E. Lee Murray, MD
CHAPTER CONTENTS
OVERVIEW
The most common nutritional disorders seen in hospital neurology practice are:
These and some other important disorders are discussed here. Links to related disorders discussed in other chapters are also shown.
B12 DEFICIENCY
B12 deficiency is usually from impaired absorption especially with advanced age. Dietary deficiency is uncommon.
PRESENTATION is neurologic and systemic:
•Neurologic: Symptoms of neuropathy, myelopathy, or cognitive impairment may occur. Signs can include confusion and tendon reflexes reduced (neuropathy) or increased (myelopathy).
•Systemic: Common symptoms are fatigue and weakness from anemia. Glossitis occurs uncommonly.
Diagnosis is considered in patients with a broad range of neurologic dysfunction, and is usually part of routine testing for neurologists.
•B12 level is usually reduced; methylmalonic acid (MMA) level testing is performed if B12 deficiency is suspected; high MMA suggests B12 deficiency.
•Folate level testing is also performed. Note that folate supplementation can prevent hematologic manifestations of B12 deficiency but not the neurologic events.
•Schilling test is performed for pernicious anemia, especially in younger patients but is seldom needed in older patients.
MANAGEMENT with B12 replacement is usually IM initially followed by oral replacement. Intra-oral absorption is better than gastric absorption for many patients so dissolvable or liquid preparations may be used.1
B1 DEFICIENCY
B1 deficiency usually occurs in the setting of starvation (cancer, anorexia nervosa, situational), alcoholism, or gastric bypass. Increased thiamine demand can occur with a variety of stresses including renal failure on dialysis, sepsis, pregnancy, or intractable diarrhea.
PRESENTATION classically has two related presentations: Wernicke encephalopathy and Korsakoff syndrome.
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