Medico 14th issue

Médico A quarterly publication of GP Liaison Centre, National University Hospital.

MICA (P) No. 018/08/2012

December 2012 - February 2013

Medical Sp

tlight

Robotic Assisted Head and Neck Surgery

Approach to Ear Discharge Endoscopic Skull Base Surgery Department of Otolaryngology, NUH

1st row (L to R) : Prof James D Smith, A/Prof Thomas Loh, A/Prof Wang De Yun 2nd row (L to R) : A/Prof Lynne Lim, Dr Raymond Ngo, Dr Ong Yew Kwang, Dr Loh Woei Shyang, Dr Lim Chwee Ming, Dr Mark Thong, Dr Chao Siew Shuen

2-4 Medical Spotlight

A member of the NUHS

5 Medical Notes

6-7 Treatment Room

8 - 13 Insight

14 - 15 Doctor’s Heartbeat

Medical Spotlight Robotic Assisted Head and Neck Surgery Dr Lim Chwee Ming, Consultant, Department of Otolaryngology - Head & Neck Surgery

Robotic assisted surgery has established itself as an accepted approach in many surgical specialties, including head and neck surgery. The advantages of using the robotic system include its enhanced magnification, 3-dimensional optics, as well as increased degree of movements with the “wristed” robotic arms which have allowed surgeons to navigate and resect tumours in “tight-cavities” such as the pelvis and oropharynx/larynx in the head and neck region.

Furthermore, with the aid of robotic system, remote access surgery is made possible since the robotic arms can allow the surgeon to operate from a distance. For example, performing thyroidectomy can be safely achieved through an axillary incision with the robotic system (Figure 1). This article serves to highlight the indication(s) of using this novel technology in head and neck surgery, and present the current and future development in robotic assisted head and neck surgery.

Fig. 1 - Trans-axillary approach to thyroidectomy

Transoral Robotic Surgery (TORS) TORS is FDA-approved in the surgical management of T1T2 oropharyngeal cancer. Traditionally, transoral resection of oropharyngeal tumour is challenging as the surgeon has difficulty visualising the deep aspect of the tongue base resection which precludes safe and oncologic resection. In many cases, a traditional lip-split, midline mandibulotomy approach is necessary (Figure 2).

With the use of TORS, oropharyngeal tumour can be effectively and safely removed and this technology is gaining widespread acceptance among head and neck surgeons (Figure 3).

Numerous clinical studies in tertiary centres in the USA have shown favourable clinical outcomes in patients treated surgically using TORS1-5. Furthermore, improved swallowing outcome is evident from these studies5,6.

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Fig. 2 - Lip split midline mandibulotomy approach to the oropharynx

Particularly relevant is the increased prevalence of human papillomavirus (HPV) associated oropharyngeal cancer (HPV-OPC) – which typically presents with a small primary tumour and relatively larger nodal metastasis7,8. This has clinical implications as the robotic system can be used to resect these small tumours transorally without the conventional open approaches.

Medical Spotlight

Training for robotic head and neck surgery With the increasingly use of robotic head and neck surgery, there needs to be a re-look in the surgical training for residents and head and neck surgeons wanting to adopt this new technology.

Fig. 3 - TORS for oropharynx cancer

In the USA, the prevalence of HPV-OPC has reached epidemic proportions with up to 90% of all OPC being HPV positive9. Locally, our NUH data has shown a prevalence of 41% of HPV-OPC (unpublished data).

Beside oncologic head and neck surgery, robotic tongue base reduction surgery can also be safely performed on obstructive sleep apnea (OSA) patients. Prior to the advent of robotic system, there are a myriad of tongue base procedures for OSA with mixed results10. Using the robotic system, a more precise reduction of the tongue base can be achieved to increase the airway without compromising on swallowing function. A recent published study showed that TORS for OSA has improved clinical outcome compared to other surgical procedures targeting to improve tongue base obstruction11. However, the long term result of TORS tongue base reduction is still unknown and we are eagerly waiting for more data on this aspect.

Remote access surgery Thyroidectomy is a common head and neck surgery for management of both benign and malignant thyroid nodules.

The standard midline neck crease incision is gradually frowned upon by patients who are concerned about the visible midline neck scar.

With this concern in mind, head and neck surgeons have started performing thyroidectomy from a remote access area (e.g. axilla). The initial experience with endoscopicassisted thyroidectomy via an axillary approach was first popularised in Korea12. With the robotic system, surgeons are increasingly utilising robotic assisted thyroidectomy via the axillary approach13,14.

First, the anatomy of the relevant area needs to be re-learned.

The traditional “lateral to medial” anatomy needs to be relooked from a “medial to lateral” perspective. The transoral anatomy is important to understand the 3-dimensional perspective for oncologic resection and to identify landmarks necessary to prevent inadvertent neurovascular injury. For example, the identification of the glossopharyngeal nerve transorally may become a standard for oncologic resection of oropharyngeal cancer. Preservation of this nerve may result in better post-operative swallowing function although a prospective study is warranted to prove this logical hypothesis.

Second, the training of using of the robot needs to be systematically addressed. Currently, there is dry-lab training available for surgeons to be acquainted with the function of the robotic system. Further training is also available in the form of didactic lectures and live dissection using animal model or cadaveric dissection. Proctorship is also available to allow adequate clinical experience to be attained with supervision from more experienced head and neck surgeons.

Future directions The future of robotic assisted head and neck surgery looks promising as more research, both clinical and preclinical, are embarked to expand its clinical indications as well as to further develop a more versatile robotic system.

Robotic neck dissection is currently performed and initial clinical experience has demonstrated good safety and oncologic outcome. Moreover, robotic-assisted nasopharyngectomy is being performed in some centres with positive early experience.

With evolution of surgical technology, there is also intense research to design smaller robotic systems to allow an even more flexible system to be employed in “tight-cavity” such as the oropharynx/larynx. Additional haptic (tactile) feedback system is also being actively explored by biomedical engineers to allow real-time tactile feedback currently not available with the present robotic system.

Outcome data from Korea has shown that this approach is associated with equivalent results with respect to complication rate and oncologic resection compared to the standard midline neck approach15.

