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|LETTER TO EDITOR
|Year : 2013 | Volume
| Issue : 5 | Page : 558-560
Look before you leap: Dynamic multiphasic contrast enhanced magnetic resonance imaging in cavernous sinus lesions
Shashwat Mishra1, Arun Kumar Srivastava1, Amit Chaudhary1, Rajanikant Yadav2
1 Department of Neurosurgery, Ram Manohar Lohia Institute of Medical Sciences, Lucknow, Uttar Pradesh, India
2 Department of Radiodiagnosis, Ram Manohar Lohia Institute of Medical Sciences, Lucknow, Uttar Pradesh, India
|Date of Submission||24-Sep-2013|
|Date of Decision||18-Oct-2013|
|Date of Acceptance||20-Oct-2013|
|Date of Web Publication||22-Nov-2013|
Department of Neurosurgery, Ram Manohar Lohia Institute of Medical Sciences, Lucknow, Uttar Pradesh
Source of Support: None, Conflict of Interest: None
|How to cite this article:|
Mishra S, Srivastava AK, Chaudhary A, Yadav R. Look before you leap: Dynamic multiphasic contrast enhanced magnetic resonance imaging in cavernous sinus lesions. Neurol India 2013;61:558-60
|How to cite this URL:|
Mishra S, Srivastava AK, Chaudhary A, Yadav R. Look before you leap: Dynamic multiphasic contrast enhanced magnetic resonance imaging in cavernous sinus lesions. Neurol India [serial online] 2013 [cited 2019 Oct 17];61:558-60. Available from: http://www.neurologyindia.com/text.asp?2013/61/5/558/121956
A 35-year-old woman presented with progressive visual decline in her right eye, inward deviation of the affected eye, ipsilateral facial numbness and masticatory difficulty. On examination, there was no perception of light in the right eye, a right sided sixth nerve palsy and a mild right trigeminal motor paresis. She noticed worsening of her symptoms during the third trimester of her pregnancy and subsequently delivered a healthy female baby a month before presenting to us. Magnetic resonance imaging (MRI) showed an intensely contrast enhancing large middle fossa lesion, which extended through the foramen ovale and encroached upon the petrous apex [Figure 1]a. This middle fossa mass was hyperintense on T2-weighted images. Computed tomography revealed an enlargement of the foramen ovale and erosion of the petrous apex. Based upon the initial clinical and radiological findings a working diagnosis of a fifth nerve schwannoma was entertained. The other differential was a hemangioma of the cavernous sinus. To further characterize the tumor, dynamic gadolinium contrast MRI was done. These sequences revealed profuse vascularity within the tumor with most of the feeders arising from the cavernous carotid artery. A characteristic "filling-in" pattern of sequential contrast enhancement was noticeable on these images [Figure 1]b-d.
|Figure 1: (a) Axial contrast magnetic resonance imaging (MRI) image; (b) early phase in dynamic gadolinium contrast scanning showing scanty peripheral enhancement close to cavernous ICA which becomes more pronounced in (c) intermediate phase and (d) finally "fills-in" the entire lesion; (e) intraoperative image showing the extradural hemangioma (arrow) visible beneath the temporal dura following bone flap elevation and temporalis (temp) retraction; (f) craniotomy; (g and h) post-operative contrast MRI showing complete tumor excision|
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A right sided temporal craniotomy was performed [Figure 1]f. The zygomatic arch was denuded and the zygomatic notch was deepened to allow for optimum exposure of the temporal base. The superior orbital fissure was uncovered. A large throbbing, red, spongy tumor was seen extradurally within the middle fossa [Figure 1]e. The tumor tented the temporal dura. The outer layer of the lateral wall of the cavernous sinus was peeled off to further define the tumor. The tumor was rapidly decompressed and removed extradurally. The sixth nerve could not be visualized during surgery. Post-operatively, the patient continued to have a sixth nerve palsy and her jaw paresis worsened. Post-operative MR revealed complete excision of the tumor [Figure 1]g and h.
Meningiomas, schwannomas, cavernomas often form the closest differentials of intracavernous lesions on imaging studies.  Purely intracavernous pituitary adenomas are extremely rare. Clinically, these pathologies are indistinguishable. However, cavernous hemangiomas are known to enlarge during pregnancy and may become symptomatic, which was also notable in this case.  Meningiomas are frequently calcified and associated with hyperostosis, a feature which helps to differentiate them from cavernomas and schwannomas. Both cavernous hemangiomas and schwannomas characteristically erode the skull base. Menigniomas, with the exception of angioblastic meningiomas, tend to be isointense on T2-weighted images. In contrast, schwannomas and cavernomas are hyperintense on T2-weighted images and often reach cerebrospinal fluid intensity. Differentiating schwannomas and cavernous sinus hemangiomas is challenging on the routine MR sequences and several times cavernous hemangiomas have been mistaken for meningiomas or nerve sheath tumors pre-operatively. 
Recently described dynamic multiphasic Gadolinium enhanced T1-weighted images are helpful in distinguishing cavernous hemangiomas from other intracavernous lesions. During dynamic contrast scanning, images in orthogonal planes are successively acquired after fixed time intervals following intravenous injection of contrast. This imaging technique is described in detail by Jinhu et al.  On these sequences, a progressive "filling - in" of the contrast is demonstrable. The contrast enhancement first appears in the periphery of the lesion and then progressively "fills-in" the entire lesion in the later sequences. This imaging feature is well described for liver hemangiomas  and is also applicable to cavernous hemangiomas.
Further characterization of these hemangiomas is also possible through these special sequences. Zhou et al.  have subdivided cavernous hemangiomas into three types (A, B and C) according to their histopathological appearances. Type A tumors are tense, pulsatile with a spongy feel and have scarce intra-tumoral connective tissue separating the vascular channels which form these tumors. Type A tumors have a well formed pseudocapsule. Type B tumors have abundant fibrous connective tissue between the vascular channels. They have a more solid "mulberry" feel, lack pulsatility and have a poorly defined pseudocapsule. Type C tumors share the characteristics of both type A and B tumors. Type A tumors demonstrate homogenous contrast enhancement earlier than Type B and C tumors on dynamic imaging.
Cavernous hemangiomas are surgical challenges because of the possibility of rapid intraoperative exsanguination and cavernous carotid injury.  Literature prior to 1983 mentions an operative mortality rate as high as 36% for these tumors. Improved understanding of cavernous sinus anatomy, advances in microsurgical techniques and novel hemostatic agents such as fibrin glue and liquid gelfoam, have helped in attenuating the operative risks. However, for adequate pre-operative preparation, surgical success and accurate assessment of operative risks, it is crucial to ascertain the diagnosis of intracavernous lesions on imaging. Dynamic contrast enhanced MR imaging is a useful tool in this regard.
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