To the Editor.
—We were interested to read of the upgoing thumb sign described by Hachinski,1 that, he stated, had a similar significance to the upgoing toe or Babinski's sign. To validate this test, three observers independently assessed 30 members of staff without a history of neurologic disease (12 male and 18 female subjects; aged 21 to 46 years). We asked each subject to 'hold out their arms, with the palms facing each other.' The position of the thumb was classified according to the Figure in Hachinski's letter as either up, down, or, if between the two positions illustrated, as uncertain. Of the 60 hand positions assessed, the three observers found 53, 48, and 37 of the thumbs to be upgoing and 7,11, and 21 downgoing with only three in total being uncertain. The finding of an upgoing thumb in between 62% and 88% of the hands studied in
Fuller GN, Blunt SB, Silva MT. Babinski Yes, Hachinski No. Arch Neurol. 1993;50(3):239. doi:10.1001/archneur.1993.00540030007002
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