The growth rate of 19 residual acoustic neurinomas was examined in a long-term follow-up study (median, 10 years; range, 5 to 17 years) following intracapsular removal. Of these, 10 (53%) had regrowth, three (16%) showed regression, and six (32%) were unchanged. The 10 acoustic neurinomas showing regrowth were divided into two categories, either solid or cystic, according to computed tomographic findings. Five acoustic neurinomas with cyst formation showed rapid regrowth, with the tumour doubling time ranging from 0.15 to 5.0 years (median, 4.5 years), and required re-operation. Five solid tumours showed slow regrowth, with the tumour doubling time ranging from 9 to 34 years (median, 15 years). Although cyst formation is a major factor in rapid regrowth, residual acoustic neurinomas without cyst formation have a slower growth potential. In this study, 74% of the residual acoustic neurinomas have never required re-operation. It is advisable to choose intracapsular removal if there is major risk of neurological deficits.
We examined growth potential of residual intracanalicular tumours left from subtotal removal of large acoustic neurinomas. Eleven patients were followed-up by magnetic resonance (MR) imaging. The interval between surgery and MR study ranged from 12 to 29 years (median, 16 years). MR images of two patients showed no evidence of tumour remnant, and in six a small tumour was localized in the internal auditory canal. The other three showed an intracanalicular tumour protruding slightly towards the intracranial portion. This result suggests that the intracanalicular residual tumours have less risk of regrowth after subtotal removal of acoustic neurinomas. It is advisable to choose intracapsular, subtotal removal without opening the internal auditory canal in the treatment of acoustic neurinoma, if it is large in size and there is a high risk of nerve injury.
Gamma knife radiosurgery (GKS) was used to treat seven patients with pituitary metastases between November 1994 and February 2003. The diagnoses were based on magnetic resonance imaging and clinical symptoms in six patients and by previous surgery in one patient. The cancer originated in the lung in five patients, and in the breast in two patients. The tumor volume was 0.2 to 9.6 cm 3 (mean 4.0 cm 3 ). The marginal dose was 10 to 14 Gy (mean 11.9 Gy) because of the close proximity to the optic apparatus. The maximum radiation dose to the optic apparatus was 8 to 10 Gy (mean 9.5 Gy). The survival period after GKS was 0.3 to 42 months (mean 11.5 months). Five patients died of systemic disease, and one patient died of unknown causes 10 days after GKS. Tumor growth was controlled in five of the six patients (83%) followed up after GKS. Tumor regrowth was seen 18 months after GKS in one patient. The clinical symptoms improved in five of the six patients (83%) followed up. GKS is effective and useful for the primary treatment of pituitary metastases with limited survival and less invasiveness compared to conventional radiation therapy.
A 59-year-old man developed postural headache associated with a low CSF pressure. A CT scan revealed no abnormal findings and the orthostatic symptoms resolved without treatment 6 weeks after onset. He was diagnosed as having spontaneous intracranial hypotension (SIH) and remained symptom-free until he experienced recurrence of postural headache 9 months later. A lumbar puncture demonstrated low CSF pressure, and a CT scan revealed slit-like ventricles with narrowing of the sulci, Sylvian fissures, and infratentorial cisterns, in addition to bilateral subdural masses. After draining the hematomas, his symptoms resolved completely, and a follow-up CT scan was normal. We hypothesize that recurrent SIH in this case was due to small recurrent tears of a root sleeve. This case emphasizes the importance of follow-up of SIH for at least 9 months after resolution of symptoms.
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