SUMMARY

Out of a total of 1041 verified neoplastic lesions of the central nervous system (CNS) operated by the Author over a period of 40 years of neuro-surgical practice in Italy and in Kenya (this series does not include vascular malformations or haematomas, parasitic or infectious lesions and/to cystic arachnoiditis), 215 patients have been operated for benign meningiomas of CNS. Meningiomas with signs of hystologic anaplasia were excluded. Of the 215 meningiomas, 174 were intracranial and 41 intraspinal. A critical review of the surgical treatment of these cases is carried out.

RESUME

En 40 ans l’Auteur a opere en Italic et au Kenya 1041 tumeurs du S.N.C., sans tenir compte des realformations vasculaire, des hematomes, des processus expansifs d’origine infectieuse ou parasitaire ni des arachnoidites. Parmi ces tumeurs, 215 etaient meningiomes benins a localization intracraniens 174 lois et intraspinale 41 lois. Une revue critique du traitement chirurgical de ces cas est exposee.

Keywords : Meningiomas, Surgical treatment

INTRODUCTION

The incidence of neoplastic lesions of the CNS constitutes normally around 10 percent of the surgical material in a neurosurgical practice (ZULCH). In our experience of nearly 6000 major neurosurgical operations carried out in 40 years, the number of 1041 verified neoplastic lesions of the CNS is the 17.5 per cent of the whole neurosurgical material. This high incidence may be due to the high incidence of neoplastic lesions admitted and operated in the Neurosurgical Clinic of the University of Padua Italy, where I have worked for fifteen years, and to the high incidence of the same lesions referred from all over Eastern Africa to Nairobi, were I have been working for the last 25 years.

In this series, the relative incidence of meningiomas compared with other tumours of the CNS, was as follows:

TABLE 1

The meningiomas constitute about 20 per cent of all neoplastic lesions of the CNS in this series, more than a third of the number of the gliomas.

The relative incidence of histopathological type of various neoplasms of this series compared in percentage with other large series, was as follows:

TABLE 2

There are not very significant difference, except for a slightly higher incidence in the meningiomas, a higher incidence in the sarcomas, osteomas and embryonic tumours and a lower incidence of neurinomas and pituitary adenomas in the Author’s series compared with those of CUSHING’S, OLIVECRONA AND ZULCH.

MENINGIOMAS OF THE CENTRAL NERVOUS SYSTEM

Age incidence
The incidence of age per decade was as follows:

TABLE 3

As seen in table 3, meningiomas may occur at any age but reach their peak of incidence in the middle age. The oldest patient of this series was 74, the youngest was 2. The average age was 36 years. The sex incidence shows, as in other series, that the meningiomas are commoner in female (123 cases or 57 percent) than in males (92 cases or 43 percent).

ANATOMICAL LOCATION

Although meningiomas may arise anywhere, they show a strong predilection for some anatomical sites. The anatomical location and the biological behaviour of the tumours lead to the recognition of typical clinical syndromes, characteristic for each group; these clinical features are not considered in this paper.

From the histopathological point of view, only benign meningiomas were included in this series, excluding the meningosarcomas and fibrosarcomas.

a) Intracranial Meningiomas

Out of the 174 intracranial meningiomas, 165, were supratentorial and only 9 in the posterior fossa. 43 of them were located on the right side, 58 on the left and 73 in the midline.

The incidence of the anatomical location of these meningiomas as well as its percentage are compared with the same location in cushing’s series and are as follows:

TABLE 4

There are some differences between the percentage in the two series: there is a higher incidence of parasagital, falx, convexity, suprasellar, ventricular and tentorium meningiomas in our series and a lower incidence of sphenoidal ridge and posterior fossa meningiomas in our series compared CUSHING’S.
Incidentally in our series the proportion of parasagital (38 cases) to falx (14 cases) meningiomas was 3 to one as in McKISSOCK’S series (GAUTIER and SMITH, 1970) and not 10 to one as in CUSHING’S series. Of the sphenoidal wing meningiomas, 15 were of the outer third, 7 of the middle third and 4 of the inner third.

Of the meningiomas of the posterior possa, 4 were located in the ponto-cerebellar angle, 2 in the clivus and 3 were in the convexity.

Out of three lateral ventrical meningiomas, all were on the left side as in the other series.

