Classification and management of cervical paragangliomas.

INTRODUCTION: Cervical paragangliomas are slow-growing tumours that eventually cause lower cranial nerve palsies and infiltrate the skull base. Surgical treatment may cause the same deficits and, in some, risks more serious neurological deficits. We describe a classification used to guide investigation, consent and management of cervical paragangliomas based on extensive experience. METHODS: The case notes of patients managed by the senior author at a tertiary referral skull base unit between 1987 and 2010 were reviewed retrospectively. A total of 87 cervical paragangliomas were identified in 70 patients (mean age: 46 years, range: 13-77 years). Of these, 35 patients had 36 vagal paragangliomas, 43 patients had 50 carotid body paragangliomas and 8 had both. One cervical paraganglioma arose from neither the carotid body nor the nodose ganglion. The main outcome measures were death, stroke, gastrostomy and tracheotomy. RESULTS: All tumours were classified pre-operatively based on their relationship to the carotid artery, skull base and lower cranial nerves. Type 1 tumours were excised with a transcervical approach, type 2 with a transcervical-parotid approach and type 3 with a combined transcervical-parotid and infratemporal fossa approach. Type 4 patients underwent careful assessment and genetic counselling before any treatment was undertaken. There were no peri-operative deaths; two patients had strokes, one required a long-term feeding gastrostomy and none required a tracheotomy. CONCLUSIONS: The use of a pre-operative classification system guides management and surgical approach, improves accuracy of consent, facilitates audit and clarifies which patients should be referred to specialised centres.

An arteriovenous malformation within the internal acoustic meatus and cerebellopontine angle cistern.

OBJECTIVES: We report a case of an arteriovenous malformation within the internal auditory meatus and cerebellopontine angle, and we discuss its imaging appearances and management. CASE REPORT: A 50-year-old man presented with a two-year history of vertigo. Magnetic resonance imaging and magnetic resonance angiography demonstrated a lesion consisting of multiple 'high flow' vessels within the left internal auditory meatus and cerebellopontine angle. Transarterial embolisation was performed, with obliteration of the arteriovenous malformation. CONCLUSION: Arteriovenous malformations of the internal auditory meatus and cerebellopontine angle are exceedingly rare. It is important that a pre-treatment diagnosis is made, as the management of arteriovenous malformation differs from that of other, more common lesions at this site.

Squamous cell carcinoma of the temporal bone.

OBJECTIVE: The aim of this study was to present the management and survival data of patients with squamous cell carcinoma of the temporal bone, and to discuss whether extensive surgery improves survival. PATIENTS AND METHODS: Retrospective, case-series review of 17 patients (18 cases) with temporal bone carcinoma (15 primary and three recurrent tumours), over a period of 20 years. SETTING: Tertiary referral centre-university hospital. MAIN OUTCOME MEASURES: Disease-specific and overall five-year survival. RESULTS: The mean age at presentation was 63 years, with a range of 39 to 75 years. Twelve cases of de novo tumour were managed by surgical resection followed by adjuvant radiotherapy in 10 cases, while three such patients were considered incurable from the outset and were given a combination of radiotherapy and chemotherapy. Of the three patients referred to our unit with recurrent disease, two were treated elsewhere with radical mastoidectomy and one with chemoradiation; all were subsequently managed by subtotal petrosectomy. The disease-specific and overall five-year survival for the entire cohort was 64.17 per cent (mean 89 months; 95 per cent confidence interval, 62-117) and 47.06 per cent (mean 70 months; 95 per cent confidence interval, 43-98), respectively. The disease-specific and overall survival for patients with advanced T3 and T4 tumours was 59 per cent (mean 83 months; 95 per cent confidence interval, 53-113) and 40 per cent (mean 62; 95 per cent confidence interval, 33-91 months), respectively. All but one recurrence developed within 12 months of initiating treatment. No deaths occurred after 26 months of follow up. CONCLUSIONS: A lateral temporal bone resection is adequate treatment for T1 and T2 tumours. Post-operative radiotherapy should probably be offered for large T2 tumours. For T3 and T4 tumours, a subtotal petrosectomy with parotidectomy followed by post-operative radiotherapy is adequate treatment, as it offers a similar outcome to that of more extensive procedures.

Extracranial glomus faciale tumour.

