NEUROPATHY-VITAMIN B12 DEFICIENCY
SUMMARY
1. Subacute combined degeneration produces a myelo-neuropathy: concomitant myelopathy & painless symmetric peripheral sensory dysfunction, absent ankle jerks.
2. Myelopathy: corticospinal and dorsal column dysfunction with spasticity & sensory ataxia. Acute onset with involvement of both UL & LL.
3. Others: hyper-pigmentation of the knuckles & flexural creases of the fingers & toes; optic atrophy; encephalopathy ('megaloblastic madness'), movement disorders (more common in young children).
4. Inx: international consensus guidelines now recommend testing Vit B12 & metabolites (MMA/Homocystine) in patients with distal symmetric neuropathy.
5. Metabolite testing reveals B12 deficiency in 5-10% of those with low-normal B12 levels (200-500 pg/mL).
6. MRI findings: striking hyperintensity of the dorsal column of the cord.
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].
