Neuro-Orbital Symposium: Abstracts

Saturday 23rd November 2019

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Orbital vascular lesions: Role of the interventional radiologist

Orbital vascular lesions are a complex and varied group of lesions requiring a multidisciplinary approach to management. The historical terminology and nomenclature of these lesions is confused and often misleading. A clear, pathological-anatomical basis to classification, as proposed by the International Society for the Study of Vascular Anomalies, provides a clear standardised lexicon allowing clear communication across medical specialties and evidence-based approaches to therapy. We discuss the important primary distinction between proliferative vascular tumours and non-proliferative vascular malformations. We then focus on the group vascular malformations: the low flow capillary malformation (CM), venous malformation (VM) and lymphatic malformation (LM) and the high flow arteriovenous malformation (AVM). We relate anatomical and pathological basis to the varying clinical presentations, natural history and treatment strategies of these lesions. We look at examples of cases and examine the role of multimodality imaging in diagnosis and of interventional neuroradiology in management. Finally, we look at conditions which can mimic orbital vascular lesions and the critical importance of recognising these.

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Orbital AVMs: Surgical management

Orbital AVMs – combined endovascular and surgical management.

Orbital arteriovenous malformations (AVM) are relatively rare. Such malformations can markedly increase in both volume and arterial flow over months to years, causing progressive orbital aching and globe displacement. Treatment of such shunts requires detailed, selective angiographic assessment and endovascular occlusion of the feeding vessels, these often including watershed arterioles from both the internal and external carotid territories.

Closure of an AVM nidus can be achieved with ‘Glubran’ (50% histoacryl/Lipiodol), ‘Onyx’ (Ethylene vinyl alcohol copolymer dissolved in DMSO and suspended micronized tantalum powder), or ‘PHIL’ (Precipitating Hydrophilic Injectable Liquid).

Three patients are presented in whom excision of an orbital AVM was achieved between 2 and 6 weeks post-embolisation without haemorrhagic complication or visual loss. One patient presented with a deep orbital AVM and a rapidly progressive preseptal lid component; successful embolization and excision of the anterior malformation was achieved with improvement in both symptoms and appearance, although a deeper-seated orbital component persists. Another patient presented with a rapidly enlarging inferior orbital AVM soon after preganancy, suggesting a hormonal influence on progression.

With a multidisciplinary approach between interventional radiologist and orbital surgeon, individual arteriovenous malformations can be selectively embolised, with the occlusive precipitant being relatively inert and permitting clear visualization and intact excision. However, the decision to intervene for deeper orbital AVMs should be balanced against the presumed higher risk of post-surgical visual loss.

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Hemifacial spasm: Surgical management

First described in 1875, the management of hemifacial spasm remains challenging.

The possible pathophysiological theories behind the cause of hemifacial spasm are considered, alongside the important pre-operative clinical and radiological features for patient selection.

Different methods of achieving decompression of the nerve as well as highlighting intra-operative anatomical considerations and possible surgical pitfalls and how these are best avoided are discussed.

The increased use of intra-operative neurophysiology monitoring is highlighted as a way of improving surgical outcomes and post-operative symptomatic relief.

Three key points:

  1. Microvascular decompression for hemifacial spasm has been reported to have more than 90% cure rates
  2. High resolution imaging allowing excellent visualisation of the nerves and the conflicting vessels is mandatory
  3. The increased use of neurophysiology, looking at several indices, will improve the likelihood of post-operative symptomatic relief still further
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The challenge & management of slow flow dural shunts

Slow flow dural fistulas involving the cavernous sinus commonly present to ophthalmology with a red eye, occasionally chemosis if severe, or a ocular motor palsy. Tinnitus and proptosis seen with high flow fistulas such as following carotid artery trauma are not common. The more serious complications of other intracranial dural fistulas, such as cerebral venous infarction or haemorrhage are rare and raised intracranial pressure may possibly never occur in these cases. Complications include loss of vision (due to glaucoma), superior ophthalmic vein thrombosis, lid varices and persistent diplopia due to lack of recovery of a ocular motor cranial neuropathy. Diagnosis can be confirmed in the majority of cases by orbital ultrasound, looking for evidence of arterialised anterior flow in the superior ophthalmic vein. However catheter angiography will be required to plan management as the choice of intervention depends upon the precise anatomy.