OBJECTIVES: To describe a unique presentation of a predominantly extracranial glomus faciale tumour. To discuss the role of imaging in the differential diagnosis and evaluation of a hypervascular parotid mass. To review the previous literature concerning the glomus faciale tumour. CASE REPORT: A 54-year-old woman presented with a six-month history of facial weakness, pain and a parotid mass. Ultrasound revealed a hypervascular parotid mass and pre-operative core biopsy suggested a paraganglioma. Computed tomography defined its deep extent and demonstrated involvement of the petrous temporal bone along the descending portion of the facial nerve canal with a pattern of permeative lucency. A tumour was surgically removed which arose from the facial nerve from the second genu to the proximal divisions within the parotid gland and histology confirmed a paraganglioma. CONCLUSIONS: A facial nerve glomus faciale tumour should be considered in the differential diagnosis of a hypervascular parotid mass and may present in a predominantly extracranial location. Computed tomography will prove helpful in such a case in order to limit the differential diagnosis and to define the extent of skull base involvement.

Mesotympanic sarcoidosis.

Sarcoidosis often presents with signs and symptoms within the head and neck. In this region, it most commonly affects the nose, larynx, parotid and cervical lymph nodes. Within the ear, it usually causes sensorineural hearing loss of varying severity. We report a patient in whom sarcoidosis involved the middle ear and presented with a conductive hearing loss. Granulomata were found in the middle ear during an exploratory tympanotomy. The granulomatous process had caused necrosis of the long process of incus and was also encasing the chorda tympani nerve. Histological examination confirmed the diagnosis.

Accumulation of Krebs cycle intermediates and over-expression of HIF1alpha in tumours which result from germline FH and SDH mutations.

The nuclear-encoded Krebs cycle enzymes, fumarate hydratase (FH) and succinate dehydrogenase (SDHB, -C and -D), act as tumour suppressors. Germline mutations in FH predispose individuals to leiomyomas and renal cell cancer (HLRCC), whereas mutations in SDH cause paragangliomas and phaeochromocytomas (HPGL). In this study, we have shown that FH-deficient cells and tumours accumulate fumarate and, to a lesser extent, succinate. SDH-deficient tumours principally accumulate succinate. In situ analyses showed that these tumours also have over-expression of hypoxia-inducible factor 1alpha (HIF1alpha), activation of HIF1alphatargets (such as vascular endothelial growth factor) and high microvessel density. We found no evidence of increased reactive oxygen species in our cells. Our data provide in vivo evidence to support the hypothesis that increased succinate and/or fumarate causes stabilization of HIF1alpha a plausible mechanism, inhibition of HIF prolyl hydroxylases, has previously been suggested by in vitro studies. The basic mechanism of tumorigenesis in HPGL and HLRCC is likely to be pseudo-hypoxic drive, just as it is in von Hippel-Lindau syndrome.

Congenital sialolipoma of the parotid gland first reported case and review of the literature.

Tumours of the parotid gland in children are uncommon, and represent only 1.3% of all benign salivary tumours. Lipomas of the parotid are also rare, and account for 0.5% of all parotid gland tumours. Sialolipoma is a new variant of salivary gland lipoma, consisting of adipose and glandular tissue that was first proposed by Nagao et al. in 2001. Ten cases of parotid gland lipoma associated with glandular elements have been previously reported in the literature. All have been in adults and none in children. We present the first reported case of congenital sialolipoma that had developed in a female infant. It was managed successfully by superficial parotidectomy undertaken at ten weeks of age.

Quality of life following microsurgery, radiosurgery and conservative management for unilateral vestibular schwannoma.

The best way to manage small and medium-sized vestibular schwannomas is currently a matter of heated debate. As these tumours are not immediately life-threatening, patients are invariably concerned about how management would affect their quality of life. Until now, no study has compared the three treatment modalities in terms of physical, psychological and social wellbeing. This study is based on a retrospective database analysis and postal questionnaire survey of unilateral vestibular schwannoma patients who had either been managed conservatively, or treated with microsurgery or radiosurgery. The results showed that: quality of life (measured by the Glasgow Benefit Inventory) deteriorated after microsurgery, particularly for small tumours; conservative management did not lead to a change in quality of life, and there was a trend towards poorer quality of life following radiosurgery. The findings suggest that a conservative management approach may be more appropriate for small tumours, and that patients who are due to undergo microsurgery or radiosurgery may benefit from counselling about the potential impact of treatment on quality of life.

3-D optical coherence tomography of the laryngeal mucosa.

