Tuesday 28 September 2010

MRCP revision battle 23.1: Henoch Schonlein purpura

No energy for an interesting introduction today... lets dive straight into the battles...

MRCP revision battle 23.1: Henoch Schonlein purpura
MRCP revision battle 23.2: Parinaud's syndrome
MRCP revision battle 23.3: Polymyositis and Dermatomyositis
MRCP revision battle 23.4: Trichomonas vaginalis
MRCP revision battle 23.5: Atrial septal defects
MRCP revision battle 23.6: Pyoderma gangrenosum

MRCP revision battle 23.1: Henoch Schonlein purpura

Henoch Schonlein Purpura (HSP) is a an IgA mediated small vessel vasculitis.

Classically it affects mainly children post infection.

Features include:
  • symmetrical macular rash over buttocks and extensor surfaces of legs
  • abdominal pain +/- blood diarrhoea
  • arthralgia

Complications of HSP include:
  • renal failure (look for microhaematuria)
  • intussusception

Management is supportive.

Now for a very quick battle, Parinaud's Syndrome...

MRCP revision battle 23.2: Parinaud's syndrome

Parinaud's syndrome refers to the combination of:
  • upward gaze palsy
  • pseudo Argyll-Robertson pupils

Causes include:
  • hydrocephalus
  • pineal tumours
  • stroke
  • multiple sclerosis

Onwards to the longer 'buy-one-get-one-free' battle of dermatomyositis and polymyositis...

MRCP revision battle 23.3: Polymyositis and Dermatomyositis

Polymyositis is an idiopathic inflammatory disorder of skeletal muscle.  When it is associated with cutaneous lesions it is dermatomyositis.

  • progressive proximal muscle weakness
  • dysphagia
  • interstitial lung disease
  • oesophageal dysfunction
  • weight loss 
  • fever
  • myocarditis
  • arthralgia

To try and remember this list I think of the condition starting in the proximal muscles of the arm then creeping to the joint (causing arthralgia) and onwards to the oesophagus, causing dysphagia and oesphageal dysfunction.  I then imagine it seeping into the lungs (interstitial lung disease) and then onwards into the heart (myocarditis).

Skin signs include:
  • heliotrope (liliac-purple) rash around eyelids/cheeks
  • macular rash over back and shoulders (=shawl sign)
  • Gottrons papules = scaly plaques on MCP/PIP joints
  • Gottrons sign = erythema over knees/elbows
  • periungal telangectasia
  • nail fold infarcts
  • photosensitivity

There is a higher prevalence of malignancy with dermatomyositis.

Investigations show:
  • raised CK/AST/LDH
  • abnormal EMG - shows fibrillation potentials
  • anti-Jo antibodies associated with a systemic form of disease

Treatment is:
  • prednisolone
  • methotrexate
  • screen for maligancy.

NB: juvenile dermatomyositis is different - it is more aggressive and includes a vasculitis and ectopic calcification.

Now onwards for our first expedition into the world of sexually transmitted diseases...

MRCP revision battle 23.4: Trichomonas vaginalis

Trichomonas vaginalis is an anaerobic protozoan that is transmitted sexually.

It needs an alkaline pH to thrive.

It can cause:
  • thin, grey, fishy discharge
  • itchiness
  • dysparenia
  • dysuria

As it inflames the endothelium it increases an individual's susceptibility to other sexually transmitted infections.

Treatment is with metronidazole.

Now on to atrial septal defects...

MRCP revision battle 23.5: Atrial septal defects

Atrial septal defects may present as:
  • dyspnoea on exertion
  • finding after AF diagnosed
  • finding after CVA
  • finding after heart failure

Clinical signs include:
  • fixed splitting S2
  • ejection systolic murmur
  • left parasternal heave

A cardiac echo may show paradoxical ventricular septal motion due to right sided overload.

There are 3 main atrial septal defects to be aware of:

1: Ostium secundum defect
  • Ostium secundum defects account for 70% of atrial septal defects
  • caused by an enlarged foramen ovale
  • ECG shows RBBB with right axis deviation and a long PR
  • 10-20% of cases will be associated with mitral valve prolapse
  • it tends to present in adulthood

2: Ostium primum defect
  • ostium primum defects account for 15% of atrial septal defects
  • ECG shows RBBB with left axis deviation and a long PR
  • it tends to present earlier, in childhood
  • it is associated with Downs, Klinefelters and Noonans
  • some feel it should be classified as a atrioventricular septal defect as it is so low down in the atria, on the endocardial cushions
  • often associated with TR/MR.

3: Sinus venous atrial septal defect
  • up to 15% of cases

Treatment is closure.

A very small atrial septal defect is patent foramen ovale.  This is different from the others as as it is so small it does not allow equilisation of atrial pressures.  It occurs in 25% of the population and can allow paradoxical emboli (see below) and is associated with migraine.

Complications of ASDs include:
  • Eisenmengers Syndrome
    • left-to-right shunt causes increased blood flow through pulmonary vasculature and so pulmonary hypertension, which increases the pressure in the right side of the heart leading to reversal of the shun to right-to-left = eisenmnegers syndrome.
  • paradoxical emboli 
    • venous emboli ending up in arterial rather than venous system
    • --> strokes, intestinal infarcts, splenic infarcts 
  • ? migraines - controversial area of research - google if you are interested.

Finally for ASDs a brief eponymous syndrome that occasionally appears in MRCP answer options: Holt-Oram.  Holt Oram is an inherited condition characterised by abnormalities of the heart and upper limb.  It is inherited in an autosomal dominant manner with incomplete penetrance.

Now skip straight to last battle of the day

MRCP revision battle 23.6: Pyoderma gangrenosum

Pyoderma gangrenosum is a nodulo-pustular ulcer, with a purulent surface and a tender bluish overhanging edge.

Below is a picture from Wiki Commons showing pyoderma gangrenosum:

In 50% of cases it is idiopathic.

Associations with pyoderma gangrenosum include:
  • inflammatory bowel disease
  • RA/SLE/ank spond
  • lymphoma/leukaemia/myeloproliferative disorders
  • primary biliary sclerosis/sclerosing chloangitis
  • sarcoid
  • thyroid problems
  • diabetes
  • Wegeners granulomatosis

Treatment includes high dose oral steroids.

Another day's battling complete.  Congratulations!