Amnesia

 Amnesia is disturbance in the memory may due to disease, drugs

Transient memory loss may be occur in due to infections,post-ictal stage,r due to Transient global amnesia.

         Transient global amnesia

Affects middle-aged persons

An abrupt discrete loss of anterograde memory lasting few hours

Patient unable to reecord new memories

Repetitive questioning is the hallmark of this condition 

Consciousness preserved

During the attack which lasts or 4-6 hours maybe retrograde amnesia of he past days,weeks or years.

Recur around 10-20-% cases

Has no physical signs so history taking from witness important

A vascular etiology is unlikely

                   Persistent Amnesia 

 Serious neurological disease must be excluded

Symptoms shoul be corroborated wit relatives colleagues. 

Mood disorders likely if poor concentration

Episodic memory may be lost in Korsakoff syndrome or Tepomoral lobe damage

Progressive deterioraton may be due to underlying dementia

Important to identify and treat dementia

Reference:

Leach JP,Daveenport RJ.Neurology.In.Ralston SH,Penman ID,Strachen MW, Hobson RP.Davidson's principles & practice of medicine.23rd edition.Elsevier.Elssevier Ltd.2018.p.1081