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Dr.Usha Singh, U05383

INTRODUCTION:

Vascular malformations of orbit are relatively uncommon and frequently require no intervention. Their involvement can range from pinpoint lesions to entire orbit and periorbita. In the orbit they are classified as superficial (preseptal), deep (postseptal), combined (preseptal and postseptal) or complex (when associated with systemic involvement). Based on type of vasculature Vascular malformations could be arterial, venous, lymphatic or combined.1,2. Because of this there is controversy regarding their nature, nomenclature, and classification and such lesions often present a diagnostic dilemma. Mulliken and Glowacki, proposed a classification on the basis of their natural history, including their growth pattern and histologic composition3.

Jack Rootman et al proposed a classification based on the classification by International Society for Study of Vascular Anomalies (ISSVA)4 of non-orbital vascular malformations. Based on pathological features and hemodynamic characteristics vascular malformations are classified as high flow, low flow. Low flow include venous, lymphatic and combined. This also includes transitional lesions which have elements of more than one type. Distensible vascular malformations of the orbit (DVMO) are characterized by significant increase in size demonstrated clinically or radiologically. They exhibit changes in their size on Valsalva maneuver or when head is placed in a dependent position.

Diagnosis of orbital vascular lesions is critical in management. Current diagnostic imaging techniques include X rays, ultrasonography, computed tomography (CT) scan, CT angiography (CTA), magnetic resonance imaging (MRI), magnetic resonance angiography (MRA), nuclear scintigraphy, colour doppler imaging, and A- and B-mode orbital echography5. There is paucity in literature about the standard technique in diagnostic imaging of distensible vascular malformations of orbit.

In this prospective study, dynamic MRA was done as a firstline investigation in patients with DVMOs, with the aim to know the flow dynamics, morphological and hemodynamic nature of the lesion, and whether this investigation alone was sufficient in planning treatment along with histopathological correlation in the cases operated upon.

MATERIAL AND METHODS

In patients with DVMOs, detailed history, morphological description of the lesion in terms of size, extent, appearance and functional deficits were noted. Complete ocular examination which includes visual acuity by using snellen’s chart, intraocular pressure by using noncontact tonometer (NCT)/ Goldmann applanation tonometer(GAT), anterior segment examination by slit lamp examination, posterior segment examination using a  90 D lens on slit lamp examination or with  a 20 D lens with indirect ophthalmoscopy, refraction, colour vision, visual fields, auscultation and Valsalva maneuver were taken into consideration.

All the above patients underwent dynamic magnetic resonance angiography on a Siemens 1.5 T system (SIEMENS AERA). The following sequence parameters were used: TR 3.47ms, TE 1.38 ms, flip angle (FA) 25°, base resolution 448, phase resolution 100%, slice resolution  81%, slice thickness 1mm. In this study, we have used a value of 15% for k space center, and sampling density of  20% for k space periphery. Gadolinium (0.1-0.2 mmol/kg) was used as contrast material.

Pre imagingcounseling about the complications of MRI and the contrast that is being used was explained .and consent taken. To study the morphology the following MR sequences were used: 1)Axial T1WI, T2WI, Fat suppressed T1WI. 2) Coronal T1WI, T2WI, Fat suppressed T1WI. 3)3D T1WI, 4) High resolution T2WI with and without Valsalva Maneuver. To study the Flow character, the following MR sequences were used: 1) Dynamic contrast MR angiography. 2)Post contrast 3D T1WI.   Characterization of contrast enhancement was done on the computer screen by comparing early and late phases. Evaluation of Images acquired were done by a neuro-radiologist who was unaware about the clinical / CT / MRI findings of the patients.

For evaluation and analysis, following points were studied,: 1) Location and extent of the lesion, 2) Presence or absence of abnormal vessels. 3) Nature of flow- low flow/ high flow/ combined. 4) Response to Valsalva maneuver: distensible versus non-distensible. Attempt was made to classify the lesion into: 1) Low flow versus high flow lesion. 2) AV malformation/ pure venous/ pure lymphatic/ mixed malformation.

For surgical consideration, every patient was informed about the surgery and the risks associated with it and informed consent was taken. All surgeries were done under general anaesthesia. Intraoperative total or near total excision of the mass was done using cyanoacrylate glue and the sample was sent for histopathological examination. Evaluation of pathological slides was done by a histopathologist who was unaware of clinical diagnosis and  DMRA findings.

RESULTS

Total 16 patients (n=16) are enrolled for study, of which 9 are females and 7 are males with mean age of 24.38yrs (SD: 12.077; range: 10yrs- 51yrs). Seven out of 16 (43.75%) patients were referred from other hospitals. Initiating events prompting the patient to seek consultation were pain(7, 43.75%),recent onset discomfort on distension (2, 12.5%), residual mass after surgery(2, 12.5%), pain and bloody discharge(1, 6.35%), trauma(1,6.3%), residual mass after surgery(2, 12.5%), recent increase in lesion size(1 of 16, 6.3%), and generalized tonic-clonic seizures(GTCS)(1, 6.3%).