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Medical Spotlight

References

Dr Lim Chwee Ming Dr Lim is currently a Consultant in the Department of Otolaryngology – Head & Neck Surgery at the National University Hospital. He is also part of the Head & Neck Tumour Group at the National University Cancer Institute, Singapore (NCIS). He graduated from the Faculty of Medicine, National University of Singapore, in 1998. He underwent residency in Otolaryngology in 2003 and was awarded the Gold Medal Award by the College of Surgeons for the best performing resident in the exit examination organised by the Specialist Training Committee in Otolaryngology in 2009.

He recently completed the 2-year Head and Neck Surgery Fellowship at University of Pittsburgh Medical Center (2010-2012) which is accredited by the American Head and Neck Society.

Dr Lim’s main practice is in head and neck oncology surgery, especially in the use of minimally invasive techniques in head and neck surgery (e.g. endoscopic or robotic assisted approaches). His other focus is in cancer research, especially in the field of cancer immunology and immunotherapy. He has published papers in peer-reviewed journals and has presented in numerous international meetings. He holds several grants including the NMRC New Investigator grant in the field of head and neck cancers.

Email address: chwee_ming_lim@nuhs.edu.sg

1. Weinstein GS, O’Malley BW, Jr., Snyder W, Sherman E, Quon H. Transoral robotic surgery: radical tonsillectomy. Arch Otolaryngol Head Neck Surg 2007;133:1220-6.

2. Weinstein GS, O’Malley BW, Jr., Cohen MA, Quon H. Transoral robotic surgery for advanced oropharyngeal carcinoma. Arch Otolaryngol Head Neck Surg 2010;136:1079-85.

3. Weinstein GS, O’Malley BW, Jr., Desai SC, Quon H. Transoral robotic surgery: does the ends justify the means? Curr Opin Otolaryngol Head Neck Surg 2009;17:126-31.

4. Henstrom DK, Moore EJ, Olsen KD, Kasperbauer JL, McGree ME. Transoral resection for squamous cell carcinoma of the base of the tongue. Arch Otolaryngol Head Neck Surg 2009;135:1231-8.

5. Moore EJ, Olsen KD, Kasperbauer JL. Transoral robotic surgery for oropharyngeal squamous cell carcinoma: a prospective study of feasibility and functional outcomes. Laryngoscope 2009;119:2156-64.

6. Leonhardt FD, Quon H, Abrahao M, O’Malley BW, Jr., Weinstein GS. Transoral robotic surgery for oropharyngeal carcinoma and its impact on patient-reported quality of life and function. Head Neck 2011.

7. Cohen MA, Weinstein GS, O’Malley BW, Jr., Feldman M, Quon H. Transoral robotic surgery and human papillomavirus status: Oncologic results. Head Neck 2011;33:573-80.

8. Psyrri A, Gouveris P, Vermorken JB. Human papillomavirus-related head and neck tumors: clinical and research implication. Curr Opin Oncol 2009;21:201-5.

9. Sturgis EM, Ang KK. The epidemic of HPV-associated oropharyngeal cancer is here: is it time to change our treatment paradigms? J Natl Compr Canc Netw 2011;9:665-73.

10. Babademez MA, Yorubulut M, Yurekli MF, et al. Comparison of minimally invasive techniques in tongue base surgery in patients with obstructive sleep apnea. Otolaryngol Head Neck Surg 2011;145:858-64.

11. Friedman M, Hamilton C, Samuelson CG, et al. Transoral robotic glossectomy for the treatment of obstructive sleep apnea-hypopnea syndrome. Otolaryngol Head Neck Surg 2012;146:854-62.

12. Lee J, Chung WY. Current status of robotic thyroidectomy and neck dissection using a gasless transaxillary approach. Curr Opin Oncol 2012;24:7-15.

13.Tae K, Bae Ji Y, Hyeok Jeong J, Rae Kim K, Hwan Choi W, Hern Ahn Y. Comparative study of robotic versus endoscopic thyroidectomy by a gasless unilateral axillo breast or axillary approach. Head Neck 2012.

14.Tae K, Ji YB, Jeong JH, Lee SH, Jeong MA, Park CW. Robotic thyroidectomy by a gasless unilateral axillo-breast or axillary approach: our early experiences.

Surg Endosc 2011;25:221-8.

15. Tae K, Ji YB, Cho SH, Lee SH, Kim DS, Kim TW. Early surgical outcomes of robotic thyroidectomy by a gasless unilateral axillo-breast or axillary approach for papillary thyroid carcinoma: 2 years’ experience. Head Neck 2012;34:617-25.

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Medical Notes First Simultaneous Pancreas and Kidney Transplant in Singapore

Transplant patient Shawn Huang (seated, in grey) with (from left) transplant coordinator Manjit Kaur, Dr Tiong Ho Yee, Dr Victor Lee, Assoc Prof Krishnakumar Madhavan and Prof A Vathsala.

Source: Shin Min Daily News Š Singapore Press Holdings Ltd. Reprinted with permission

The first simultaneous pancreas and kidney (SPK) transplant in Singapore was successfully carried out last month at the National University Hospital (NUH).

The five-and-a-half hour surgery was led by Associate Professor Krishnakumar Madhavan, Director of NUH’s Adult Liver and Pancreas Transplantation Programme, and performed together with Dr Victor Lee, Director, Pancreas Transplant and Consultant, Department of General Surgery, SGH; and Dr Tiong Ho Yee, Director, Kidney Surgery and Transplantation, NUH.

Potential recipients should have confirmed Type 1 diabetes and be on insulin with life-threatening or significant diabetic complications. They should not be above 55 years old at the time of referral, as the risk of surgery is higher for older patients. For SPK transplant recipients, they should also qualify for kidney transplant on their own merit, that is, be on dialysis and be eligible to be put on the national waitlist for kidney transplant.

The pancreas transplant service is currently piloted in NUH.

The patient, a 29-year-old Singaporean male, suffered from Type 1 diabetes and renal failure. He had been on insulin for over 15 years and on dialysis for more than a year. He has been registered on the waiting lists for both pancreas and kidney transplants since August 2011.

