The short cases

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Chapter 6 The short cases

Clinical examination is more art than science. When the art is practised well, the science (investigation) is merely confirmatory.

The authors’ mantra

The short cases require practice over a period of time.

Purpose

The individual short cases are the examiners’ oppor tunity to see how candidates elicit physical signs and therefore give candidates the opportunity to showcase what they do on a daily basis.

Format

Each candidate sees four short cases, two cases with one pair of examiners and two cases with a different pair of examiners. Each of the four examiners will act as the lead for an individual case. For each pair of cases you have 20 minutes, although the time allocated to each case may not be equal, depending on the complexity of cases. As with the long case, bells are used to signal the start and finish of each section. When the bell sounds for the end of the first 20-minute session, you will be redirected to sit outside another room ready for the second session. Following a five-minute break, you will be taken by the second pair of examiners to your other two cases for a further 20 minutes.

The ‘typical’ split of the short cases is one cardio vascular, one neurological, one of either respiratory or abdominal and one other. However, the actual cases used will depend on availability on the day. Therefore, more than one case may be given from the same system. None of the above categories are mandatory and the order of cases varies. At least one short case will be paediatric.

As a guide, for each case approximately seven minutes is usually assigned to the clinical examination before presentation and questions. You will be given the choice of presenting your findings as you go or at the end. Any further discussion will relate only to the case at hand. The focus will be on synthesising findings for a diagnosis or differential diagnosis, including further methods to clarify this. On occasion you may be shown results of relevant investigations that assist in the differential diagnosis, although time constraints will usually prevent this.

Preparation

The majority of short cases will be outpatients with painless, stable, well-documented signs. Most of these patients are well trained and follow instructions easily. Really well trained patients will even anticipate your next move and position themselves accordingly. However, a good ‘hot’ case from the emergency department will not be overlooked. For this reason, your examination technique also has to work for the ‘untrained’ patient — and, as such, it has to work in your everyday work life. Remember, the most effic ient way to examine a system is via the short case tech nique. You should therefore consider practising this tech nique as preparing for all your future patient exam in ations, not simply rehearsing for the fellowship exam.

There is no substitute for practice. Each component of the short case is important and requires preparation and practice. This means becoming familiar with:

• the equipment you will use
• the setting in which you see patients
• the range of patients you will see
• the technique and timing of the clinical examination
• presenting each case
• answering questions on each case.

The only way to look slick and present with ease is to have done it a sufficient number of times so you do not have to think about it.

Become familiar with your chosen location for your equipment, especially pins, cotton wool, tuning fork and tendon hammer for the neurological exami nation. Most candidates prefer to use their own ophthalmoscope and auroscope. By necessity, those provided are often slightly different from the kind normally in use at your workplace. Practising on ‘normal’ volunteers is an excellent way to become familiar with your examination ‘kit’ without having to suffer the embarrassment of disorientation in front of real patients.

Be comfortable doing basic observations. A FACEM should look slick measuring blood pressure, pulse rate, respiratory rate, SaO2 and temperature. Practising these skills will help enormously. Recording them in the notes at work and encouraging others to do likewise will also engender good working relationships with the nursing staff.

When given a patient’s name, use it a few times straight away (as this is also your only time to ask again or be corrected successfully if you get it wrong) and regularly afterwards. This technique is a favourite for salespeople. Calling people by name engages them earlier, makes them relaxed and engenders a sense that you are taking a personal interest in them. Try it, and compare the results with when you don’t do this.

You will be given the choice of presenting your findings as you go or at the end. Most major systems (e.g. cardiovascular) are better suited to a summation at the end as you accumulate diagnostic information along the way. For others where the diagnosis is apparent but several signs need to be demonstrated (e.g. rheumatoid hands or examination of a lump), presenting as you go ensures you do not omit findings.

Top athletes are taught: ‘Train as you intend to compete, because you will always compete as you train.’ Become familiar with examining each system in a maximum of seven minutes. If your ‘normal’ approach varies with each patient and changes in duration, your performance at the examination (competition for marks) will reflect this. Practise individual examinations with someone timing you. This can be done at home with friends or family members who are happy to volunteer: they will soon be able to tell you when you have missed something. A word of warning: if your partner or family members become the ‘subjects’ for your practice, remember that time spent together in this way does not count as ‘quality time’.

Teaming up with physician trainees is a great way to discover medical short cases, and they will also make useful allies as practice examiners and examinees. A number of textbooks include likely medical short cases. However, the specialty of emergency medicine covers much more than general medical cases: you must also search out short cases from other specialty areas in wards, clinics and rooms. Seeing patients in surroundings that are unfamiliar to you is good practice for the exam itself.

