The main idea is that how long symptoms last and how severe the initial injury was help tell the difference between post-concussive syndrome and lasting cognitive problems from brain injury. Post-concussive syndrome typically follows a mild TBI (a concussion) and includes headaches, dizziness, and cognitive complaints that hover for weeks to months after the injury, often without clear structural brain damage on imaging. When cognitive impairment persists after a moderate to severe TBI, it’s more likely due to ongoing structural injury to the brain and tends to have a longer, more protracted recovery—sometimes with imaging showing abnormalities. The other statements aren’t accurate because PCS is not identical to persistent impairment, imaging can be normal in PCS, and persistent impairment is not restricted to children.

Severe mass effect and brain swelling on CT predict poorer outcomes in pediatric TBI. When a CT shows a large intracranial hemorrhage with compressed basal cisterns, midline shift, and diffuse edema, it reveals substantial brain injury with high intracranial pressure and limited compensatory space. The large bleed increases intracranial volume and risk of herniation; compressed basal cisterns reflect raised pressure with little room for the brain to expand; midline shift demonstrates significant asymmetrical swelling and mass effect; and diffuse edema indicates widespread cerebral swelling and impaired perfusion. Together, these signs correlate with higher mortality and worse functional recovery, making this the strongest CT predictor of poor outcome. In contrast, no edema or an isolated skull fracture generally suggests a milder injury, while subcutaneous air by itself isn’t a reliable predictor of prognosis.

Secondary brain injury is the damage that develops after the initial trauma, driven by ongoing biological and physiologic processes such as swelling, reduced blood flow, hypoxia, and inflammation. Because it unfolds after the initial injury, it can compound the original damage and worsen outcomes. The initial injury is the mechanical damage that happens at the moment of impact, so describing secondary injury as occurring after that event is the correct framing. The other ideas—occurring during the initial injury (that would describe the primary injury), being the same as the primary injury, or being unrelated to the initial injury—don’t fit the concept of secondary injury.

Autonomic dysfunction after traumatic brain injury is a disturbance of autonomic control that leads to unstable cardiovascular function. The most characteristic feature is labile heart rate and blood pressure, often with episodes of tachycardia and hypertension that can occur along with sweating, fever, and agitation during autonomic storms. This description fits best because it centers on the autonomic system’s regulation being disrupted by brain injury, rather than pointing to unrelated symptoms like chest pain without neurologic signs, morning seizures, or isolated facial weakness. Management aims to stabilize the autonomic responses and reduce triggers. Nonpharmacologic approaches include close vital-sign monitoring, maintaining normovolemia and electrolyte balance, ensuring adequate analgesia and sedation to minimize agitation, and environmental measures to prevent overheating or overstimulation. Pharmacologic strategies commonly involve blunting sympathetic outflow with alpha-2 agonists such as clonidine or dexmedetomidine, using beta-blockers to control tachycardia and hypertension, and employing benzodiazepines for sedation and anxiety. In some cases, medications or infusions to reduce spasticity or additional supportive ICU care are used. The overall goal is to protect cerebral perfusion and support recovery by smoothing these autonomic fluctuations.