A 9-month-old with Tay-Sachs disease is admitted due to seizures. Which assessment is most important for the nurse to obtain?

Choice A reason: Positioning the infant on the stomach occasionally when awake and active is the best response that the nurse can give to the mother. This is because it can help prevent and correct the flat head syndrome, also known as plagiocephaly, by taking pressure off the back of the head and allowing the skull to reshape naturally. It can also promote the infant's motor development and strengthen the neck and shoulder muscles. However, the nurse should also remind the mother to always place the infant on the back when sleeping, as this is the safest position to reduce the risk of sudden infant death syndrome (SIDS) .

Choice B reason: Turning the infant on the left side braced against the crib when sleeping is not a good response that the nurse can give to the mother. This is because it can increase the risk of SIDS, as the infant may roll over to the stomach or suffocate from the bedding or the crib. It can also worsen the flat head syndrome by creating another flat spot on the left side of the head.

Choice C reason: Placing a small pillow under the infant's head while lying on the back is not a good response that the nurse can give to the mother. This is because it can increase the risk of SIDS, as the pillow may cover the infant's face or cause the infant to overheat. It can also interfere with the natural reshaping of the skull and cause neck strain.

Choice D reason: Propping the infant in a sitting position with a cushion when not sleeping is not a good response that the nurse can give to the mother. This is because it can put too much pressure on the spine and the pelvis, which are still developing in the infant. It can also limit the infant's movement and exploration, which are important for learning and development.

Choice A reason: The ability to crawl is not the most important assessment for the nurse to obtain. Tay-Sachs disease causes progressive loss of motor skills, so the infant may not be able to crawl or may have regressed from crawling. However, this is not a specific sign of the disease and does not indicate the severity of the condition.

Choice B reason: The eyes with cherry-red spot are not the most important assessment for the nurse to obtain. Tay-Sachs disease causes accumulation of gangliosides in the retina, which results in a cherry-red spot in the center of the macula. However, this is not a specific sign of the disease and does not indicate the severity of the condition.

Choice C reason: The difficulty with swallowing is not the most important assessment for the nurse to obtain. Tay-Sachs disease causes muscle weakness and spasticity, which may affect the infant's ability to swallow. However, this is not a specific sign of the disease and does not indicate the severity of the condition.

Choice D reason: The exaggerated startle reaction is the most important assessment for the nurse to obtain. Tay-Sachs disease causes increased sensitivity to sound and touch, which results in an exaggerated startle reaction. This is a specific sign of the disease and indicates the severity of the condition. The exaggerated startle reaction may also trigger seizures, which can be life-threatening. The nurse should monitor the infant's vital signs, seizure activity, and neurological status closely.