Question 5

Highest mark

Compare and contrast the clinical and diagnostic features of ascending polyneuritis (Guillain Barre Syndrome), myasthenia gravis and motor neurone disease.

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This could be answered using a table format. Suggestions include the following:

	ascending, polyneuritis	myasthenia gravis	motor neurone disease
weakness	yes	yes	yes
reflexes	absent	present	May be increased (eg. amyotrophic lateral sclerosis)
characteristic distribution	ascending symmetrical	Eyes & cranial nerves	asymmetrical`
progression	acute and recovery	relapsing	progressive
fatigue	no	characteristic	no
fasiculation	no	no	characteristic
increased CSF protein	yes	no	no
UMN signs present	no	no	May be present(eg. amyotrophic lateral sclerosis)

sensory features	often dysthesia + pain	no	no
pain	May be present	no	no
delayed nerve conduction	yes	no	no
fade + post tetanic facilitation	no	yes	no
‘jitter’ on EMG	no	no	yes
response to anticholinesterases	no	yes	no
response to plasmapheresis	May occur	yes	no

Discussion

Approach to the ICU patient with generalised weakness is discussed elsewhere.

This table is a detailed version. The features listed by the college here have been incorporated into the greater table in the abovelinked summary ("Causes of Weakness in Intensive Care Patients ")

In short:

Only Guillain-Barre will have delayed nerve conduction, increased CSF protein and sensory features
Only myasthenia will have characteristic fatiguability, and will respond to anticholinesterase treatment (or plasmapheresis)
Only motor neuron disease will have increased reflexes, and will be assymetrical.

References

Oh's Intensive Care manual:

Chapter 51 (pp. 568) Acute cerebrovascular complications by Bernard Riley and Thearina de Beer

Chapter 57 (pp. 617) Neuromuscular diseases in intensive care by George Skowronski and Manoj K Saxena

Reeves and Swenson have an excellent online textbook chapter (12) entitled "Evaluation of the Patient with Weakness"

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