The patient is recovering well and will continue to receive follow-up care at the NUH. A pancreas transplant provides a potential cure for diabetes, particularly Type 1. It can improve the quality of life and reduce long-term diabetic complications such as kidney failure, blindness and stroke. It has been shown to prolong survival in patients with Type 1 diabetes and renal failure.

Without transplant, the 5-year survival for such patients in Singapore is 38 per cent. With a successful dual pancreas kidney transplant, the expected 5-year survival is more than 90 per cent.

For more information, please contact: National University Centre for Organ Transplantation (NUCOT) Main Building Level 1 Lift Lobby 1 Ms Manjit Kaur Tel: 6772 4439 Fax: 6778 7913 Email address: transplant_manjit@nuhs.edu.sg

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Treatment Room Approach to Ear Discharge Dr Ngo Yeow Seng Raymond, Consultant, Department of Otolaryngology – Head & Neck Surgery

Having ear discharge can be a very bothersome symptom. Often, this symptom is accompanied by pain, itch or hearing loss. The causes can range from a simple acute otitis externa to a dangerous large erosive cholesteatoma. Thankfully, the ear canal can be easily visualised and the cause can be identified based on the patient’s history and a physical examination.

Pertinent points to identify in the patient’s history include the duration of the discharge, the consistency of the discharge, the presence of previous ear problems or skin problems.

New onset ear discharge In a history of a preceding upper respiratory tract infection with blocked ears and pain, the clinician should consider the possibility of an acute infective otitis media with resultant tympanic membrane perforation. This has implications, as some eardrops are ototoxic if they enter the middle ear.

A new onset of acute ear discharge is most frequently due to an acute otitis externa. The causative organisms are pseudomonas and staphylococcus in the majority of cases.

Treatment of an acute otitis externa is mainly with antibiotic eardrops. This is preferred over oral antibiotics as the concentration is better topically with less systemic side effects.

Common eardrops available contain aminoglycosides and steroids. In any doubt about the integrity of the tympanic membrane, the use of ototoxic eardrops is discouraged.

Allergic otitis externa A patient who gets recurrent otitis externa should be suspected of having an allergic otitis externa. There is frequently concomitant eczema elsewhere. Because topical eardrops often contain steroids, it may improve the symptoms for a period of time, only to have it recur again.

The treatment should be targeted at the eczema with corticosteroid ointments and oral antihistamines.

Some patients may be worse on topical antibiotic eardrops, due to an allergy to the preservative of the eardrop. The treatment would be to stop the eardrops.

Chronic Hypertrophic Otitis externa

Acute Diffuse Otitis Externa

Persistent ear discharge In long-standing ear discharge, or if the condition does not improve after treatment with topical antibiotic eardrops, the clinician needs to consider other differentials.

Chronic suppurative otitis media (CSOM) Patients with long standing tympanic membrane perforations may complain of a persistent ear discharge if the middle ear becomes infected. The perforation should be obvious on examination with an otoscope.

These patients can be treated with topical or systemic antibiotics. Ototoxic eardrops should be avoided. If the discharge persists or is recurrent, a myringoplasty operation to repair the tympanic membrane is recommended.

Otomycosis This is frequently mistaken for a bacterial otitis externa. The typical history is a patient with ear discharge, pain, and maybe itch which does not improve with topical antibiotics after multiple clinic visits. Careful examination with an otoscope may reveal fungal spores. The treatment is to use topical antifungal agents, either as eardrops or an ointment.

CSOM Mucopus

Otomycosis (Aspergillus Niger)

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Treatment Room

Chronic Myringitis Patients with myringitis are difficult to cure. The tympanic membrane, which is typically squamous lined, becomes mucosalised. This leads to a mucoid secretion from the tympanic membrane, which presents as ear discharge.

antibiotics that contain steroids. However, the infection may persist in the skull base and will require long term antibiotics at least 6 weeks with good glucose control.

The tympanic membrane would be intact, but has a wet look to it with many blood vessels. This condition occurs after recurrent ear infections or after myringoplasty. These patients require regular ear toilet and the use of a steroid based ointment may improve the symptoms.

Necrotizing Otitis Externa

Granular Myringitis

Cholesteatoma Most cholesteatomas are secondary to a retraction pocket that starts to trap keratin debris.

These pockets frequently form in the superior or posterior aspect of the tympanic membrane. The opening of these pockets can be small and hence missed on routine otoscopic examination.

A patient with persistent ear discharge without an obvious cause should lead the physician to carefully examine the ear after cleaning the ear canal. Some clues include granulation tissue formation or mucus track leading from the opening of the retraction pocket.

Conclusion In NUH, a study was conducted in 2010 to review the microbiology of otorrhoea referred to a tertiary institute. The findings showed that the 3 most common microorganisms responsible for otorrhoea are Pseudomonas Aeruginosa, Staphylococcus Aureus and fungal organisms in that order.

Persistent discharge despite empirical treatment should trigger an ear culture to identify the causative organism and its antibiotic sensitivity. A persistent ear discharge can be reviewed by an Otolaryngologist to exclude and identify dangerous or less common diagnoses.

Dr Raymond Ngo Dr Raymond Ngo is an ENT Surgeon at the National University Hospital, with a subspecialty practice in middle ear surgery for infections and hearing loss, cochlear implantation, lateral skull base surgery and vestibular management.

He is also a Clinical Teacher with the National University of Singapore (NUS), Faculty of Medicine, where he is involved in the teaching of medical undergraduates, mentoring of junior doctors and providing continuous medical education and updates to fellow doctors.

Email address: raymond_ngo@nuhs.edu.sg

Epidermoid Cholesteatoma

Malignant Otitis Externa This diagnosis is often delayed due to the hidden nature of the problem. The key to getting this diagnosis is to suspect it in any patient that has poorly controlled diabetes or is immuno-compromised.

