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Introduction Annotated
Bibliography Questions
Case Presentation A 57 year old woman was rushed to the ED by her son because of a concern that she was having a stroke. The patient had a completely negative past medical history and took no medications. She did not smoke or drink alcohol. She had never had any heart trouble, chest pains, or stroke-like symptoms. She had called her son 2 hours before presentation because she suddenly felt “confused”. The son related that she had said she didn’t know what day it was and couldn’t remember what she was supposed to do that day. She was tearful and distraught about this, and the son hurried over to her house. He found her to appear well but very upset. She denied any other problem, but asked him several times what day it was, why he was there, and whether she was supposed to be going anywhere. On arrival in the ED shortly thereafter, there was no change in the patient’s condition. She denied headache, motor or sensory changes, visual complaints, or dizziness. She denied chest pain, back pain, dizziness, sweating, shortness of breath, nausea, or vomiting. There had been no head trauma, seizure-like activity, or use of alcohol, medication, or other drugs. The physical examination, including a careful neurological exam, was completely normal except for the patient’s disorientation to time, place, and events, and her distraught affect. Gait, fundoscopic exam, speech, and alertness were normal. When questioned carefully, she knew her name and birthdate but could not state her age. She recognized her son and could name her family members, but could not remember the last time she had seen them. She remembered her address from several months before, but could not remember the address she had moved to 2 months previously. She could not remember 3 objects (“Dr. Wilson, 33, brown shoes”) for more than one minute, and had to be re-introduced to the nurse and physician whenever they re-entered the room. When reassured by the physician about her memory loss, she promptly calmed down, but became distraught again within a few minutes. She continued to ask about why she was at the hospital, what day it was, and what had happened, always forgetting these things within a minute or so of being told. She repeatedly burst into tears when told she was 57 years old. She was given a card to hold that said, “Don’t worry. Your memory loss is temporary. You will be OK soon”, but of course forgot to look at it. Introduction Transient global amnesia (TGA) is characterized by
an abrupt onset of both anterograde and retrograde amnesia, and the
patient resembles in many respects someone who has just suffered a
traumatic cerebral concussion.
Patients with TGA typically present with confusion as to where
they are and how they got there.
They are unable to retain new information and repeatedly ask
orienting questions such as “Where am I?”
Recall of a series of numbers or of a physician’s name may
remain intact for up to 30-60 seconds, but is then lost.
There is, however, retention of personal identity and there
is no impairment of consciousness, motor skills, writing, speech,
language, or judgment. This
anterograde amnesia lasts from several hours to 24 hours, following
which there is permanent amnesia for any events occurring during the
attack. Retrograde amnesia
-- for events occurring hours, months, or even years before the attack
-- is typically patchy, but easily demonstrated.
These memories are regained progressively as the patient recovers
from the episode. The incidence of TGA is somewhere between 5 and 30
per 100,000, depending on age and the population studied.
More than 1000 cases have been reported in the literature.
The disorder occurs most commonly in persons between 50 and
70 years of age, and about 50% of TGA patients are hypertensive.
Dizziness, headache, drowsiness, nausea, or vomiting are occasionally
noted during attacks, but illusions, delusions, hallucinations, and
seizures are not. Reported possible precipitating factors include emotionally
intense or stressful events, sexual intercourse, physical exertion,
painful stimuli, bathing, heat exposure, or Valsalva’s maneuver.
TGA has also been reported in association with cerebral angiography,
CNS infection, polycythemia, cardiac valvular disease, exposure to
altitude, and heparin-induced thrombocytopenia.
Rarely, TGA has been associated with tumors, hemorrhage,
or infarction in the temporal lobe, thalamus, or parieto-occipital
lobe; in the vast majority of patients, however, the CT is normal.
The EEG is likewise typically normal, although there are patients
in whom presumed TGA can be shown to be due to non-convulsive seizures.
Interestingly, a history of migraine in more common in patients
with TGA, and a number of investigators have suggested that TGA may
be a “migraine-like” phenomenon. The reported recurrence rate of TGA ranges from 10%
to 25%, with an average of about 5% annually.
The second episode has been reported to occur from 1 month
to 9 years after the initial event.
Studies using single photon emission computed tomography
(SPECT) and positron emission tomography (PET) have suggested that
TGA results from a transient decrease in blood flow to one or both
temporal lobes in the region supplied by the posterior cerebral artery.
However, these findings are by no means universal.
