see Phang I, Leach J, Leggate JRS, Karabatsou K, Coope D, D'Urso PI. Minimally Invasive Resection of Brain Metastases. World Neurosurg. 2019 Jun 21. pii: S1878-8750(19)31643-2. doi: 10.1016/j.wneu.2019.06.091. [Epub ahead of print] PubMed PMID: 31233927.
The primary aims for surgical treatment of brain metastases are to improve neurological performance and to prolong overall survival. With the introduction of image-guided and microscopic surgical techniques, these goals have become more readily attainable 1).
As novel methods of localization and resection become available, the surgical repertoire is enhanced, and treatment is greatly improved. However, depending on the clinical course of each individual patient, certain surgical techniques may engender a better outcome than others 2).
Control of local recurrence is an important aspect in the management of brain metastases. As many as 46% of resected lesions eventually recur 3).
However, the method of resection has significant impact on local recurrence rate. Tumors that were resected in a piecemeal fashion (without violating the tumor capsule) have been found to have a recurrence rate 1.7 times higher than those removed en bloc (circumferential resection). The 14% local recurrence rate for en bloc resected tumors most likely reflects less intraoperative tumor spillage, compared with piecemeal procedures 4).
En bloc resections are particularly useful in resecting posterior fossa metastases and lesions in contact with the CSF pathway, tumors that are highly prone to lemptomeningeal spread following surgery. 5) 6).
However, piecemeal resection may be unavoidable in some situations, as in cases where the tumor is adherent to or infiltrating eloquent brain regions, or when the lesion is extremely friable 7).
In these situations, it is not uncommon for local recurrence, even with postoperative MRI confirmation of complete tumor removal. Following gross total resections of well-circumscribed brain tumors, microscopic infiltrates are often left on the tumor bed 8).
To prevent this residual cancer, Yoo et al. suggested a novel technique, microscopic total resection, in which apparently normal-looking parenchyma is suctioned to a depth of 5 mm by ultrasonic aspiration. In their prospective assessment, microscopic total resection led to a decrease in metastatic local recurrence (29% one year local recurrence rate, as compared with 59% after gross total resection, P = 0.01). Thus, en bloc resection and microscopic total resection techniques are highly effective in limiting local recurrence, and their use should be assessed in applicable clinical scenarios 9).
Wolpert et al. defined risk profiles for the development of BM-related epilepsy and derived a score which might help to estimate the risk of post-operative seizures and identify individuals at risk who might benefit from primary prophylactic antiepileptic drug therapy 10).