The name is a misnomer as it is not a true malignancy, but a skull-base osteomyelitis. The presentation is severe otalgia with minimal external ear canal inflammation. At times, there maybe slight ear discharge and granulation tissue formation. But the signs easily resolve with topical

Footnote: All images in this article are copyright to Michael Hawke MD. Credit: “The Hawke Library.�

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Insight Endoscopic Skull Base Surgery – Development of a Sub-specialty in Otolaryngology Dr Ong Yew Kwang, Consultant, Department of Otolaryngology – Head & Neck Surgery

Introduction The introduction of functional endoscopic sinus surgery (FESS) in 1985 has revolutionised the surgical treatment of sinonasal disorders1,2. Almost all inflammatory conditions and benign sinonasal tumours are now exclusively treated using an endonasal approach. Endoscopic sinus surgery is not confined to the domain of otolaryngology but has also spread to ophthalmology and neurosurgery. Ophthalmic conditions such as lacrimal duct obstruction and thyroid orbitopathy can be treated with endoscopic dacrocystorhinostomy and orbital decompression respectively. In neurosurgery, endoscopic resection of pituitary tumours is becoming commonplace.

With increasing experience gained with the treatment of cranial base lesions such as cerebrospinal fluid (CSF) leak and pituitary tumours, the limits of endoscopic sinus surgery are constantly being redrawn and the surgical indications have expanded. The whole of the ventral skull base is now entirely accessible using an endonasal approach. The term “expanded endonasal approach’ (EEA) was coined to describe approaches that access the anterior, middle and posterior cranial fossa3.

Technological developments Over the past decade, renowned skull base centres such as the University of Pittsburgh Medical Center (UPMC) have spearheaded the development of endoscopic skull base surgery to deal with pathologies involving the whole skull base. This is made possible with a better understanding of the skull base anatomy from the endonasal perspective and advances in innovative technologies.

Improvements in the optics of the rod-lens endoscope, highresolution cameras and high-definition monitors have greatly enhanced the quality of the visual display. This improved visualisation is vital during dissection of the tumour from the surrounding neurovascular structures. Another area of interest is the development of a three-dimensional scope to overcome the lack of depth perception4. Current threedimensional systems, however, lack high definition and future ones will likely address this shortcoming.

Intra-operative navigation is essential for all endoscopic skull base surgery, as it defines anatomical landmarks, tumour boundaries and important neurovascular structures.

Refinements of these systems have further improved accuracy and precision. Though it is no substitute for anatomical knowledge, image guidance has helped expand the limits of the expanded endonasal approach. Image fusion capability, combining both computed tomography (CT) and

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magnetic resonance imaging (MRI) scans, has also evolved5.

This allows the unique features of each component imaging modality to be used at different stages of the surgery. Intraoperative CT or MRI scanners have also been employed to allow the surgeon to assess the completeness of resection.

Extended instrumentations specific for endonasal skull base surgeries have also been developed. These include the highspeed drill, as removal of thick and dense bone is a hallmark of skull base surgery. A hybrid or coarse diamond drill bit is preferred as it combines the advantages of haemostasis with rapid and yet precise bone removal.

Although not universally available, neurophysiological monitoring can be an aid during surgery. These include somatosensory evoked potentials (SSEPs), cranial nerve electromyography and acoustic doppler ultrasonography6.

SSEPs monitors cortical responses to simultaneous stimulation of the peripheral nerves of the upper (median nerve)) and lower (tibial nerve) extremities. Changes in the cortical responses due to inadequate cerebral blood flow can be detected earlier than changes in other physiologic parameters. It provides an early alert to a developing complication such as intracranial hemorrhage or parenchyma edema and is recommended in cases where there is potential for such injury. Electromyography is useful to identify and alert against injury to specific cranial nerves during the dissection of a tumour, while acoustic doppler sonography helps to identify important vessels such as the internal carotid artery that may be obscured or displaced by a tumour, or, to identify the viability of the pedicle of a reconstructive flap.

Another major area of concern is haemostasis during endonasal surgery. Bleeding impedes visualisation by soiling the lens and by obscuring the surgical field; it prevents complete tumour excision and increases the risk of neurovascular injury. Warm saline (40º C) irrigation coupled with endoscopic bipolar electrocautery and new hemostatic agents helps to provide a ‘dry’ and clear surgical field.

Absorbable gelatin powder, sponge oxidised regenerated cellulose, microfibrillar collagen, fibrin or synthetic sealants are all effective haemostatic agents available now. The addition of thrombin to gelatin powder facilitates its delivery and improves haemostasis.

Endoscopic endonasal approach The endoscopic endonasal approach (EEA) consists of modules that are oriented in the sagittal and coronal planes.

The sphenoid sinus is often used as the starting point for the modules. Key anatomical structures such as the optic

Insight nerve and internal carotid arteries can be identified here and then followed to other areas of the skull base. The sagittal plane extends from the frontal sinus to the second cervical vertebrae (Figure 1) while the coronal plane subdivides into anterior, middle and posterior planes according to the corresponding cranial fossae 8.The lateral limit of the coronal modules is limited by critical neurovascular structures such as the optic nerve and carotid artery. This is the basic tenet of endoscopic skull base surgery. Lesions medial to these neurovascular structures can be safely resected without the need for brain retraction and there is also minimal manipulation of these neurovascular structures. Conversely, lesions lateral to these structures are best dealt with via an open approach.

Fig. 1. Schematic depiction of the sagittal plane module on a computed-tomography (CT) scan of the skull base. They are numbered as follows: (1) transfrontal, (2) transcribriform, (3) transplanum, (4) transsellar, (5) tranclival and (6) transodontoid

Some common approaches used in EEA are briefly described here. The transfrontal module provides access to the posterior wall and floor of the frontal sinus. Examples of lesion in this area include mucocoele, osteomas and dermoids. Transcribriform module extends from the crista galli to the planum sphenoidales (roof of the sphenoid sinus) and across the ethmoid roof to the mid-orbital roof. Lesions in this area include sinonasal malignancies with skull base involvement such as olfactory neuroblastoma and olfactory meningiomas.

Transsellar approach is the standard approach for pituitary tumours but may need to be extended to the planum (transplanum approach) for those pituitary tumours with suprasellar extension (Figure 2) and craniopharyngioma.