The following are some of the more likely conditions with which you should seek experience in addition to those that physician trainees will be seeking, although this list is far from exhaustive:

• Paediatrics: almost any adult condition can be present in children as well. Your interaction with the child and parent will be on display. Children also present with a variety of syndromes, not all of which will have names you are familiar with. Identifying abnormalities is more important than knowing the name. Ensure that you know the normal childhood milestones and how to do a ‘baby check’.
• Surgery: hernias, organomegaly, ulcers, vascular insufficiency, varicose veins, and breast and thyroid examination.
• Orthopaedics: joints, especially the knees.
• Obstetrics: normal pregnancy assessment and features of pre-eclampsia.
• Trauma unit: peripheral nerve injuries including the brachial plexus, and facial injuries with complications (e.g. cranial nerve injury, orbital blow-out fractures).

Practise presenting your cases as succinctly as possible. Remember that some descriptors are patho gnomonic and should be used only if you are confident of the diagnosis. For example, a ‘collapsing pulse’ and a ‘plateau pulse’ are specific for aortic incompetence and aortic stenosis, respectively. Describing the pulse as ‘full volume’ or ‘low volume’ is safer if you are unsure. Practising as both examiner and examinee will allow you to iron out quirks and habits that can be annoying. Using ‘um’ excessively needs to be brought to your attention early, so you can amend your language accordingly. Avoid using terms such as ‘middle-aged’ and ‘gentleman’, which can become points of debate in themselves: ‘man’, ‘woman’, ‘child’ and ‘baby’ are safer terms. If you can practise some sessions with an examiner, they can help with this task. Your DEMT and other FACEMs will also be helpful, as will other trainees preparing for the fellowship exam. Be con structive in your critique of others and encourage them to be likewise. The intention of this practice is to allow you to develop a ‘style’ where you present as a competent colleague. You do not want to be giving a lecture (over-confident) or to look stunned before each question expecting a hidden agenda (under-confident). Constructive critique from and of others will help you to find your way.

Whenever you need to get some fresh air, spend it casually watching people walk in and out of the outpatient clinic and/or main entrance of the hospital (or while shopping or going for a walk). This is espe cially good practice for analysing gait patterns, and you can challenge colleagues on how many people you can diagnose from a distance. You will be surprised how often this can be done!

Anticipate the questions that will be asked and practise your answers. The expected series of questions the examiners will ask are:

• What else would you like to examine?
• Present your findings so far.
• Can you put these findings together?
• What else could it be?
• What supports one differential over another?
• What else could you do to clarify things further?
• Are there any features suggesting a specific aetiology?

Examining a candidate who provides the answers in a logical fashion without being asked is more satisfying than having to drag the answers out of a candidate one at a time. The more competent you are, the higher you will score. Later sections in this chapter include examples of responses that enable you to keep talking until you are stopped.

Some systems are well suited to prepared answers. Cardiovascular examination, for example, has a relatively limited number of diagnoses, and the more common ones should be rehearsed. Well-prepared candidates will anticipate these diagnoses and present their findings in a thorough polished manner before being asked. Being well prepared saves time and enables you to maximise the information you are giving. If, for some reason, you are off track, the exam iners will stop and redirect you.

The final part of your preparation is the ‘dress rehearsal’. Ensure that you practise a couple of each of the major system examinations in your examination outfit. This will confirm that it is comfortable and practical and make you more at ease on the day.

On the day

In the current structure, the short cases are undertaken on the afternoon of the first day, after the long case. There is a lunchbreak for the examiners between the long and short cases, so your break will be at least this long. Typically, you will have a few hours between your sessions. Use the time to relax and eat something that is easy to digest and will not make you sleepy.

At the end of the break, expect to get right down to business. The examiners will be ready, directing you straight to your first case.

Hand-cleaning facilities will be available in each patient area, similar to everyday practice. Good FACEMs wash their hands between patients. Act like a FACEM.

Listen carefully to the introduction, including the patient’s name and what you are being asked to examine. Use the patient’s name as soon as possible, as you have practised. If you do not understand an instruction, ask for clarification.

The issue of whether to present the examination findings as you go or to complete the examination before summarising what you have found is a matter of personal choice. The examiners will allow you to present either way. Regardless of which method you choose, be mindful of the time. The examiners will want to ask questions, so your examination and presentation need to be timed to allow for this. If you elect to present at the end and your examination is slow, the examiners will stop you when they need to ask questions. If you present as you go but spend time presenting irrelevant material, you may run out of time.

After each case, try to clear your mind and be ready to start afresh for the next one. Each case is marked independently from the others so treat them as such. Although it is human nature to mull over past performance, it is not helpful. During the fiveminute break between sessions, collect your thoughts, and ensure that your ‘kit’ is back together and everything is in its correct pocket. The second set of examiners will not know how you performed in the first two cases.

Depending on the number of candidates, after you have completed your four cases you may be quarantined until the last group has finished. Be prepared for this and use it as an opportunity to wind down, as you will be tired after a long day.

Examination approaches

It is the theory that decides what we can observe.

Albert Einstein

The following sections provide a suggested method for approaching commonly encountered cases, along with possible introductions that may be used by your examiners. These descriptions are not exhaustive of the countless number of clinical signs that may be detectable, but they do provide an organised framework that will enable you to detect all abnormal findings.

