1.Peripheral neuropathy
2.Vasculopathy ( microangiopathy )
3.Immunopathy ( infection )
This is called the 'devil's triad'
The closest differential to DFU you have to always think of is peripheral arterial disease. Cellulitis, abscess, osteomyelitis can come as a complication of infected DFU, ( remember that infection makes up the triad which defines DFU. This infection can be in the form of cellulitis, abscess, osteomyelitis, necrotizing fasciitis etc ). So when you come across a case of cellulitis, abscess, necrotizing fasciitis or osteomyelitis in the foot, make sure you take DFU history to see if this is a standalone infection or an infection complicated with DFU.
Before giving chief complain or HOPI, state the relevant comorbidities which can be a risk factor for DFU and PDA
What is DFU ?
Long standing, uncontrolled diabetes mellitus will cause microangiopathy, peripheral neuropathy and immunopathy. A foot ulcer complicated by this triad defines DFU.
What is Peripheral Arterial Disease ( PAD )?
What you call MI in a coronary artery is PAD when it occurs in a lower limb large artery. The plaque forms in the lower limbs and causes macroangiopathy.
UNDERSTANDING ATHEROSCLEROTIC DISEASES:
Atheroma in coronary artery: acute coronary syndrome
Atheroma in cerebral vessel : stroke
Atheroma in abdominal aorta or common iliac artery: Leriche syndrome
Atheroma in lower limb artery: Peripheral arterial disease
In Leriche syndrome, Classically, it is described in male patients as a triad of symptoms:
1. Claudication of the buttocks and thighs
2. Atrophy of the musculature of the legs
3. Impotence (due to paralysis of the L1 nerve)
So what are the comorbidities that you mention, before stating your chief complaint?
Diabetes mellitus ( DFU and PAD risk )
Hypertension ( PAD risk )
Dyslipidemia ( PAD risk )
Hypercholesterolemia ( PAD risk )
Obesity ( PAD risk )
Remember, you are approaching a patient with a foot ulcer. You are not sure if it is DFU or PAD. You cannot be biased. So you have to take history relevant to both diagnoses.
Chief complain:
Symptom + duration
Eg. – pus discharge over wound at foot for the past 1 day…
( do not write chief complain as ‘ patient was electively admitted ). Elective admission is NOT a chief complaint.
Even if someone is admitted electively for a procedure ( like amputation ), chief complaint goes back to the reason why he was even planned for an elective procedure ( reason for his first admission ). An elective admission is just a continuation of management which tails from the 1st admission.
Then start writing History Of Presenting Illness.
Write everything relevant to the diagnosis, complications and management in the HOPI.
In your history, you have to get the cues which are suggestive for peripheral neuropathy, vasculopathy and infection.
Questions to ask for peripheral neuropathy ( must HAVE in diabetic foot ulcer ):
1. Ask if the patient was aware of the trauma which led to the wound over the foot. Patient will usually present with an ulcer, so ask if he recalls as to how he got the wound. A patient with peripheral neuropathy will not be aware of the trauma which induced the wound due to loss of sensation. Ask further to beautify your sentence, enforcing the history. For example, prompt the patient –ask if he possible stepped on a thorn, rock or walked on a hot surface. The patient may draw a parallel to it and give a possibility.. eg ( .. yes I might have had a thorn pierce my foot because I do gardening barefooted. .. )… why barefooted? – because probably the patient has lost sensation over the foot and does not need any coverage.. ( why wear slippers when I can walk barefooted without pain and discomfort ? )
2. Ask on neuropathic pain. This is characterized as a burning sensation. Additionally, ask if the patient has pin prick sensation over his foot at night. At times, patient will say that they have ‘sakit macam tarik’. They use this term to describe neuropathic pain.
3. Ask on glove and stocking anesthesia. Ask the patient if he feels numb over the foot. If yes, confirm if it is in the pattern of glove and stocking. Meaning, patient will have numbness over the foot with normal sensation at a point above the foot ( could be above malleolus or midshin.. ) – as though they are wearing socks. The degree of numbness will be highest ( most numb ) at the toes.. and as u ascend up towards the hindfoot.. the degree of numbness decreases…
4. Ask for temperature dysregulation. In peripheral neuropathy, the autonomic nervous system ( ANS )will be affected. Temperature regulation is impaired. So ask the patient if he is able to cover the foot with a blanket at night. Such patients will feel discomfort and warmth over the foot when they attempt to cover it ( due to ANS dysfunction ). Don’t write silly stuff like ‘patient says he cannot cover foot at night’. Make your statement clear. Correlate with ANS and temperature dysregulation. Don’t make yourself sound so random..For example, present your history as ‘ patient is unable to cover his feet during sleep due to discomfort suggestive of autonomic neuropathy.
