neurological and physiological symptom memory loss symptoms A neurological and physiological symptom that is characterized by an unusual forgetfulness. One may not be able to remember new events, recall one or more memories of the past, or both. Memory loss may be for a short time and then resolve (transient), or it may not go away and get worse over time. ICD9CM_2005:780.93 UMLS_CUI:C0751295 SYMP:0000543 UMLS_ICD9CM_2005_AUI:A2797424