For comprehensive background material, you will find it invaluable to refer to excellent resources such as:

• Talley N, O’Connor S. Clinical Examination: A Systematic Guide to Physical Diagnosis, 5th edn. Elsevier, Sydney, 2006.
• Ryder REJ, Mir MA, Freeman EA. An Aid to the MRCP Short Cases, 3rd edn. Blackwell, Oxford, 2003.
• Harris W, Timms B, Choong R. Examination Paediatrics: A Guide to Paediatric Training, 3rd edn. Elsevier, Sydney, 2006.
• Browse N et al. Browse’s Introduction to the Symptoms and Signs of Surgical Disease, 4th edn. Hodder Arnold, London, 2005.

This chapter does not aim to be a substitute for these educational sources. Rather, it complements these books by reviewing areas of key importance, with particular emphasis on areas that FACEM exam candidates are commonly asked and/or classically struggle with (e.g. neurology).

Examples are also provided of the lay language that may be used when engaging with patients in the exam. This is not meant to be condescending to prospective candidates, but is included as an extension of the requests we sometimes receive from trainees to model how we would succinctly interact with and instruct patients under exam conditions. Ultimately, we recommend using the same approaches you would use in ‘real life’ and encourage you to develop your own efficient but friendly professional banter.

Cardiovascular system examination

The examiner’s introduction is usually nondescript and directs you to examine the whole cardiovascular system:

‘Mr Jones has a cardiac condition. Please examine his cardiovascular system.’

Specific direction indicates key findings the exam iners wish to focus on, maximising your time. Do not be concerned: this gives you more time for a detailed examination. If you are directed to the praecordium, examine the praecordium — do not examine the peripheries. However, you will be able to note the patient’s general appearance and usually JVP while auscultating.

Getting started

Introduce yourself to the patient using the patient’s name, while making a show that you are confirming the patient’s posture at 45 degrees.

Hello, Mr Jones. Can I just check you’re sitting comfortably?

Once the patient is settled, step back sufficiently to be able to scan the whole area, including the bedside table, underneath the trolley and so on for any clues. Note them as you discover them:

I don’t see any evidence of medical therapy such as oxygen. I presume that this is Mr Jones’ walking stick.

Observe the patient’s general appearance, colour (anaemia, plethora, cyanosis), pursed-lip breathing, respiratory rate and obvious scars. The JVP may be visible at a distance. Head bobbing is an uncommon sign of aortic incompetence (AI), but easily missed if not specifically checked for.

Peripheries

Start from the hands checking for anaemia, cyanosis, pulsations in the nail beds (AI) and stigmata of endocarditis (e.g. splinter haemorrhages in the nail beds, digital septic emboli, haemorrhagic Janeway lesions in the palms).

Feel the pulse for rate, rhythm and volume. While checking the pulse, you have more opportunity to check the hands and scan the rest of the patient. If the pulse is particularly good volume, try feeling with your fingers flattened against the radial pulse with the patient’s forearm elevated (tapping pulse of AI).

As you move up the arm, feel the brachial pulse and politely ask the examiners:

Is there a blood pressure available?

Listen carefully to the numbers and remember them. Occasionally you may be directed to measure the patient’s blood pressure yourself. This is neither a good nor a bad thing. You may be asked to do so because the blood pressure is interesting (low pulse pressure in aortic stenosis (AS), high in AI) or because the case allows time for this and the examiners want to see whether you are competent in a basic procedure. Looking off ended when directed to measure the blood pressure or fumbling around indicating that this is something you haven’t done in a long time is not a good way to impress.

Move to the neck, feel the carotid pulse for character and auscultate for bruits:

I’m just going to listen to your neck.

If breathing is noisy, give clear instructions:

Breathe in … Breathe out … Stop … Now breathe normally.

Assess the JVP. If it is not visible, make sure it is not too low (try a hepatojugular response — Mr Jones, is it okay if I just press on your belly briefly?) or too high, in which case the distended vein will become measurable sitting up. Sinus rhythm gives a regular double pulsation. If the patient is in AF, look care fully for cannon waves on top of single pulsations. Large fluctuations (CV waves) are seen with tricuspid incompetence (TI).

Check briefly for conjunctival pallor and central cyanosis (lips and tongue).

Praecordium

Inspect for a visible apex beat or heaves and scan for scars (which may be in the axilla). Sternotomy scars without evidence of vein grafting should raise suspicion of surgery for valves or transplant. Internal mammary grafts are associated with multiple vascular clips on CXR. Do not miss a pacemaker or ICD insertion pocket scar.

Feel for the apex beat. If not palpable, reach out to the posterior axilla. If still not palpable, consider that it may be on the other side (dextrocardia). Once located, confirm its position relative to the mid-clavicular line (or anterior/mid-axillary lines if displaced significantly) and whether it is normal, force ful or otherwise.

