Contents of this paper:

Preface
The big view
Definition
Incidence
Aetiology
Pathology
Symptoms
Signs
Special investigations
Diagnosis
Management
Some important     definitions
How valid, how useful?
Postscript
References

Preface

There is a confidence trick played on every successive generation of medical students. It is this:

Your clinical teacher comes out with a heap of impressive facts in a tidy-looking sequence, and pretends it is logic.

It is NOT logic, but habit and repetition which has got it flowing smoothly off his/her tongue or on blackboard/overhead transparency. It is as much logic as a cat finding its way home, or small children singing something fluently.

At the back of your teacher's brain (much the same as yours, except for acquired traces of inappropriate arrogance) are some little tables, like multiplication tables or rules for spelling. Quite likely your teacher isn't even aware of them, and if he/she was, wouldn't let on.

This little booklet contains many simple mental templates for learning about diseases quickly and efficiently. Later on you won't use the relevant information in the pattern shown here, because you will learn to do things in order of probability, which is a different kind of pseudo-logic. Nor will this booklet help you with physical signs, or be a substitute for practice and experience in a wide variety of areas.

However these tables are about as logical as anything in clinical medicine can be, and will be invaluable for your first 2 - 3 years of clinical study, and post-graduate examinations. Quite often they will allow you to make intelligent guesses where your memory is unfilled, or shaky, and to Incorporate information from other sources - which might even be an article in CLEO magazine or something you heard casually.

Best of luck!

The big view - a general plan for consideration of disease

You will see there are ten headings. They are arranged a bit like a hockey team to make them easier to remember.

The first column is "theory", and it comprises definition, incidence, aetiology, and pathology. We will look at every one of these expressions in more detail, to make them very powerful mental tools indeed for your study, memorisation, and examination technique.

The next column is "clinical features", what you actually worry about in relation to an individual patient. The third column is diagnosis, and the last one is treatment, or management. This is represented by the letter R with a slash across it like this Rx , which is shorthand for "recipe" (pronounced "reckipay"), the Latin second person singlular imperative mood of a verb, translated to mean "Take this!" for medicines prescribed in ancient times. The same symbol R was also used by astrologers to represent one of the planets and was a good luck sign, in case the prescription didn't work.

One nice thing about the first list you have learned is that you now know when you have covered everything. You avoid that embarrassing harassing moment of eternity when you wonder if there is something you have forgotten. You have come to the end, full stop, and sit back with a confident polite smile. If the examiner thinks of something you should have added, he will stop to question his own interpretation.

Of course you won't be reciting this particular list in an examination, but you will certainly be matching information you have against this mental "check-list".

Check-lists are not new. The history of mnemonics (memory-techniques) goes back to the ancient Greeks, and makes a fascinating study. Rudyard Kipling wrote of the journalist's six little servants - who, what, why, how, when, where - and you will come across many non-logical schemes such as A-B-C for AirwayBreathing-Circulation taught in CardioPulmonary rescussitation.

Now let's consider the sub-schemes from the main headings in more detail.

DEFINITION

The subject being defined may be malaria, a chronic infectious disease due to a protoz... etc. etc. It might be the dyspnoea of bronchial asthma, or -- consider the pain of ureteric colic, wrongly referred to as renal colic.

This is a pain often described as having the quality of gripping or knifelike, occurring in bouts of a few minutes or an hour or two, perhaps hours or weeks apart,which may start in one loin or more distally, radiate to the testicle or labium majus, severe or excruciating in intensity, and not brought on by any obvious factor. The patient is likely to vomit, cry out, sweat, and roll around, and will be relieved by strong analgesia, typically pethidine 100 mgm. either intramuscularly, or by cautious intravenous injection over two to four minutes according to the patient's response.

If a full discussion is to follow, some of the points just mentioned will be left till later, but it is handy to have, right at the start, at least something to "hang your hat on", a mental peg.

In this case it also serves to highlight the differences between the pain of right ureteric colic, when it is in the right iliac fossa, and appendicitis. In appendicitis, the effect of the pain on the patient is to make him lie still rather than roll around, except for the less common type of "obstructive" appendicitis, in the hour or two before perforation, followed by the "period of illusion".

