Lowgrade Gliomas In Adults

Fig. 9.5. Case MB 9 years after surgery. The small area of high signal on this FLAIR sequence has remained unchanged since surgery and presumably represents gliosis.

Using speech mapping with awake cran-iotomy and multiple marginal biopsies, what appeared to be complete removal was achieved without producing any neurological deficit. Ten years later, the patient remains free from fits, is off anticonvulsants with no evidence of recurrence on follow-up scanning, and is on active service in the army.

Comment: If the patient had not been operated upon and had been judged to have an effectively "inoperable brain tumor", he would have lost his job as well as remaining at risk of the tumor progressing. He would also have had the psychological burden of "living with" the tumor. Modern techniques have made resection reasonably safe although, from a single case such as this, one cannot know whether surgery has improved his chances of survival or not when compared with conservative treatment.

3. Tumors where it is Uncertain Whether Complete Resection can be Achieved

It is easy to justify an attempt at radical, curative resection of a small tumor, superficially placed in the tip of a lobe, without MRI evidence of extensive infiltration. The risks of such an operation are the risks of any craniotomy - that is, the risks of hemorrhage or infection - and these risks are almost certainly less than the risks of the tumor undergoing malignant change and proving fatal in the future. It can become a question of fine surgical judgement as to the point at which it becomes unrealistic to hope for total resection.

Radical resection depends upon:

Careful study of a pre-operative MRI scan, supplemented by functional MRI studies and neuronavigation if appropriate and available;

The use of intraoperative mapping methods combined with smear biopsy analysis (if the surgeon is lucky enough to work with a neuropathologist who is able to carry out smear analysis on many dozens of marginal biopsies as the resection proceeds). In a few centers, intraoperative MRI scanning is now available, but it is not yet clear if this makes a major difference to the surgery of these tumors.

Two principles must guide selection of patients for radical surgery of this sort. Firstly, there must be a realistic chance of "total" excision of the tumor. It will often not prove possible during the operation to achieve such a removal, but there must be a reasonable possibility of achieving this on the basis of examining the pre-operative MRI scan. Secondly, it is not acceptable to produce any degree of permanent neurological impairment since all of these patients are, by definition, in perfect condition and we know that the majority of them will eventually die from the tumor, despite treatment. That having been said, of course, there is bound to be some morbidity, although often temporary, especially when operating in the supplementary motor area. In the author's series of 130 "radical" operations for low-grade gliomas, there has been a 7% incidence of significant, permanent morbidity (although no mortality) and all in patients who ended up having only partial excision of their tumor. The morbidity, in short, probably conferred little benefit on the patients in terms of eventual outcome. Temporary neurological deficits, which resolved completely, occurred in 20% of patients.

By using neuronavigation, magnification, intraoperative mapping under local anesthetic

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