Final answer:
The most dangerous complication of acute mastoiditis is bacterial meningitis, a severe infection that inflames the meninges and can lead to serious neurological effects or death if not treated rapidly with antibiotics.
Step-by-step explanation:
Bacterial meningitis is an inflammation of the meninges with potentially severe neurological consequences. It is particularly dangerous because the meninges protect the central nervous system (CNS), which includes the brain and spinal cord. The bacteria can gain access to the CNS via the bloodstream or from nearby structures like the oropharynx, nasopharynx, sinuses, and especially the middle ear in the case of acute mastoiditis.
Once the bacteria reach the meninges, they can cause profound inflammation. Symptoms of meningitis include severe headache, fever, confusion, stiff neck, and sensitivity to light, which can evolve rapidly into more grave conditions such as shock, convulsions, or coma. If not treated promptly with aggressive antibiotic therapy, such as a combination of ampicillin and gentamicin, meningitis can lead to long-term complications like deafness or cognitive deficits, or can be fatal within hours.