Keywords
spinal meningiomas - gingko leaf sign - dentate ligament - intradural extramedullary
tumors - spinal nerve sheath tumors.
A 75-year-old lady presented with progressive ataxia, weakness and sensory deficits
in both lower limbs, difficulty in holding urine and constipation of 3 months duration.
Magnetic resonance imaging (MRI) of the spine ([Fig 1A–D]) revealed a right-sided T1 isointense and T2 mildly hyperintense intradural extramedullary
lesion-enhancing homogenously on contrast at D11-D12 levels compressing the spinal
cord to the left. Axial imaging showed the lesion to be ventral and lateral to the
spinal cord with a hypointense band traversing it ([Fig 1E,F]). Intraoperatively, the tumor was moderately vascular, attached to the anterior
and lateral dura and easily separable from surrounding nerve roots and SC. It was
traversed by the dentate ligament, sectioning of which enabled easy access to the
anteriorly located part of the tumor and ventral dura. Complete removal with coagulation
of the attachment was done with no postoperative deficits.
Fig. 1 Magnetic resonance imaging of the spine showing on sagittal T2 section (A) a mildly hyperintense mass at D11-D12 levels. This is hypointense on the T1 sagittal
section (B). T2 coronal section (C) shows the intradural extramedullary lesion compressing the cord to the left and
post contrast T1 coronal section (D) shows homogenous enhancement of the lesion. Post contrast T1 axial (E) and plain T2 axial (F) sections show a hypointense band (yellow arrows) representing the dentate ligament traversing through the tumor. The fan-shaped compressed
cord with the stalk as dentate ligament is highlighted by superimposing a green line
on the T2 axial section (G) and (H) shows a schematic drawing of the “Gingko leaf.”
Dentate ligaments are pial condensations extending outwards bilaterally from the lateral
aspect (between the ventral and dorsal roots) of the SC to the dura and stabilize
the SC in the spinal canal.[1] While the medial attachment to the SC is continuous, laterally they condense into
thin triangular extensions at their attachment to the dura.[1]
Yamaguchi et al[2] first described the “Gingko leaf” sign as being highly specific for spinal meningiomas.
They found it in seven cases of spinal meningiomas and later Zhai et al[3] too found this sign in two of their cases of lateral or ventrolateral meningiomas.
We have encountered only two papers[2]
[3] describing this sign in the literature though others have quoted them and mentioned
that this sign is specific for meningiomas. It must be stressed that only a laterally
arising spinal meningioma, which extends both anterior and posterior to the dentate
ligament will “deform the spinal cord like a fan” even as the lateral aspect of the
cord remains tethered to the dura by the dentate ligament.[2]
[3] The spinal cord thus represents the leaf of the Gingko plant, while the ligament
represents the stalk of the leaf ([Fig 1G,H]). Unlike meningiomas nerve sheath tumors never show this finding[2]
[3] because they originate from dorsal or rarely ventral rootlets and not the dura and
thus either push the dentate ligament either forward or backward. A similar displacement
will occur when meningiomas too arise completely from either the dorsal or ventral
dura and this probably accounts for the rarity of this finding in the majority of
cases.
While diffuse homogenous enhancement, “dural tail” sign, hypointensity on T2 sequences
are characteristic radiological findings in spinal meningiomas, the Ginko leaf sign
caused by the stretched dentate ligament traversing the tumor is another useful adjunct
in identifying the tumor preoperatively. Knowledge of this sign helps in preoperative
planning as sectioning of the dentate ligament will be needed to mobilize the cord
and access the anterior component of the lesion.