Transclival approach deals with pathology of the clivus such as chorodma, but, in the local setting, it is the standard approach used for resection of recurrent nasopharyngeal carcinoma.

Fig. 2. Magnetic resonance imaging (MRI) of a large pituitary tumour with suprasellar extension. An endonasal transsellar and transplanum approach is used to remove the tumor.

Figures A and B are the pre-operative scans and Figures C and D are the post-operative scans.

Principles of oncological resection Evolving from an endoscopic assisted approach, it is feasible now to completely resect malignant sinonasal and skull base tumours endoscopically. One of the major criticisms of endoscopic resection of sinonasal tumours is that en-bloc resection cannot be achieved. It has been shown when properly performed, piece-meal resection of the tumour does not compromise results as long as the final margins are clear8,9. Although sinonasal tumours often fill up the whole of sinonasal cavity, its involvement of the skull base is often more confined. In the case of esthesioneuroblastoma, the intranasal component is debulked towards its attachment at the skull base. This exposed the whole anterior skull base from the floor of the frontal sinuses anteriorly, medial orbit and fovea ethmoidalis (roof of ethmoid) laterally and planum sphenoidale posteriorly. The dura is then incised around the periphery of the tumour and the tumour dissected free from the surface of the brain with inclusion of the olfactory bulbs and tracts (Figure 3A). Thus, the area of skull base involvement is removed en bloc and clear margins are then confirmed with frozen section analysis.

Fig 3. Endoscopic view (A) of the surgical dural defect (delineated by white arrows) following an endoscopic transcrifbriform resection of an esthesioneuroblasma. The ventral surface of the frontal lobe and the cut end of the olfactory tracts are seen. Reconstruction of the defect is performed using a nasoseptal flap (NS) (B).

Following resection, there is a need to re-establish the separation between the nasal cavity and the brain. This is one of the greatest challenges in endonasal skull base surgery. Previously, this has been attempted using multiple non-vascularised ‘sandwich’ graft such as cartilage, bone, mucosa or artificial graft. However, this still results in a fairly high incidence of cerebrospinal fluid leak (30%)10. The introduction of the vascularised nasoseptal flap is one of

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Insight the most significant advances in skull base reconstruction in the pass decade11,12. This vascularised flap is based on the posterior septal branch of the sphenopalatine artery and can provide complete coverage of the defect from the frontal sinuses to the planum sphenoidale and from orbit to orbit (Figure 3B). It has dramatically decreased the incidence of post-operative cerebrospinal fluid leak following skull base reconstruction to about 6%13. If this flap is unavailable, then a pericranial or temporoparietal fascial flap can also be used.

As this technique is relatively new, there are not many longterm studies on its outcome compared to open approach.

Nevertheless, early reports appear to suggest that the shortterm outcome for endoscopic skull base resection are at least equivalent compared to traditional approaches6.

Team Unlike other team surgeries that employ sequential teams of surgeons, endonasal skull base surgery involves participation of two skull base surgeons (usually an otolaryngologist and neurosurgeon) simultaneously during the surgery. This is also described as binarial surgery where 2 instruments are introduced through each nostril (Figure 4). The benefits of a team surgery approach include dynamic visualisation, increased operative efficiency and improved decision making and problem solving. These benefits become more apparent during a vascular emergency where time is of essence.

Recurrent nasopharyngeal carcinoma Current treatment options for recurrent nasopharyngeal carcinoma options are mainly re-irradiation and/or surgery.

Re-irradiation, due to its high cumulative radiation dose, may result in late and morbid complications such as multiple cranial nerve palsies, temporal lobe necrosis, osteoradionecrosis, trismus, hearing and visual impairment and even carotid rupture. Alternatively, surgery presents a reasonable choice when the recurrent tumour is resectable.

It gives satisfactory local control and there is less morbidity than re-irradiation14.

Surgical resection is traditionally achieved with an open approach. As access to the nasopharynx is difficult, these approaches are often complex and may result in considerable morbidity such as facial scarring, trismus, dental malocclusion, and injury to cranial nerves among others. An endonasal approach to the nasopharynx, on the other hand, avoids these morbidities. In fact, endoscopic nasopharyngectomy should be considered as the first option if the tumour is resectable (Figure 5). Current evidence suggests that it is safe and feasible for early recurrences (rT1 and some rT2 tumours)14. For advanced tumours such as those involving internal carotid artery or with intracranial invasion, concurrent chemoirradiation should still be considered first.

Fig. 4. A 2-surgeon binarial approach in a 5-year-old child with 5 instruments in both nasal cavities.

Fig. 5. A 60 year-old patient with recurrent nasopharyngeal carcinoma involving the left fossa of rosenmulla. An endoscopic nasoharyngectomy is carried out. The figure showed the lateral extent of the dissection being limited by the internal carotid artery.

Advantages Advantages of an endonasal approach include the avoidance of a facial incision, craniotomies, decreased pain, faster recovery and better patient acceptance. The avoidance of brain retraction from an open craniotomy also reduces the possibility of brain contusion, edema and eventual encephalomalacia. The use of the endonasal approach is becoming more appropriate in select situations. Below are two examples.

Paediatric population The use of an endonasal approach in a child may also potentially avoid craniofacial growth abnormalities as it does not disrupt the facial growth centres. This makes it especially suitable for paediatric population. The smaller nares and nasal cavities in young children do not preclude endonasal surgery. An 8-month-old old girl recently underwent

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Insight endoscopic assisted decompression of her right optic nerve without making any external incisions.

Applications of EEA in the paediatric population include biopsy for diagnosis, and treatment of neoplasms such as juvenile nasopharyngeal angiofibroma and rhadomyosarcoma. An example is illustrated in Figure 6.

References 1. Kennedy, D.W., Functional endoscopic sinus surgery. Technique. Arch Otolaryngol, 1985. 111(10): p. 643-9.

2. Stammberger, H., [Personal endoscopic operative technic for the lateral nasal wall--an endoscopic surgery concept in the treatment of inflammatory diseases of the paranasal sinuses]. Laryngol Rhinol Otol (Stuttg), 1985. 64(11): p. 559-66.