After feeling for the apex beat, palpate vertically alongside the sternum for thrills or ventricular heaves (using the heel of your palm) and finally feel horizontally across the heart base.

Auscultation starts at the apex beat with the stethoscope diaphragm. Deliberately focus on the first heart sound, then the second (including splitting and change of splitting with respiration; identify mechanical valvular sounds). Specifically listen for a third, fourth and then additional heart sounds. Clicks may be loud and dismissed as extraneous sounds. Listen first for systolic and then diastolic murmurs.

After listening at the apex (mitral area), listen in turn to the lower left sternal edge (tricuspid area), then the left upper sternal edge (pulmonary area) and right upper sternal edge (aortic area). Confirm the timing of any murmur by simultaneously palpating the carotid pulse and listen in the axilla and carotids for radiation. Right heart murmurs are louder with inspiration and the opposite is true for left-sided murmurs, so ask the patient to take some slow, deep breaths while listening for changes with the respiratory cycle.

After listening with the diaphragm to all four areas, change to the bell on the stethoscope. The tone difference of mitral stenosis requires a change in mental focus initially to ‘tune in’: listen with the bell held lightly against the chest over the apex. Do not press firmly as this may obliterate a soft mitral diastolic murmur. Lying on the left side accentuates mitral murmurs. Flatten the bed in anticipation of further examination: Could I please ask you to lie down on your left side? Palpate the apex beat again (it usually moves) and identify mitral murmurs.

Sit the patient up: Can I get you to sit up and lean forward? Feel the parasternal area again for thrills or heaves. An AI murmur is best heard with the diaphragm as the patient leans forward at end expiration: Please take a big breath in… Breathe right out … Stop … Now breathe normally.

If you have heard a clear aortic outflow murmur, you may wish to try isometric exercise at this stage: Make a loose fist with your hands. Squeeze hard when I say so. Listen for the character of the murmur: Squeeze now [listen] … and relax [listen again]. Murmurs associated with HOCM will decrease with isometric exercise, while those associated with aortic valve obstruction will increase. Valsalva has the opposite effect. If you are seriously considering HOCM at this stage (it is more common in exams than in real life), it may be worthwhile going ahead with other manoeuvres such as squatting in a mobile patient (HOCM decreases with squatting down and increases on rising from the squat; aortic valve obstruction is the reverse). Although it is uncommon to demonstrate these manoeuvres, if you do suggest them during dis cussion, you must be prepared to demonstrate them.

When the patient is sitting up, check for sacral oedema and basal crackles. Thoracotomy and valvotomy scars are also best seen from behind.

With the patient supine, check for hepatic enlarge ment and pulsatility. Checking the legs for oedema, deep vein thrombosis and scars from bypass grafting completes the examination.

With practice, you can complete all the above within seven minutes. If not, you will be stopped before you complete your examination.

As you progress through your cardiovascular system examination you will receive ‘clues’. For example:

• The presence of AF makes mitral valve disease more likely, while absence makes it less likely. Low-volume pulses are associated with obstructive lesions, while high-volume pulses are associated with valvular incompetence.
• A high JVP and exaggeration of a pansystolic murmur with inspiration suggest a right-sided lesion. Tricuspid incompetence is likely and therefore a pulsatile liver is to be expected.

If you detect all the peripheral clues, you should have a reasonable indication of the likely diagnosis before you even auscultate. If so, you should be think ing of other features that support or refute your diagnosis or give indications of severity.

Discussion

The examiners will stop you with a clear statement, followed by: ‘What else would you like to examine?’ Respond with:

I would complete my cardiovascular system examination with [whatever you have not done] as well as completing a general examination including [whichever observations have not been done] and a urinalysis looking for …

You will be given results if relevant to the discussion, then asked to ‘present your findings so far’. At this point you can wait for the questions to come one by one or you can anticipate them and keep going until stopped. The examiners will commonly follow with the pattern of asking about possibilities, the likelihood of each possibility, the rationale for and against each, and confirmation for and against each.

The following is an example of how to respond in a manner that demonstrates your knowledge and understanding of the clinical signs and displays your ability to be a ‘real’ FACEM. Read it first with the questions being asked and then again with the questions removed. An excellent candidate will progress through each aspect of questioning without being prompted by the examiners’ questions.

‘Present your findings so far.’

Mr Jones is a well-looking man comfortable at rest and in no distress. He has no peripheral stigmata of disease. His pulse rate is 80 beats per minute, regular, full volume and tapping in nature at the wrist. Blood pressure was given at 160/70, and JVP is normal. Central pulses confirm the full volume. Praecordial examination demonstrates a well-localised apex beat displaced 2 cm lateral to the mid-clavicular line. There is a suggestion of a left ventricular heave with no thrill palpable. Auscultation reveals a mixed murmur heard loudest in the aortic area with radiation to the carotids but also well heard at the apex. Both heart sounds are heard with normal splitting. The diastolic murmur was loudest on sitting forward on exhalation with no appreciable change during the respiratory cycle. There is no evidence of cardiac failure and the liver is not pulsatile.

