Transient Global Amnesia with Reversible White Matter Lesions: A Variant of Posterior Reversible Encephalopathy Syndrome?

Acute neurological disease as a trigger or co-occurrence of transient global amnesia: a case series and systematic review

BACKGROUND

Transient global amnesia (TGA) represents a benign neurological syndrome of unknown pathophysiology, often accompanied by vanishing hippocampal punctate lesions on diffusion-weighted imaging (hippocampal punctate diffusion lesion, HPDL). The recent literature suggests that TGA may be triggered by acute neurological conditions.

OBJECTIVE

To study patients with TGA triggered by an acute neurological disease.

METHODS

We retrospectively reviewed patients from two neurology centres with TGA (with or without HPDL) in whom an acute neurological condition could be identified as trigger. We also performed a systematic review of the literature of this situation using predefined search terms.

RESULTS

We identified 38 patients (median age 62 years, 55.3% female): 6 from our centres and 32 from the literature. Acute neurovascular diseases that preceded or were associated with TGA included ischemic and haemorrhagic strokes, convexity subarachnoid haemorrhage, and reversible cerebral vasoconstriction syndrome. As non-vascular acute neurological diseases, we identified migraine and peripheral-origin vertigo. The clinical manifestation of the neurological trigger showed a variable temporal relation with TGA onset; in some cases preceding and in others co-occurring with TGA manifestation. In some cases, presumed neurological triggers were asymptomatic and diagnosed from the neuroimaging done for the TGA.

CONCLUSIONS

Acute vascular and non-vascular neurological events may trigger TGAs or may occur simultaneously. In the first case, such an acute neurological disease may activate direct pathways within the nervous systems leading to TGA, or alternatively elicit a bodily sympathetic overactivity cascade. In the second case, both neurological events may be the result of a common external stressor.

Prevalence of Mimics and Severe Comorbidity in Patients with Clinically Suspected Transient Global Amnesia

BACKGROUND

Transient global amnesia (TGA) is a syndrome featuring acute anterograde amnesia as the most striking clinical symptom. Its etiology is still a matter of debate. Most neurological guidelines allow the diagnosis on the basis of clinical criteria only; a more extensive evaluation is recommended only for patients with "red flags" like severe headache, nausea or vomiting, or metabolic abnormalities. The aim of our study was to assess the frequency of a severe underlying disease or alternative diagnoses (mimics) in patients fulfilling the clinical criteria.

METHODS

We evaluated the medical records and the imaging data of an unselected consecutive cohort of patients with suspected TGA over a 7-year period. All patients were hospitalized and received a neurological workup including brain imaging, color-coded duplex sonography of the brain supplying arteries, electroencephalography, and laboratory studies of blood and (in selected cases) cerebrospinal fluid.

RESULTS

163 patients with 166 episodes of suspected TGA were hospitalized (3 patients twice). After the workup, the diagnosis of TGA was confirmed in 148/166 (89.2%) episodes ("simple TGA"). Eighteen patients (10.8%) either had an alternative diagnosis or a severe comorbidity that was assumed to have had an impact on the occurrence of the amnestic episode ("complicated TGA/mimic"). The most important differential diagnosis was stroke (11 patients, 6.6% of all TGA suspects and 61.1% of the complicated TGA/mimic group). Other mimics were transient epileptic amnesia (2 patients) and steroid-induced delirium (1 patient). Important comorbidities that had not been obvious at the time of presentation were severe sleep apnea (2 patients), triptan overuse (1 patient), and an involuntary amlodipine intoxication during TGA.

CONCLUSION

As approximately every tenth patient with suspected TGA either had an alternative diagnosis or a severe comorbidity, which had not been obvious at the time of admission, we consider in-patient treatment of all suspected TGA cases as appropriate, preferably in the setting of a stroke unit, as ischemic stroke was the by far most important diagnosis mimicking TGA.

Transient Global Amnesia in a Patient Presenting with Hypertensive Emergency; a Case Report

Transient global amnesia (TGA) is characterized by the abrupt onset of global amnesia, particularly anterograde amnesia. The pathophysiology of TGA is poorly understood and it could be caused by various factors and be associated with various diseases. We report a 58-year-old man who presented to the local emergency room with TGA lasting for several hours. The patient had complete anterograde amnesia without a past medical history of migraine or neurological findings. His systolic blood pressure on presentation was 220 mmHg, which was immediately treated with intravenous calcium ion influx inhibitor. Other than global amnesia, there was no evidence of neurological disturbance. Computed tomography and magnetic resonance imaging results were unremarkable. After treatment of his hypertension, his amnesia resolved within 12 hours. Emergency department physicians may encounter TGA. Correct diagnosis of the condition depends on recognizing the disease.

A global amnesia associated with the specific variant of posterior reversible encephalopathy syndrome (PRES) that developed due to severe preeclampsia and malignant hypertension

A case is reported of a 26-year-old primiparous woman in the 32nd week of gestation who presented to the emergency department with the symptoms of a severe headache, nausea and vomiting. The patient was diagnosed with preeclampsia that later progressed to eclampsia. This state was characterized by a sudden onset of a headache and diplopia that advanced to cortical blindness and precipitated significant alterations in mental status, most notable being global amnesia that resolved within 48 h. A post-partum magnetic resonance imaging of the brain in FLAIR mode revealed multiple cortico-subcortical areas of hyperintense signals suggestive of edematous lesions that chiefly involved occipital and parietal lobes with additional atypical manifestations. Such radiologic findings suggested a posterior reversible encephalopathy syndrome variant with the global amnesia as an extraordinary constituent. This unique feature should be acknowledged when treating a preeclamptic or hypertensive patient that exhibits neurological symptomatology and vision disturbances.