<P> An upper motor neuron lesion (also known as pyramidal insufficiency) occurs in the neural pathway above the anterior horn cell of the spinal cord or motor nuclei of the cranial nerves . Conversely, a lower motor neuron lesion affects nerve fibers traveling from the anterior horn of the spinal cord or the cranial motor nuclei to the relevant muscle (s). </P> <P> Upper motor neuron lesions occur in the brain or the spinal cord as the result of stroke, multiple sclerosis, traumatic brain injury and cerebral palsy . </P> <P> Changes in muscle performance can be broadly described as the upper motor neuron syndrome . These changes vary depending on the site and the extent of the lesion, and may include: </P> <Ul> <Li> Muscle weakness . A pattern of weakness in the extensors (upper limbs) or flexors (lower limbs), is known as' pyramidal weakness' </Li> <Li> Decreased control of active movement, particularly slowness </Li> <Li> Spasticity, a velocity - dependent change in muscle tone </Li> <Li> Clasp - knife response where initial higher resistance to movement is followed by a lesser resistance </Li> <Li> Babinski sign is present, where the big toe is raised (extended) rather than curled downwards (flexed) upon appropriate stimulation of the sole of the foot . The presence of the Babinski sign is an abnormal response in adulthood . Normally, during the plantar reflex, it causes plantar flexion and the adduction of the toes . In Babinski's sign, there is dorsiflexion of the big toe and abduction of the other toes . Physiologically, it is normally present in infants from birth to 12 months . The presence of the Babinski sign after 12 months is the sign of a non-specific upper motor neuron lesion . </Li> <Li> Increased deep tendon reflex (DTR) </Li> <Li> Pronator drift </Li> </Ul>

Which of the following is a manifestation of an upper motor neuron lesion