Biomedical subjects
Publications and source records attributed to D S Sethi.
This paper focuses on the spectrum of sphenoid sinus lesions that may be seen radiologically and the mapping of disease extent. Imaging plays a central role in the assessment of sphenoid sinus disease. Although primary sphenoid sinus disease is uncommon, this sinus is nevertheless affected secondarily by a variety of pathological processes.
Endoscopic pituitary surgery is a minimally invasive method which allows simple transnasal transphenoidal surgical access without retractors, and has been used by our team in 536 patients from 1993 to 1999. In 326 of these patients, computer-aided image-guided techniques (CAN) were used in conjunction with endoscopy. We found that CAN techniques and endoscopy allow accurate and precise minimal access to small, deep/lateral microadenomas and enable a more complete resection of large pituitary tumors especially those which are firm/fibrous in nature. Overall results were better than conventional pituitary surgery with a lower morbidity and shorter hospital stays. However, special training and expertise is needed for surgeons to carry out these procedures with acceptable results.
Sinonasal inverted papillomas are well known for high recurrence rates after surgery and the risk of malignant change. Recurrent disease occurs because of inadequate excision as a result of poor exposure and visualization. For these reasons, aggressive surgery has been advocated-classically a lateral rhinotomy and en bloc medial maxillectomy. Endoscopic techniques have provided excellent visualization and a less invasive approach to these tumours. We describe 18 patients with inverted papillomas treated endoscopically at the Singapore General Hospital since 1993. The presentation, sites of involvement and diagnostic imaging are presented. All the patients had a minimum follow-up of 18 months with a mean of 32.8 months. One case of recurrence at the frontal recess is reported. Endoscopic management is appropriate for the diagnosis, follow-up and treatment of circumscribed primary and recurrent inverted papillomas.
BACKGROUND: The pattern of nodal metastasis in previously untreated nasopharyngeal carcinoma (NPC) has been studied and reported. In order to analyse the pattern of recurrent nodal disease in previously treated NPC, a retrospective study on 68 patients who underwent radical neck dissection for regionally recurrent NPC was conducted. METHODS: Seventy-four neck dissections were performed on 68 patients who developed nodal recurrence after a mean disease-free interval of 39.2 months. None of the patients had evidence of local or systemic disease at the time of surgery. Histopathological reports of the 74 neck dissections were analysed with regard to the number of positive nodes as well as the number of involved nodal levels. RESULTS: Of the 65 neck dissection specimens with analysable data, 31 showed metastatic disease at a single nodal level with a mean number of positive nodes of 1.2, while 34 showed metastatic disease at multiple levels with a mean number of positive nodes of 6.6. Nodal recurrence occurred at level II with the greatest frequency (78.5%). Of the 31 specimens with single level nodal involvement, 21 (67.7%) occurred at level II. Isolated involvement at the other levels did occur, but was uncommon (range 3-16%). Of the 34 specimens with multiple level nodal involvement, 30 (88.2%) showed involvement at level II. Once more than one level was involved, the frequency of involvement at any given level was at least 30%. CONCLUSION: The predominant involvement at level II and the high frequencies of involvement at all levels support the use of a classical radical neck dissection in treating recurrent nodal disease in NPC.
Isolated sphenoid lesions are rare. It is likely that isolated sphenoid sinus disease is underreported for a number of reasons. First, the presenting symptoms are often nonspecific; second, the inaccessibility of the sinus precludes optimal physical examination; and third, before the advent of CT and MRI scanning, radiologic examination of the sinus was inadequate. Endoscopic evaluation and current imaging techniques with CT or MRI have contributed to an increase in diagnosis of these lesions. Twenty-one patients with isolated sphenoid lesions that I treated in a 4-year period are presented. The pathology was unilateral sphenoid sinusitis (8), sphenoid mucoceles (4), inflammatory sphenochoanal polyp (3), inverting papilloma (2), invasive pituitary adenoma (1), carcinoma (1), aspergilloma (1), and fibrous dysplasia (1). Endoscopic biopsy was carried out in 7 patients (33.3%). A precise diagnosis after endoscopy, biopsy, and imaging studies was established in all patients. Definitive treatment included an endoscopic sphenoidotomy in 15 (71.4%). Five patients (23.8%) were treated with other therapeutic modalities. One patient did not require any definitive treatment. The combined use of imaging techniques and diagnostic nasal endoscopy allows for an accurate diagnosis and enables minimally invasive techniques to be tailored to the patient's disease.