Laryngeal carcinoma is one of the commonest primary head and neck malignancy and the need for early identification is very important for successful treatment. Outpatient fibreoptic examination of the larynx is unreliable in differentiating benign, pre-malignant and malignant lesions, and therefore surgeons have to rely on biopsies for a definitive diagnosis. This is an invasive procedure requiring general anaesthesia and may have a detrimental effect on the patient's voice. Conventional imaging modalities (ultrasound, computed tomography and magnetic resonance imaging) have a limited resolution and hence cannot give sufficient information on the extent or nature of laryngeal lesions. The aim of our study is to investigate the feasibility of optical coherence tomography (OCT) in imaging the normal larynx, to lay the foundations for an investigation of its ability to differentiate between benign and malignant disease. Ten tissue specimens from normal larynges were imaged with an 850 nm OCT system that was capable of providing both B-scan (longitudinal or cross-section) images as well as C-scan (en-face or images at constant depth). The en-face OCT mode allowed us to reconstruct 3-D OCT images of the tissue examined. Imaged specimens were processed with standard histopathological techniques and sectioned in the plane of the B-scan OCT images. Haematoxylin-eosin stained specimens were compared with the OCT images thus collected. Preliminary results showed good correlation between OCT images and histology sections in normal tissue.

Mycobacterial disease of the parotid gland.

Mycobacterial disease is an unusual but important condition that should be considered in the differential diagnosis of a discrete parotid gland swelling or mass. The management of this condition involves exclusion of neoplastic disease and combined medical and surgical therapy. We present 5 cases of mycobacterial involvement of the parotid gland and discuss issues surrounding the diagnosis and treatment options.

Design and evaluation of a system for microscope-assisted guided interventions (MAGI).

The problem of providing surgical navigation using image overlays on the operative scene can be split into four main tasks--calibration of the optical system; registration of preoperative images to the patient; system and patient tracking, and display using a suitable visualization scheme. To achieve a convincing result in the magnified microscope view a very high alignment accuracy is required. We have simulated an entire image overlay system to establish the most significant sources of error and improved each of the stages involved. The microscope calibration process has been automated. We have introduced bone-implanted markers for registration and incorporated a locking acrylic dental stent (LADS) for patient tracking. The LADS can also provide a less-invasive registration device with mean target error of 0.7 mm in volunteer experiments. These improvements have significantly increased the alignment accuracy of our overlays. Phantom accuracy is 0.3-0.5 mm and clinical overlay errors were 0.5-1.0 mm on the bone fiducials and 0.5-4 mm on target structures. We have improved the graphical representation of the stereo overlays. The resulting system provides three-dimensional surgical navigation for microscope-assisted guided interventions (MAGI).

Stereo augmented reality in the surgical microscope.

We present an augmented reality system that allows surgeons to view features from preoperative radiological images accurately overlaid in stereo in the optical path of a surgical microscope. The purpose of the system is to show the surgeon structures beneath the viewed surface in the correct 3-D position. The technical challenges are registration, tracking, calibration and visualisation. For patient registration, or alignment to preoperative images, we use bone-implanted markers and a dental splint is used for patient tracking. Both microscope and patient are tracked by an optical localiser. Calibration uses an accurately manufactured object with high contrast circular markers which are identified automatically. All ten camera parameters are modelled as a bivariate polynomial function of zoom and focus. The overall system has a theoretical overlay accuracy of better than 1 mm. Implementations of the system have been tested on seven patients. Recent measurements in the operating room conformed to our accuracy predictions. For visualisation the system has been implemented on a graphics workstation to enable high frame rates with a variety of rendering schemes. Several issues of 3-D depth perception remain unsolved, but early results suggest that perception of structures in the correct 3-D position beneath the viewed surface is possible.

A system for microscope-assisted guided interventions.

We present a system for surgical navigation using stereo overlays in the operating microscope aligned to the operative scene. This augmented reality system provides 3D information about nearby structures and offers a significant advancement over pointer-based guidance, which provides only the location of one point and requires the surgeon to look away from the operative scene. With a previous version of this system, we demonstrated feasibility, but it became clear that to achieve convincing guidance through the magnified microscope view, a very high alignment accuracy was required. We have made progress with several aspects of the system, including automated calibration, error simulation, bone-implanted fiducials and a dental attachment for tracking. We have performed experiments to establish the visual display parameters required to perceive overlaid structures beneath the operative surface. Easy perception of real and virtual structures with the correct transparency has been demonstrated in a laboratory and through the microscope. The result is a system with a predicted accuracy of 0.9 mm and phantom errors of 0.5 mm. In clinical practice errors are 0.5-1.5 mm, rising to 2-4 mm when brain deformation occurs.

