What condition is indicated by symptoms such as headache, nuchal rigidity, confusion, and drowsiness?

The symptoms of headache, nuchal rigidity, confusion, and drowsiness are highly indicative of meningitis. This condition is characterized by the inflammation of the protective membranes covering the brain and spinal cord and can lead to severe neurological symptoms.

Headaches are a common symptom due to increased intracranial pressure and inflammation. Nuchal rigidity, or stiffness of the neck, is particularly characteristic of meningitis because it is often associated with irritation of the meninges. Confusion and drowsiness can arise from the infection's impact on brain function and the overall systemic effects on the body, leading to decreased alertness.

While subdural hematoma and subarachnoid hemorrhage can also present with headache and altered mental status, they do not typically cause nuchal rigidity. Encephalitis can exhibit similar symptoms but usually includes additional features such as seizures or significant alterations in consciousness and is primarily due to direct inflammation of the brain itself rather than the meninges.

Therefore, the combination of these symptoms strongly points toward meningitis as the most likely diagnosis.