MYASTHENIA GRAVIS-INVESTIGATIONS

SUMMARY

1. Measure antibodies against acetylcholine receptor (AChR-Abs, only in ~60% of those with isolated ocular disease but 90% isolated in generalized disease) and against muscle-specific tyrosine kinase (MuSK-Abs).

2. Ice pack test to differentiate from other causes of ptosis: ice in a glove is applied to the closed eyelid for 2 minutes, which results in less ptosis. 80% sensitivity.

3. Do TFT as 30% of patients have chronic autoimmune thyroiditis.

4. Image the chest with CT or MRI in all to rule out thymoma.

5. NCS. Repetitive stimulation demonstrates a decrement:


6. EMG. Single fibre EMG demonstrates "jittering":

Reference(s)

Wilkinson, I., Furmedge, D. and Sinharay, R. (2017). Oxford handbook of clinical medicine. Oxford: Oxford University Press. Get it on Amazon.
Feather, A., Randall, D. and Waterhouse, M. (2020). Kumar And Clark’s Clinical Medicine. 10th ed. S.L.: Elsevier Health Sciences. Get it on Amazon.
Hannaman, R. A., Bullock, L., Hatchell, C. A., & Yoffe, M. (2016). Internal medicine review core curriculum, 2017-2018. CO Springs, CO: MedStudy.
Therapeutic Guidelines. Melbourne: Therapeutic Guidelines Limited. https://www.tg.org.au [Accessed 2021].