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Endoscopic approaches to the orbit

Transnasal endoscopic orbital surgery is a nascient field incorporating the multi-disciplinary expertise of rhinologic and ophthalmic plastic surgeons to treat a variety of orbital tumors and disorders. In this lecture, we will describe the CHEER classification system which provides guidance to surgeons as to the accessibility of orbital locales from an endonasal perspective. We will also present a series of surgical videos highlighting salient considerations in a variety of diagnoses and orbital locations.

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Paranasal sinus cancer: Radiology and management

The holistic surgical management of sinonasal malignant disease is best considered as a triangle of patient, surgical and disease factors. Patient factors include patient preferences and wishes, as well as medical comorbidities. Surgeon factors include expertise and experience and choice of technique. The disease itself determines treatment choice through its location, spread and cell type.

These surgical approaches may be classified as open: rhinectomy, rhinotomy, midfacial degloving and craniofacial resection; and endoscopic - " piecemeal disassembly" resections. All of these interventions should take place within the setting of a multi-disciplinary team approach in a specialist centre with access to appropriate radio- and chemotherapeutic options.

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Endoscopic skull base surgery

Raj Bhalla, ENT rhinologist, and Omar Pathmanaban, neurosurgeon, from Manchester describe their experience of collaborative working to treat diseases of the skull base and orbital apices. They discuss the endoscopic corridors that they use and applications for their surgery, particularly for pathologies in and around the chiasm and optic sheaths. They discuss advantages of the endoscopic approach, but also scenarios where it is less appropriate. Also their tips on how to set up such a specialised service.

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Reconstruction of the skull base and orbit

This talk will briefly describe the history of recent reconstructive advances and how they have revolutionised the treatment of head and neck cancer and skull-base disease. It will focus on the late 20th century from the 1970s onwards when surgeons studied fresh cadavers to identify the blood supply of skin, muscle and bone tissue that could be removed from one part of the body and transplanted to another part of the body without causing undue harm at the donor site. It will list the advances in radiology that have aided diagnosis and treatment planning and the advances in anaesthesia which have enabled surgeons to substitute one long operation for many operations extended over months or years. And it will list the advances in surgical equipment particularly related to microsurgery that have facilitated this reconstructive revolution of microvascular free flap surgery.
Several examples will be used to show how large parts of the face and skull base can be removed or lost through trauma but reconstructed to a point where the patient can have confidence that the brain will be separated from the face, so not susceptible to infection, and facial appearance can be restored to a point where the patient can resume relatively normal life. These examples will also show the limitations of these advances in restoring special structures and facial expression.
Sometimes, the aim of surgery is not to cure the patient of disease but to prolong good quality life. The planning of this involves strong partnership with the patient and the family to ensure the expectations of the patient match those of the surgeon and the ability of the surgeon to deliver. The brings in the concept of surgical palliation of disease.

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Sphenoid wing meningioma: Neuroradiology

Meningiomas are the most common primary orbital brain tumour, with 20% centred on the sphenoid wing (SWM). There are two main growth patterns: the nodular or 'en-masse', and the more diffuse 'en-plaque' patterns. They are classified according to their site of origin along the sphenoid ridge: lateral, middle or clinoidal. Hyperostosis and sclerosis are common and are usually due to tumour infiltration rather than a reactive phenomenon.

MRI gives excellent contrast and spatial resolution, particularly with intravenous gadolinium. SWM is characterised as a well-circumscribed durally based mass, with variable T1 and T2 signal characteristics. On T2 they are usually iso- to hyperintense, and a dural tail occurs in about three quarters of cases. Up to 50% of tumours have elicited parenchymal vasogenic oedema, although this doesn't correlate with tumour size. Vessels that occur in a meningioma are visualised as serpiginous flow-void structures and can give an indication of tumour vascularity.