INCIDENCE

"Incidence" may be regarded as "predisposing aetiology". Most of the above terms should explain themselves, with the exception of the last -

Diathesis refers to a particular bodily set of features making some disease more likely. For example, fair, fat, fertile, forty, female, and flatulent probably means gall-stones. A middle-aged man with light blue eyes and hair which is prematurely silvery grey at the temples is quite likely to have pernicious anaemia.

AETIOLOGY

This is so important and detailed a main heading that it will have to be considered in its constituent parts. The main subheadings of "Aetiology" are the well-known "surgical sieve". It is so-called because the possible cause for a lump can be picked out (hopefully) if the parts of this list are tried one at a time, catching the particular cause like a particle too big too pass through a fine mesh. Here are the main subheadings:

We will consider these one at a time. Before going to the next page, why don't you try work out what they might be?

AETIOLOGY - Congenital

The main division here is between genetic and intra-uterine causes of disease. Each of these two classes may be further sub-divided, so the scheme looks like this:

(The last level of subdivision has different items on the same line, to save space in this little booklet. When you practice drawing out this scheme, or your own modification of it, you should use a large piece of paper with a big lateral "tree" diagram).

AETIOLOGY - Traumatic

AET IOLOGY - Inflammatory

This heading is mostly a slang shorthand for "infectious", but could include chemical factors from the previous section if you prefer, especially the irritating discharge of a fistula.

Consider the various damaging organisms in a spectrum of size, namely:

These, of course, can be further subdivided to give an instant text-book of bacteriology - but that is not the aim here, which is to provide you with strategies not available elsewhere.

While still considering this subheading, we provide a second subclassification; there are more ways than one of skinning a cat or considering entities in medicine. You can have a one-dimensional list, a two-dimensional grid, or an n-dimensional matrix which just has to be considered one sub-set at a time. Here is another way of looking at AETIOLOGY -

Note that acute and chronic refer to time and not severity. Both meningitis and a pimple can be acute. Acute means "a condition which develops its characteristic clinical features in hours or a day or two", sub-acute means a time-scale of days to a couple of weeks, while chronic refers to a process developing over weeks to years. Subacute does not necessarily mean "mild", like the pain of a dubious or a wellpadded appendicitis.

What about a coronary occlusion, or rupture of a cerebral aneurysm - are these "acute"? No - they are too quick, and may best be referred to as "sudden".

At this stage we are about half-way through the subheadings for AETIOLOGY, and will just plug away at the rest of them. I hope this "check-list" approach is giving you a fresh insight into thinking about and remembering features of individual diseases.

There are even more important reasons than examinations for thinking in such terms, which I'll mention by way of a break later on.

To continue ...

AETIOLOGY - Neoplastic

For the second time we have more than one method of classification readily available - in fact, quite a few methods. It gets confusing to relate these to each other in the abstract, rather than applying them to individual diseases, so they will merely be listed here.

* Cerebral tumours are confusing because they are pathologically benign but clinically malignant. At the cellular level, pathologists argue so badly that after conferences they sometimes end up not on speaking terms.

AETIOLOGY - Vascular

Once again there are several classifications possible. Each of these is useful for particular purposes.

AETIOLOGY - Constitutional

This is another useful cross-classification, useful for putting across other matrices. It Is a list of systems in the body. How many are there? Answering is as simple as remembering the chapter headings in a special text-book - which is very hard - try it on yourself or a friend.

Remember that a system is a collection of organs carrying out a set of functions - that hierarchy goes:

Now for the "constitutional" causes of disease:

To the mnemonic "CRAUNBELS", for the first letter of each item, you might also add "Metabolic", for several odds and ends it is hard to classify otherwise, such as metabolic upsets.

Let us further classify just one of the sub-headings, to illustrate a point. How many endocrine glands are there in the body? From top to bottom there are:

To these add aberrant endocrine tissue, and the growing number of gut hormone secreting sites - stomach, small intestine, appendix.

This last list illustrates another important principle of lists and classifications. Theoretically, the strongest classifications are "dichotomies", splitting or bifurcating into two at each stage. These are clumsy to remember and use, like binary arithmetic in your head.

