Miscellaneous multi-system diseases

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

Ankylosing spondylitis

This has come up in Question 2 from the first paper of 2019. The examiners asked for characteristic plain Xray findings in the C-spine series, which is baffling because nobody has ordered one since 2008. However, in case they ask it again, here they are, from Radiopedia and Østergaard (2012):

• Romanus lesions of the spine (shiny corner sign): small erosions at the corners of vertebral bodies with reactive sclerosis
• vertebral body squaring
• Andersson lesion: noninfectious spondylodiscitis:
• Bamboo spine: diffuse syndesmophytic ankylosis 
• Dagger spine: interspinous ligament ossification
• enthesophyte formation from enthesopathy
• dural ectasia

Parkinson's disease

This appeared in Question 14.4 from the second paper of 2019, as a tiny shred of a question worth 25% of the marks (i.e. 2.5 marks out of the total 300 for the paper). The college wanted to know what problems might arise in a patient who has severe Parkinson’s disease and who must miss out on their medications because of bowel rest. There are a couple of excellent articles which appears almost designed to answer this sort of question (Freeman et al, 2007, and Katus et al, 2014).  The contents of these was distilled into what follows:

• Airway issues:
  • Upper airway obstruction may develop due to laryngeal muscle involvement, which may complicate extubation by virtue of stridor (Vincken et al, 1984)
• Respiratory issues:
  •  Swallowing difficulty predisposes this patient to aspiration
  • The rigidity of chest wall muscles makes total lung compliance worse
  • Post extubation, this rigidity predisposes them to atelectasis
  • While ventilated, muscle tremor may cause patient-ventilator dyssynchrony, and rigidity may make triggering more difficult
• Haemodynamic issues
  • There may be haemodynamic instability because of autonomic involvement (i.e. the patient will remain hypotensive even though their sepsis is resolving
• Neurological problems
  • Parkinsonian medications may need to be converted to parenteral forms (eg. rotigotine patches).
  • Often, anti-Parkinsons medications are themselves a risk factor for delirium and confusion, as is abrupt withdrawal thereof
  • There is an increased sensitivity to sedative medications
  • Once they do become confused, anti-dopaminergic medications (eg. antipsychotics) are relatively contraindicated
• Gastrointestinal problems
  • Autonomic dysfunction of the gut leads to slower recovery from bowel surgery
  • The patient may be coming from a poor nutritional baseline 
  • Perioperative antiemetics and prokinetics (mainly metoclopramide and droperidol) are antidopaminergic and will worsen the symptoms

Problems of routine housekeeping:

• Once a normal diet is permitted, it may be difficult to institute because of swallowing difficulty
• There is an increased risk of DVT and PE due to immobility and rigidity
• There is often delayed mobilisation due to this movement disorder, which promotes muscle wasting and deconditioning
• Autonomic dysfunction also leads to a failure of thermoregulation (piloerection and cutaneous vascular supply is not under such tight control as it should be).

Down syndrome

Question 22 from the second paper of 2020 asked for the important features of Down syndrome which could impact on the management of a six-year-old boy. There's an article by Donoso from 2017 which seems like it was tailor-made for this SAQ, but it is in Spanish. Still, it contained gold. Armed with nothing but highschool-level Spanish and Google Translate, the author embarked on an expedition to extract its wisdom:

Airway features: 

• Increased risk from sedation due to a labile upper airway with weaker muscle tone and frequent laryngomalacia.
• A greater risk of aspiration, owing to muscular hypotonia
• Small mouth, large tongue - likely, intubation will be more difficult
• Atlantoaxial instability is reportedly very common, 15-30% of patients

Respiratory function:

• Morbidity and mortality from respiratory disease(eg. ARDS) is greater in the Down syndrome population. Increased susceptibility to oxidative stress is blamed. 
• Often, they have subpleural cysts, which can predispose them to pneumothoraces with high pressure ventilation
• Often there may be pulmonary hypertension; of particular interest is pulmonary vein stenosis, which is rare but hideous and with a very high early childhood mortality

Cardiovascular features:

• About 40-50% of these children have congenital cardiac abnormalities, and there's a fair spectrum of them, but the most common are ASDs and VSDs which can become cyanotic when pulmonary pressure increases (eg. in pneumonia)

Neurological features:

• Hypotonia, i.e. poor muscle tone, may become an issue with ventilator weaning
• Cognitive developmental delay may change the way you need to assess their neurology for extubation assessment

Endocrine associations

• Hypothyroidism is common among Down syndrome patients

Nutritional issues 

• Celiac disease is common; gluten-free NG feeds and oral diet may be necessary

Immune features

• For unclear reasons, these children have worse outcomes from sepsis and respiratory infections than the general population.