Intracranial subdural empyema and its management. A review of the literature with comment

Parafalcine subdural empyema: The unresolved controversy over the need for surgical treatment

Background:

Parafalcine subdural empyema (SDE) is a rare entity consisting of pus accumulating below the longitudinal sinus, between the falx cerebri and the arachnoid layer covering the medial surface of the cerebral hemisphere. Its treatment strategy is controversial, but most clinicians have the general belief that appropriate treatment consists of prompt surgery combined with long-term antibiotic therapy. Nevertheless, six reports published in the 1980s provided evidence that antibiotic therapy alone is a safe and suitable option. The treatment strategies and outcomes of the 31 well-described cases previously published, in addition to our own, are discussed.

Case Description:

We report a 21-year-old female with a right-side parafalcine SDE who presented with fever, headache, generalized tonic-clonic seizures, and contralateral hemiparesis 3 weeks after undergoing sinonasal surgery. Despite clinical symptoms almost entirely abating after starting treatment with broad-spectrum antibiotics, magnetic resonance imaging performed during the 2^nd and 3^rd weeks showed progressive enlargement of the interhemispheric collection (from 4 cm³ to 30 cm³). We reflect on the treatment strategy chosen for this patient, who experienced a total recovery.

Conclusion:

A nonsurgical strategy for parafalcine SDE might be contemplated for patients with a good clinical condition and no major midline shift on neuroradiological studies, given their usual indolent course and the relative difficulty in reaching the interhemispheric fissure. Conversely, surgery should be contemplated when the collection significantly enlarges despite antibiotic therapy. When surgical drainage is added to antibiotics, broad- range 16S ribosomal DNA polymerase chain reaction of the empyema is recommended to identify the causative organism as pus cultures are usually sterile.

Two surgical methods used in 90 patients with intracranial subdural empyema

We studied the efficacy of two surgical methods used for the treatment of intracranial subdural empyema (ISDE) at our centre. A cross-sectional study (1999-2005) of 90 patients with non-traumatic supratentorial ISDE revealed that the two surgical methods used for empyema removal were burr hole/s and drainage (50 patients, 55.6%) and a cranial bone opening procedure (CBOP) (40 patients, 44.4%). Patients in the CBOP group had a better result in terms of clinical improvement (chi-squared analysis, p=0.006) and clearance of empyema on brain CT scan (chi-squared analysis, p<0.001). Reoperation was more frequent among patients who had undergone burr hole surgery (multiple logistic regression, p<0.001). The outcome and morbidity of ISDE survivors were not related to the surgical method used (p>0.05). The only factor that significantly affected the morbidity of ISDE was level of consciousness at the time of surgery (multiple logistic regression, p<0.001). We conclude that CBOP and evacuation of the empyema is a better surgical method for ISDE than burr hole/s and drainage. Wide cranial opening and empyema evacuation improves neurological status, gives better clearance of the empyema and reduces the need for reoperation. Level of consciousness at the time of presentation is a predictor of the morbidity of ISDE. Thus, aggressive surgical treatment should occur as early as possible, before the patient deteriorates.