MYELOPATHY-SUBACUTE COMBINED DEGENERATION OF THE SPINAL CORD

SUMMARY

1. B₁₂ deficiency causes segmental loss of myelin in the dorsal and lateral columns.

2. Clinical: gradual weakness associated with paresthesias and loss of proprioception with development of ataxia.

3. Severe cases end in extensive bilateral lower extremity weakness, spasticity, and urinary incontinence +/- cognitive impairment.

4. Cognitive changes include progressively worsening confusion, apathy, delusions, paranoia.

5. Think of B₁₂ deficiency in a patient with brisk knee jerks (due to pyramidal tract dysfunction) and absent ankle jerks (due to peripheral neuropathy).

6. Diagnose by measuring serum B₁₂, methylmalonic acid (MMA), and homocysteine (HC) levels. In states of B12 deficiency, both MMA and HC are increased.

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].