Neurosurgery notes/Other specialities/Neurology/Neurology general/Vit Deficiency causing neurology/Vit B1 (thiamine)

Vit B1 (thiamine)

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Vit Deficiency causing neurology

Function

  • In thiamine pyrophosphate (TPP), a cofactor for several dehydrogenase enzyme reactions (Be APT):
    • Branched-chain ketoacid dehydrogenase
    • α-Ketoglutarate dehydrogenase (TCA cycle)
    • Pyruvate dehydrogenase (links glycolysis to TCA cycle)
    • Transketolase (HMP shunt)

Deficiency

  • Impaired glucose breakdown → ATP depletion, worsened by glucose infusion; highly aerobic tissues (e.g., brain, heart) are affected first. In patients with chronic alcohol overuse or malnutrition, give thiamine before dextrose to reduce the risk of precipitating Wernicke encephalopathy.
  • Diagnosis is made by increased RBC transketolase activity following vitamin B₁ administration.

Syndromes caused by deficiency

Disorder
Characteristics
Wernicke encephalopathy
Acute, reversible, life-threatening neurologic condition. Symptoms: Confusion, Ophthalmoplegia/Nystagmus, Ataxia (CorONA beer).
Korsakoff syndrome
Amnestic disorder due to chronic alcohol overuse; presents with confabulation, personality changes, memory loss (permanent).
Wernicke-Korsakoff syndrome
Damage to medial dorsal nucleus of thalamus, mammillary bodies. Presentation is combination of Wernicke encephalopathy and Korsakoff syndrome.
Dry beriberi
Polyneuropathy, symmetric muscle wasting. Spell beriberi as Ber1Ber1 to remember vitamin B₁.
Wet beriberi
High-output cardiac failure (due to systemic vasodilation). Spell beriberi as Ber1Ber1 to remember vitamin B₁.