This document discusses the pathophysiology of retrograde amnesia and its distinction from anterograde amnesia, highlighting the complexities of post-traumatic amnesia (PTA) and the neurological mechanisms involved. It emphasizes the impact of emotional trauma on memory, the role of diaschisis in memory impairment, and the effects of increased acetylcholine levels following brain injury. Additionally, it reviews brain imaging studies that reveal significant reductions in blood flow in key brain areas during episodes of PTA.

1. 1
Pathophysiology Of
Retrogradeamnesia
PROBLEM BASED LEARNING (PBL)
PREPARED BY: MUHAMMAD ARIFF B. MAHDZUB
BACHELOR MEDICINE AND SURGERY (MBBS)
UNIVERSITY COLLEGE SHAHPUTRA, KUANTAN

2. • There are two types of amnesia: retrogradeamnesia (loss of
memories that were formed shortly before the injury)
and anterogradeamnesia (problems with creating new
memories after the injury has taken place).
• Both retrograde and anterograde forms may be referred to as
PTA, or the term may be used to refer only to anterograde
amnesia.

3. • Currently, the pathophysiological mechanisms which produce
post-traumatic amnesia are not completely known.
• The most common research strategy to clarify these
mechanisms is the examination of the impaired functional
capabilities of people with posttraumatic amnesia (PTA) after
a traumatic brain injury.

4. Neurological
mechanisms
Brain
imaging
studies
diaschisis

5. Neurological Mechanisms
• Research on the effect of emotional trauma on memory retention
and amnesic symptoms has shown that exposure to prolonged
levels of extreme stress has a direct effect on the hippocampus.
• Elevated stress levels can lead to an increase in the production of
enkephalins and corticosteroids.
• produce abnormal neural activity and disrupt long-term
potentiation (a neural mechanism associated with learning and
memory)

6. Diaschisis
• Diaschisis refers to the sudden dysfunction of portions of the brain
due to lesions in distant but connected neurons.
• Play an important role in PTA, more particularly in the declarative
memory impairments observed in patients experiencing an episode
of PTA.
• there is an increase in acetylcholine concentrations in the brain
after head injury.
• recent evidence implicates increased activity levels of choline
acetyltransferase, as a major cause.
• This increase in acetylcholine levels has also been tied to behavioral
suppression and unconsciousness.

7. Brain-Imaging studies
• Brain imaging techniques are useful for examining the changes in
the brain that occur as a result of damage.
• Metting et al. (2001) used CT-Scan to examine the
pathophyiological damage in patients currently experiencing an
episode of PTA, patients with resolved PTA, and a control group that
had not experienced PTA.
• Bloodflow to the occipital lobe, the caudate nucleus, and the grey
matter of the frontal lobe was significantly reduced in patients who
were scanned during the episode of PTA.
• No differences were seen between patients with resolved PTA and
the control group.