Which statement about deep tendon reflexes can occur with brain lesions?

Which statement about deep tendon reflexes can occur with brain lesions?

• A. Reflexes always become hyperactive
• B. Deep tendon reflexes become normal
• C. Deep tendon reflexes may become hypoactive
• D. Gag reflex becomes exaggerated

Answer: (C)

Deep tendon reflexes are shaped by the spinal reflex arc and by input from higher brain centers that normally modulate that arc. When a brain lesion occurs, the common impact is loss of inhibitory control from above, which tends to cause hyperreflexia and, over time, increased tone. But that isn’t universal. In the acute phase of brain injury or in certain patterns of brain damage, overall brain function can be severely depressed or the circuitry needed for the reflex can be disrupted, leading to diminished or absent reflex responses. So deep tendon reflexes can indeed become hypoactive with brain lesions, especially early on or with particular lesion patterns. The gag reflex, on the other hand, is mediated mainly by brainstem circuits (cranial nerves IX and X), and its exaggeration is not a typical consequence of cerebral lesions, which is why that option isn’t the best fit.

Deep tendon reflexes are shaped by the spinal reflex arc and by input from higher brain centers that normally modulate that arc. When a brain lesion occurs, the common impact is loss of inhibitory control from above, which tends to cause hyperreflexia and, over time, increased tone. But that isn’t universal. In the acute phase of brain injury or in certain patterns of brain damage, overall brain function can be severely depressed or the circuitry needed for the reflex can be disrupted, leading to diminished or absent reflex responses. So deep tendon reflexes can indeed become hypoactive with brain lesions, especially early on or with particular lesion patterns.

The gag reflex, on the other hand, is mediated mainly by brainstem circuits (cranial nerves IX and X), and its exaggeration is not a typical consequence of cerebral lesions, which is why that option isn’t the best fit.