The EEG in the diagnosis of subdural empyema

Abstract

Summary,The EEG findings in 9 pataents with a subdural empyema are reported. In all cases the EEG, recorded before the diagnosis had been established, contained focal zeta waves, extensive unilateral depression of cortical activity and, in all but one, a diffuse slowing of the background activity. This combination has not been reported before in the literature and it is concluded that in its presence the existence of a subdural empyema should be seriously considered. Comparison with CT scan findings in 3 cases indicated that sometimes EEG may be more sensitive than CT scanning in the diagnosis of subdural empyema. The value of EEG and CT scan in the diagnosis of patients presenting with an acute or subacute bacterial meningo-encephalitis is briefly discussed. Keywords: subdural empyema -EEG -zeta waives -CT scan -meningo-encephalitisAlthough as early as 1943 EEG findings in a patient with a subdural empyema were described by Kubik and Adams, to the best of our knowledge no specific study of the EEG in subdural empyema has been performed. In clinical series the EEG findings were described as non-specific and non-valuable for the diagnosis of subdural empyema (Hitchcock and Andreadis 1964;Kaufman et al. 1975;Luken and Whelan 1980;Williams 1982). To determine more precisely the value of the EEG in the diagnosis of subdural empyema the EEG records of 9 patients have been reviewed and correlated with the clinical data and, when available, with results of CT scans. Patients and MethodsThe data for this study are derived from a retrospective survey of 103 patients in whom the diagnosis of subdural empyema had been established in the years 1935-1984, collected from the files of the neurosurgical departments of 5 hospitals in The Netherlands (Mauser 1986 thesis). In 43 of these patients EEGs had been recorded prior to operation. In 9 of them the EEGs were still available for further study. The diagnosis of subdural empyema was confirmed at operation (8 cases) or with CT scan (1 case). In 3 of the 9 patients CT scans, performed before the moment of diagnosis, were also available.The 9 EEG records were interpreted by two of the authors (H.M. and A.H.) without knowledge of the original description. All EEGs had been recorded with montages using the 10-20 system. Special attention was given to technological data (e.g., filter settings and paper speed) and to the presence of Results Clinical dataThe clinical data of the 9 patients are summarized in Table I and are in close agreement with the clinical data of the larger series of 103 patients. The patients were diagnosed in the years [1965][1966][1967][1968][1969][1970][1971][1972][1973][1974][1975][1976][1977][1978][1979][1980][1981][1982][1983][1984]. There was a preponderance of males (7 out of 9) and all patients but one were in their second or third decade. Paranasal sinusitis was the most common cause (7 patients). The symptoms and signs in all patients fitted the clinical picture of an acute or subacute meningo-encephalitis. Seven patients were somnolent at the time o...

Zeta Waves, an Unusual EEG Finding in Structural Brain Lesions: Report of Two Patients

“…The mechanism of generation of these waveforms is not well understood. They have been reported in acute as well as chronic brain conditions (Magnus and Vander Holst 1987, Dunne and Silbert 1991, Mauser et al 1986). The various conditions causing zeta waves, as described in the literature, are summarized in Table 1 Our first patient had zeta waves as a clearly focal disturbance of the EEG, with a well-preserved posterior alpha rhythm.…”

Subdural empyema due to mixed infections successfully treated medically: A case report with review literature

“…The case was diagnosed as SDE depending on the clinical history (fever, disturbed conscious level, meningeal irritation signs, fits, and preceding infection), CSF findings (which showed the proof of mixed infection), and MRI brain findings. Also, there was evidence of EEG changes in the form of slowness activity, which is going with Mauser H.W et al They found multiple EEG changes that may occur with SDE cases, including diffuse slowness 54 . Thus, diagnosis depends only on clinical history, signs, laboratories, EEG, and radiology findings.…”

“…Our case showed a thin rim in CT and no significant midline shift in MRI, so it is considered a mild case. Although surgery is the first line in the treatment of SDE, there is a widely unutilized option to use antibiotics in mild cases 18,54 . So we treated our patient medically with acyclovir (10 mg/kg IV tid) for viral infection; ceftriaxone (2 g IV bid) and vancomycin (750 mg IV bid) for bacterial infection and dexamethasone (4 mg qid).…”

“…Also, there was evidence of EEG changes in the form of slowness activity, which is going with Mauser H.W et al They found multiple EEG changes that may occur with SDE cases, including diffuse slowness. 54 Thus, diagnosis depends only on clinical history, signs, laboratories, EEG, and radiology findings.…”

“…Although surgery is the first line in the treatment of SDE, there is a widely unutilized option to use antibiotics in mild cases. 18,54 So we treated our patient medically with acyclovir (10 mg/kg IV tid) for viral infection; ceftriaxone (2 g IV bid) and vancomycin (750 mg IV bid) for bacterial infection and dexamethasone (4 mg qid). The treatment was effective, and the patient had recovered with no severe side effects or disability.…”