T h e n e w e ng l a n d j o u r na l o f m e dic i n e

images in clinical medicine
Lindsey R. Baden, M.D., Editor

Upper Limb Clonus

Damien Biotti, M.D.
Alain Vighetto, M.D.
Hôpital Neurologique Pierre Wertheimer
Lyon, France
damien.biotti@chu-lyon.fr

A

48-year-old man was seen because of abnormal movements of
the left arm. Four months earlier, he had been admitted because of left hemi­
plegia caused by a hemorrhage in the right internal capsule and thalamus.
Since that time, only spasticity in the left arm and hand persisted, but occasional
intrusions of an unintentional tremor were reported. The physical examination
showed brisk reflexes, spasticity, and a marked clonus provoked by the sudden hyper­
extension of the wrist (video). Clonus, which is usually encountered in the knee or
ankle, is a classic symptom of spasticity occurring as a result of lesions in upper
motor neurons. Wrist clonus, as was seen in this patient, is much less common and
can be confusing and misdiagnosed. Wrist clonus in patients with hemiplegia was
notably described in lectures published in 1883 by the French neurologist Jean-Martin
Charcot, who called the phenomenon “provoked trepidation” and wrote, “These pa­
tients, on raising the paralysed arm, often experience a trembling similar to that
which occurs in the lower limb under like circumstances. But the wrist-phenomenon,
provoked or spontaneous, is much more uncommon.” In our patient, the spasticity
improved and clonus disappeared a few weeks after the initiation of baclofen.

DOI: 10.1056/NEJMicm1206994
Copyright © 2013 Massachusetts Medical Society.

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n engl j med 369;10

nejm.org

september 5, 2013

The New England Journal of Medicine
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Copyright © 2013 Massachusetts Medical Society. All rights reserved.