The sorting key is very simple - from the top of the head to the bottom of the feet, and stop at each endocrine you can think of on the way.

In the vascular sub-heading earlier, we used:

This same "troika" can be used for any of the many tubes in the body, or outside it for that matter, which you could also expand with "pressure drop".

PATHOLOGY

Genesis
Site
Macro
Micro
Complications
Spread

This fourth main heading is the last of the "theory" group. Some of the halfdozen headings will be broken down into more detail in the pages that follow.
"Genesis", like the Bible, is how it all starts. An ulcer (see definitions at end of book) starts off with necrosis of cells, due to ischaemia or a bacterial toxin for example, or to loss by trauma (traumatic ulcer), though the site of finger-tip amputation may not be thought of as an ulcer. A tumour starts off with just a few cells going wild.

PATHOLOGY - Site

The site of the pathology can be described in terms of:

and anatomically in terms of

PATHOLOGY - Macro

Here are 15 headings for describing any lump, clinically as well as in a specimen jar. Some only apply to live patients, but are included in a standard list to be consistent

Each of these could be discussed in more detail.

Size is stated in centimetres for the three dimensions
Shape can be circular, ovoid, rectangular, irregular, or many other adjectives.

Countour may be regular or not, wellor ill-defined
Consistency can range from semi-liquid to stony hard. In a live patient it may include pulsation, the presence of a fluid thrill and the sign of emptying.

Tenderness (for a clinical lump) can actually be measured (Patkin, 1970) ,but this has not yet proven to be of clinical use.

Other categories of property possible include specific gravity - will the lung float, is the testicular lump heavy to palpation? - and doubtless others have been left out.

PATHOLOGY - Micro

In this section goes all the information you know - or can guess - about the histology of the condition under discussion. The general rule is to go from the larger to the smaller structures, from the general to the particular, from organ, through particular structure, to tissue, to cells and extra-cellular material, to subcellular structures.

Remember there are only four main types of tissue in the body:

Epithelial - a few main types.
Connective - from areolar to bone.
Muscle - skeletal, smooth, cardiac.
Nervous -

If you approach your histology in the same structured way as the other analyses in this study, this will give you the sane benefits.

PATHOLOGY - Complications

The "four B's" are the short crisp list of complications of a peptic ulcer, of an ovarian cyst, and of diverticulitis, if you will allow just a bit of stretch of the imagination. Let us consider these one by one.

Bleeding can be acute - upwards or downwards in the stomach, i.e. haematemesis or melaena, or chronic - occult (so small as to be hidden) loss over a period of time.

Blocking can be functional or organic, i.e. spasm as in pylorospasm, or structural as in the fibrosis of pyloric stenosis. You can think of the torsion of an ovarian cyst on its pedicle to block its blood supply as well.

Busting - and burrowing - can be a sudden dramatic perforation, as of a peptic ulcer, or a slow penetration, into other organs, forming a fistula if the other tissue is hollow. Examples are a duodenal ulcer penetrating the pancreas, when the typical pre-prandial or hunger pain changes to become continuous, or a colo-vesical fistula from diverticulitis.

Becoming malignant - or Being hard to tell from malignant. How often gastric ulcers became malignant (especially prepyloric) is debatable. Some are malignant from the start. The distinction between diverticulitis and carcinoma of the sigmoid colon can be difficult at emergency laparotomy, though the first condition does not turn into the second.

If you merely remember
     
      Bleeding
      Blocking-
      Busting or Burrowing (ie penetrating)
      Becoming or being hard to tell from malignant,

you are a long way towards organising clinical pathology in your mind.

Regional and general complications are those of spread - direct, by lymphatics, along tissue planes and cavities, and through the blood stream.

SYMPTOMS

How many symptoms are there? There are probably about 4000 different symptoms, of which most are rare ones found in neurology. About one-tenth this number are symptoms you should be acquainted with, and there are about one-hundredth, or approximately 40 symptoms, which you should know really well - well enough to press the mental button and respond with the following information:

- two lists of causes (logical, and in order of
frequency)
- diagnostic management.

