You are asked to assess a 54 year old man scheduled for an urgent laparotomy for a suspected perforated duodenal ulcer. He has recently developed symptoms of double vision, ptosis, dysarthria and generalised muscle weakness. He was due to be reviewed by a neurologist next week. The anaesthetist asks for a post-op bed in ICU. The patient has a 25-pack year history of smoking but ceased smoking 3 months ago.
11.1 What are your differential diagnoses for his weakness?
11.2 The above patient is admitted to ICU post-op. A perforated DU was oversewn in theatre.
a) What are the essential pieces of information you would expect from the anaesthetist at handover upon the patient’s admission to ICU?
11.3 What investigations could help you establish the diagnosis for his weakness?
11.1 What are your differential diagnoses for his weakness?
11.2 The above patient is admitted to ICU post-op. A perforated DU was oversewn in theatre.
a) What are the essential pieces of information you would expect from the anaesthetist at handover upon the patient’s admission to ICU?
Specific:
GA drugs used – esp muscle relaxants; muscle relaxation in response to sux (if used)
Findings on nerve stimulator NMJ monitoring
Reasons extubation could not be attempted
General:
Operative findings
Haemodynamic stability
Antibiotics used
11.3 What investigations could help you establish the diagnosis for his weakness?
The fist part of the question is a straightforward differential-generating exercise. What are the causes of subacute-onset weakness in a smoker? Guillain-Barre, myasthenia gravis and motor neuron disease are reasonable guesses which apply everywhere. Particularly, diplopia would make one think of myasthenia gravis. The Lambert-Eaton (or Eaton-Lambert) Myasthenic Syndrome is a special one, which relates partiocularly to people with neoplasms (it is a paraneoplastic syndrome of autoantibody secretion, resulting in the destruction of voltage-gated calcium channels). Botulism is thrown in for some reason. Periodic paralysis is also mentioned, even though it is an insanely rate genetic disorder. Drug-induced myopathies are more common, but are mentioned last.
What would you want to know from the anaesthetist?
Well; for one, you would like to know whether they used any muscle relaxant, and if yes- then how much, what kind, and when. One would also be interested in the nerve stimulator test. The administration of gentamicin may potentiate NMJ disturbances and it would be good to know whether one should expect something like this.
As for investigations... A panel of standard tests would include the following:
It is worth noting that the college is not too proud to seek a neurology consult when confronted by this sort of problem.
Approach to the ICU patient with generalised weakness is discussed elsewhere.
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.
Engel, Andrew G., ed. Myasthenia gravis and myasthenic disorders. Oxford University Press, 2012.