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Familial Transient Global Amnesia

      To the Editor:
      We acclaim the excellent, comprehensive review of transient global amnesia (TGA) by Arena and Rabinstein
      • Arena J.E.
      • Rabinstein A.A.
      Transient global amnesia.
      in the February 2015 issue of Mayo Clinic Proceedings. Considering the unknown pathophysiology of TGA, we note the authors make minimal mention of the possible contribution of genetics (on page 267). We request that the authors comment further on this possibility.
      We report herein our experience with 2 sisters who presented with classic episodes of TGA. The first sister was a 57-year-old woman who suddenly became amnesic after having intercourse with her husband. Her husband noticed that she could not remember their sexual act right after they finished, and she kept repeating the same questions several times over. Approximately 1 year later, her 71-year-old sister presented. That morning, she said she had a mild headache and was “not feeling well.” On the drive home from church, she kept asking the same questions repeatedly and could not recall having been at church just a few minutes before.
      Neither sister had other neurologic or systemic symptoms. Their presentation examination results were normal except for poor short-term memory. Other than having impaired memory for the events associated with their presentations, they were back to normal the following day. The first sister had experienced a transient ischemic attack 7 years before. Neither had a history of stroke, head trauma, seizures, migraines, or episodes of memory loss.
      The second sister’s work-up included brain magnetic resonance imaging, which revealed an isolated punctate region of hyperintense signal on diffusion-weighted imaging in the left hippocampus but no signal changes on the T2-weighted or fluid-attenuated inversion recovery sequences. The magnetic resonance imaging study was not repeated.
      We are not the only clinicians who have encountered familial cases of TGA. Among the most prominent published series is that of Corston and Godwin-Austen,
      • Corston R.N.
      • Godwin-Austen R.B.
      Transient global amnesia in four brothers.
      who described 4 brothers who each had had multiple attacks. Segers-van Rijn and de Bruijn
      • Segers-van Rijn J.
      • de Bruijn S.F.T.M.
      Transient global amnesia: a genetic disorder [letter]?.
      described a family in which 4 of 8 siblings had TGA experiences, one of whom had 2 episodes. Dupuis et al
      • Dupuis M.J.M.
      • Pierre P.
      • Gonsette R.E.
      Transient global amnesia and migraine in twin sisters [letter].
      described twin sisters who experienced multiple episodes of TGA associated with migraines. Finally, Munro and Loizou
      • Munro J.M.
      • Loizou L.A.
      Transient global amnesia—familial incidence.
      decribed a family of 2 siblings and their father who had experienced TGA episodes, 2 of whom had multiple episodes.
      We acknowledge that these rare familial clusters of TGA cases may just be coincidental. Yet in the absence of a confirmed etiology for TGA, they do provide evidence that TGA may have a genetic component. We suggest that clinicians obtain careful family histories of their patients with TGA and consider publishing reports of any who may have a positive family history. Whether they lead to predisposing factors, a diagnostic marker, or the etiology, such reports will advance the understanding of TGA.

      References

        • Arena J.E.
        • Rabinstein A.A.
        Transient global amnesia.
        Mayo Clin Proc. 2015; 90: 264-272
        • Corston R.N.
        • Godwin-Austen R.B.
        Transient global amnesia in four brothers.
        J Neurol Neurosurg Psychiatry. 1982; 45: 375-377
        • Segers-van Rijn J.
        • de Bruijn S.F.T.M.
        Transient global amnesia: a genetic disorder [letter]?.
        Eur Neurol. 2010; 63: 186-187
        • Dupuis M.J.M.
        • Pierre P.
        • Gonsette R.E.
        Transient global amnesia and migraine in twin sisters [letter].
        J Neurol Neurosurg Psychiatry. 1987; 50: 816-817
        • Munro J.M.
        • Loizou L.A.
        Transient global amnesia—familial incidence.
        J Neurol Neurosurg Psychiatry. 1982; 45 ([letter]): 1070

      Linked Article

      • Transient Global Amnesia
        Mayo Clinic ProceedingsVol. 90Issue 2
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          Transient global amnesia (TGA) is a clinical syndrome characterized by the sudden onset of anterograde amnesia (the inability to encode new memories), accompanied by repetitive questioning, sometimes with a retrograde component, lasting up to 24 hours, without compromise of other neurologic functions. Herein, we review current knowledge on the epidemiology, pathophysiology, clinical diagnosis, and prognosis of TGA. For this review, we conducted a literature search of PubMed, with no date limitations, using the following search terms (or combinations of them): transient global amnesia, etiology, pathophysiology, venous hypertension, migraine, magnetic resonance imaging, computed tomography, electroencephalography, prognosis, and outcome.
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      • In reply—Familial Transient Global Amnesia
        Mayo Clinic ProceedingsVol. 90Issue 5
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          We thank Dr Dandapat and colleagues for their complimentary comments on our review and for sharing their clinical experience with us. As they correctly point out, there have been a few reports of familial clusters of transient global amnesia (TGA) cases.1-6 Given the relative infrequency of TGA, it is reasonable to consider that these familial clusters may not be just coincidental. Details provided on these familial cases have been sometimes incomplete, but we found that migraine was a comorbidity in at least one of the family members with TGA in 4 of the 6 familial cases reported in the literature.
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