The tentorium meningiomas were all supratentorial, on being located on the free edge of the tentorium.

B) Intraspinal meningiomas

Out of 41 cases of intraspinal meningioma, 17 were located in the cervical spinal whilst 24 in the thoracic spine. Of the 17 cervical meningiomas, 11 were located in the upper cervical and 6 in the middle cervical spine. In the thoracic spine 7 meningiomas were located in the upper thoracic spine, 12 in the middle and 5 in the lower thoracic spine. No meningiomas have been found in this series in the lumbar spine.

SURGICAL TREATMENT

The results of the surgery ofmeningiomas depends on many factors: the size and location of the tumor, the degree of involvement of vascular and nervous surrounding structures, the experience of the surgeon, and his attitude to the alternatives of total or partial extirpation. The removal of some meningiomas is often a matter of great difficulty, mainly in the deeply placed ones. It is in such deeply placed tumors that the modern aids such as intravenous mannitol, lumbar CSF drainage, controlled respiration, induced hypotension, improved light and magnification helps in reducing and better controlling the haemorrhage as well as improving the approach and excision of the tumours.

Since the successful total removal of a large olfactory groove meningioma, my first meningioma of this series operated on the 4th of November, 1960, my policy has always been to try to achieve a total removal of these tumours, and this for the following reasons:

1 ) Operations on recurrent meningiomas are much more traumatizing and often complicated by thick adhesions, with consequent high mortality and morbidity

2) At least 90 per cent of all meningiomas can be totally removed in one stage (rarely in two stages close to each other) with a reasonable surgical risk, low morbidity and relative low mortality.

By total removal it is intended that not only the tumour, but its dural or vascular implant and any bone possibly involved has to be largely removed. If this is not the case, and only a doubt is left that some tumoral cells are left behind, one has to talk of a subtotal removal because most certainly a recurrence may occur, even at a long distance.

In my personal experience two are the golden rules for the removal of these tumours: one is the large access to the lesion and the second, the most important, is to interrupt as soon as possible its blood supply.

There is no doubt that convexity, falx, lateral ventricle and intraspinal meningiomas can be removed totally. The greatest problem arises in the parasagital, the sphenoidal ridge, mainly the ones of the inner third, the suprasellar and the ones of the posterior fossa and clivus.

For those in the last group, there are rare cases where the risk of total removal may suggest a subtotal one. The results of surgery in this series are as follows:

TABLE 5

A few comments on the results, although the statistics are often complicated and of doubtful value, mainly when there are not on very large series.

Nevertheless, out of 203 maningiomas totally removed, the mortality rate was of 8 cases, around 4 per cent, and it has to be mentioned that one of the eight cases, a meningioma of the falx died of a cardiac arrest, without any connection with the surgery. Out of 12 subtotal removal, the mortality was of 4 cases, meaning 33 per cent: it is obvious that the subtotal removal was performed in the poor risk patients and in the poor risk tumours. I remember that the one of these cases was a very bad recurrence of a meningioma of the tentorium operated elsewhere.

A relatively high mortality rate is found in the meningiomas of the tentorium (20%), less in the suprasellar meningiomas (8%), posterior fossa (11%) and sphenoidal ridge meningiomas (8%).

Out of 205 survivors, 149 (73%) made a good recovery with full working capacity, 43 patients (21%) made a fair recovery, able to support themselves but with neurological deficits (several of them had visual problems) 13 patients (6%) are completely disabled.

The best prognosis for the meningiomas of the CNS is for the meningiomas of the convexity and for the intrapinal meningiomas. For the rest, the prognosis, as said before, depends on many factors. It may be possible that the next generation of neurosurgeons may achieve always a total removal without mortality and very low mobility as has been emphasized some years ago by GOSTA NORLEN.

And eventually the problem of the recurrence should be mentioned. In this series a final assessment on the recurrence is difficult to do, mainly due to the short time the patient in Italy has been followed up: in seven years of time there have been no recurrence. Many of the cases operated in Kenya have gone lost in the follow up. Again, in all cases followed up for a long period of time (twenty years) there have been only one recurrence of a suprasellar meningioma 13 years after surgery.

In conclusion, in the surgery of the meningiomas an aggressive attitude towards a total removal is probably the treatment of choice.