‘Can you put these findings together?’

The mixed murmur has a number of possible diagnoses. I believe the most likely is mixed aortic valve disease with aortic incompetence as the dominant lesion, given the large pulse pressure and collapsing nature of the pulse.

‘What else could it be?’

A number of other possibilities can account for these murmurs. The diastolic component could be due to mitral stenosis or less commonly tricuspid stenosis or pulmonary incompetence. The systolic component could be due to mitral or tricuspid incompetence, pulmonary stenosis or a pulmonary or aortic flow murmur. VSD or ASD could also cause systolic murmurs, and to-and-fro murmurs can be caused by more complex lesions such as coarctation or anatomical abnormalities including transposition of vessels.

‘What supports one differential over another?’

In this age group, without signs of surgical intervention and in a well patient the likelihood of coarctation is remote. This would be a more common consideration in young children and evidenced by radiofemoral delay. I don’t think the murmurs were louder with inspiration, making right-sided valvular lesions less likely. Mitral valve lesions are best heard at the apex, whereas this murmur was loudest at the base. However, it was well heard at the apex, which may represent an Austin Flint murmur. Of note, Mr Jones is in sinus rhythm. This would be unusual for mitral valve lesions where AF is more likely. Both heart sounds were well heard, which is also against significant mitral incompetence; however, this would still be an important differential diagnosis.

Other conditions such as VSD are possible, but these are usually well localised, mostly systolic only and would not be expected to be associated with such a large pulse pressure. It would be unusual for a diastolic murmur to be present with HOCM and this is also effectively ruled out by the systolic murmur increasing with isometric exercise.

‘What else could you do to clarify things further?’

After completing the physical examination, the key initial investigations will be an ECG and chest X-ray. The ECG will confirm sinus rhythm and may demonstrate left ventricular hypertrophy. The chest X-ray may show valvular calcification, dilation of the left atrium if there is mitral valve disease and I expect it will also reveal enlargement of the left ventricle and absence of cardiac failure.

The definitive investigation is echocardiography. This will confirm the diagnosis, the degree of incompetence or stenosis, the flow gradient, the size of the left ventricle and the ejection fraction and determine whether the aortic valve is tri- or bicuspid.

‘Are there any features suggesting a specific aetiology?’

If you have been following the path of questions above, the bell may have gone by now. If you took the initia tive and led the discussion, the time saved may have created an opportunity to score some bonus marks.

If you are confident of the diagnosis, as an alternative approach to the presentation, you could start by providing your diagnostic assessment and then present the findings that support this condition and exclude the major differential diagnoses. In that case, you can also take a different tack when the examiners stop you and ask ‘what else would you like to examine?’ and make sure you get these responses in from the outset:

Mr Jones has features of aortic incompetence. As well as completing my usual cardiovascular system examination I would like to additionally check for DeMusset’s head-nodding sign and Quinke’s sign of nail-bed capillary pulsation, measure the blood pressure in both arms for evidence of aortic dissection, check for Argyll-Robertson pupils of tertiary syphilis and for a high arched palate and check for increased joint mobility of collagen disorders such as Marfan’s syndrome.

The cardiovascular system examination is particu larly well suited to prepared responses that allow you to demonstrate your knowledge and differential diagnosis. Make sure that you know the features of all the valvular lesions including indications of severity. Do not omit VSD, ASD, HOCM, coarctation of the aorta and congenital malformations. Once you are familiar with the list of differentials for various murmurs and changes in heart sounds, having a discussion or presentation along the lines of the above dialogue will become increasingly easy.

Neurological system examination

Cranial nerves

If no specific direction is given, go through in num erical order. Occasionally, you will be directed to the ‘lower’ cranial nerves, in which case you should start from the end (CN XII) and work backwards. If the examiners wish to focus on a particular area, they will direct you accordingly.

Patients are best positioned sitting with their head at equal height to yours. This can mean sitting on a chair (which may find you crouching down) or on the side of the bed. Introduce yourself to the patient and remember to use the patient’s name. Position the patient appropriately: Mr Jones, could you please sit facing me with your legs over the side of the bed? Let your hands rest in your lap.

Enquire, Mr Jones, are you sore anywhere?, to ensure that you will be able to proceed with your examination in the usual manner. Then take a step back to make the same general observations as with any other system examination. Ptosis from Horner’s syndrome or a third nerve lesion, facial droop with absence of a smile from facial nerve lesions, neck masses and so on are all more obvious when you step back. If there is a clear abnormality, say so.

CN I: olfactory nerve

CN I is rarely tested. Asking the patient, Can you smell normally?, is generally sufficient.

CN II: optic nerve

Acuity

Have your visual acuity chart prepared with the same print on both sides. Make sure that you know the distance specified on the chart (usually an arm’s length). Ask the patient whether they wear glasses and, if they do, check uncorrected vision first, corrected later. Ask the patient to cover one eye and hold the chart in front of the patient. Ask: What is the lowest line you can read? Then check the other eye.

