Miscellaneous Multi-system Diseases

Created on Thu, 08/31/2017 - 06:02
Last updated on Thu, 08/31/2017 - 22:48

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Often, the college asks the candidates to discuss diseases with a significant community prevalence which have some sort of serious impact on the ICU management of affected patients. it makes sense to expect final-stage CICM trainees to be able to discuss SLE or scleorderma, and the attention directed at these diseases is understandable.

On the other hand, there are occasionally questions in the Fellowship Exam which cannot be explained by this framework. There is a group of rare diseases which have only ever appeared once and which can reasonably be expected to never appear again. These are grouped here in no particular order, basically because there is nowehere else to put them.

Myotonic dystrophy

Question 30.1 from the first paper of 2017 asked for six clinical features of myotonic dystrophy, a  congenital disorder which results in an abnormal skeletal muscle myosin kinase protein. The college answer lists 11 features, but in fact there may be many more. An excellent review by Turner et al (2010) adds a few extra features.  Remixed with the college answer, the full list looks like this:

Neuromuscular phenomena
  • Myotonic facies
  • Wasting of facial muscles, sternocleidomastoids, muscles of distal extremities
  • Ptosis
  • Myotonic spasms (e.g. delay in opening fingers after making a fist)
  • "Warm up phenomenon" - grip strength increases with repeated contractions
  • Slurred speech (pharyngeal myotonia)
  • Percussion myotonia
  • Absent reflexes

Other features

  • Frontal baldness
  • Cardiomyopathy
  • Cardiac conduction defects
  • Cataracts / lenticular opacities
  • Testicular atrophy
  • Intellectual impairment
  • Insulin insensitivity


What ICU relevance might we wring from this? Well. These people do end up in ICU a lot. Not the least of their presentations are from theatre recovery, as they are referred to the ICU by concerned anaesthetists as elective post-operative admissions. An excellent (though somewhat dated) article by Mudge et al (1980) discusses some of these concerns, which remain relevant in the contemporary anaesthetic setting.

In short, the following anaesthetic problems usually arise, which are worth knowing about

  • Cardiac arrhythmias
  • Abnormal response to suxamethonium (persistant contraction of all muscles, occasionally making ventilation impossible)
  • Using neostigmine to reverse the curare toxins may in fact precipitate myotonia
  • Increased respiratory sensitivity to sedating agents, particularly narcotics (thus, safest to leave them intubated)
  • Myotonia in response to stimulation (which is unaffected by neuromuscular junction blockers) tends to frustrate the surgeons, so virtually every procedure can be expected to take longer. Apparently warming the operating theatre canhelp with this, but then you have to deal with sweaty surgeons whinging at you.
  • Cough will be weakened and clearance of secretions will be poor, with implications for extubation

Acromegaly

This also came up in Question 30.1 from the first paper of 2017, where the college wanted candidates to identify acromegaly from Wikipedia's copyright-free images (originally from Chanson et al, 2008). Additionally, some of the clinical features were asked for (specifically, biochemical abnormalities).

Clinical Features of Acromegaly
Pituitary tumour effect
  • Visual-field defects (bitemporal hemianopia)
  • Cranial-nerve palsy (usually 3rd nerve)
  • Headache
Skeletal effects
  • "Acral enlargement" - basically, "acral" is a term used to refer to the extremities, particulalry fingers and toes. "Acromegaly at a basic level is a disease of big hands and feet.
  • Large stature, "gigantism"
  • Arthralgias and arthritis
  • Carpal tunnel syndrome
  • Acroparesthesia (fingers and toes again)
  • Hypertrophy of the frontal bone of the skull, giving rise to a prominent brow ridge

Muscular effects

  • Proximal myopathy

Cutaenous manifestations

  • Hyperhidrosis
  • Oily texture
  • Skin tags
  • Prognathism
  • Jaw malocclusion

Airway consequences

  • Prognathism
  • Jaw malocclusion
  • Abnormally large larynx (thus, cuff leak with normal-sized tubes)
  • Large tongue
  • Enlarged thyroid (gets in the way of tracheostomy)
  • Large nasal polyps frustrate nasal intubation
  • Large stature makes ETT position difficult (i.e. it may not reach far enough into the trachea)

Respiratory effects

  • Sleep apnea (central and obstructive)
  • Narcolepsy
  • Restrictive disease due to kyphosis/scoliosis

Cardiovascular effects

  • Left ventricular hypertrophy
  • Asymmetric septal hypertrophy
  • Cardiomyopathy
  • Hypertension
  • Congestive heart failure
  • Mitral and aortic regurgitation

Electrolyte, endocrine and metabolic abnormalities

  • Menstrual abnormalities
  • Galactorrhea
  • Decreased libido, impotence, low levels of sex hormone–binding globulin
  • Low renin, cortisol and aldosterone levels 
  • Hyperglycaemia (impaired insulin sensitivity)
  • Hypercalcemia
  • Hypernatremia (due to DI)

Renal problems

  • Obstructive uropathy (prostatomegaly)
  • Kidney enlargement (may be reported as hydronephrosis)
  • Hypercalciuria

Haematological problems

  • Hepatosplenomegaly


 

 

References

Mudge, Barbara J., Peter B. Taylor, and Abraham FL Vanderspek. "Perioperative hazards in myotonic dystrophy." Anaesthesia 35.5 (1980): 492-495.

Turner, Chris, and David Hilton-Jones. "The myotonic dystrophies: diagnosis and management." Journal of Neurology, Neurosurgery & Psychiatry 81.4 (2010): 358-367.

Philippe Chanson and Sylvie Salenave - AcromegalyOrphanet Journal of Rare Diseases 2008, 3:17. doi:10.1186/1750-1172-3-17

Molitch, M. E. "Clinical manifestations of acromegaly.Endocrinology and metabolism clinics of North America 21.3 (1992): 597-614.

Melmed, Shlomo. "Acromegaly." New England Journal of Medicine 355.24 (2006): 2558-2573.