Symptom Finder - Amnesia
AMNESIA
The most common causes of this disorder are head injury, epilepsy, migraine, drug use, and hysteria. However, it is wise to have a systematic method of remembering the many etiologies to avoid mistakes in diagnosis. The mnemonic VINDICATE provides an excellent method.
V—Vascular disorders include cerebral arteriosclerosis, hemorrhage, thrombosis, embolism, and migraine. Transient cerebral ischemia (TIA) may cause amnesia.
I—Inflammatory disorders include meningitis, encephalitis, cerebral abscess, malaria and other cerebral parasites, and neurosyphilis. Amnesia and delirium may be caused by high fever regardless of the cause of the fever.
N—Neoplasm of the brain including primary and metastatic lesions may cause a sudden loss of memory.
D—Deficiency of thiamine brings to mind Wernicke encephalopathy as a cause of sudden memory loss, but pellagra and pernicious anemia are also associated with memory loss even though it is not usually acute. Degenerative disorders such as as Alzheimer disease are associated with gradual onset of memory loss so are not likely to be confused with amnesia.
I—Intoxication with lysergic acid diethylamide (LSD), alcohol, bromides, opiates, and a host of other drugs can produce acute amnesia. Uremia, hypoxemia, and liver failure can do the same.
C—Convulsive states, especially temporal lobe epilepsy, can be associated with transient amnesia. However, this amnesia rarely lasts more than 1 to 2 hours as it is likely to be confused with the amnesia of hysteria.
A—Autoimmune disorders include the acute cerebritis of lupus erythematosus that may be associated with a transient amnesia. Other collagen disorders may do the same.
T—Trauma should help recall concussion and epidural and subdural hematomas.
E—Endocrine disorders include hypoglycemia and diabetic acidosis. Hypoparathyroidism and other hypocalcemic states may cause seizures and temporary memory loss. Emotional causes of amnesia include hysteria, depressive psychosis, and schizophrenia. Malingering could be recalled under this category.
Approach to the Diagnosis
The workup of amnesia must include a drug screen, CT scan, or magnetic resonance imaging (MRI) and often an electroencephalogram (EEG) to rule out epilepsy. Migraine may be ruled out by a careful history. A neurologist or psychiatrist will need to be consulted in most cases. If there is fever, a CBC, chemistry panel, antinuclear antibody (ANA), urinalysis, and blood cultures should be ordered. A spinal tap may be necessary as well.
Other Useful Tests
1. Carotid sonogram (TIA)
2. Psychometric testing (hysteria)
3. Four-vessel cerebral angiography (TIA)
4. Histamine test (migraine)
5. Glucose tolerance test (insulinoma)
6. VDRL test (neurosyphilis)
7. Blood smear for malarial parasites (malaria)
8. Response to intravenous thiamine (Wernicke encephalopathy)
9. Magnetic resonance angiography (basilar insufficiency)
10. Serum B12 and folate levels (pernicious anemia)
The most common causes of this disorder are head injury, epilepsy, migraine, drug use, and hysteria. However, it is wise to have a systematic method of remembering the many etiologies to avoid mistakes in diagnosis. The mnemonic VINDICATE provides an excellent method.
V—Vascular disorders include cerebral arteriosclerosis, hemorrhage, thrombosis, embolism, and migraine. Transient cerebral ischemia (TIA) may cause amnesia.
I—Inflammatory disorders include meningitis, encephalitis, cerebral abscess, malaria and other cerebral parasites, and neurosyphilis. Amnesia and delirium may be caused by high fever regardless of the cause of the fever.
N—Neoplasm of the brain including primary and metastatic lesions may cause a sudden loss of memory.
D—Deficiency of thiamine brings to mind Wernicke encephalopathy as a cause of sudden memory loss, but pellagra and pernicious anemia are also associated with memory loss even though it is not usually acute. Degenerative disorders such as as Alzheimer disease are associated with gradual onset of memory loss so are not likely to be confused with amnesia.
I—Intoxication with lysergic acid diethylamide (LSD), alcohol, bromides, opiates, and a host of other drugs can produce acute amnesia. Uremia, hypoxemia, and liver failure can do the same.
C—Convulsive states, especially temporal lobe epilepsy, can be associated with transient amnesia. However, this amnesia rarely lasts more than 1 to 2 hours as it is likely to be confused with the amnesia of hysteria.
A—Autoimmune disorders include the acute cerebritis of lupus erythematosus that may be associated with a transient amnesia. Other collagen disorders may do the same.
T—Trauma should help recall concussion and epidural and subdural hematomas.
E—Endocrine disorders include hypoglycemia and diabetic acidosis. Hypoparathyroidism and other hypocalcemic states may cause seizures and temporary memory loss. Emotional causes of amnesia include hysteria, depressive psychosis, and schizophrenia. Malingering could be recalled under this category.
Approach to the Diagnosis
The workup of amnesia must include a drug screen, CT scan, or magnetic resonance imaging (MRI) and often an electroencephalogram (EEG) to rule out epilepsy. Migraine may be ruled out by a careful history. A neurologist or psychiatrist will need to be consulted in most cases. If there is fever, a CBC, chemistry panel, antinuclear antibody (ANA), urinalysis, and blood cultures should be ordered. A spinal tap may be necessary as well.
Other Useful Tests
1. Carotid sonogram (TIA)
2. Psychometric testing (hysteria)
3. Four-vessel cerebral angiography (TIA)
4. Histamine test (migraine)
5. Glucose tolerance test (insulinoma)
6. VDRL test (neurosyphilis)
7. Blood smear for malarial parasites (malaria)
8. Response to intravenous thiamine (Wernicke encephalopathy)
9. Magnetic resonance angiography (basilar insufficiency)
10. Serum B12 and folate levels (pernicious anemia)