The relationship between pure tone thresholds and the radiological dimensions of acoustic neuromas.

A retrospective analysis of 109 consecutive patients presenting with acoustic neuromas between 1986 and 1997 were undertaken. Sufficient data were available in 104 cases for comparison. In 65 cases patients had undergone surgery and the radiological diagnosis of acoustic neuroma was confirmed histologically. In this group there were 25 large and 40 small tumors when a maximal radiological diameter of 2.5 cm was used to subdivide the groups. When pure tone thresholds were compared at specific frequencies, in those with hearing ears, there was no significant difference between the two groups. Our results are compared with recent series and the causes of hearing loss associated with acoustic neuroma are discussed.

Malignant vagal paraganglioma.

Vagal paraganglioma is a rare usually benign tumour of neural crest origin. The malignant form of this tumour is very uncommon and the diagnosis is made on the basis of its clinical behaviour rather than its histological appearance. We report a case of vagal paraganglioma metastatic to adjacent cervical nodes and discuss the diagnosis and management of this tumour.

Feasibility study of magnetic resonance imaging-guided intranasal flexible microendoscopy.

Interventional magnetic resonance imaging (MRI) offers potential advantages over conventional interventional modalities such as X-ray fluoroscopy, ultrasonography, and computed tomography (CT). In particular, it does not use ionizing radiation, can provide high-quality images, and allows acquisition of oblique sections. We have carried out a feasibility study on the use of interventional MRI to track a flexible microendoscope in the paranasal sinuses. In this cadaver study, high-speed MRI was used to track a passive marker attached to the end of the endoscope. Automatic image registration algorithms were used to transfer the coordinates of the endoscope tip into the preoperative MRI and CT images, enabling us to display the position of the endoscope in reformatted orthogonal views or in a rendered view of the preoperative images. The endoscope video images were digitized and could be displayed alongside an approximately aligned, rendered preoperative image. Intraoperative display was provided in the scanner room by means of an liquid crystal display (LCD) projector. We estimate the accuracy of the endoscope tracking to be approximately 2 mm.

Solitary infantile and adult myofibromatosis of the nasal cavity: a report of two cases.

Myofibromatosis is an uncommon, usually cutaneous, condition in which there is a benign proliferation of myofibroblasts. Solitary and multicentric nodular forms with, and without, visceral involvement have been described. Infantile and adult sub-types have been reported, each having distinct clinicopathological features. Presentation in the head and neck is common. It is frequently misdiagnosed because of its peculiar histological features. The first documented cases of infantile and adult myofibromatosis involving the nasal cavity are reported.

Expression of adhesion molecules on the microvasculature of the pharyngeal tonsil (adenoid).

We have examined the vasculature of 12 human adenoids and the expression and distribution of four endothelial adhesion molecules, ICAM-1, VCAM-1, P-selectin and E-selectin, in tissue sections using histology, immunocytochemistry and immunoelectron microscopy (IEM). The connective tissue septa and septula contained arterioles, veins and efferent lymphatics. Branches of arterioles supplied lymphoid follicles and divided into sub- and intraepithelial capillary plexuses which drained into interfollicular venules, mostly high endothelial venules (HEV), before joining larger veins. No afferent lymphatics were observed entering the adenoid. Although ICAM-1 was widely distributed in the tissue, it was preferentially expressed on luminal aspects of HEV. E-selectin was found only in a few areas on HEV and subepithelial capillaries, whereas P-selectin was strongly expressed on segments of HEV, adjacent small venules and a few follicular capillaries. IEM showed the localisation of VCAM-1 on the components of the perivascular sheath, but not on the endothelium, of some HEV and capillaries. Its strongest expression was on follicular dendritic cells (FDC). These findings showed that in addition to HEV, lymphocyte-binding molecules are expressed on other segments of adenoid vasculature and their distribution and intensity of expression varies. In the non-inflamed adenoid, the VCAM-1 does not seem to participate in the adhesive mechanism of recirculating lymphocytes to the endothelium which, in this study, lacked the expression of VCAM-1 in all vessels.