Diffusion-weighted sequences can be helpful and rely on free random “Brownian” motion of water molecules between the intracellular and extracellular space. In lesions with increased cellularity, such as SWM, that restriction of water molecule motion is depicted as hyperintensity on the diffusion-weighted trace image. This is quantified on the corresponding apparent diffusion coefficient (ADC) map, and gives a measure of cellularity, with restricted diffusion depicted as low signal. It can also help to differentiate between tumour mass and vasogenic oedema in SWM.

Meningiomas have a typical spectrum on MR spectroscopy (MRS) with an alanine peak and sometimes a glutamine peak, and although MRS is not routinely used in clinical practice, it may be helpful in atypical meningiomas. Meningiomas also express somatostatin receptors, hence the value of 68-Gallium Dotatate CT/MR imaging: the radio-labelled gallium attaches to the somatostatin receptor thus is avidly taken up thes tumours. This modality is useful where there is uncertainty about the diagnosis, where subtle recurrence is suspected or to clarify whether associated bony changes are reactive or due to infiltration.

The differential diagnoses for SWM include metastasis and fibrous dysplasia, amongst other lesions, but CT can differentiate the latter due to the presence of preservation of the cortex and typical regions of intra-diploic “ground-glass” matrix despite the additional bony expansion and sclerosis.

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The Manchester experience

Surgical resection of spheno-orbital meningiomas (SOM) is challenging, requiring a multidisciplinary surgical approach. In Manchester we have a dedicated skull base service with bimonthly MDT clinics involving Neurosurgeons, ENT and Orbital surgeons. We present a difficult case which came through our service of a young female developing sequential spheno-orbital meningiomas requiring surgical intervention.

We then present a retrospective analysis of patients with SOM who underwent joint neurosurgical and orbital surgical procedures between January 2000 and June 2017. Twenty four operations were performed. The indication for surgery was evidence of visual dysfunction in 17 (71%), the remaining 7 (29%) had high risk of visual loss clinically or radiologically. Three-months post operatively, vision was stable in 13 (58%), improved in 6 (21%) and worse in 5 (17%). Average long-term follow-up was 82 months (1-220). Fourteen (58%) maintain improved or stable visual function. Four (17%) had reduced vision due to regrowth of the tumour at an average of 24 months.

SOMs are very challenging to treat surgically. In our experience they predominantly affect young females with aggressive disease. Visual function can be improved or stabilised in the majority.

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Orbital surgery for sphenoid wing meningioma: When, why, and how

Sphenoid wing meningiomas are not curable, which raises the questions of “how to deal with residual disease”, “does partial resection make the tumour more pervasive”, and “how can we reduce or stop the marked periocular oedema due to fluid congestion around the superior orbital fissure (this oedema often being the earliest, and very troublesome, symptom)”?

With compressive optic neuropathy due to orbital tissue, one can get an excellent relief of neuropathy using a retrocaruncular medial decompression (complete ethmoidectomy, medial half of floor, and posterior half of infero-medial strut), whereas lateral bone decompression and soft-tissue resection through an extended upper lid skin-crease incision is especially useful where there is a larger hyperostotic component with marked proptosis; all orbital approaches can be combined with neurosurgery where necessary. Radiotherapy does slow the progression of the disease and so is very useful adjunct.

Remember to avoid progestogen-containing HRT, as these tumours are known to be driven by them and the medication is often prescribed at the age when the tumours are most common.

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Our current neuro orbital surgical approaches

There are 2 important and commonly used neurosurgical approaches to the orbit; variations of the pterional oblique lateral craniotomy to the middle and anterior fossae and secondly the supra-orbital craniotomy ideal for reaching the superior contents of the orbit. Both approaches will be described and examples given with both intra and extradural pathologies.

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Radiotherapy: State of the art

This presentation covers sphenoid wing meningioma from a radiotherapist’s perspective. An example case history of a grade II sphenoid wing meningioma is used to outline the indications for radiotherapy in meningioma and the principles of radiotherapy planning, including the typical radiotherapy doses used for different grades of meningioma and how nearby radiosensitive normal tissues influence the radiotherapy plan. The evidence for the effectiveness of radiotherapy is discussed and the case history concludes by considering the treatment options for recurrent disease, including re-irradiation. Finally, the presentation touches on proton therapy and the need for comparative studies to evaluate its place in the management of meningioma.