Acuity is recorded as the lowest line the patient can read and includes the number of mistakes. For example, 6/12 – 2 indicates that the patient is able to read the 6/12 line but with two errors. If the patient is unable to read the top line, move forward until they can, recording the distance at which the 60 line becomes visible. If they still can’t read it, check for movement, then light perception.

Visual fields

Face the patient. Hold the hatpin between you and ask, Can you see the pin? Then ask the patient to cover their left eye while you cover or close your right eye. Use the hatpin to come in from each quadrant in turn. Tell the patient: Keep looking straight at me. Tell me when you first see the pin out of the corner of your eye.

Use your own fields as ‘normal’ to identify restric tions in the patient’s fields. Find the blind spot, estimat ing its size. Ask: Tell me when the pin disappears. Once it does, ask: And tell me when it comes back.

Repeat the same process for the other side. Note whether one or both blind spots are abnormally large (consider papilloedema, optic neuritis). Under standing the visual pathway anatomy is crucial to local ising lesions (see Figure 6.1). Table 6.1 illustrates the principal abnormalities that may be encountered.

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Figure 6.1 The visual pathway anatomy

TABLE 6.1 Visual field defects

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Fundi

Ask the examiners, Would you like me to examine the fundi? Occasionally you will be asked to do so. Get used to examining the patient’s right eye with your right eye and the patient’s left eye with your left eye. If you are able to use the ophthalmoscope with either hand, this will reduce the chances of you tilting your head in the path of the patient. Tell the patient: I’m going to look at the back of your eyes now. Could you please look straight at that corner? [pointing with the ophthalmoscope light]

Do not ask the patient to look at a light source or the pupils will constrict. Advise: Blink if you need to, but keep looking there so I don’t have a moving target. If my head gets in the way, try to still keep looking at the same spot.

Once the red reflex is found, move in and examine the optic disc. Follow the vessels out peripherally noting any pathology. Specifically look for haemor rhages, silver wiring and venous pulsation. Check the macula last of all by asking the patient to look at the light.

CN III, IV and VI: oculomotor, trochlear and abducens nerves

• oculomotor = moving the eye
• trochlear = acts via a trochlear attachment
• abducens = abducting

Eye movements tend to confuse those who have forgotten their anatomy (or never learned it in the first place). Understanding anatomy is fundamental to appreciating why the ‘direction of action’ of some muscles is almost the opposite of the direction in which they are tested. Figure 6.2 will refresh your memory. The photographs and diagrams demonstrate the muscles involved when testing eye movements.

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Figure 6.2 Anatomy of the extraocular muscles

(a) Muscles tested with eye movements

(b) Anatomy of extraocular muscles testing eye movements

(c) Anatomy of extraocular muscles in neutral position

The key is to consider the difference between the alignment of the resting visual axis (forward), the line of the orbits (out at an angle) and the angle of pull of the extraocular muscles in relation to these. These align with the eyes deviated ∼45 degrees and this is why we test up and down gaze in this position. The oblique muscles insert posterior to the rotational axis of the globe. Acting on their own as an individual muscle in the resting position, they each abduct the globe. The superior oblique will also cause the eye to look down and internally tort. The inferior oblique has the opposite effects. However, when the eye is adducted, the visual axis is aligned with the direction of pull of the obliques and so their actions are reduced to simply causing the eye to look up (inferior oblique) or down (superior oblique).

The same consideration applies to the superior and inferior rectus muscles — acting as isolated muscles in the neutral position, they each adduct the eye. However, they are tested with the eye abducted (aligning the pull of the muscles with the visual axis) by their ability to move the abducted eye up (superior) or down (inferior).

Once you have mastered this anatomy, practise drawing it and showing/teaching it to junior staff and medical students. A summary of the functions and innervations of the individual extraocular muscles is provided in Table 6.2.

TABLE 6.2 Extraocular muscles

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Extraocular muscles

With the hatpin (or ophthalmoscope) still in hand from testing CN II, now is the time to test eye movements. Using an ophthalmoscope has the advan tages of producing a light for the patient to focus on, a light reflection that highlights minor deviation between the eyes and a ready light source for testing pupil light responses, and keeps it poised if you have not examined the fundi and the examiners wish to direct you that way. Alternatively, use your torch. Do not shine the light directly at the patient’s eyes as this ‘blinds’ them and causes pupil constriction. Aim for the mid forehead level so you can see the light is still on. You can use your finger instead of the pin but it looks less ‘slick’ and, unless you hold it perfectly vertically, the patient may report diplopic images ‘at an angle’ when they are not.

If there is ptosis, you may need to hold the upper lids open. Even without ptosis, this does make abnormality of eye movement more obvious and so is a good technique to practise. Tell the patient: Keep looking at the pin [or light]. Tell me if you see double.

Move the pin from one side to the other holding it at each side (medial and lateral recti). Check for correct movement and nystagmus. The light reflection in the pupils is a sensitive test of misalignment if the patient fails to report diplopia.

