the pinna briefly for meatal abnormalities and previous surgical wounds.

Fig.3. The commonest scars around the ear are those from postaural and endaural incisions. Eczema around the meatus usually indicates the presence of otitis externa. With your free hand, gently pull the pinna upwards and backwards to straighten the external ear canal. This is not usually necessary in young children as the canal is straighter. While resting the side of your hand against the patient's temple introduce the speculum gently into the canal. The patient may cough as the cutaneous branch of the vagus is stimulated.

 

What to look for

Examine the external canal and the tympanic membrane systematically. You should learn Figure 2 thoroughly because if you are not sure what you should be looking for you will undoubtedly miss things.

Firstly, look at the external canal wall. Does the skin look normal or is it inflamed with debris in the canal (otitis externa)? Next identify the handle of the malleus. If it is not immediately obvious then look for its lateral process, which is rarely absent.

You should then inspect the pars tensa systematically, starting in the posterosuperior quadrant and then moving forwards, downwards, and backwards until all 360 degrees has been covered. Try to identify as many structures as you can. Finally, carefully inspect the pars flaccida - this is where abnormalities are often missed.

To make sure you do not miss anything ask yourself the following questions.

 

Common problems

Although this is not a comprehensive system, it should give you some idea ofthe likely abnormality. If you are in any doubt refer the patient to an ear, nose, and throat specialist.

 

Case histories

Otoscopic view of normal ear.

Case 1. A 23 year old man had had intermittent odourless discharge from his right ear for two years since experiencing sudden earache while diving on holiday. He felt he was deaf in that ear and had recently noticed some high pitched tinnitus on the right, although his ear was currently dry. What does otoscopy of his right tympanic membrane show? Answer.

Case 2. A 5 year old girl had multiple attacks of otitis media, was falling behind in her schoolwork, and was mispronouncing words. Her teacher felt she was not paying attention in class and her parents noticed that she turned up the television volume to unacceptably loud levels. The picture above shows the otoscopic appearances. What is the likely diagnosis? Answer.

Case 3. A 28 year old woman had put up with an intermittent foul smelling discharge from her ear for over 10 years. Topical antibiotics controlled her symptoms for only a few weeks. She had suddenly become very deaf in the affected ear and had asked for a specialist opinion. What do the otoscopic findings suggest? Answer.

 

Buying an otoscope

Good otoscopes are generally expensive, and as most wards and clinics should have one available it is not usually necessary for you to buy your own. Many students, however, will want to buy an ophthalmoscope, and otoscopic attachments may either be included or can often be purchased for a small extra cost. It is worth checking the quality of the otoscopic parts because a poor otoscope will not allow an accurate assessment of the tympanic membrane, no matter how skilled you are. Adequate dedicated otoscopes can be purchased for around £150.

 

Conclusions

It is not essential to have a vast knowledge of ear, nose, and throat surgery to detect most common complaints diagnosable with the otoscope. After your ear, nose, and throat attachment, your examination skills often deteriorate because of lack of practice. If you continue to look in the ears of patients seen on other wards otoscopy will soon become as routine as the rest of the physical examination. The more normal ears you look in, the easier it becomes to detect disease when you come across it.

 


 

Answers

Case 1. The man has a perforation of the posterosuperior quadrant of the tympanic membrane. No cholesteatoma is visible, and the intact long proces of the incus and stapes head can be seen through the perforation.


Case 2. The tympanic membrane is intact but is dull and a golden colour. This child has otitis media with effusion (glue ear). If this is persistent she may benefit from the insertion of ventilation tubes (grommets).


Case 3. There is a large mass of infected squamous epithelium and keratin behind the pars flaccida - a cholesteatoma. This can cause infective complications such as meningitis and may erode into the labyrinth or facial nerve. The cholesteatoma therefore needs to be removed. The operation entails exploring the mastoid to identify the fundus of the sac, removing the disease, and grafting the surgical defect.