Wernicke's and Korsakoff's syndromes are the result of Thiamine deficiency - usually related to chronic alcohol consumption, but can be seen in other disorders of malnutrition (eg. anorexia nervosa, gastrointestinal surgery).
Wernike's Encephalopathy presents as a classic triad of
- Oculomotor dysfunction: in particular lateral rectus palsies - uni or bilateral, but nystagmus and oculomotor nerve deficits are also seen.
- Gait ataxia
MRI may show lesions around the cerebral aqueduct. Mamillary body atrophy is quite a specific sign from Werneke's encephalopathy.
Korsakoff's Syndrome represents permanent neurological damage from thiamine deficiency. Patients have anterograde and retrograde amnesia, but a preserved sensorium and often have preservation of long term memory and other cognitive skills. Confabulation is classic feature in this disorder.
When patients present to hospital and chronic alcoholism is suspected, we always give Thiamine upfront - before glucose - to prevent Wernicke's and Korsakoff's syndromes.
You can read more about alcohol withdrawal here.
Here is a good review article from NEJM about Alcohol and Drug withdrawal.