3. Kassam, A., et al., Expanded endonasal approach: the rostrocaudal axis.

Part I. Crista galli to the sella turcica. Neurosurg Focus, 2005. 19(1): p. E3.

4. Tabaee, A., et al., Three-dimensional endoscopic pituitary surgery. Neurosurgery, 2009. 64(5 Suppl 2): p. 288-93; discussion 294-5.

5. Leong, J.L., P.S. Batra, and M.J. Citardi, CT-MR image fusion for the management of skull base lesions. Otolaryngol Head Neck Surg, 2006. 134(5): p. 868-76.

Fig. 6. MRI scan (A) showed enhancement of the left infraorbital (*), trigmeninal nerve, trigeminal ganglion and infratemporal region. A post-surgery MRI scan (B) 3 months later did not reveal any recurrence.

This is a 9-year-old child with rhadomyosarcoma involving the left infratemporal fossa, parotid gland (with left facial nerve palsy) and paramengingeal involvement of the left trigeminal ganglion. He subsequently underwent chemo-irradiation followed by surgical extirpation. Post chemoradiation MRI scan (Figure 6A) showed persistent enhancement of the left infraorbital, trigmeninal nerve, trigeminal ganglion and infratemporal region. Resection of the tumour was performed via a combined approach.

An open parotidectomy was performed to approach the infratemporal fossa laterally while the medial infratemporal fossa was approached endoscopically (transmaxillary). The resected parotid tissue and the left infraorbital nerve did not reveal any residual tumour. The trigmeninal nerve was also explored and did not reveal any evidence of tumour involvement. As a result, there was no further escalation of his chemotherapy regime. A post-surgery MRI scan (Figure 6B) 3 months after surgery did not reveal any recurrence.

Conclusion Setting up a skull base team requires a team of surgeons who are committed and interested in working collaboratively.

At the National University Hospital, Singapore, we have assembled a team of both neurosurgeons and otolaryngologists that have undergone training in this area and have worked well as a team in complex cases. Being a tertiary hospital also means that there is sufficient surgical volume to maintain our expertise. This will continue to grow and it will ultimately benefit our patients.

6. Ong, Y.K., et al., New developments in transnasal endoscopic surgery for malignancies of the sinonasal tract and adjacent skull base. Curr Opin Otolaryngol Head Neck Surg, 2010. 18(2): p. 107-13.

7. Snyderman, C.H., et al., What are the limits of endoscopic sinus surgery?: the expanded endonasal approach to the skull base.

Keio J Med, 2009. 58(3): p. 152-60.

8. Snyderman, C.H., et al., Endoscopic skull base surgery: principles of endonasal oncological surgery. J Surg Oncol, 2008. 97(8): p. 658-64.

9. Patel, S.G., et al., Craniofacial surgery for malignant skull base tumors: report of an international collaborative study. Cancer, 2003. 98(6): p. 1179-87.

10. Zimmer, L.A. and P.V. Theodosopoulos, Anterior skull base surgery: open versus endoscopic. Curr Opin Otolaryngol Head Neck Surg, 2009. 17(2): p. 75-8.

11. Hadad, G., et al., A novel reconstructive technique after endoscopic expanded endonasal approaches: vascular pedicle nasoseptal flap. Laryngoscope, 2006. 116(10): p. 1882-6.

12. Kassam, A.B., et al., Endoscopic reconstruction of the cranial base using a pedicled nasoseptal flap. Neurosurgery, 2008. 63(1 Suppl 1): p. ONS44-52; discussion ONS52-3.

13. Zanation, A.M., et al., Nasoseptal flap reconstruction of high flow intraoperative cerebral spinal fluid leaks during endoscopic skull base surgery. Am J Rhinol Allergy, 2009. 23(5): p. 518-21.

14. Ong, Y.K., et al., Endoscopic nasopharyngectomy and its role in managing locally recurrent nasopharyngeal carcinoma. Otolaryngol Clin North Am, 2011. 44(5): p. 1141-54.

Dr Ong Yew Kwang Dr Ong is currently a Consultant at the Department of Otolaryngology – Head & Neck Surgery, National University Hospital, and an Assistant Professor at the Department of Otolaryngology, National University of Singapore.

Read more about him as the Specialist in Focus in this issue on pages 14-15.

Email address: entv2@nus.edu.sg

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Insight Risk Assessment in Obstetrics Dr Anita Kale, Consultant, Department of Obstetrics & Gynaecology

What is a high risk pregnancy?

In general, a pregnancy should be considered a unique, naturally occurring episode in a woman’s life. However, pre-existing medical conditions or unexpected illness of the mother or the foetus can complicate the pregnancy.

The pregnancy is said to be ‘high risk’ when these medical conditions or illnesses increase the probability of an adverse outcome for the mother or the baby over and above the baseline risk among the general pregnant population.

High risk pregnancies may be classified under these 3 categories: • Pre–existing maternal conditions • Maternal illness arising during pregnancy • Foetal conditions diagnosed during pregnancy Pre-existing medical conditions If one was to list all the conditions, the list will be exhaustively long. The more commonly encountered medical conditions are:

• Chronic hypertension • Diabetes mellitus • Thyroid disorder • Systemic Lupus Erythematosus (SLE) • Anti-phospholipid syndrome • Cardiac disease • Asthma • Epilepsy • Recurrent miscarriages • Advanced maternal age • Obesity • Renal disease like nephritic syndrome • Post-transplant (liver, kidney)

In these patients, pre-conception counseling is of paramount importance. The risk to the unborn foetus and the mother can be minimised by making sure that the medical conditions are optimised prior to conception. In an epileptic patient who is on anti-convulsant medication, risk of open neural tube defects in the foetus can be minimised by supplementation of folic acid in the peri-conceptional period. In a diabetic patient, optimising the sugar control prior to conception reduces the risk of miscarriage and foetal malformations.

Some patients with renal or cardiac disease may suffer deterioration of their condition during the pregnancy and it may not be reversible. They need to be aware and informed of this possibility.

