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March 1993

The Upgoing Thumb: A Sign in Search of a Name-Reply

Author Affiliations

Department of Clinical Neurological Sciences University Hospital London, Ontario Canada N6A 5A5

Arch Neurol. 1993;50(3):239-240. doi:10.1001/archneur.1993.00540030007005

In Reply.  —On reading an account of 80% of subjects displaying upgoing thumbs, as stated by Fuller et al, I wondered whether the authors made their observations in front of Charing Cross (the railway station) or in Charing Cross (the hospital). However, when Mahler reported upgoing thumbs in 10 of his 12 subjects, I realized that the fault was mine, for I was too brief.1 The upgoing thumb sign varies in degree from a slightly greater extension at the proximal interphalangeal joint of the thumb to the pattern displayed in the original illustration.1 Moreover, we have found that showing the subjects the outstretched hands with the thumbs touching the hand proved quicker and more reliable than verbal instructions. Asymmetry of thumb position is a key feature, although the thumb sign can occur bilaterally in association with other corticospinal signs.We conducted two studies. (1) We examined 31 neurologic

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