EMS Trauma Emergencies - Amnesia

EMS Providers should have a solid understanding of the causes and types of amnesia to effectively assess and manage patients presenting with memory disturbances. Here's what they need to know:

Causes of Amnesia

Head Trauma: Traumatic brain injury (TBI) is a common cause of amnesia, especially retrograde amnesia (RA), where memory loss occurs for events preceding the injury.

Stroke: Lack of blood flow to the brain can lead to transient global amnesia (TGA), characterized by sudden onset memory loss.

Seizures: Particularly prolonged or severe seizures can cause memory impairment.

Neurodegenerative Diseases: Alzheimer's disease, dementia, and other conditions can lead to progressive memory loss.

Psychological Trauma: Emotional shock or severe stress can result in dissociative amnesia, where memories are blocked due to psychological distress.

Drug or Alcohol Abuse: Substance abuse can lead to blackouts or memory gaps.

Infections: Encephalitis, meningitis, and other brain infections can impair memory function.

Brain Tumors: Tumors can affect memory centers in the brain, leading to amnesia.

Metabolic Disorders: Conditions like vitamin B12 deficiency or thyroid disorders can cause memory impairment.

Medications: Certain medications, such as benzodiazepines, can cause memory problems as side effects.

Types of Amnesia

Retrograde Amnesia (RA):

Definition: Memory loss for events that occurred before the onset of amnesia.

Causes: Typically associated with head trauma, brain injury, or neurological conditions.

Example: A patient may not remember events leading up to a car accident due to retrograde amnesia.

Anterograde Amnesia (AA):

Definition: Inability to form new memories after the onset of amnesia.

Causes: Often seen in cases of head trauma, stroke, or neurodegenerative diseases affecting the hippocampus.

Example: A patient may repeatedly ask the same question or fail to recall recent conversations due to anterograde amnesia.

Differential Diagnosis

Differentiating Retrograde vs. Anterograde Amnesia: Assessing the patient's ability to recall events before and after the onset of symptoms helps distinguish between the two types.

History and Physical Examination: Detailed history-taking, including information from family members or witnesses, and a thorough physical examination can help identify potential causes of amnesia.

Neuroimaging: CT scans or MRI scans may be necessary to detect structural abnormalities in the brain, such as tumors or lesions.

Laboratory Tests: Blood tests can help rule out metabolic causes of amnesia, such as vitamin deficiencies or infections.

Management

Stabilization: Ensure the patient's vital signs are stable and address any immediate life-threatening issues.

Supportive Care: Provide reassurance and support to the patient and their family members.

Referral: Depending on the underlying cause, patients may require further evaluation and management by neurologists, psychiatrists, or other specialists.

By understanding the causes and types of amnesia, EMS providers can effectively assess and manage patients experiencing memory disturbances, providing appropriate care and ensuring the best possible outcomes.

Further Reading

Alexander, M. & Belle, R (2012) Advanced EMT: A Clinical Reasoning Approach (2nd Ed). New Jersey: Pearson.

Bledsoe, B. E., Cherry, R. A. & Porter, R. S. (2023) Paramedic Care: Principles and Practice Volume 1 (6th Ed). New Jersey: Pearson.

Brown, C. A., III., & Walls, R. M. (2023) The Walls Manual of Emergency Airway Management (6th Ed). Pennsylvania: Lippincott Williams & Wilkins.

Mistovich, J. J. & Karren, K. J. (2014) Prehospital Emergency Care (11th Ed). New Jersey. Pearson Education.