Retrograde venous flows in the internal jugular veins during strain are associated with transient global amnesia (TGA), Sander et al report in the 9 December Lancet (Lancet 2000 356:1983-1984). The retrograde flow leads to venous ischaemia and metabolic alterations to bilateral diencephalic or hipocampal structures.

Dr Sander and colleagues from the University of Munich examined the blood flow of internal jugular veins in 21 patients with TGA and 21 matched controls. Using duplex ultrasonography they demonstrated that strain that increase the intrathoracic pressure (the Valsalva manoeuvre) generates a retrograde flow component significantly more often in the TGA group than in controls.

TGA is a very distinctive attack that begins abruptly with inability to form new memories. Patients are confused and keep asking the same questions. The prognosis is good, but it is a frightening experience for both the patients and their relatives.

The findings support the hypothesis that...

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