Next move the pin out to one side and test up (and hold it to confirm both sides have moved) and down (holding and checking again). Referring back to our anatomy discussion, this is testing the various obliques and recti. Move the pin to the other side. Repeat the up and then down movements.

If diplopia occurs, enquire about the orientation of the images: Are they side by side or at an angle or above each other? The direction of gaze where the diplopia occurs or is maximal indicates the muscle involved. If there is any doubt which eye is the cause, cover one eye and ask: When I cover this eye, does the inside or outside one disappear? The outer image is always from the eye with the palsy.

If a disorder of gaze is observed, test each eye individually with the other covered. This is important for several reasons. First, it allows you to concentrate on one eye, reducing confusion as you try to remember the anatomy of both eyes at the same time. Second, it confirms which eye has the abnormality. Finally, it reveals disorders of conjugate gaze that may be con fus ed with medial and lateral recti palsies in particular.

Pupils

Examine the following:

• Size: check equality and estimate size in millimetres. Your acuity chart may have pupil size on it.
• Shape: irregular pupils may be due to trauma (including surgery), adhesions from past iritis or neurosyphilis.
• Light response: instruct the patient to look straight at you while you shine the light from the side. Swing the light in from the side so it does not obstruct your view. Do it twice for each side. The first time look for constriction of that pupil (direct reflex). Pause long enough to watch it dilate again. The second time, observe constriction of the other pupil (consensual reflex). Finish by ‘swinging’ the light between the patient’s eyes, observing the contraction of each as light is shone in it. Afferent pupil defects will become obvious only when this is done.
• Accommodation: hold your pin/ophthalmoscope at an arm’s stretch away from the patient. Tell them to keep looking at the light (or pin). As you bring it in, watch for convergent gaze and pupil constriction accompanying it.

Disorders

Common causes of disorders of eye movement include trauma and multiple sclerosis. Consider also CNS lesions including tumours, vascular malformations and brain stem strokes. A variety of neuromuscular disorders, as well as lesions of CN III and the sym pathetic nervous system can cause ptosis.

• Nystagmus: this is expected in normal individuals on extreme lateral gaze where it is brief. Only test lateral gaze to 45 degrees. Where one direction of nystagmus is faster, it is named in that direction. Learn a list of causes for horizontal and rotary nystagmus. Find a colleague who is very short-sighted and practise testing ocular movements on them without their glasses/contact lenses. Rotatory nystagmus should be expected.
• Horner’s syndrome: sympathetic innervation of part of the levator palpebrae superioris (raiser of the upper lid) causes ptosis, which is usually incomplete. Ocular movements are preserved, which differentiates this from a lesion of CN III. Look for the other features resulting from sympathetic loss on that side of the face: a constricted pupil (miosis), lack of sweating (anhidrosis) and sunken eye (enophthalmos). If present, follow the anatomical path of the sympathetic fibres backwards along the arteries (ophthalmic, carotids), root of neck/apex of lung (stellate ganglion) and back to the origin from T1. Proximal lesions will have the full complex, whereas orbital lesions will lack facial anhidrosis. Lesions of the lateral spinal cord (syringomyelia), brain stem (lateral medullary syndrome) or cerebral cortex will have other neurological features.
• CN VI: isolated lesions can cause a failure of abduction of the affected eye. Palsies of this nerve are not uncommon as CN VI has the longest intracranial course and is therefore subject to compression at multiple locations. Its crossed origin may lead to false localising signs with a diversity of conditions causing raised intracranial pressure.
• CN IV: isolated lesions of CN IV are uncommon but possible. The superior oblique has little influence on the resting eye and hence there is usually no obvious palsy on initial inspection. It becomes apparent with an inability for the adducted eye to look down.
• CN III: the upper eyelid and most of the extraocular muscles are supplied by CN III. Lesions may be complete or partial. In the resting position a complete lesion causes a prominent ptosis with the eye being pulled by the unopposed actions of CN IV (down and out) and CN VI (out). Partial lesions can be clarified by ‘adding together’ individual muscle defects.
• CN III and IV: an interesting challenge is to determine the presence of a CN IV nerve defect in the presence of a complete CN III defect. Remember that the adducted eye looking up tests CN IV, but a lesion of CN III makes adduction impossible! The solution: simply ask the patient to look to the other side. Although adduction is not possible, the superior oblique, acting on its own, will internally tort the eye. Inward rotation of the eye on attempted adduction confirms that CN IV is intact. Knowledge of anatomy is a wonderful thing!
• Internuclear ophthalmoplegia (INO): lesions of the medial longitudinal fasciculus cause an inability of adduction on the side of the lesion and nystagmus in the abducting eye. This is often bilateral and is almost always caused by multiple sclerosis. INO simulates medial recti palsies when both eyes are tested together. However, the astute clinician will test each eye individually while the other is closed, confirming the medial recti function (normal adduction) is intact and the condition is limited to a disorder of conjugate gaze — not a cranial nerve or extraocular muscle lesion. Bizarre defects of all three nerves may be seen in Wernicke’s encephalopathy, a syndrome caused by thiamine deficiency. It is characterised by a triad of ataxia, ophthalmoplegia and impaired short-term memory. A true unilateral INO has been described in this condition.

