Organic Amnestic Syndrome and Korsakoff Psychosis

Dr Waleed Ahmad

Vignette

A 30-year-old woman is brought to you with memory deficits and rigid behaviour. On examination, she appears lean and weak, dishevelled, is disoriented to time, has a flat affect, registration is 3/3, short-term memory is 0/3 and long-term memory appears intact. She does not have any difficulty naming objects. On physical examination, her weight is 42Kg and her height 152 cm. The lady says, there is nothing wrong with her, while her father says she is speaking too many lies these days. The rest of the clinical evaluation is insignificant except for chronic diarrhoea and recent episodes of vomiting. 

What finding will you look for on MRI?

Diagnosis

The clinical picture, in this case, is consistent with organic amnestic syndrome, specifically Korsakoff Psychosis. The most common cause of organic amnestic syndrome is thiamine deficiency.(1)

Magnetic Resonance Imaging

Increased signal (ie, hyperintensity) in midline structures occurs in the acute Korsakoff psychosis. 

Laboratory test

Red cell transketolase activity is the most specific test for Korsakoff psychosis. 

Other causes: 

1. Diencephalic amnesia
2. Infarct in medial thalamus
3. Tumour in medial thalamus
4. Encephalitis
5. Head injury

Causes of thiamine deficiency

1. Alcoholism
2. Malnutrition 
3. Diarrhoea
4. Vomiting

Neuropathological Changes in Korsakoff Psychosis

1. Neuronal loss
2. Gliosis
3. Microhaemorrhages

Location of Neuropathological Changes 

1. Periventricular
2. Thalamus
3. Mamillary bodies

Lesions causing Organic Amnestic Syndrome

Organic Amnesia results from lesions in the medial temporal lobe and medial thalamus. Medial temporal lobe lesions cause pure amnesia without impairments in other cognitive domains. 

About the Author

The author is a consultant psychiatrist at the department of psychiatry, Mercy Teaching Hospital Peshawar, and a member of the faculty at the department of psychiatry and behavioural sciences, Peshawar Medical College, Peshawar, 25000, KP, Pakistan. Email: dr.waleed@outlook.com 

References

1. Kopelman MD. The Korsakoff Syndrome. British Journal of Psychiatry. 1995;166(2):154-173. doi:10.1192/bjp.166.2.154
2. Jung Y-C, Chanraud S, Sullivan EV. Neuroimaging of Wernicke's encephalopathy and Korsakoff's syndrome. Neuropsychol Rev. 2012;22(2):170-180. doi:10.1007/s11065-012-9203-4
3. Chandrakumar A, Bhardwaj A, Jong GWt. Review of thiamine deficiency disorders: Wernicke encephalopathy and Korsakoff psychosis. Journal of Basic and Clinical Physiology and Pharmacology. 2019;30(2):153-162. doi:doi:10.1515/jbcpp-2018-0075