1)      Head injury – retrograde amnesia (cannot remember events prior to head injury) and anterograde amnesia (cannot remember events after the head injury)

2)      Thyroid function tests - abnormalities

3)      Vitamin B12 assay - abnormalities

4)      Delirium state with ataxia, eye movement abnormalities, elderly persons with poor nutrition, alcoholism

5)      Ataxia, visual changes, neuropathy, memory deficits onset and evolve within day to weeks (paraneoplastic limbic encephalitis in lung cancer, Hodgkin’s, breast, colon, bladder,  testicle cancer)