There is a normal plantar muscle reflex consisting of contraction of the toe flexors following sudden stretching. This response is barely, if at all, perceptible normally, but becomes more obvious with reflex hyperactivity, when percussion of various portions of the foot may cause plantar flexion of the toes. The best known of this group of reflexes is Rossolimo’s sign, which is elicited by percussion of the ball of the foot. Normally, the only resulting movement is slight jiggling of the toes from the hammer strike. In the presence of corticospinal tract disease, the percussion may cause flexion, primarily of the small toes.
The video shows Rossolimo’s sign in a patient with spastic paraparesis following an episode of transverse myelitis. The movement is small and recognition requires close observation. There were also very brisk extensor plantar responses.
The same toe flexion responses can be elicited by striking slightly different parts of the foot. At least 20 variations have been described. Dr. Robert Wartenberg believed all of these were the same reflex, and Foster Kennedy said these variations described, “…small distinctions without differences, of no true significance and usually of little help.” (3)
1. Campbell WW. DeJong's the neurologic examination, 7th ed. Philadelphia: Wolters Kluwer Health/Lippincott Williams & Wilkins, 2013.
2. Campbell WW. Clinical signs in neurology: a compendium. Philadelphia: Wolters Kluwer Health, 2016.
3. Wartenberg R. The Examination of Reflexes: A Simplification. Chicago: Year Book Medical Publishers, 1945.)