[Pathogenesis and methods of treatment of otogenic brain abscess]

Otitis media, acute or chronic, is a potentially dangerous disease which may lead to fatal complications. Meningitis is the most common intracranial complication, followed by otogenic brain abscesses while lateral sinus thrombosis is fairly uncommon. Mortality from otogenic brain abscesses remains relatively high. The aim of the study was to investigate mechanisms of development, diagnostic methods and treatment of these complications of otogenic brain abscesses.

The retrospective study covered 42 patients with otogenic brain abscess (28 cerebral and 14 cerebellar) treated from 1973 to 1995 at the ENT and Neurosurgical Hospital in Belgrade. Medical records of the studied patients were analyzed for the occurrence of the disease, diagnosis and mode of therapy. Special care was dedicated to type of otitis, surgical findings, diagnostic methods, mode of therapy and therapy outcome.

In the period of 23 (1973-1995) 114 patients with otogenic intracranial complications were treated at the Clinic of Otorhinolaryngology and Maxillofacial Surgery. Meningitis was the most common complication in this series, followed by cerebral abscess, lateral sinus thrombosis, cerebellar abscess, while extradural abscesses were rare, and subdural occurred only exceptionally (Table 1). In somewhat more than half of the patients (55%) one intracranial complication was present, While in 54% two or more intracranial complications were recorded (Table 2). Otogenic brain abscesses are usually associated with meningitis. Meningitis was present in 20 patients with cerebral abscess (71%), and in 5 (33%) patients with cerebellar abscess. Meningitis and lateral sinus thrombosis were more commonly associated with cerebellar abscess (41%), and less with cerebral abscess (10%). In our group of patients otogenic brain abscesses were most common in the third decade of life, than in the second, while the frequency of the complication fell significantly in older age groups (Figure 1). Headache (92%). fever (91%), vomiting (68%) were the most common symptoms, while photophobia and vertigo were less common (38% and 30%, respectively). Active chronic otitis with cholesteatoma was most commonly present in patients with otogenic brain abscess, only somewhat more common in patients with cerebral abscess (84%), than in those with cerebellar abscess (80%). Neurological examination of 28 patients with cerebral abscess evidenced the abscess in 11, while in 15 the examination suggested meningitis. (Table 3). The diagnosis of abscess was most commonly established by computerized tomography. It revealed cerebral abscess in 18 out of 28 patients, and cerebellar abscess in 10 out of 12 patients. (Table 3). Radical trepanation of the temporal bone was performed in all our patients, while in nine patients revision was required after the surgery, since the initial operation was not sufficiently radical. (Table 4). Out of 28 patients with cerebral abscess 5 (18%) died while 3 (29%) patients died out of 14 patients with cerebellar abscess (Table 4).

Otogenic brain abscesses imply accumulation of pus in the cerebrum or cerebellum developing after encephalitis, caused by pyogenic microorganisms originating from inflammatory process in the middle ear cavity. This is a severe otogenic complication with high mortality. Even with modern therapeutic alternatives, mortality remained high, about 40% (7). According to the data reported by several authors introduction of antibiotic therapy resulted in drastic fall of associated mortality. The annual risk of otogenic abscess of the brain is 1 per 1000 adults with active chronic otitis. The incidence of abscess is significantly higher in a certain age groups, i.e. 1 per 200 between the ages of 20 and 40 (3). The diagnosis of brain abscess established clinically is not quite reliable. The disease is usually associated with severe meningitis, so that neurological examination usually detects only signs of meningi