Motor Deficits after Transsection of a Bulbar Pyramid in the Cat

The aim of the study was to determine whether the extended position of freely hanging limbs contralateral to transsection of one pyramid in cat is due to extensor hypertonia or deficient flexor reflexes and to determine the duration of motor defects produced by unilateral pyramidotomy. The posture was due to absence of activity in contralateral flexors; action potentials in extensors were absent both on the operated and unoperated side. Placing reactions were delayed or absent in contralateral limbs, struggling was diminished and there was a tendency for the paws to remain in awkward positions. After one month operated cats could be distinguished from unoperated cats only by diminished flexor reflexes in contralateral legs and by a slight delay in contact placing. Damage of the medial lemniscus produced the tendency to place contralateral paws in awkward positions lasting for one week. Unlike pyramidal section, lemniscal damage did not produce deficient flexor reflexes.