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J Neurol Neurosurg Psychiatry doi:10.1136/jnnp-2012-304542
  • Neurological picture

Transient global amnesia associated with bilateral restricted diffusion in the lateral hippocampus

  1. Peter Malcolm Rothwell
  1. Stroke Prevention Research Unit, Department of Clinical Neurosciences, University of Oxford, John Radcliffe Hospital, Oxford, UK
  1. Correspondence to Dr Alastair John Webb, Stroke Prevention Research Unit, Department of Clinical Neurosciences, University of Oxford, John Radcliffe Hospital, Headington, Oxford OX3 9DU, UK; alastair.webb{at}ndcn.ox.ac.uk
  • Received 7 November 2012
  • Revised 7 December 2012
  • Accepted 27 December 2012
  • Published Online First 5 February 2013

A 48-year-old man with no significant cardiovascular risk factors developed 3 h of severe anterograde and mild retrograde amnesia, repeatedly asking ‘Is this my coat?’ on emerging shivering from the (cold) English Channel. No other focal neurological symptoms were seen and by the time he reached the emergency department, he had fully recovered, had a normal neurological examination and did not recall the event. He had a past history of gout and reported symptoms consistent with mild Raynaud's syndrome, but had no other significant medical history. Diffusion-weighted brain imaging performed 48 h later showed symmetrical, punctate, restricted diffusion in both hippocampi, without abnormalities on any other sequences (figure 1).

Figure 1

Symmetrical, bilateral, punctate areas of restricted diffusion in the lateral hippocampi, seen on one slice of a 3T MRI scan, 48 h after a 3 h episode of transient global amnesia.

Areas of restricted diffusion after transient neurological episodes are most often related to transient ischaemic attacks. However, such lesions can be seen in the hippocampi of patients with transient global amnesia, most commonly in the left hippocampus but bilaterally in rare instances.1 These lesions are more common after a short interval has elapsed, unlike ischaemic events, and are most often seen at about 48 h after the event, although the diagnosis of transient global amnesia remains a clinical one. The onset of transient global amnesia has been associated with activities that involve a Valsalva manoeuvre or exposure to cold water, which increase venous blood pressure. The striking symmetry of the lesions found in this patient is consistent with a haemodynamic aetiology, resulting in transiently increased venous pressure,2 ,3 as one might reasonably expect during a swim in the English Channel.

Footnotes

  • Contributors AJSW was responsible for the clinical consultation and preparation of the manuscript and figures. PMR supervised the clinical management and was responsible for preparation of the manuscript.

  • Competing interests ASJW is in receipt of an Medical Research Council clinical research training fellowship. PMR is in receipt of a National Institute for Health Research senior investigator award.

  • Patient consent Obtained.

  • Provenance and peer review Not commissioned; externally peer reviewed.

References

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