Posterior fossa metastases by nature of their location can prove life threatening if untreated. Patients may deteriorate within days, from intracranial hypertension and/or brain stem compression. This may also be the scenario in patients undergoing radiation for cerebellar lesions, with increased swelling and acute hydrocephalus. Yet, many patients with primary malignancies have no knowledge about their disease burden until presenting with neurological complaints. In our study, we found that 34% of our patients had no prior diagnosis of cancer and learned of their malignancy only after neurological complaints led to appropriate imaging. Surgery should be strongly considered in patients harboring large lesions with significant edema and neurological symptoms.
A review of the literature yields little information on treatment and clinical scenarios of cerebellar metastases []. The first large series published was conducted by Fadul
et al., in 1987, encompassing 59 patients. Sixteen of the patients underwent surgical decompression in addition to radiation and steroids—the remaining received radiation and steroids alone.[
6] Patients who underwent surgery all had solitary cerebellar metastases. Surgical results proved disappointing with two patients dying postoperatively and two developing meningitis. Additionally, reported survival time was similar in the surgical and non-surgical groups, questioning the benefit of surgery in patients with cerebellar metastases.
Ampil
et al. described their experience at LSU in 45 patients from 1981 to 1993.[
1] Eleven of the patients underwent surgery followed by radiation, the remainder underwent radiation alone. When comparing surgery and radiation to radiation alone, they found a much longer survival time in the surgery group (median survival time of 15 months versus 3 months). This sharply contradicted the outcomes noted by Fadul
et al. However, the authors noted that patients treated with radiation alone had a poorer prognosis and failed to note complications encountered in their experiences.
The largest study is that of Yoshida, which included 109 patients.[
22] Patients either received radiation alone, surgery alone, or both. The group found that surgery combined with radiation conferred improved prognosis and that surgery alone proved more beneficial than radiation alone. However, complications encountered following surgery, including morbidity/mortality, and the number of patients receiving VPSs was not addressed.
In the article presented by Pompili
et al., the authors made note of the complications encountered in 44 patients undergoing resection of cerebellar metastases.[
12] Of the nine significant complications encountered, eight included cerebellar hematomas which required evacuation and one occipital infarct believed to be a result of retraction. One common factor among these nine patients was a tumor dimension greater than 3 cm. From a surgical perspective, the authors utilized both a trans-tentorial occipital approach and a suboccipital approach, and found that hematomas were a complication of both approaches.
Wronski
et al. looked at 74 patients with intracranial metastases from colorectal cancer, 26 of which included surgically treated cerebellar lesions.[
21] 23% of these patients required a VPS, and more importantly, 19% experienced postoperative complications requiring reoperation. Whether complications occurred in tumors of greater dimensions is not mentioned nor are the specific details of the complications encountered. Rajendra
et al. included 13 patients in their series.[
13] Unique to their paper, the authors include the average hospitalization stay (15 days), but make no remarks on complications.
In review of the literature, several papers note complications involved in resection of posterior fossa metastases, and only two describe specific complications requiring surgical intervention []. From a technical standpoint, only Ampil et al. and Pompili et al. make reference to surgical technique. In comparison to other publications, we found a dramatic decrease in operative complications and a shorter hospital stay. In our series, there was no mortality and only 4% morbidity. Also, no symptomatic postoperative hematoma developed in any surgical case. Two patients who underwent re-operation for wound complications were discharged without any permanent neurological changes. Length of stay at 5 days was favorable, shorter than the 15 days in the series found by Rajendra et al.
We feel there are several explanations to address our low complication rates compared to those found in the literature. Preoperatively, we utilize stealth imaging in order to better delineate tumor from “normal” brain parenchyma as well as from important vascular structures, which translates into intraoperative stealth guidance and safer surgery. Our group also emphasizes the importance of intraoperative hemostasis and we prophylactically transfuse platelets and blood factors to reverse patients who are taking anti-coagulants and/or are found to have elevated international normalized ration (INR) of greater than 1.5. If patients are taken to the operating room on a semi-elective basis while taking aspirin, they are told to hold aspirin 1 week prior to surgery. Additionally, postoperative patients are monitored with arterial lines in a neurological intensive care unit and placed on anti-hypertensive oral or intravenous medications in order to achieve meticulous blood pressure goals following surgery in order to prevent postoperative hematoma formation.
In our study, 76% of patients with preoperative hydrocephalus were able to forgo permanent CSF shunting following surgical resection. We could find no study in the literature describing the benefits of surgery or radiation in avoiding a VPS. Our data suggests that surgery reverses hydrocephalus in the majority of patients with hydrocephalus, eliminating the need for further surgery and possible complications that may arise from placement of a VPS (i.e., malfunction, infection, hemorrhage). Whether radiotherapy can have such an impact may be a topic for future studies.
From a technical standpoint, suboccipital craniotomy is a safe and efficient way to treat cerebellar metastases in the hand of an experienced surgeon. Surgery has been shown to increase the mean duration of survival in patients with cerebellar metastasis when compared to radiation alone, and shortens the need for corticosteroid therapy, provides immediate symptomatic relief, and many times avoids the requirement of a VPS. We advocate such procedures in patients medically stable for surgery, or otherwise those with acute obstructive hydrocephalus and deterioration.
Several limitations exist in our paper. The study was a retrospective study assessing surgical outcomes. Additionally, many of the patients in this analysis were sent to our institution from referring oncologists from outside institutions, and returned back to their oncologists for further fare following surgery. As a consequence, after reviewing the patient charts and clinic notes within our hospital database, much of the data on prior and/or future radiation treatment as well as patient survival was not obtainable for review. We would like to stress, however, the importance we aim to emphasize is to show that by surgical resection, we can avoid the need for VPS in these patients and the problems associated with this procedure both operatively and post-operatively.
