Acquired Metabolic Diseases of CNS

1. Acquired Metabolic Diseases

4. • Thiamine deficiency may lead to the development of psychotic
symptoms or ophthalmoplegia that begin abruptly, a syndrome
termed Wernicke encephalopathy
• The acute stages, if unrecognized and untreated, may be followed
by a prolonged and largely irreversible condition, Korsakoff
syndrome, characterized clinically by memory disturbances and
confabulation
• The syndrome is particularly common in the setting of chronic
alcoholism, but may also be encountered in patients with
thiamine deficiency resulting from gastric disorders, including
carcinoma, chronic gastritis, or persistent vomiting

5. • Wernicke encephalopathy is characterized by foci of hemorrhage
and necrosis, particularly in the mammillary bodies but also
adjacent to the ventricle, especially the third and fourth
ventricles
Morphology

7. • Deficiency of vitamin B12 often causes anemia, but its most
severe and potentially irreversible effects are related to nervous
system lesions
• Complete paraplegia may occur, usually only later in the course of
the disease
• The combined degeneration of both ascending and descending
tracts of the spinal cord is characteristic of vitamin B12 deficiency
and has led to the designation of the disorder as subacute
combined degeneration of the spinal cord

10. • Some regions of the brain are more sensitive to
hypoglycemia than are others
• Glucose-deprivation initially leads to selective injury to large
pyramidal neurons of the cerebral cortex, which, if it is
severely involved, may result in pseudolaminar necrosis of
the cortex, predominantly involving layers II to V
• The hippocampus is also vulnerable to glucose depletion, as
it is to hypoxia, and may show a dramatic loss of pyramidal
neurons in Sommer sector (area CA1 of the hippocampus)

11. • Purkinje cells of the cerebellum are also vulnerable to
hypoglycemia, although to a lesser extent than to hypoxia
• If the level and duration of hypoglycemia are of sufficient
severity, there may be widespread injury to many areas of
the brain

13. • Hyperglycemia is most commonly found in the setting of
inadequately controlled diabetes mellitus and can be
associated with either ketoacidosis or hyperosmolar coma
• The patient becomes dehydrated and develops confusion,
stupor, and eventually coma
• The fluid depletion must be corrected gradually, otherwise
severe cerebral edema may follow

15. • The cellular response in the CNS is predominantly glial
• Alzheimer type II changes are evident in the cortex and
basal ganglia and other subcortical gray matter regions