Manifestations of upper and lower motor neuron dysfunction - McMaster Textbook of Internal Medicine

Table 1.29-1. Manifestations of upper and lower motor neuron dysfunction
Manifestation	Upper motor neuron	Lower motor neuron
Weakness	Often hemiparetic pattern	Often proximal in muscular weakness and distal in peripheral nerve weakness
Tendon reflexes	Hyperreflexia	Reduced or absent
Clonus (eg, foot clonus)	Present	Absent
Pathologic signs	Present (Babinski sign)a	Absent
Muscle atrophy	Absent; secondary atrophy possible due to lack of use of weak muscles	Develops relatively rapidly
Muscle tone	Increased (spastic)	Normal or reduced (flaccid)
Abdominal skin reflexes	Absent	Present
Pathologic movements (eg, chorea)	Present	Absent
Fasciculations	Absent	Occasionally present
a Babinski sign: dorsiflexion (extension) of the big toe on scratching the sole of the foot (with a blunt object moved along the outer aspect of the foot from the heel towards the front and the big toe).