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During the antenatal period, these women need more frequent follow-up visits, extra blood tests and sometimes, additional ultra sound scans. Multi-disciplinary management is essential for some of them. Patients with endocrine disorders like hypo- or hyperthyroidism are co-managed with an endocrinologist whereas those with SLE are comanaged with a rheumatologist.

Maternal illness arising during pregnancy: Sometimes a pregnancy that has started well may take a turn for the worse. The common conditions that arise during pregnancy are:

• Pre-eclampasia (high blood pressure with proteinuria) • Pregnancy-induced hypertension • Gestational diabetes • Anaemia • Antepartum haemorrhage • Obstetric cholestasis

These expectant mothers then need close monitoring, sometimes as an in-patient. The timing and mode of delivery needs to be decided so as to minimise the risk to the mother as well as the foetus.

Foetal conditions diagnosed during pregnancy These days, it is routine practice to have ultrasound scan during pregnancy. The first scan is usually done at the first visit to confirm the gestational age, viability and to rule out multiple pregnancies.

Subsequently, the pregnancy is screened for the likelihood of trisomies between 11 to 14 weeks, for foetal anomaly at around 22 weeks and then around 32 weeks for checking foetal growth. The pregnancy is considered high risk if the foetus is found to have any birth defect or chromosomal abnormality. Multiple pregnancies also are more likely to have complications and will require follow-up in our High Risk Pregnancy Clinic. The same is true for the foetuses with intra-uterine growth restriction.

Care at the NUH Women’s Centre High Risk Pregnancy Clinic Regular antenatal care is now the accepted norm in most places. The caregivers can be trained midwives, general practitioners or obstetricians. The women with low risk pregnancies usually can be sufficiently cared for by the GPs; but the high risk pregnancies need to be managed by obstetricians with special interest in foetal and maternal medicine. Continuity of care is also of paramount importance while caring for these pregnancies.

Insight

At NUH Women’s Centre, we have a dedicated ‘High Risk Pregnancy Clinic’ that is run by Prof Arijit Biswas, Associate Prof Mahesh Choolani and Dr Anita Kale.

Recent advances in pre-natal screening Screening pregnancies for aneuploidy is rapidly becoming common knowledge. Aneuploidy is a condition where there exists an abnormal number of chromosomes, and is a type of chromosome abnormality. An extra or missing chromosome is a common cause of genetic disorders (birth defects). The pregnancies which are found to be at a higher risk are then subjected to diagnostic test by doing Chorionic Villous Sampling (CVS) or amniocentesis. It takes two weeks to obtain the results. The wait of two weeks can be quite agonising to the parents.

Recurrent Pregnancy Loss Clinic Women who have lost three or more pregnancies are said to have recurrent pregnancy loss. These couples go through very difficult times. They need careful counseling and moral support. Investigations to diagnose a likely cause of recurrent miscarriage are extensive and time consuming. At the NUH Women’s Centre, we have a dedicated recurrent pregnancy loss clinic to look after this special sub-group of population The Recurrent Pregnancy Loss Clinic is held on every 4th Monday of the month.

For more information, please contact: NUH Women’s Clinic Kent Ridge Wing, Level 3

To alleviate this long wait, a quicker and reliable method of FlashFISH, a technique for ultra-rapid fluorescence in situ hybridisation on uncultured amniocytes, has been invented by the researchers in our department. Using this technique, we are now able to make the results available on the same day of amniocentesis.

Appointment Line: 6772 2255 / 2277 Fax: 6872 0103 / 6778 8683

In-Utero treatment Certain foetal malformations jeopardise proper foetal growth and development. For example, congenital diaphragmatic hernia can affect foetal lung development due to herniation of abdominal organs into the chest. Congenital hydrocephalus will hamper the brain development. Severe foetal anemia may lead to cardiac failure, hydrops and foetal death.

Dr Anita Kale

Some of these conditions can be tackled while the foetus is still in-utero, under the ultrasound guidance. For example, foetal anaemia can be corrected by in-utero foetal blood transfusion. A shunt can be put in to relieve the hydrocephalous. A hydrothorax, which refers to a condition that results in accumulation of fluids in the space between the foetus’ lungs, can be tapped. At NUH, these procedures are carried out in our Fetal Care Centre.

Email address: womens_clinic@nuhs.edu.sg

Dr Anita Kale completed her MBBS from Mumbai University, India in 1992 and obtained her MD (India) in 1995. Subsequently, she went on to work in UK and obtained her MRCOG in 1998. She started working as a Registrar in NUH’s Department of Obstetrics and Gynaecology in January 2005. Since then, she has completed the advanced training in the specialty and received the FRCOG (UK) in 2010.

Dr Kale looks after women in all age groups, from adolescent to elderly, who are seeking care for any gynaecological complaints. She also provides obstetric care to all pregnant women. Her special interest is in high risk pregnancy and feto-maternal medicine.

Email address: anita_sugam_kale@nuhs.edu.sg

Fluid collection in the fetal chest

Picture before tapping the hydrothorax

Fetal hydrothorax after tap

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Doctor’s Heartbeat Specialist in Focus:

Dr Ong Yew Kwang MB BCh BAO (Dublin), MRCS (Ed), M Med (ORL), DO-HNS (Eng)

Dr Ong graduated from Trinity College Dublin, Ireland in 1998 with 2nd class honours. He began his general surgical training in 1998 and was accepted into the National Specialty Training program for Otolaryngology in 2002. He is currently a Consultant at the Department of Otolaryngology – Head & Neck Surgery, National University Hospital and an Assistant Professor at the Department of Otolaryngology, National University of Singapore.

Dr Ong provides outpatient and surgical care for general ear, throat and neck conditions. His main area of interest is Rhinology and he completed his fellowship in minimally invasive skull base surgery at the University of Pittsburgh Medical Center in 2010. His other clinical interest is functional septorhinoplasty, for which he did a mini-fellowship at the Asan Medical Center, Seoul, Korea.

Dr Ong is part of the department faculty involved in the teaching of medical undergraduates for their anatomy and ENT curriculum. He also lectures the dental, nursing and speech and language pathology students. He is a core faculty member of the ACGME ENT program at NUHS and member of the program’s clinical competency committee and program evaluation committee. He is also the department facilitator for GP CME and department representative for JCI accreditation.

