MRCP revision battle 55.1: Trypanosomiasis

More randomness...


MRCP revision battle 55.1: Trypanosomiasis
MRCP revision battle 55.2: Hypokalaemia
MRCP revision battle 55.3: Cryoglobulins
MRCP revision battle 55.4: Cold agglutinins
MRCP revision battle 55.5: Lateral medullary syndrome
MRCP revision battle 55.6: Purtscher retinopathy
MRCP revision battle 55.7: Optic atrophy




MRCP revision battle 55.1: Trypanosomiasis

Trypanosomiasis = diseases causes by parasitic protozoa trypanosoma.


2 main divisions:



1. African = sleeping sickness

• spread by tsetse fly
•  caused by
• t. rhodesiense - east africa - quicker
• t.gambiense - west africa - slower
• classical presentation 
• fever, rigors, headache, hepatosplenomegaly, lymphadenopathy
• sleepy during day, awake at night
•  meningoencephalitis
• look for chancre and posterior cervical nodes (=Winterbottom's sign)
• diagnosis is by microscopy
• treatment:
• IV pentamide
• IV melarsoprol

Below is an image of t.gambiense:

2. American - Chagas disease

• carried by triatomine bugs
• caused by t. cruzi
• classical presentation
• fever, rash, hepatosplenomegaly, lymphadenopathy 
• myocarditis
• meningoencephalitis
• megaoesophagus/megacolon
• look for:
• chagoma (=indurated, erythamatous nodule at site of infection)
• periorbital oedema (=Romana's sign)
•  diagnosis is by blood culture
• treatment: benznidazole

Now for some low potassium....

MRCP revision battle 55.2: Hypokalaemia

Hypokalaemia is defined as K <3.5mmol; if <2.5mmol it is severe.


Symptoms/signs include:

• muscle weakness
• hypotonia
• cramps
• tetany
• worsening of dig toxicity
• cardiac arrhythmias

ECG may show:

• small/inverted T waves
• U waves
• long PR
• depressed ST

Causes of hypokalaemia


Low K with hypertension

• raised plasma renin
• Cushings
• renin-secreting tumour
• low plasma renin
• Conns
• liquorice
• Liddles

Low K without hypertension

• diuretics
• GI loss
• CRF
• Bartters
• Gitelmans
• secondary hyperaldosteronism

On to cryoglobulins...

MRCP revision battle 55.3: Cryoglobulins

Cryoglobulins are immunoglobulins that undergo reversible precipitation at 4c and dissolve when warmed to 37c.

Cryoglobulins may be IgG, IgM or IgA.

One third of cases are idiopathic.



Type 1 cryoglobulinaemia

• monoclonal
• high titres, usually >5mg/ml
• associated with:
• myeloma
• Waldenstroms
• features include vasculitis, ulceration and Raynaud's

Type 2 cryoglobulinaemia

• mixed mono and polyclonal
• titres usually >1mg/ml
• associated with:
• RA
• sjogrens
• lympoma
• CLL
• hep C
• HIV
• features include vasculitis, mesangiocapillary GN

Type 3 cryoglobulinaemia

• mixed polyclonal
• associated with:
• RA
• sjogrens
• SLE
• features include purpura, GN, arthritis

Now on to a similar but distinct topic...

MRCP revision battle 55.4: Cold agglutinins

Cold agglutinins are molecules, usually IgM, which act against red cells agglutinising and haemolysing them at low temperatures.

Symptoms of cold agglutinins include:

• Raynauds
• acrocyanosis
• mild haemolytic anaemia

Causes of cold agglutinins include:

• idiopathic
• CLL
• lymphoma
• mycoplasma
• coxsachie
• mononucleosis
• HIV

Management is to avoid cold weather.



Now to diversify to neurology....

MRCP revision battle 55.5: Lateral medullary syndrome

Lateral medullary syndrome is a condition in which a patient has a set of symptoms as a result of insult to the medulla.

Lateral medullary syndrome is usually due to PICA or vertebral artery occlusion.


Features include:

• cerebellar signs
• contralateral pain and temperature sensation loss
• ipsilateral Horners
• ipsilateral loss of pain and temperature sensation on face
• ipsilateral paralysis of palate, pharynx and cords

On to some vision loss...

MRCP revision battle 55.6: Purtscher retinopathy

Purtscher's retinopathy is characterised by cotton wool spots on fundoscopy with sudden detioration in vision.


It is classically associated with head trauma or chest trauma.

Other associations include:

• pancreatitis
• fat embolism
• amniotic fluid embolism
• vascular diseases

There is no treatment.


Finally - optic atrophy...

MRCP revision battle 55.7: Optic atrophy

Optic atrophy is loss of fibres of the optic disc.  It is characterised by decreased vision (particulary loss of colour vision) and a pale disc on fundoscopy.


Causes include:


Congenital:

• Friedrichs ataxia (battle 30.6)
• Lebers optic atrophy (battle 46.3)
• DMOAD (=diabetes mellitus, optic atrophy and deafness)
• retinitis pigmentosa (battle 30.1)

Acquired:

• MS
• papilloedema
• glaucoma
• ischaemia
• B6, B12, folate deficieny
• lead poisoning
• arsenic poisoning
• methanol
• ethambutol
• isoniazid
• chloramphenicol