Moreover, some investigators have suggested that these changes are consistent with the “spreading depression”
associated with migraine and may be secondary rather than primary. The long-term prognosis of TGA is nevertheless excellent.
A number of studies report rates of stroke and TIA among TGA
patients that are comparable to those in a matched population without
TGA. Of note, a mild
permanent memory impairment has been noted in a few patients after
episodes of TGA. Differential Diagnosis
In evaluating a patient with suspected TGA, one must
rule out other causes of CNS dysfunction or amnesia such as head injury,
epilepsy, brain tumor, CVA, Wernicke-Korsakoff syndrome, migraine,
CVA, meningitis, encephalitis, hypoglycemia, medications (eg, benzodiazepines),
drugs of abuse, and psychogenic fugue state. The following is a well-accepted set of criteria for
the diagnosis of TGA: The
attack must be witnessed by someone who can provide further information.
Anterograde amnesia must be present during the attack.
There is no clouding of consciousness or loss of personal identity.
There is no cognitive impairment beyond the amnesia.
There are no focal neurologic signs, including no aphasia or
apraxia.
There are no epileptic features.
There is no history of recent head injury or recent (within
2 years) seizure.
The attack resolves within 24 hours.
Emergency Department Evaluation
The Emergency Department physician must take a careful
history and perform a complete physical examination and thorough neurological
examination. The patient,
family members, and other witnesses should be closely questioned regarding
the amnestic episode and possible precipitating events. A CT scan is often recommended to rule out hemorrhage,
infarction, or tumor. Whether,
in the absence of other specific indications, this needs to be done
immediately is questionable.
Similarly, an EEG is often ordered as part of the eventual
evaluation. SPECT or
PET scanning might also be considered.
Other studies, such as CBC, electrolytes, calcium, BUN, creatinine,
EKG, or liver function tests, have essentially no utility in the absence
of other indications. A
toxicology screen may be appropriate in certain situations, however.
Emergency Department
Management and Disposition As noted above, TGA is generally a benign condition
with an excellent prognosis.
Overnight hospitalization has been recommended for repeated
neurological examinations and observation until the episode has resolved.
No specific treatment is recommended. It might be speculated that anti-migraine agents might be useful
DURING an attack, but this is at present not supported by any data.
Likewise, low-dose aspirin after the attack is probably reasonable
anyway in most patients in the TGA patient’s typical age range.
Transient Global AmnesiaAnnotated
Bibliography
1. Hodges JR, Warlow CP: The aetiology of transient global amnesia. A case-control study of 114 cases with prospective follow-up. Brain 1990;113:639-657.
This study by Hodges, the big name in TGA, used a strict
definition to select patients with TGA and compared them with patients
with TIA and with normal controls.
It demonstrated an association of TGA with migraine, but
not with the usual accepted risk factors for cerebrovascular disease.
Patients with TGA had a good prognosis.
Seven percent of patients with TGA developed seizures during
follow-up. The authors
conclude that a vascular etiology is unlikely in the vast majority
of patients with TGA.
2. Hodges JR, Warlow CP: Syndromes of transient amnesia: towards a classification. A study of 153 cases. J Neurol Neurosurg Psych 1990;53:834-43.
In
this paper, Hodges presented the now well-accepted clinical definition
of the syndrome of TGA, using it to select those with TGA from a
larger group presenting with amnesia.
3. Zorzon M, Antonutti L, Mase G, et al.: Transient global amnesia and transient ischemic attack: natural history, vascular risk factors, and associated conditions.
Stroke 1995;26:1536-1542.
Another case-control study demonstrating the good prognosis
of TGA, the lack of association with TIA and vascular disease, and
the positive association with migraine.
As in previous studies, in a small subset of patients TGA
was felt to be related to seizure.
4. Sandson TA, Price BH: Transient global amnesia. Sem Neurol 1995;15:183-187.
This is a concise, balanced, and practical review of TGA.
It features a nice discussion of differential diagnosis and
attempts at establishing an etiology.
5. Brown J: ED evaluation of transient global amnesia. Ann Emerg Med 1997;30:522-526.
A scholarly, well-written review written from the emergency
medicine perspective.
6. Lewis SL: Aetiology of transient global amnesia. Lancet 1998;352:397-399.
This is a well-argued “thought piece” advancing the hypothesis that
some cases of TGA are caused by transient increases in CNS
venous pressures.
7. Zeman AZJ, Boniface SJ, Hodges JR: Transient epileptic amnesia: a description of the clinical and neuropsychological features in 10 cases and a review of the literature. J Neurol, Neurosurg & Psychiatry 1998;64:435-443.