We will go on to list the common symptoms by system a little later, but first it is easier to list the four types of symptom:

(This list of four types was proposed by Professor R.D.Wright of Melbourne, who was nick-named Pansy, because he looked like a chim-pansy).

Now for the systematic list of symptoms:

The remaining systems - nervous, blood, endocrine, locomotor, and skin - each have enough to warrant separate booklets on their own, destroying the continuity here if they were discussed. The point to make here is that for each of these symptoms - which may arise from more than one system - you must have a set mental routine of discussion, in your own mind, and for others.

SIGNS

Signs, the findings on physical examination of the patient, are divided into

and also into

corresponding to the five senses, where touch and pressure are combined.
Your favourite text-book or teacher of clinical examination will be your best source here.

You should have clearcut mental checklists for lumps in each area of the abdomen (mostly using the AETIOLOGY sub-headings) and in other parts of the body - but do keep a sense of perspective based on frequency of occurrence.

SPECIAL INVESTIGATIONS

The huge number and bewildering range of special investigations means there is special value In having a simple mental check-list to use in thinking about each condition, so you don't forget the obvious ones which even a lay person would know from reading popular magazines, or from personal experience. Here goes:

These are arranged more or less in order of invasiveness, frequency, or expense. If there is some way of making these categories more memorable, 1 should be glad to hear of it.

DIAGNOSIS, and DIFFERENTIAL DIAGNOSIS

A diagnosis is made by correlating the history and symptoms of the patient, the physical signs on examination, and the results of relevant special investigations, and by considering and excluding one at a time other conditions that are closely related.

There IS a logic to diagnosis, but it is mostly a matter of experience, like learning to recognize someone's face at a distance, or their voice. The pseudologic of diagnosis is important if:

1. It is a rare condition, in your experience at any rate,
2. If you have a mental block,
3. If you have to impress an examiner.

But do remember- common things occur commonly - leave rare conditions till last, if anywhere.

MANAGEMENT

Management of a clinical condition referes to both its diagnosis and its treatment. In this booklet, diagnosis has already been considered, so the following discussion is restricted to treatment.

There are many ways of classifying treatment, according to the situation. Several different classifications follow:

Nursing Measures

There is a neat way to consider the management of bacterial inflammatory conditions, viz:

This systematic approach is expanded in detail in "Principles of Treating Bacterial Inflammation" (Patkin. M, 1965, British Journal of Clinical Practice, May). You an find the text of this on this website here

Surgical treatment can also be considered as:

For post-graduate study, each of these can be sub-classified. Special areas such as orthopaedics have their own traditional and very useful approach, such as

for fractures.

SOME IMPORTANT DEFINITIONS

Many problems in the understanding of medicine arise because there Is no clear mental or conceptual picture of basic elements. Some examples:

Your best friends here can be a good medical dictionary, or definitions gleaned from text-books.

HOW VALID, HOW USEFUL?

On its own, the analysis in this book is dangerous. In the 1950's, there flourished an American-type eatery in Swanston Street, Melbourne, on the way to 9 a.m. lectures. It was called the Downyflake Donut Restaurant, and on the wall facing the bleary diners was this deathless verse:

Good practical sense is more important for your future patients and your professional fulfilment than theoretical lists. However if you can master the two, you have a conceptual framework on which to base your memory, to build on, to refine, to use from time to time, and on which to base your presentations to examiners and to students.

Last and far from least, a systematic approach is easily wedded to the coming use of flow-charts, and therefore of electronic data manipulation.

Computer diagnosis of abdominal pain has already proven itself (see papers by de Dombal of Leeds, England). Many have now seen the future, and it works!

POSTSCRIPT

There are many gems of conceptual thinking tucked away in small circles of medical teaching. If you have one suitable for the next edition of this booklet, please forward it, for a modest reward and an acknowledgement if you are the first to send it.

REFERENCES

Patkin, M. (1965) Principles of Treating Bacterial Inflammation, British Journal of Clinical Practice, 19, 73-4.
Patkin, M. (1970) Measurement of Tenderness, 'with Description of a Simple Instrument. Medical Journal of Australia, 1, 670-672.

-o0o-