You are an Emergency Department provider in a rural, critical-access hospital. It has been a rather uneventful day when suddenly, a 64-year-old female patient presents to the ER screaming in pain. She is pushed into the ER by her sister, who says that the patient’s pain has been steadily getting worse for the past several hours. The patient has an extensive history of chronic low back pain and is scheduled for neurosurgical intervention within the next couple of weeks. She reports a subjective pain level of 10/10 and describes the pain as sharp, searing, and constant. She is initially hypertensive and mildly tachycardic, further supporting her complaint of severe pain.
You go in to examine the patient, and in the middle of your interview, the patient suddenly stops writhing in pain and looks at you with tremendous surprise. She no longer has any pain whatsoever. None. In the blink of an eye, the patient’s severe pain simply disappeared. Now, the patient states that she doesn’t know why she’s at the ER, nor does she recollect how she got there. She becomes scared and when asked, determines that the last thing she remembers is dinner 2 nights ago. She now has repetitive questioning and is unable to create new memories. She has sudden-onset anterograde amnesia and retrograde amnesia involving the previous 48–72 hours.
You initially suspect acute stroke and begin an appropriate stroke workup. The patient has a completely negative neurologic examination, and all diagnostic imaging and laboratory work are negative for any acute abnormalities. Throughout the patient’s ER encounter, she remains strangely pain-free and grossly neurologically intact. Unfortunately, you are in the country and unable to obtain a neurology consult or transfer due to no need for immediate intervention and a lack of available beds. The patient is subsequently admitted to the hospital for observation and further workup. You find the patient’s amnesia interesting. She is unable to create new memories and has no recollection of the past 72 hours. However, she can recall events that occurred more than 40 years ago with tremendous detail, as if they happened yesterday. Throughout the next 24 hours, the patient’s initial pain slowly returns, and she regains the ability to make new memories. She is discharged with an outpatient MRI and neurology follow-up on hospital day 2, after full resolution of her anterograde amnesia. Her final diagnosis is transient global amnesia, likely secondary to overstimulation from her intense low back pain.
DISCUSSION
Transient global amnesia (TGA) was first named almost 70 years ago and was described as an abrupt, self-limited disruption in anterograde memory and concurrent retrograde amnesia, which presents with variable extent (5) (8). It presents without focal neurological deficits and is best described as a self-limiting condition that resolves spontaneously within 24 hours of onset (10). Patients are suddenly unable to create new memories (anterograde amnesia) and often present with time disorientation and repetitive questioning . TGA is primarily a clinical diagnosis and is thought to be secondary to a physically or psychologically stressful event (1) (10). Events thought to precede TGA in 50–90% of cases include emotional stress, physical effort, acute pain, water contact/sudden temperature change, sexual intercourse, and Valsalva maneuvers (11). TGA has been associated with other stress-induced conditions, including migraine headaches and takotsubo cardiomyopathy (10). TGA is thought to involve a transient functional hippocampal abnormality due to the experienced psychological stress . There is a hypothesis that the hippocampal dysfunction is secondary to transient venous congestion from impaired drainage (3) (10).
TGA is regarded as a rather rare diagnosis with an overall reported incidence of 3–8 cases per 100,000 people (8) (10). TGA is more frequently diagnosed in patients older than 50 years of age. Despite its described rarity, it is thought to be an often-misdiagnosed condition approximately 90% of the time, as it is frequently confused for stroke or atypical epileptic seizure activity (2) (3) (4) (10). Research has suggested that the misdiagnosis of TGA has resulted in rather extensive and perhaps unnecessary evaluations, as would be expected in a patient suffering from acute stroke (1) (10). Unfortunately, considering that TGA often presents as a stroke-mimic, extensive evaluation is unavoidable in most patients as more serious conditions require significant workup to be excluded (10)(11).
As TGA is considered a primarily clinical diagnosis, there is limited evidence of recommended imaging. In recent years, however, MRI has shown some promise as a useful imaging modality due to some observed hippocampal ischemia being present during episodes of TGA (1)(7)(9)(11)(12). As a traditionally clinical diagnosis, if only in part, a diagnosis of exclusion, there are specific diagnostic criteria that must be observed to make the diagnosis of TGA. Main diagnostic features of TGA include a need for the attack to be witnessed, presence of anterograde amnesia during the attack, cognitive impairment limited to amnesia, no alteration in level of consciousness, no loss of personal identity, no focal neurological signs/symptoms, no epileptic features, resolution of attack within 24 hours, and no recent head injury or active epilepsy (9)(10).
The treatment of TGA is largely supportive as TGA is a self-limiting condition and is typically without recurrence or prolonged deficit. Personally, I feel that there is a benefit to having the patient seen by speech-language pathology, as they can provide the patient with memory-retention therapies that I have noted expedited the resolution of the patient’s symptoms. There is no noted established specific treatment for TGA episodes, and the likelihood of recurrent episodes is low (10). Research has traditionally observed recurrent episodes in less than 25% of patients diagnosed with TGA, with some estimates as low as 15% (1)(8). Of note, those patients with recurrent episodes of TGA should be further evaluated by neurology for a less benign etiology (1)(4)(5)(6)(8)(9). Additionally, there is no observed or perceived increased risk of cerebrovascular events or epilepsy noted in patients who have suffered a single episode of TGA (2)(10)(11). Despite limited long-term data, there has not been an identified link between TGA and increased risk of dementia. In fact, the prevalence of post-TGA dementia was about 2.9%, which is similar to that of the general population (11).
After hospital discharge, the need for specialty follow-up or additional diagnostic investigation is debated. Some have felt additional workup to be unnecessary after a single, resolved episode of TGA (2)(4)(10)(12). This provider feels that an outpatient referral to neurology is reasonable and honestly, prudent, especially in the rural, critical-access setting where specialty coverage is sparse.
TGA is a temporary, self-limiting memory loss syndrome that remains enigmatic almost 70 years after it was first described. It is known to primarily affect patients greater than 50 years of age and is not commonly observed in younger patients (1)(4)(6)(10). It is largely a clinical diagnosis, despite some recent evidence that MRI can be beneficial (4)(5)(7)(10). It is essential that more serious acute neurological and amnestic syndromes be ruled out quickly, especially in the emergency setting (10)(11). TGA patients all require hospital admission until the anterograde amnesia resolves and they are once again able to create new memories. This provider recommends the inclusion of speech-language pathology early in the patient’s hospital course to assist with expedient resolution of symptoms and memory deficits. After resolution of symptoms and hospital discharge, the decision to refer for outpatient neurology follow-up is left to the provider. Thankfully, patients who suffer an episode of TGA will likely not experience recurrence and will go on to achieve complete restoration of past and present memories. While TGA presents suddenly and in some cases, rather dramatically as outlined in the case study above, it is a generally benign condition with an excellent prognosis for complete recovery and return to one’s previously enjoyed quality of life (1)(3)(4)(5)(8)(9)(10)(11)(12).
For this article and more like it, download our FREE Digital Magazine, Fields of Care.
To learn more about our service lines, explore partnership opportunities, or stay up to date on RPG news, visit www.RuralPhysiciansGroup.com and follow us on Instagram and Facebook @RuralPhysiciansGroup.
“Control, Alt, Delete”: When Our Brain Can’t Handle the Pressure – Blog Author: John Lichlyter, APRN