Clonus is due to?: (A) Upper motor neuron damage, (B) Lower motor neuron damage, (C) Extrapyramidal damage, (D) Cerebellar damage
Answer is A. Ans. A Upper motor neuron damageRef: Ganong, 25th ed. pg. 233Clonus is characterized by repeated rhythmic contractions of muscle subjected to sudden maintained stretch.It is Caused by* Increased Gamma motor neuron discharge* Spinal cord injury causing damage to Renshaw cell which is an inhibitory inter-neuron.Conditions in Which Clonus is seen:1. Amyotrophic lateral sclerosis2. Stroke3. Multiple sclerosis4. Spinal cord damage5. Hepatic encephalopathyClonazepam and botulinum toxin is useful in management of clonus.