Rigidity in Man Due to Spinal Interneuron Loss

OUR laboratory experiments1have clearly demonstrated that intense hind-limb rigidity in dogs may be caused by spinal interneuron destruction. Such severe hypertonus, unlike decerebrate rigidity, or spasticity, is abolished neither by spinal cord severance above the lesion nor by posterior root division. Penry et al2and Rushworth et al3have provided evidence suggesting that our findings may also explain a certain type of rigidity in man. The patient to be presented, previously briefly reported,4afforded the opportunity of demonstrating unequivocally that spinal interneuronal destruction produces intense rigidity. (The term rigidity is used because the hyperactive reflexes and clonus, as well as the lengthening reaction ["clasp-knife" phenomenon] so characteristic of spasticity, were not present in this case.) It was unaffected by spinal cord transection or by deafferentation of the affected extremities but was abolished by severing the anterior roots. Report of a Case A 31-year-old woman entered the