37 yo F Engineer PC: Double vision, fatigue, difficulty swallowing. HPC:

1. 37 yo F Engineer PC: Double vision, fatigue, difficulty swallowing. HPC: • 3/52 of worsening diplopia, worse in afternoons • 3/7 of intermittent weakness in legs following long walks • 3/7 difficulty swallowing

2. PMHx: nil PSHx: nil Meds: COCP FHx: thyroid disease All: NK SHx: Engineer, married with two children

3. Let’s be clear here. This is an absolutely shocking history. But I guess it is for educational purposes.

4. Where could her lesion(s) localise? To add some structure… Diplopia Tell me some stuff about that. Ok, chuck in some difficultly swallowing. How can we relate it to the diplopia. Ok, what about leg weakness? Alright so it is a bit more complicated, the diplopia has been around for 3 weeks and is worse in the afternoon, and the leg weakness is only after a long walk.

5. What signs will you look for on examination to aid in localisation? Would have been nice if a better history was taken. Start with the diplopia. Ok so considering the dysphagia separately. The leg weakness.

6. O/EAfebrile;  BP 110/70;  HR 76/min;  RR 24/minNo thyromegaly  No rashesCN II: PERLA (pupils equal, reactive to light and accommodation)CN III, IV, VI:  mild asymmetric ptosis bilaterally, variable eye movement abnormalities with repeated testing.CN V:  facial sensation intactCN VII:  mild bifacial weakness with cheeks puffed, able to raise eyebrowsCN VIII: hearing intactCN IX, X, XII:  tongue and uvula midline, palate elevates symmetrically, diminished gag reflex.CN XI:  intact SCM strength bilaterallyMotor:  normal strength, tone, and bulk of all muscle groups to directed testing.  After prolonged neck flexion, arm and leg raise strength 4/5.  No fasciculation.Reflexes:  2+ throughout,  Babinski negativeSensation:  intactCo-ordination: NADGait:  NAD

7. Following the physical exam can you localise the lesion/s?

8. Name three diseases that affect the neuromuscular junction and describe the clinical differences. Really only two diseases – myasthenia gravis and eaton-lambert (lambert-eaton) syndrome. Myasthenia gravis has been categorised into two forms based on the autoantibody and two forms based on the clinical appearance. Any idea what these are and how they affect the neuromuscular junction. Then there are toxins of which there are quite a number. There are also some metabolic states.

9. Botulism • Minor cranial nerve palsies associated with symmetric descending weakness to rapid respiratory arrest. • 1gm of aerolised botulism toxin could kill 1.5 million. Snake venom • There are different types of venom that do different things. • The neurotoxic venom affects the cranial nerves first, resulting in ptosis, ophthalmoplegia, dysarthria, dysphagia, and drooling, progressing to weakness of limb muscles.

10. Eaton-Lambert Syndrome – anti-VGCC • Slowly progressing proximal muscle weakness • Often autonomic dysfunction • Cranial nerve involvement infrequent – ocular • Oropharyngeal symptoms have been observed • Postexercise or postactivation facilitation. Myasthenia gravis • Proximal limb muscles, extraocularmuslces, muscles of mastication, speech and facial expression seen early on. • Worsening symptoms towards the end of the day or after exercise.

11. Which diagnostic test would you order? The diagnosis is made clinical. But it can be confirmed by some investigations. Any ideas? Tensilon test, ice pack test, serological testing, electromyography

12. Management Maximise the activity of the AchR in the neuromuscular junction. - anticholinesterases Limit or remove the immune attack. • Thymectomy • Plamsa exchange • Plasmapheresis • IV immunoglobulin • Corticosteroids

13. I have reversed the order of questions 3 and 4 to make this hopefully a little bit more interesting for people.