Final answer:
Bilaterally dilated and nonreactive pupils after a severe closed head injury may indicate significant neurological injury or brainstem damage, suggesting high intracranial pressure or a global injury to the central nervous system. It is a critical sign requiring immediate medical attention.
Step-by-step explanation:
When assessing the pupils of a patient with a severe closed head injury, bilaterally dilated and nonreactive pupils may indicate damage to the brainstem or other significant neurological injury. Generally, pupillary response can be affected due to impairment in either the afferent pathways (optic nerve) or the efferent pathways (oculomotor nerve). In the case where both pupils are dilated and nonreactive, it could imply a more global injury to the central nervous system or severe intracranial pressure that is nonlocalizing. This is because light shined in one eye normally not only causes that pupil to constrict (direct reflex) but also causes the opposite pupil to constrict (consensual reflex) due to the bilateral efferent limb of the pupillary light reflex. A lack of response in both eyes could be catastrophic and may require immediate medical attention.
The presented case appears to involve issues with the brain's ability to send and/or receive signals through the optic and oculomotor pathways, which can result from trauma related to a head injury. Assessing pupil responses helps determine which part of the pupillary reflex pathway may be damaged. It's crucial for health care professionals to monitor these signs as they can provide critical information about the severity and location of the brain injury.