A COMPARISON OF EFFECTS OF UPPER AND LOWER MOTOR NEURONE LESIONS ON SKELETAL MUSCLE

Abstract

Using albino rats, the atrophy of the gastrocnemius-soleus group of muscles following an upper motor neurone lesion (produced by spinal cord section at the 6th thoracic segment) was compared with the atrophy following a lower motor neurone lesion (section of the sciatic nerve). The 2 types of lesions produced atrophic processes which were quantitatively similar for the first 14 days. Thereafter the muscle groups with severed upper motor neurones started to recover lost wt. while those with lower motor neurones cut showed an uninterrupted development of atrophy. Both types of injury produced hypersensitivity to acetylcholine in the muscles involved. This lasted only as long as the atrophic process was active and was most marked in the cases of section of the lower motor neurone. Fibrillation was seen only when the lower motor neurone was cut.