DO SPINAL MENINGIOMAS PENETRATE THE PIAL LAYER - CORRELATION BETWEEN MAGNETIC-RESONANCE-IMAGING AND MICROSURGICAL FINDINGS AND INTRACRANIALTUMOR INTERFACES
Fm. Salpietro et al., DO SPINAL MENINGIOMAS PENETRATE THE PIAL LAYER - CORRELATION BETWEEN MAGNETIC-RESONANCE-IMAGING AND MICROSURGICAL FINDINGS AND INTRACRANIALTUMOR INTERFACES, Neurosurgery, 41(1), 1997, pp. 254-257
OBJECTIVE: To study the relationships between spinal dura-arachnoid an
d tumor-cord interfaces in spinal meningiomas and to investigate wheth
er a disruption of the pial layer and penetration of the tumor in the
spinal cord occurs. METHODS: Fifteen patients with histologically prov
en meningiomas underwent magnetic resonance imaging (MRI) preoperative
ly. All patients underwent microsurgery. The histological characterist
ics of the tumors were compared with MRI and microsurgical findings. R
ESULTS: At surgery, the peritumoral hypointense rim revealed by MRI in
10 of 15 patients corresponded to a well-defined cerebrospinal fluid-
containing space confined between the outer arachnoidal layer and the
inner leptomeningeal layer. In those patients in whom the hypointense
peritumoral rim was absent, the inner layer was either difficult to id
entify or clearly absent, and the blood vessels were extremely adheren
t to the tumor, requiring a more cautious dissection. Penetration of t
he tumors through disruption of the pial surface was not documented. C
ONCLUSION: Previous anatomic and electron microscopy studies demonstra
ted, in human spinal meninges, the presence of an intermediate layer a
ttached to the inner aspect of the arachnoid, extending laterally over
the dorsal surface of the spinal cord and arborizing over the nerve r
oots and blood vessels. The intermediate layer is not present in human
cerebral leptomeninges. The presence/absence of this layer might expl
ain the hypointense rim detected by MRI and might also explain why no
penetration and no peritumoral edema is observed in spinal meningiomas
as compared with intracranial meningiomas.