A delineation of the related syndrome of TEA, with detailed reports
of 10 cases.
8. Hodges JR: Unraveling the enigma of transient global amnesia. Ann Neurol 1998;43:151-153.
A recent editorial that incorporates new data on advanced
imaging in TGA.
Transient Global AmnesiaQuestions1. A 65 year old woman is brought to the ED by her friends after becoming confused while playing slot machines in an Atlantic City casino. She does not smoke or drink, takes no medications except thiazide for high blood pressure, and has an otherwise negative past medical history. While in the casino she suddenly became disoriented and asked her friends where they were and how they had gotten there. She had no memory of having taken a bus to the casino that morning, and continued to ask the same questions over and over again. She otherwise felt well. In the ED, she denies headache, visual or speech changes, or motor or sensory complaints. Her friends confirm that she has not been drinking or taking pills and that there has been no head trauma. The patient is very worried, and asks the examiner again and again where she is and how she got there. The last she can remember is watching television the night before. The
most appropriate next step in the evaluation is: A.
Stat
head CT with contrast B.
Stat
bedside EEG C.
Stat
head CT without contrast D.
Psychiatric
evaluation E.
Careful
neurologic examination
2.
A
45 year old female is rushed to the ED by EMS after being unable
to remember her name. She
is accompanied by her niece, who states that the patient had just
received news of the death of a close friend and had become extremely
agitated. Her past
medical history is negative. On
examination, the patient has normal vital signs except for a pulse
of 120. Neurologic exam is completely normal, as is the remainder of
the physical exam. The
patient has a coarse tremor but is calm and stoic.
She is disoriented to place, time, and person.
Her speech is fluent and she appears very attentive to her
surroundings. She attempts
to answer questions, but cannot remember what city she lives in
or what her niece’s name is.
She cannot remember the name of the high school she attended.
When asked by the examiner to remember his name and the nurse’s
name, however, she is able to do so over more than a one hour period. The
best initial management for this patient is: A.
Stat
drug screen B.
Head
CT without and with contrast C.
Gentle
suggestion that she will slowly recover from this problem D.
Involuntary
psychiatric commitment E.
Bedside
EEG
3.
A
75 year old retired physics professor was driving home from the
movies with his girlfriend when he suddenly began asking her what
time it was and where they were going.
He continued to operate the car normally and drove to his
house without difficulty.
He felt otherwise well, but continued to be unsure as to
what he had been doing earlier in the evening.
Fearing he was having a stroke, the girlfriend drove him
to the ED. On
examination the patient was in no distress and appeared normal. His examination, including a careful neurologic exam, was normal.
He denied headache, hallucinations, weakness, or anything
else other than being confused as what had happened earlier in the
evening. He was able
to converse amiably and with obvious expertise on his previous research
in physics and was delighted to hear that the doctor had taken college
physics with one of his former colleagues.
When the examiner left the room to answer a page and returned
3 minutes later, the patient had no memory of their former conversation,
and in fact was delighted to hear that the doctor had taken college
physics with one of his former colleagues! The
evaluation of this patient must include: A.
Stat
drug screen B.
Stat
head CT C.
A
magnetic resonance angiogram in the morning D.
All
of the above E.
None
of the above 4.
A
55 year old truck driver is brought to the ED by his buddy after
developing a glazed look in his eyes and, when asked if he was OK,
answering only “I’m alright” over and over again.
There was no apparent seizure activity and no loss of consciousness.
On arrival to the ED, the patient is conscious, alert, and
oriented, and has no complaints.
His friend says he is now acting normal, but that he was
clearly not acting right for 30 minutes. The
patient smokes a pack of cigarettes a day, but denies drinking alcohol
or taking any drugs. He
had a concussion when he fell out of a tree at age 13, but has otherwise
had no medical problems. He
states that he has occasionally had similar spells in the past,
but is generally able to ignore them.
He has never had a driving accident.
He knows when a spell is coming on because he sees a human
face before his eyes. He
has a faint memory of his friend asking him if he was OK earlier
this evening, he remembers
coming into the ED and calling his wife to tell her he would be
home a little late. His
remote memory is excellent and he has no difficulty remembering
3 objects for 5 minutes. This
patient most likely:
A. has recently
applied for a workmen’s compensation claim B.
has classic transient global amnesia C. has atypical transient global amnesia D. has had a small TIA E.
has partial
complex seizures
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