Tuesday 14 September 2010

MRCP revision battle 11.1: Guillain Barre Syndrome

When you're working 12 hr days (plus commute) fitting in revision can feel a bit like trying to squeeze that extra towel into the suitcase - you may manage it, but the suitcase is then stretched and prone to snap open at unfortunate times.  If you extend this metaphor to the suitcase being your sanity it explains why junior doctors can often become more emotionally incontinent/irrational as MRCP exams get nearer.  So whats the solution?  Well, in the suitcase scenario you'd add some of those rubber bands round to keep it closed.  In real life, your friends, family and managing to keep some form of hobby/interest going are your rubber bands.

Since I don't want to overpressure my 'rubber bands' I'm going to limit today's battles to

MRCP revision battle 11.1: Guillain Barre Syndrome
MRCP revision battle 11.2: Miller Fisher Syndrome
MRCP revision battle 11.3: Syringomyelia
MRCP revision battle 11.4: Kallmans
MRCP revision battle 11.5: Carcinoid Syndrome

MRCP revision battle 11.1: Guillain Barre Syndrome

Guillain Barre Syndrome is a rare, post-infective demyelinating polyneuropathy.

It tends to occur a few weeks after 'the flu' or a minor illness.  The most commonly associated pathogens are:
  • campylobacter jejuni
  • mycoplasma
  • CMV
  • EBV
  • HIV
  • zoster

Guillain Barre Syndrome is characterised by an ascending, symmetric muscle weakness.  Proximal muscles are more affected than distal ones.  Cranial nerves may also be involved, with CN VII being the most common.

There is usually a 'progressive' phrase for around 4 weeks, after which the patient starts to improve.

Features associated with GBS that appear in MRCP questions include:
  • papilloedema
  • urinary retention
  • arrhythmias

Diagnostically GBS is characterised by:
  • very high protein in CSF
  • decreased nerve velocity on EMG
  • areflexia

The prognosis for patients with GBS is worse if:
  • rapid onset of symptoms
  • older age
  • axomal neuropathoes
  • preceeded by campylobacter infection

Management is:
  • 4 hourly FVC, to check the patient's respiratory muscles aren't affected
  • ventilation if needed
  • plasma exchange
  • IV IG

Overall, 85% of patients make a complete/new complete recovery.
10% will relapse
Less than 5% will die.

Now to to meet a close relative of GBS, Miller Fisher Syndrome.

MRCP revision battle 11.2: Miller Fisher Syndrome

Miller Fisher Syndrome is essentially a rarer variant of Guillain Barre Syndrome.

It's classical triad is:
  • areflexia
  • ataxia
  • opthalmoplegia

Anti-ganglioside antibodies, especially to GQ1b, will be positive in 90% of cases.

On to syringomyelia...

MRCP revision battle 11.3: Syringomyelia and Syringobulbia

Syringomyelia and syringobulbia have always confused me, partly because for some reason I even have problems pronouncing their names!  However, in terms of MRCP there isn't too much you need to know...

Syringomyelia is a cyst/cavity forming in or close to the central canal of the spinal cord.

The cause may be anything that is hindering CSF circulation, but the classical cause is an Arnold Chiari malformation (=condition where the cerebellum herniates through the foramen magnum.)

The essential features are:
  • wasting and weakness of muscles of the hands (possibly 'claw hand')
  • loss of pain and temperature sensation in hands

Other possible signs/symptoms are varied and include Horner's syndrome, eye movement abnormalities and UMN signs in the legs.

Treatment is surgery.

If the cavity/cyst extends from the cord into the brain stem it is known as syringobulbia and causes bulbar palsy type symptoms, facial pain and dizziness.

After that neurology binge onto a slightly lighter topic, Kallmans...

MRCP revision battle 11.4: Kallmans

Kallmans syndrome is an x-linked recessive condition caused by failure of GnRH secreting neurones to migrate to the hypothalamus.

Its features are:
  • anosia
  • 'delayed puberty'
  • hypogonadism, crytoorchidism
  • may be tall or of normal height

Investigations: blood LH/FSH/testosterone and all either normal or low

The most important complication to remember for MRCP is the increased risk of osteoporosis

Next up: Carcinoid syndrome

MRCP revision battle 11.5: Carcinoid Syndrome

Carcinoid tumours are common - 1% of the population will have one at post mortem.

They primarily secrete serotonin (5HT) but may also produce histamine/adrenal hormones/insulin...

45% of carcinoid tumours are in the appendix and a further 30% in the ileum.
They can cause complications such as appendicitis, obstruction or intussception.

Having said carcinoid tumours are common, it's important to understand that carcinoid syndrome is rare - it only occurs when the liver is involved, as tumours in other places will have their 5HT metabolised rather than it have an effect.

Features of carcinoid syndrome are:
  • flushing
  • diarrhoea
  • bronchospasm
  • pellegra
  • hypotension

Diagnosis is by:
  1. urinary 5-HIAA
  2. plasma chromograffin - the new way which, depending on the leve,  also gives an indication of the mass of tumours

Treatment is:
  • surgery
  • ocreotide

Survival from diagnosis tends to be 5 to 8 years.
Patients with carcinoid heart disease have a worse prognosis.

It is also worth remembering that if these tumours are over-handed (eg during surgery) or out-grow their blood supply, a massive 'hormone hit' can be released in one go, causing a carcinoid crisis.

Features of a carcinoid crisis:
  • vasodilation
  • hypotension
  • tachycardia 
  • bronchoconstriction
  • hyperglycaemia 

So those are today's battles fought, and hopefully won.  Click here if you want to partake of the 'war' of questions to check your recall of yesterday's topics.

    MRCP questions: War 10

    As with previous 'wars' after 'battles' these are just a few quick questions to see if your brain cells have retained the information provided in battles 9.1 to 9.6.

    Grab a piece of paper, jot down your answers then compare them to my answers here

    Question 1:
    What are the diagnostic criteria for hereditary haemorrhagic telangiectasia?

    Question 2:
    List 3 possible causes of increased shortness of breath on sitting up compared to lying down.

    Question 3:
    Which form of MND affects only LMN?

    Question 4:
    Name the only drug treatment available for MND

    Question 5:
    List 5 causes of bulbar palsy

    Question 6:
    What condition is associated with a 'Donald Duck' voice?

    Question 7:
    Which genetic condition causes an increase in uric acid levels?

    Question 8:
    List 5 causes of low voltage ECG complex

    Question 9:
    What causes electrical alternans on ECG?

    Question 10:
    How is multifocal motor neuropathy treated?

    answers here