Question 20

An elderly woman presents with a 9 month history of increasing weakness of all four (4) limbs and a two-day history of inability to swallow her saliva, or cough. She is dyspnoeic, hypoxaemic and her Vital Capacity is 400mls. Outline the key features of your management.

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College Answer

This appears to be a chronic problem, and there is probably not time to discuss possible/probable
futility of more active therapy. Key features of management should include:
•    clinical assessment to help establish the diagnosis (especially sensation, pattern of weakness
[eg. lower motor neurone, long tract signs etc])
•    reasonable to intubate/ventilate (hopefully after a full clinical examination has been performed)
•    drugs for intubation – such as the acute risk with suxamethonium, and the potential harm associated with the use of neuromuscular blockade
•    establishment of specific diagnosis (from disorders of muscle, neuromuscular junction, peripheral nerves, anterior horn cell disease, cord lesions and central lesions)
•    collaboration with neurologists,
•    relevant investigations (eg. EMG, LP, CT, MRI etc)
•    general supportive care, including consideration of early tracheostomy.

Common problems related to lack of relevant detailed knowledge.

Discussion

This question brings about another round of differential diagnosis generation, for the question "what is causing this whole-body weakness". The assessment of the critically ill patient with weakness is well discussed elsewhere.

Thus:

First, one would take a detailed history, and perform a focused clinical examination, with attention paid to airway and breathing.
If these are stable (i.e. intubation is not imminent) then a complete neurological examination can be performed.
Then, the airway control can be definitively established. The patient needs intubation before she aspirates.
Muscle relaxant choice would rest with some sort of non-depolarising agent
Once intubated, the ventilation can be addressed, and normoxia established.
Now, aspiration pneumonia can be investigated with a chest Xray, which would also confirm line placement and ETT position.
Once the ABCs have been controlled, investigation of the underlying disrder can be approached
Potential causes and their investigations include
- Central cerebral lesions - CT brain
- Brainstem lesions - CT/MRI
- Spinal cord lesions - MRI
- Infectious and autoimmune CNS pathology - LP
- Peripheral nerves - nerve conduction studies
- NMJ diseases - electromyography (EMG) and acetylcholine receptor antibodies
- Myopathy - raised CK and muscle biopsy
- Critical illness polyneuropathy - clinical diagnosis
- Steroid myopathy - history, and its a clinical diagnosis
- Electrolyte derangement - electrolyte levels
Collaboration with neurologists is essential, because you will be discharging this patient into their care
A tracheostomy needs to be thought about if the course of ventilation is expected to be prolonged.

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

Yuki, Nobuhiro, and Hans-Peter Hartung. "Guillain–Barré syndrome." New England Journal of Medicine 366.24 (2012): 2294-2304.

Jani, Charu. "Critical Illness Neuropathy." Medicine (2011): 237.

Young, G. Bryan, and Robert R. Hammond. "A stronger approach to weakness in the intensive care unit." Critical care 8.6 (2004): 416.

Mareska, Michael, and Laurie Gutmann. "Lambert-Eaton myasthenic syndrome." Seminars in neurology. Vol. 24. No. 2. [New York]: Thieme-Stratton Inc.,[c1981-, 2004.

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