Pick ‘n’ Mix Week 1 March 2023

Estimated Reading Time: 3 minutes

We are really grateful to Trudie Pestell for sharing Pick ‘n’ Mix: a fabulous education initiative that she has been producing for University Hospital Southampton Emergency Department for a while.

Each week we will bring you some clinical pearls to add to your knowledge and understanding with links to other resources as well as an OSCE of the week.


Myasthenia Gravis (MG) An unexplained autoimmunity disorder of Neuromuscular Junction (NMJ), characterised by weakness and fatigability of skeletal muscles.

Patients develop either:

  • Anti-acetylcholine receptor (anti-AChR) antibodies seen in 80% – 90% Antibodies against muscle specific protein kinase (MuSK) seen in 10% – 20%
  • Myasthenia gravis is highly associated with thymic abnormalities (75% of patients with MG).

Classes of Myasthenia Gravis

  • Acquired Autoimmune (most common)
  • Transient neonatal (Maternal Anti-AChR antibodies)
  • Drug induced (Ciprofloxacin, Propanolol, CCBs, Botox, Lithium, Magnesium, etc.)
  • Congenital syndromes (Ach receptor deficiency, slow and fast channel syndromes)

Symptoms and Signs

  • Weakness worsens with repetition but gets better with rest
  • Ptosis (90% of cases)
  • Diplopia
  • Proximal limb weakness
  • Facial weakness
  • Neck flexor/extensor weakness


Myasthenic crisis (under treatment of myasthenia gravis)

  • Weakness of upper airway muscles causing obstruction and/or aspiration
  • Weakness of respiratory muscles causing reduced tidal volume

Cholinergic crisis (over treatment of myasthenia gravis)

  • Respiratory failure with other cholinergic symptoms (e.g. miosis, diarrhoea, urinary incontinence, bradycardia)
  • Weakness of respiratory muscles causing reduced tidal volume


  • ‘Usual’ investigations: blood tests; chest Xray;
  • ICE PACK TEST – Apply ice pack to the eye for 2-5 mins, positive if ptosis improves by >2mm or more
  • Serum acetylcholine-receptor antibodies (diagnostic gold standard)
  • Anti-MuSK antibodies (for seronegative myasthenia gravis)
  • Single fibre electromyography


  • Acetylcholinesterase inhibitors (pyridostigmine)
  • Immunosuppressants (1st line = prednisolone)
  • Plasmapheresis and intravenous immunoglobulin

The case of a ‘spotted’ infant

The beginning:

A mother has brought her child to the ED with a four-day history of what she thought was the ‘common cold’. Whilst washing her child she noticed a rash that started on the child’s head and has now extended down to its body.

A rash

From the history you know the child is not vaccinated. On examination, you see the rash (shown below) and decide to examine the mouth where you notice tiny white spots inside their cheeks.

Measles – Sadly, misinformation about vaccination has led to reduced uptake, particularly of the MMR vaccine. The white spots are Koplik spots and pathognomic of measles infection

More information is available on the excellent Paediatric FOAMed

OSCE of the Weeks – Dermatological Examination

“Hello, my name is Phil. I am one of the medical students”

“Please can you confirm your name and date of birth, while I wash my hands, put on my PPE and ensure we are somewhere private?”

“Are you comfortable? Do you need any pain relief or a drink?”

“I have been asked to see you because of a rash, is that correct? I will need to examine this rash, and also look at your mouth, scalp and eyes.”

“Would you like a chaperone present?”

“I will talk out loud as we go”

“If at any time you want me to stop or you are in pain, let me know”

“Briefly tell me about this rash.”

  • Recent medications
  • Change in cosmetics/cleaning products
  • Illnesses
  • Foreign travel
  • Systemic symptoms

“In terms of general inspection, I am assessing…”

Patient’s appearance

  • level of comfort
  • location of rash: symmetrical or extremities


  • BP
  • Resp Rate
  • Sats
  • Temperature
  • Blood glucose

“I will need to examine your rash…”

  • Describe characteristics of rash using SOCRATES (see Chapter 3)
  • Examines: hair; eyes; mouth; lymph nodes
  • If appropriate comment on the need to examine the genitalia

“Thank you very much the examination is now over.”

“Would you like any help getting changed?”

“In summary my working differential diagnosis is…

“I think we should try, e.g.

  • Dry: emollient: weak steroids 
  • Itchy: antihistamines 
  • Infected: topical fusidic acid; flucloxacillin 

“Does that sound reasonable to you? Do you have any questions or concerns?”

Additional resources

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