Since the adhesions existing in the subdural space are absent at birth and develop with aging, bilateral SDHs are more common in infants. Interhemispheric SDHs often are associated with child abuse. Patients generally lose consciousness, but this is not an absolute. Chronic SDH is more difficult to anticipate, and about half of such cases offer no history of head trauma. Hemophiliacs can develop SDH with a seemingly trivial head trauma.
Alcoholics are prone to thrombocytopenia, prolonged bleeding times, and blunt head trauma.
Maintain a high level of suspicion in this population. Promptly obtain a CT scan of the head when the degree of trauma is severe, focal neurologic signs are noted, or intoxication does not resolve as anticipated. In alcoholics, more than any other cohort, acute or chronic SDHs can be due to the deadly combination of repetitive trauma and alcohol-associated coagulopathies. Patients on anticoagulants can develop SDH with minimal trauma and warrant a lowered threshold for obtaining a head CT scan. Signs of external trauma alert the physician to the expected location of coup or contrecoup injuries on CT scan.