Which signs are typical of upper motor neuron lesions?

• A. Hyporeflexia and atrophy
• B. Fasciculations and cramps
• C. Hyperreflexia and spasticity
• D. Normal tone

Answer: (C)

Disruption of the corticospinal pathways leaves the spinal reflex arcs more excitable, because the brain can no longer dampen them. This leads to two hallmark features: increased muscle tone (spasticity) and exaggerated reflex responses (hyperreflexia). You may also see features like abnormal reflexes (Babinski) and clonus. In contrast, signs like muscle wasting with fasciculations or cramping, and reduced or absent reflexes with low tone, point to lower motor neuron involvement. Normal tone isn’t typical for an upper motor neuron lesion.