A 78-year-old man with traumatic brain injury develops hyperreflexia and an extensor plantar reflex. What is the most likely cause?

In the context of a 78-year-old man who develops hyperreflexia and an extensor plantar reflex following a traumatic brain injury, the presence of hyperreflexia and an extensor plantar response (indicative of upper motor neuron involvement) suggests damage to the central nervous system pathways that modulate reflexes.

A subdural hematoma arises from the rupture of bridging veins, often seen in elderly individuals who have experienced trauma, especially those with atrophic brains. This condition can lead to increased intracranial pressure and subsequent neurological deficits. The mechanism involves the accumulation of blood between the dura mater and the arachnoid membrane, which can cause compression of the underlying brain tissue.

As the subdural hematoma develops, it can disrupt the normal inhibitory controls on spinal reflexes, leading to an increase in reflex excitability, which is observed as hyperreflexia. The extensor plantar reflex (Babinski's sign) presents when there is upper motor neuron dysfunction, further supporting the idea that the injury has affected the neural pathways originating from the brain.

This scenario is fitting given that the patient's age and mechanism of injury (trauma) correlate with the typical presentation of subdural hematoma, which is more common than other types