Which reflex may appear in adults with upper motor neuron lesions?

Which reflex may appear in adults with upper motor neuron lesions?

• A. Babinski reflex
• B. Hoffmann sign
• C. Moro reflex
• D. Gallant reflex

Answer: (A)

The main idea here is that upper motor neuron (UMN) lesions disrupt the corticospinal pathways, leading to abnormal reflexes in adults. The Babinski sign is the classic indicator: when the sole is stimulated, instead of curling downward, the big toe dorsiflexes and the other toes fan out. This upgoing big toe reflex results from loss of inhibition of spinal reflexes by the intact cortex, signaling a corticospinal tract lesion above the level of the brainstem. Moro and Gallant are primitive infant reflexes that normally disappear within the first few months of life; their presence in adults is not a typical marker of a focal UMN lesion. Hoffmann sign is also an upper motor neuron sign, but the Babinski response is the most characteristic and widely recognized example in adults.

The main idea here is that upper motor neuron (UMN) lesions disrupt the corticospinal pathways, leading to abnormal reflexes in adults. The Babinski sign is the classic indicator: when the sole is stimulated, instead of curling downward, the big toe dorsiflexes and the other toes fan out. This upgoing big toe reflex results from loss of inhibition of spinal reflexes by the intact cortex, signaling a corticospinal tract lesion above the level of the brainstem.

Moro and Gallant are primitive infant reflexes that normally disappear within the first few months of life; their presence in adults is not a typical marker of a focal UMN lesion. Hoffmann sign is also an upper motor neuron sign, but the Babinski response is the most characteristic and widely recognized example in adults.