1) Why did you decide to specialise in Otolaryngology?

I had actually wanted to be a pilot as a child as I was fascinated by planes. Unfortunately, I developed myopia and so I had to ditch the idea.

Ever since I chose Medicine, I have always envisaged being both a surgeon and a physician.

Otolaryngology has a nice balance of both aspects. It is one of the few specialities that does not have a medical equivalent and so I get to reprise both roles.

I also like the wide scope of work that it offers. It has 7 different subspecialities: Otololgy, Rhinology, Head & Neck, Paediatrics, Laryngology, Sleep Medicine and Facial Plastics. Each subspeciality is very different and requires a different set of skillset and technical abilities. Otology requires good microsurgical skills, head and neck sugery requires a good grasp of anatomy, rhinology requires good eye hand coordination for endoscopic sinus surgery. To be able to do all these well is challenging and I constantly strive to excel in every aspect of my work.

2) Who has had the biggest influence on your career?

My mother has been my biggest influence throughout my whole life. She has always placed the needs of her children ahead of her own. She urged me on in my work during my school days but never pressurised me. She always has words of encouragement during times of difficulty or failure.

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Though she does not have a high education background, she is the one who constantly reminds me the ethos, responsibility and moral obligations of being a doctor - to treat every patient, regardless of their background, as equal with dignity, compassion and respect.

3) Are there any exciting new developments in the treatment for nose and sinus problems?

The most exciting new development in endoscopic sinus surgery is the advent of the minimally invasive skull base surgery. This is a collaboration with the neurosurgeon to remove skull base tumors and some brain lesions such as pituitary tumours and meningioma entirely through the nose. This pushes the limit of traditional endoscopic sinus surgery beyond just treating nose and sinus problems. It avoids the morbidity of an open cranial surgery and the patient has a shorter hospital stay and faster recovery. Patients are surprised that there are no facial or scalp incisions despite the extent of the surgery involved.

4) Are there any interesting projects you are currently working on?

My aim is to develop a minimally invasive skull base surgery centre in NUH, which is not only known nationally but also recognised as a regional centre of excellence and referral centre. This is a big undertaking as it involves a paradign shift from performing traditional open cranial surgery.

Doctor’s Heartbeat

My family visiting me during my fellowship in Pittsburgh in 2010.

It is a technically demanding team surgery. Both the otolaryngologists and neurosurgeons need to be welltrained in the endoscopic anatomy of the skull base. But we have developed good understanding with our neurosurgical colleagues and I am optimistic that we will be able to take this field to greater heights.

5) What do you enjoy most in your current practice?

I love many aspects of my jobs. Making my patients well and knowing that I have helped them give me the biggest satisfaction.

I am happy whenever my patients tell me that I have solved their problems. But, I realise that at times it is not all about solving their medical problems, a listening ear is sometimes all that they need. I have become friends with several of my patients and their families.

Being in a teaching hospital also means that I have the privilege to help teach the next generation of doctors and otolaryngologists in training. Apart from sharing my experiences with them, I also hope to incalcate in them the right set of values. Knowing that I have a part to play in influencing some of their decisions in their careers is indeed graftifying.

7) What do you enjoy doing in your free time when you’re not taking care of patients?

I enjoyed long distance running. It takes my mind off work and help me relax. I spend my weekends with my family. Whenever time permits, I bring them out for walks and nature trekking.

This is a time when the whole family bonds and shares the fun and joy.

8) Any personal heroes or models?

All my patients are my heroes. They have taught me many things that I don’t learnt from textbooks including strength, preseverance, resilence and humility.

In the face of illnesses – especially terminal illness – I have learnt that everyone becomes equal regardless of their social status or wealth. My patients showed tremendous courage in dealing with their illnesses and the effects of their treatments. This makes me even more determined to do my best to help them.

6) What are the important milestones and achievements that you are most proud of?

The otolaryngology training programme was a competitive programme and it took me some time before I was admitted.

It was thus an important milestone for me when I eventually completed it and became an otolaryngologist. I also felt blessed that I was able to further my fellowship training in my favourite subspecialty.

Another important achievement was completing my first marathon in 2010. I have completed a few more races since then and I hope to be able to do one every year.

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Médico Upcoming Events

NUH GP CME Programme 2013 Please refer to our GPLC website for online registration.

Date

Clinical Specialty / Topic

05 Jan

Medicine

19 Jan

Paediatrics

02 Feb

Family Medicine

23 Feb

Orthopaedic Surgery

Case Studies & Presentations on What is New in Spinal Pathologies

Management of HIV for GPs

Paediatric Infectious Diseases – Case Studies

Travel Medicine – Case Studies

* Event information listed is correct at time of print.

While every attempt will be made to ensure that all events will take place as scheduled, the organisers reserve the rights to make appropriate changes should the need arises.

Please refer to our events calendar at www.nuh.com.sg/nuh_gplc for more updates and information.

A Publication of NUH GP Liaison Centre (GPLC) Advisors A/Prof Goh Lee Gan Editor Esther Lim Editorial Member Lisa Ang We will love to hear your feedback on Médico.

Please direct all feedback to: The Editor, Médico GP Liaison Centre, National University Hospital 1E Kent Ridge Road, NUHS Tower Block, Level 6, Singapore 119228 Tel: 6772 5079 Fax: 6777 8065 Email: gp@nuhs.edu.sg Website: www.nuh.com.sg/nuh_gplc Co. Reg. No. 198500843R The information in this publication is meant for educational purposes and should not be used as a substitute, or relied solely upon, for medical diagnosis or treatment. Please seek further medical advice if you have questions related to any medical condition. Although great effort has been made in compiling and checking the accuracy of the information given in this publication, the authors, publisher and National University Hospital shall not be responsible, or in any way liable, for the continued currency of the information, or for any errors, omissions or inaccuracies, whether arising from negligence or otherwise, or for any consequences arising therefrom. Contents in this newsletter are not to be quoted or reproduced in any form without the prior permission of National University Hospital.

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