5. Ask if they have frequent episodes of postural hypotension, syncope, fainting even in the absence of hypoglycemia. Normally, when you stand up, gravity causes blood to pool in the veins of your legs and lower body. In response, the ANS increases vascular tone (constriction of blood vessels) to push blood upwards against gravity and maintain blood pressure. So when ANS is impaired, you have pooling of blood at the extremities which cannot go against gravity. So they will have postural hypotensive symptoms. But remember, these can be very well found in hypoglycemia. So ask if the patient took a glucose monitoring. Take it significant only if patient was not found hypoglycemic…
When you present the history to your examiner, make sure you let the examiner know that you are thinking about autonomic neuropathy. Just saying ‘postural hypotension’ vaguely may not register the intended context. For example, say something like ‘ patient also claims to have episodes of postural hypotension suggestive of autonomic neuropathy’
So if you are wanting to sell diabetic foot ulcer, you must have as much points favouring peripheral neuropathy… if you have no points favouring peripheral neuropathy, your ulcer could be of a PAD..cheers.
Questions to ask in vasculopathy
1. In PAD, you will get macroangiopathy. The most important history which is suggestive for PAD is ischemic claudication. What is ischemic claudication? Image yourself walking for 1 km.. you will notice cramping, fatigue pain at your calf muscles. This is when your blood supply cannot meet the oxygen demand, pushing the calf muscles into anaerobic respiration which produces lactic acid. When you rest, you clear the oxygen debt and the pain goes off.
In someone with PAD, a plaque is already blocking the lumen of the big artery. So, they will get an oxygen debt even with minimal effort. So they will get a heavy crampy sensation over the calf even if they walk a short distance. Don’t ask silly questions like ‘ do u feel pain when walking?’.. specify the type of pain.. it will be heavy, fatigue pain at the calf ( betis ).
If they have ischemic claudication, ask on the claudication time and distance. Claudication time is the time taken for them to walk until they need to rest ( due to the fatigue pain at calf ).. claudication distance is the distance ( eg.. they can walk for 100 meters until they get that pain ).
Ask if they have claudication of buttocks and thigh, impotence and weakness of lower limb muscle ( Leriche syndrome - scroll up to read on it )
In DFU, you do not expect ischemic claudication. In PAD, must have a positive history of ischemic claudication. ( the severe form is critical limb ischemia, where there is pain even o rest! ).
2. Ask for any risk factors which can cause vasculopathy. Ask on smoking history but only mention what is relevant to the diagnosis ( pack years ). 1 pack year = smoking one pack ( 20 sticks ) daily for a period of one year. PAD will usually have a very strong history of exposure to smoking, passive smoking counts.
3. ask for other risk factors which can suggest PAD. Ask if the patient had any ACS or CVA ( stroke ) previously. If a plaque can form in the cerebral vasculature or coronary arteries, they can very well form in the lower limbs… so ask if the patient had an MI, stroke, did angio before..
4. In storying, see if the patient describes any discoloration ( purplish, black ) of the toes. Ask if patient had any history of amputation.. ( eg. Rays amputation )
Questions on immunopathy
1. Non healing wound. The contracted wound doesn’t seem to heal. Patient will describe an increase in size usually. Do not give dimensions to describe size. Use a relevant object. ( eg.. patient’s wound was at the size of a 10 cent coin initially and it progressed to the size of a 50 cent coin ).
2. Pus discharge. Describe pus discharge if any.
3. Fever. Patient would have had episodes of fever which usually does not completely resolve. OTC antipyretics or oral antibiotics might have provided temporary relieve.
Peripheral Neuropathy + microangiopathy + infection = DFU
If no peripheral neuropathy, think of PAD which is confirmatory if ischemic claudication is present.
