Surgical management of posterior fossa metastases

Abstract

The diagnosis of brain metastases is associated with a poor prognosis reflecting uncontrolled primary disease that has spread to the relative sanctuary of the central nervous system. 20 % of brain metastases occur in the posterior fossa and are associated with significant morbidity. The risk of acute hydrocephalus and potential for sudden death means these metastases are often dealt with as emergency cases. This approach means a full pre-operative assessment and staging of underlying disease may be neglected and a proportion of patients undergo comparatively high risk surgery with little or no survival benefit. This study aimed to assess outcomes in patients to identify factors that may assist in case selection. We report a retrospective case series of 92 consecutive patients operated for posterior fossa metastases between 2007 and 2012. Routine demographic data was collected plus data on performance status, primary cancer site, details of surgery, adjuvant treatment and survival. The only independent positive prognostic factors identified on multivariate analysis were good performance status (if Karnofsky performance score >70, hazard ratio (HR) for death 0.36, 95 % confidence interval (CI) 0.18-0.69), adjuvant whole brain radiotherapy (HR 0.37, 95 % CI 0.21-0.65) and adjuvant chemotherapy where there was extracranial disease and non-synchronous presentation (HR 0.51, 95 % CI 0.31-0.82). Patients presenting with posterior fossa metastases may not be investigated as thoroughly as those with supratentorial tumours. Staging and assessment is essential however, and in the meantime emergencies related to tumour mass effect should be managed with steroids and cerebrospinal fluid diversion as required.

Keywords: Brain metastasis; Cerebellar metastasis; Neurosurgery; Posterior fossa metastasis.

Fig. 1

Illustrative cases. Case 1 images (a) and (b) 54 year old female. PMH Breast cancer (Her2 positive) Treated with mastectomy 1 year ago plus adjuvant chemotherapy (trastuzumab). Presented with 2 weeks of headaches and unsteadiness. CT brain revealed (a) large solid left cerebellar tumour, confirmed on MRI (b). KPS 90 pre-operatively. CT staging pre-op showed local lymph node involvement but no other metastatic disease. Underwent craniotomy and gross total resection with adjuvant WBRT and further systemic chemotherapy. Re-presented with similar symptoms 21 months later and MRI showed recurrent tumour at the same site. CT staging showed no evidence of extracranial disease. Further craniotomy and gross total resection performed. No further adjuvant therapy given. Gradual deterioration 10 months after second surgery and died 36 months after initial diagnosis. Case 2 images (c) and (d) 67 year old male. PMH Testicular cancer - orchidectomy 12 years ago. Presented with increasing confusion, headache, unsteadiness and falls. Acute deterioration the previous day. KPS 50 on arrival. CT head revealed 36 × 25 mm left cerebellar haemorrhagic tumour with triventricular hydrocephalus (c). Transferred to regional neurosurgical unit and external ventricular drain (EVD) inserted. MRI confirmed solitary bulky left cerebellar (d). Gross total resection performed later that admission, histology revealed metastatic carcinoma. Post- operatively the patient developed bulbar dysfunction and swallowing difficulty. Staging CT performed post-operatively revealed metastatic lung cancer with mediastinal and liver metastases. EVD reinserted due to post-operative hydrocephalus. 5 days of palliative WBRT administered as an inpatient. Continued deterioration and the patient died in hospital 5 weeks after surgery

Fig. 2

a Kaplan–Meier survival analysis for patients with good Karnofsky performance status (>70) versus those with poor (<70) (log rank = 21.042, p < 0.001). b Kaplan–Meier survival analysis for patients receiving adjuvant WBRT versus those who did not receive WBRT. (log rank test = 17.525, p < 0.001). c Kaplan–Meier survival analysis for synchronous versus metachronous presentation. (log rank test = 5.97, p = 0.021). d Kaplan–Meier survival analysis comparing patients who received adjuvant chemotherapy for synchronous or uncontrolled systemic disease versus patients who did not receive this treatment. (log rank test = 8.951, p = 0.003)