We reviewed 22 epidermoid and 10 dermoid tumours of the skull and brain from patients operated on consecutively at Henry Ford Hospital between 1975 and 1991. There were 19 intradural (16 epidermoid, 3 dermoid) and 13 extradural (6 epidermoid, 7 dermoid) lesions. The average age at presentation was 35 years for patients with epidermoids and 15 years for those with dermoids. Common clinical presentations for patients with intradural lesions included headache, visual deficits, and seizures, whereas patients with extradural lesions harbored asymptomatic scalp masses. All patients with intradural lesions were investigated with computed tomography (CT) and cerebral angiography, and 8 patients underwent magnetic resonance imaging (MRI). Total resection was possible in 12 (92%) of 13 extradural tumours, all with excellent outcomes. Eight (42%) of the intradural tumours were completely resected. Overall, with the intradural tumours we had good to excellent results in 17 patients (90%), poor results in 1 (5%), and 1 death (5%). Re-operation was needed in 5 intradural recurrences (26%) with deterioration in only one patient's neurologic status postoperatively. From a review of ours and others' data, we conclude that 1) these tumours have an insidious onset despite significant size and mass effect as demonstrated by imaging studies; 2) CT, angiography, and particularly MRI help to define the extent of subarachnoid tumour spread and involvement of neurovascular structures, thus permitting better surgical planning; 3) a significant number of intradural tumours are difficult to excise because of their adherence to neurovascular structures, and thus are related to higher morbidity and mortality; and 4) because of extremely slow growth, complete tumour resection should not be the goal at the risk of injury to neurovascular structures.

Recurrence of intracranial meningiomas after surgery has long been recognized, but there is still no consensus about factors responsible for recurrence. To better understand such factors, we analysed data on 276 patients with meningiomas who were treated at our institution from 1976 to 1990 (mean follow-up = 5.1 years). Effects of sex, tumour histology, tumour site, and radiotherapy on recurrence were closely studied. Using World Health Organization criteria to define malignancy, 254 of the tumours were benign and 22 were atypical or malignant. For data analysis, distinction was made between "recurrence"(i.e., reappearance of tumour after total resection) and "regrowth" (i.e., tumour enlargement after subtotal removal). Recurrence was seen in 2 of 183 benign meningiomas and in 10 of 16 malignant meningiomas. Recurrence and regrowth rates for malignant meningiomas far exceeded those for benign meningiomas (p = 0.001). Neither sex nor tumour site was associated with subsequent recurrences in patients whose tumours had been completely resected. The influence of radiotherapy was studied in terms of its effects on benign versus malignant meningiomas, whether given after complete or incomplete resection, and whether given after primary resection or on reoperation. We found that radiotherapy did not decrease "recurrence" or "regrowth" regardless of when administered, either at first resection or on recurrence. This was true for benign as well as malignant meningiomas. However, due to the small number in our series, we cannot conclude that radiotherapy has no beneficial role in the treatment of meningiomas.(ABSTRACT TRUNCATED AT 250 WORDS)

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