Severity of Diabetes
If you are selling DFU, you have to talk on the severity. Only uncontrolled long standing diabetes mellitus will lead to peripheral neuropathy ( thus dfu ).. it can take upto 5 years to manifest. So your history must be strongly suggestive of an uncontrolled long standing DM.. not everyone with diabetes mellitus and ulcer over the foot is having DFU…
Bullet level points to suggest long standing uncontrolled DM:
Medication ( insulin suggests that at one point of time, the DM has been uncontrolled )
HbA1c value ( get it from the diabetes book of the patient, if he has )
Compliance
Follow up
Diet
Bazooka level point ( this history alone, if positive is enough to establish uncontrolled long standing DM )
Ask if the patient has systemic manifestations of DM. Ask if he was at any point of time referred to an ophthalmologist or nephrologist by his physician who is following up with his DM. The patient will only get a referral for diabetic retinopathy and diabetic nephropathy if the following physician is certain of an uncontrolled long standing DM. So just ask about the referral. You are not here to diagnose diabetic retinopathy or nephropathy, you are here to just check if the patient was at all referred.
OTHER IMPORTANT DIAGNOSES TO KEEP IN MIND:
At times, a patient may present with symptoms of vasculopathy ( claudication, loss of pedal hair, weak pulses etc ) even when they do not have atherosclerotic risk factors. ( eg- no comorbidities, nonsmoker, young age, athletic ).
When this happens, think of two differentials:
1. Adductor canal compression syndrome
It is caused by compression of the femoral artery by the musculotendinous band from adductor magnus muscle.
2. Popliteal fossa entrapment syndrome
Similar principle- the calf muscles compress the popliteal artery
In these two differentials, the lumen of the artery becomes smaller due to external compression, and not due to an internal atheroma ( like in the case of PAD )
How to differentiate adductor canal compression and popliteal fossa entrapment?
Ans: Extend the knee fully. The pedal pulse will be present in adductor canal compression syndrome. The pedal pulse will be absent in Popliteal fossa entrapment.
EXAMINATION ( Video link here. Please use these videos to get a better visual learning )
1. LOOK
Inspect around the patient to see if you can find his/her foot wear. Inspect the footwear. See if it has a rough insole, appropriate in size, has rough and worn out areas ( anything suggestive for pressure exertion, which could be a potential risk factor for DFU )
Inspect around and look for any walking aid ( crutches etc )
Then, access gait if patient can walk. Patient may present with high steppage gait ( due to foot drop by peripheral neuropathy advancing to a point it affects the common peroneal nerve ).
Inspect the feet. We are going to apply our triad here. If history taking is science, examination is the application of the science.
Inspect for signs of peripheral neuropathy which are dryness of skin, brittle nail, swelling, deformities namely hallux valgus, claw toe, mallet toe, hammer toe, charcot arthropathy.
Look for diabetic dermopathy
Next, inspect for vasculopathy by looking for diminished pedal hair ( look at base of great toe ) and any amputated toe or dry gangrene.
Inspect for signs of immunopathy which is onicomycosis ( fungal infection ) at nailbed. Inspect between webspaces to look for fungal infection also
Then, inspect for the wound. Use the flow:
number
site
size
shape
edge ( mode of communication between floor and margin eg. punched out in neuropathy )
margin
floorl; the exposed part of ulcer. Mention whether floor is filled with granulation ( red or pink budding tissue ) or slough ( sallow, yellow, cheesy, dirty, black )
2. Palpation
Palpate for the pulses DPA and Posterior tibial pulse. Stand in front of patient and palpate for pulses bilaterally at the same time. Comment if pulse is present. If present, if it is of good volume. That’s all. Nothing else. DON’T TALK ABOUT RATE, RHYTHM ETC.
In DFU, pulse can be felt ( perhaps with weaker volume because of oedema and swelling ) because here we have microangiopathy unlike PAD where pulse won’t be palpable
Then, check for capillary refill time
Then palpate for the ulcer.
TOUCH THE ULCER, gently but confidently. Start from the periphery.
Palpate the floor of the ulcer. See if there is tenderness ( peripheral neuropathy ). Look at patient's face for grimace, bleeding ( vasculopathy ) and pus discharge ( immunopathy )
Palpate for the base of the ulcer. If the ulcer’s consistency is hard, the base is bone. If it is firm, the base is muscle.
Example of presentation of palpation:
Upon palpation, the dorsalis pedis pulse and posterior tibial pulse was present on the right foot with good volume and left foot with poor volume. The capillary refill time on both foot is more than 2 seconds. Upon palpation of the floor of the ulcer, there is no tenderness, no bleeding and purulent discharge is present. Upon palpation of the base of the ulcer, it is hard in consistency suggestive for bone.
3. Move
Nothing much. The most you can do is to ask patient to dorsiflex the ankle to rule out foot drop.
4. Special test
Semmes Weinstein Monofilament
Joint position sense
Vibration
Ankle reflex
Mention that you will do Ankle brachial index
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