All patients best corrected median visual acuity(BCVA) logmar was 0 in both eye. Four patients had refractive errors of which two had simple myopic astigmatism, one had compound myopic astigmatism and other had mixed astigmatism. Eyelids were involved in 10.  Extraocular extension of lesions were seen in 7(43.75%). On clinical Valsalva maneuver increase in size of lesion was seen in 12(75%) and 4(25%) had protrusion of globe

Hemodynamics revealed the following:  1) On T1WI, 12(75%) had hypointense lesions and isointense in 3(18.75%) and hyperintense in 1(6.25%). 2) On T2WI all( 100%) had hyperintense lesions. 3) On magnetic resonance angiography (MRA) no abnormal flow seen in any patient suggestive of absence of arterial feeder. 4) On DMRA venous flow of lesion is seen in 10 (62.5%) patients and in 6(37.5%) no arterial or venous feeders present. 5) Seven patients (43.75%) had intensely enhancing lesions, 6(37.5%) had progressively enhancing lesions and 3(18.75%) had both intense enhancement and pooling of contrast (Figure 1). Location: 1) Orbit was involved in all, involving superior orbit in 8, inferior orbit in 3 and remaining 5 it was primarily located in retroorbital region. 2) Six lesions were located in preseptal area and extended to the orbit.

Diagnosis included 7 (43.75%) with cavernous hemangioma, 7 (43.75%) with venous varix and 2 (12.50%) with mixed malformations after imaging. All (100%) were low-flow vascular malformations. Lesions were excised in 8 for symptoms of pain, cosmesis and swelling. Histopathology revealed cavernous hemangioma in 6, lymphangioma and venous varix in 1each which are all low-flow lesions. In terms of flow pattern based on the above hemodynamic study there was 100% correlation between preoperative and postoperative diagnosis. However, specific tissue diagnosis of orbital lesions correlated with only 50% of imaging diagnosis.

DISCUSSION

Vascular malformations of orbit are relatively infrequent, and some are very rare. VMs can be either distensible or non-distensible. Distensible vascular malformations are those that may exhibit distensibility on clinical examination (positive Valsalva response) and/or during dynamic investigations, such as ultrasound with Doppler assessment, dynamic arterial and Valsalva augmented venous phase multi detector CT angiography(DP-MDCTA), MRI, or on direct injection of contrast with and without Valsalva maneuver6. They communicate with venous system either directly or through dysmorphic channels. Only 60% can undergo distensibility on Valsalva maneuver and remaining 40% may show distension during appropriate imaging. Distensible VMs can be painful due to thrombosis or hemorrhage or even on sudden expansion due to physical stress.7-9 In our study we had 6 patients with complaints of pain. Histologically three types of VMs are noticed in the orbit which includes dysmorphic, spongy, and cavitary. Of these dysmorphic variety is more common, followed by spongy and cavitary.

There are two major retrospective studies which have used DMRA (TRICKS/ TWIST) in the evaluation of vascular lesions involving orbit. Kahana et al6 carried out TRICKs in 5 cases, one each of cavernous hemangioma, solitary fibrous tumor, AV malformation and in two cases of orbital varix (Table 4). They found DMRA useful in counseling, changing diagnosis, change in treatment decision and planning intraoperative embolization.  Ramey et al10 carried out TRICKS in mass lesions of head and neck, of which 12 lesions involved the orbit. They advocate TRICKS for cases with uncertain diagnosis and for better management of lesions. Overall TRICKS helped to clarify diagnosis in 19 of the 49 (38.7%) cases. To the best of our knowledge there is no prospective study regarding usage of DMRA for differentiating various types of distensible vascular malformations and in their management. So we did aprospective study, using DMRA (TWIST) as the primary imaging modality in a selected group of vascular lesions of the orbit and adnexa, which demonstrated distensibility on clinical evaluation.

In this study, all the patients with clinical distension on Valsalva maneuver were found to be hemodynamically low flow lesions. All had enhancement of lesions after injection of contrast. Type of enhancement differed based on the hemodynamic nature of the lesion. In progressive enhancement, increase in signal intensity is present in the late phase of DMRA as compared to early phases. Prolonged injection of the contrast causes pooling of contrast material in the late phase, which is a very important feature in differentiating lesions. Smoker et al.11 stated that cavernous hemangiomas mostly show progressive enhancement whereas varices show intense enhancement. Pooling of contrast helps in differentiating cavernous malformations from arterio-venous malformations, capillary hemangiomas, aneurysms. One of our caseof orbital varix showed progressive enhancement.  Imaging here revealed simultaneous venous flow in sagittal sinus as well as in the lesion and hence was diagnosed as orbital varix. However, histopathology reported it to be a hemangioma. Three cases clinically diagnosed as varix had intense enhancement of contrast and absence of arterial feeders on DMRA.