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Optic nerve sheath meningioma: Diagnostic challenges

Dr Braithwaite’s presentation provides a brief overview of the pathology, morphology, epidemiology, natural history and visual prognosis of optic nerve sheath meningiomas. Case-based reviews from Moorfields Eye Hospital and The National Hospital for Neurology and Neurosurgery illustrate the different ways in which optic nerve sheath meningiomas may present, and these are used to support a focused discussion of the differential diagnosis, and how this may be advanced. The emerging role for optical coherence tomography as a biomarker for monitoring and assessing visual prognosis in compressive optic neuropathies is highlighted, with particular focus on the value of segmenting the macular volume scan to examine the retinal ganglion cell layer volume for evidence of irreversible axonal loss.

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Optic nerve sheath meningioma: Neuroradiology

Optic nerve-sheath meningiomas (ONSMs) constitute a diagnostic and management challenge. Neuroradiology is integral in the diagnosis and management of these tumours. Neuroradiology is most effective when clinical assessment raises the possibility of ONSMs such that specialised imaging modalities, such as MRI and Gallium Dotatate scans, and imaging specific protocols can then be used to effectively detect and monitor these tumours.

There are specific imaging features which strongly suggest the diagnosis of ONSMs however, it is the role of an experienced neuroradiologist to exclude other pathologies such as schwannomas and cavernous haemangiomas which can mimic these appearances. This precludes the undesirable consequences of a biopsy of ONSMs.

Advanced neuroimaging holds some promise as a surrogate marker for treatment response given that there is a poor correlation between visual acuity recover and size/morphology of ONSMs.

Future initiatives should be directed towards curating a national and/or international database of cases thereby facilitating larger scale series, informing us of the natural history, facilitating effective biomarkers of prognosis and treatment response and for artificial intelligence intiatives for detection of these lesions.

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Advances in radiotherapy

The management of perioptic meningioma has moved from first line surgery to radiotherapy over the past 30 years. Radiotherapy can be expected to stabilise or improve vision in most cases when disease is confined to the orbit. Modern stereotactic fractionated delivery systems reduce the risk of radiation injury to the eye and adjacent structures. The threshold for treatment intervention is determined by the demonstration of progressive loss of function without delaying until irreversible advanced loss has occurred.  There remains a role for surgery to decompress the optic canal in selected cases, and the management of patients with significant middle cranial fossa involvement remains primarily surgical.

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Cherubism: Rare fibro-osseous dysplasia

Cherubism is a rare, genetic, fibro-osseous dysplasia which presents with progressive bilateral upper and lower jaw enlargement, with typical facial characteristics. First described by Jones in 1933, there are about 300 reported cases in the literature, the facial features bearing a passing resemblance to a biblical cherub.

Features include remodelling of normal bone to fibrous tissue with cyst formation, leading to early tooth loss, mandibular and maxillary enlargement. Orbital involvement is very rare, tending to present in advanced cases, leading to globe dislocation, ophthalmoplegia, optic nerve compression and macular striae and scarring. Where patients present with significant globe displacement and/or optic neuropathy, mass debulking of the lesion can be successful, as described in this case.

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Sphenoid wing meningioma: Complex cases

Three challenging cases of sphenoid wing meningiomas are presented. Each posed a unique challenge in either the diagnosis (case 1), symptom control (case 2) or management (cases 1- 3).

Case 1 presents a 35 year old gentleman with a history of a medulloblastoma operated on as a child and who received whole brain radiotherapy. He presented with proptosis. His MRI scan showed an extrinsic lesion centred around the left sphenoid wing which had both intra cranial and intra orbital components.

Case 2 presents a 38 year old lady with bilateral sphenoid wing meningiomas who underwent multiple surgeries over the years but unfortunately still lost her vision on the right. She also developed hypopituitarism and trigeminal neuralgia as a result of the tumour.

Case 3 presents a 41 year old lady who experienced proptosis in the immediate post-partum period that caused disabling diplopia. MRI revealed a sphenoid wing meningioma with a predominantly intra osseous component.

These cases each underwent a different management strategy despite having a common diagnosis. This presentation highlights the need for individualised patient care for patients with sphenoid wing meningiomas. Collaboration between the different specialties is key for success.

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