Bilateral defects in lateral gaze during conjugate eye movement (with nystagmus of the adducting eye) are most often associated with excess alcohol consumption and represent another form of INO. Normal abduction when testing eyes individually differentiates INO from bilateral CN VI lesions.

• Argyll-Robertson pupil: the pupil reaction associated with neurosyphilis is due to a defect in the Edinger-Westphal nucleus near the nucleus for CN III and results from dissociation of the accommodation and light reflexes. The easiest way to remember the lesion is with the aide memoir: just like contracting the syphilis, the pupil accommodates nicely but does not react well to light!

Holmes-Adie syndrome: this is due to a defect in the parasympathetic pathway. The parasympathetic fibres originate in the Edinger-Westphal nucleus near the origin of CN III and travel in the periphery of the optic nerve. They leave the nerve prior to reaching the globe and are distributed within the orbit via the ciliary ganglion. Interference with the parasympathetic pathway results in a dilated pupil, with reduced or absent light and accommodation reflexes. It may also be associated with other features, including decreased tendon reflexes.

Because of their peripheral location in the optic nerve, pressure on the nerve will often cause loss of parasympathetic function (dilated pupil) prior to visual defects. This is a classic finding with com pression from a berry aneurysm.

Of note, lesions of the visual pathway posterior to the Edinger-Westphal nucleus will have intact pupil reflexes.

• Marcus-Gunn pupil: disorders of the visual pathway anterior to the chiasm (afferent defects) can be caused by retinal or optic nerve lesions. Light perception is not relayed and so no light reflex occurs. However, a consensual response mediated via the parasympathetic fibres will cause constriction if the lesion is retinal or involves the optic nerve distal to the point at which the parasympathetic fibres depart the optic nerve. The good eye has both light reflexes; the one with the afferent defect only a consensual response. When a light is shone in the eye with the afferent defect, neither the ipsilateral pupil nor the contralateral pupil will constrict. However, the pupil will constrict from light in the other eye. ‘Swinging’ the light from one side to the other will cause constriction of both pupils when light is shone in the ‘good’ eye, but no constriction when shone in the eye with the afferent defect. As the light is swung from side to side, the ‘good’ pupil constricts relative to the one with the afferent defect. In particular, the side with the afferent defect will appear to dilate while the light is shone in it as it recovers from the constriction triggered by the previous consensual response.

CN V: trigeminal nerve

Named for the three sensory branches, it has a motor component as well.

Sensation

Begin by testing light touch. As you dab (not stroke) cotton wool on an area expected to have normal sensation, such as the upper sternum, explain: This is a piece of cotton wool. Can you feel this? Close your eyes. Say ‘yes’ when you feel me touch you.

Test the mid forehead on each side (V1), over the infraorbital region (V2) and the jaw below the outer border of the mouth (V3). These are roughly in a line that also coincides with the foraminal openings.

Test pin-prick sensation next. As you dab the pin against the same ‘test’ area as before, explain: This is a specially blunted pin that won’t hurt your skin. Is this sharp? Then, as you dab the blunted side, tell the patient: This is dull. Explain: Close your eyes. Say ‘sharp’ or ‘dull’ as I touch you.

Test as for light touch. If a ‘dull’ response is consistently obtained or no response is obtained, go back over that area. For areas that are abnormal, ensure that you have tested ‘sharp’ and ‘dull’ to ensure the patient isn’t simply saying ‘sharp’ or ‘dull’ to everything.

Motor

CN V supplies the muscles of mastication: masseter, temporalis and the pterygoids. It also supplies the tensor tympani and tensor palatini muscles, which are not normally tested. However, keep this in mind because defects of CN V will be associated with sensitivity to noise. This can be enquired about when the examiners ask what else you would do. It also explains why people clench their teeth and tighten their facial muscles (CN VII supplies stapedius) in response to loud noises.

Ask the patient to clench their teeth, and palpate the masseter and temporalis on each side. Get the patient to open their mouth, which will cause deviation to the side of weakness by the stronger pterygoids on the ‘good’ side. Finally, ask the patient to push against your hand while your hand is on the lateral jaw to test the pterygoids, confirming the side of weakness.

Taste

Although not often part of the examination, taste is easily tested with a salt sachet from the kitchen. Tear off the corner, dab the sachet on each side of the anterior two-thirds and posterior third of the tongue. Recall from your growing confidence with anatomy that taste sensation is derived from CN VII but the fibres travel with CN V after the chorda tympani join it shortly after exiting the skull in front of the ear. Innervation of the tongue is summarised in Table 6.3.

TABLE 6.3 Innervation of the tongue

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Anterior two-thirds Posterior one-third
Touch

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