Embolization of vascular anomalies of the head and neck region with N-Butyl cyanoacrylate (NBCA) has been used for many years. It has been used for endovascular embolization of intracranial arteriovenous malformations, to enable neurosurgical resections, in the treatment of arteriovenous fistulas.12-13 Tsai et al14used intraoperative embolization with NBCA in a case of orbital varix prior to resection. We too used intraoperative NBCA for total or near-total surgical resection of various vascular lesions. We found its undiluted use had quick polymerization, localized effect, minimized bleeding and no damage to surrounding tissues.

Histopathological diagnosis in eight distensible lesions corresponded with 50% of DMRA verdict. This is in difference with the 85% accurate diagnosis reported by Ramey et al. However, it is important to clarify this high correlation referred to various miscellaneous vascular lesions of head and neck only. In their 12 orbital cases, only two DMRA diagnoses were confirmed histopathologically. Akin to this study, Kahana et al had one clinical case of cavernous hemangioma with a revised DMRA verdict of hemangiopericytoma, which was reported as solitary fibrous tumor based on histochemical staining.

Overall, application of DMRA in distensible vascular lesions was useful in hemodynamically characterizing and localizing this subset of vascular lesions. Distensible vascular lesions are low flow and have either progressive or intense enhancement after dye administration. Pooling of dye was seen in orbital varices. It also provides data on the absence of feeder arteries and presence of draining veins, thus assisting in planning surgical excision. This study also brings forth the presence of distensible cavernous hemangiomas, its variable enhancement pattern and distensibility of lymphangioma. Histopathological confirmation was evident in only half the cases. Undoubtedly, these vascular lesions range from simple to complex in clinical presentations, radiologically and in histopathological context.  There is a need for further hemodynamic studies, with more evolved technology for evaluating vascular lesions in order to characterize them and perhaps assist in their effective management.

REFERENCES

  1. Brouillard P, Vikkula M. Vascular malformations: localized defects in vascular morphogenesis. Clin Genet 2003;63:340–51.
  2. Lasjaunias P. A revised concept of the congenital nature of cerebral arteriovenous malformations. IntervNeuroradiol1997;3:275–81.
  3. Mulliken JB, Glowacki J. Classification of pediatric vascular lesions. PlastReconstrSurg1982;70:120–1.
  4. RootmanJ, Heran MKS, and Douglas AG. Vascular Malformations of the Orbit: Classification and the Role of Imaging in Diagnosis and Treatment Strategies. OphthalPlastReconstrSurg2014;30:91–104.
  5. Johnson JB, Cogswell PM, McKusick MA, Binkovitz LA, Reiderer SJ, Young PM.Pretreatment imaging of peripheral vascular J Vasc Diagn 2014;2:121-126.
  6. Kahana A, Lucarelli MJ, Grayev AM, Buren JJV, Burket CN, Gentry LR. Noninvasive Dynamic Magnetic Resonance Angiography with Time-Resolved Imaging of Contrast KineticS (TRICKS) in the Evaluation of Orbital Vascular Lesions. Arch Ophthalmol 2007;125:1635-1642
  7. Mavrikakis I, Heran MK, White V, et al. The role of thrombosis as a mechanism of exacerbation in venous and combined venous lymphatic vascular malformations of the orbit. Ophthalmology 2009;116:1216–24.
  8. Wright JE, Sullivan TJ, Garner A, et al. Orbital venous anomalies. Ophthalmology 1997;104:905–13.
  9. Menon SV, Shome D, Mahesh L, et al. Thrombosed orbital varix- a correlation between imaging studies and histopathology. Orbit 2004;23:13–8.
  10. Mavrikakis I, Heran MK, White V, et al. The role of thrombosis as a mechanism of exacerbation in venous and combined venous lymphatic vascular malformations of the orbit. Ophthalmology 2009;116:1216–24.
  11. Smoker WRK, Lindel RG, Norbert KY, Deborah LR, Jeffrey AN. Vascular lesions of the orbit: More than meets the eye. Radiographics2008;28:185-204
  12. Wright JE, Sullivan TJ, Garner A, et al. Orbital venous anomalies. Ophthalmology 1997;104:905–13.
  13. Menon SV, Shome D, Mahesh L, et al. Thrombosed orbital varix- a correlation between imaging studies and histopathology. Orbit 2004;23:13–8.
  14. Tsai AS, Fong KS, Lim W, Jejeh IA, et al. Bilateral orbital varices: an approach to management. OphthalPlastReconstrSurg2008;24:486–488.

 

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