MYOPATHY-TYPES

SUMMARY

1. Inflammatory myopathies: caused by chronic muscle inflammation. Causes: dermatomyositis, polymyositis, IBD.

2. Endocrine myopathy: proximal muscle weakness of varying degrees may be seen in patients with hyperthyroidism, acromegaly, severe vitamin D deficiency, and conditions of steroid excess.

3. Metabolic myopathy - consider in patients with muscle fatigue, pain, cramping, contractures and myoglobinuria exacerbated by exercise. Caused by disorders of carbohydrate, lipid metabolism or mtochondrial function.

4. Muscular dystrophy - genetic abnormalities. Duchenne muscular dystrophy: X-linked disorder that causes progressive muscle weakness, starting at 2yrs, and progressing to death as a young adult. Myotonic dystrophy consists of 2 types of inherited, adult-onset, neuromuscular disorders with systemic effects.

5. AlDS-related myopathy is uncommon and typically thought to be due to zidovudine (ZDV, AZT).

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].