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Updated: Apr 19, 2026

Behavioral Characterization of Pentylenetetrazole-induced Seizures: Moving Beyond the Racine Scale
Published on: July 8, 2025
Jaw clonus frequency does not support hypothesis of peripheral mechanism of self-re-excitation
Joseph H Friedman1,2, Michelle Mellion3
1a Director, Movement Disorders Program, Butler Hospital , Providence , RI , USA.
Abstract:
Jaw clonus is an uncommon pathological reflex thought to indicate corticospinal tract dysfunction above the Vth cranial nerve. It is useful as a sign of upper motor neuron dysfunction above the spinal cord. One theory of self excitation posits an inverse and linear relationship between clonus frequency and the length of the reflex arc, to explain the higher frequency of clonus in the ankles than the wrist. Only two previous cases of jaw clonus have been published. One of these plus the present case suggest that an inverse and linear relationship is not correct.
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