Ingested foreign bodies are the commonest otolaryngological emergency in Singapore and other parts of Southeast Asia. One of the uncommon complications of ingested foreign bodies is migration, which has the potential to cause morbidity and mortality. A retrospective study of 24 patients presenting from 1990 to 1996 at Singapore General Hospital was done to evaluate the presentation, investigation, and diagnosis of migrated foreign bodies. Of interest, most patients had ingested foreign bodies within 24 hours. All the migrated foreign bodies were linear, sharp fish bones. Migration is said to have occurred in the presence of positive neck radiography and negative rigid esophagoscopy. Computed tomography is the investigation of choice to confirm migration. All patients had neck exploration, and factors for successful outcome are discussed. This is the largest series in the literature to date.
The place of coronal computed tomography (CT) in the assessment of patients prior to functional endoscopic sinus surgery (FESS) is well established. The ability to accurately correlate radiological and surgical anatomy enhances precision and safety during FESS. This pictorial essay reviews the conceptual anatomical framework that forms the basis of FESS.
Excision of the submandibular gland is a surgical procedure often undertaken. The procedure is the treatment of choice for patients with neoplasm of the submandibular gland and those with non-neoplastic submandibular disorders which are not controlled with conservative medical measures. Extirpation of the submandibular gland may also be undertaken for diagnostic purposes. This retrospective study of 93 consecutive patients who underwent excision of the submandibular gland in the Department of Otolaryngology, Singapore General Hospital over a five-year period was undertaken to study the indications of surgery, the pathology of the excised submandibular gland and the demographic profile of patients. Fifty-six (60.2 per cent) patients underwent submandibular gland excision for non-neoplastic salivary gland disease while 37 (39.8 per cent) had neoplastic submandibular gland disorders. The commonest pathology encountered was sialadenitis/sialolithiasis (53.76 per cent) followed by pleomorphic adenoma (33.33 per cent). Fine needle aspiration cytology (FNAC) was a valuable pre-operative investigation with a sensitivity and specificity of 94.7 per cent and 100 per cent respectively for neoplastic disease. The morbidity rate for this surgery was 4.3 per cent.
Isolated sphenoethmoid recess (SER) polyps are rare. They usually arise from the sphenoid sinus. We report six patients with SER polyps as the only abnormal clinical finding at initial presentation. All cases were investigated with outpatient biopsy and computed tomography (CT) or magnetic resonance (MR) imaging. Pre-operative histology revealed three cases of inflammatory disease, two cases with inverted papilloma, and one case of an ectopic pituitary adenoma arising from the sphenoid sinus. One of the inflammatory polyps arose directly from the mucosa around the sphenoid ostium. The other five cases involved the sphenoid sinus. Except for the ectopic pituitary adenoma all the polyps were managed by transnasal endoscopic surgery. We emphasize that isolated SER polyps may signify existing sphenoid pathology and a pre-operative biopsy is valuable for planning surgery.
We describe two cases of sphenoid sinus mucocoele. Both presented with isolated oculomotor nerve palsy. Mucocoeles involving only the sphenoid sinus are uncommon. They are probably under-diagnosed as they may be asymptomatic or cause non-specific symptoms. Nasal symptoms occur infrequently but the close relationship of the sphenoid sinus to the orbital apex means that ocular symptoms including cranial nerve palsies are a common presenting feature. Involvement of the third cranial nerve in isolation is rare but has important neurosurgical implications which must be excluded before this symptom is attributed to the sphenoid sinus.
A 14-year-old Chinese female presented with severe sorethroat and swinging fever for two weeks despite one course of oral amoxycillin followed by one course of Unasyn (combination of sultamicillin, sulbactam and ampicillin). Throat swab grew Pseudomonas pseudomallel. Serology for its antibodies was very strongly positive (> 1:512). In this part of the world the IHA titre of 1:16 or greater is significant. She was successfully treated with intravenous ceftazidime. The swinging fever settled within two days. The nasopharyngeal and oropharyngeal lesions cleared after a week of therapy. A further two weeks of Ceftazidime were given to ensure a complete resolution of the infection. Oral tetracycline was given for maintenance therapy. Melioidosis involving various organs have been reported particularly pulmonary melioidosis. Nasopharyngeal melioidosis has not been reported, as far as we know. This is the first reported case.
The excellent visualisation and atraumatic surgical techniques of endoscopic sinus surgery were applied to the management of 5 patients with cerebrospinal fluid (CSF) fistulae in the anterior skull base. The CSF fistula was iatrogenic in three patients, post-traumatic in one patient and primary in another patient. The role of endoscopes in the diagnosis and management of CSF rhinorrhoea is discussed. These five case reports illustrate the use of rigid transnasal endoscopy for diagnosis and management of CSF fistulae. The use of endoscopes allowed us to accurately localise and repair CSF fistulae. Our technique and results of endoscopic management of CSF fistulae are discussed. Using the endoscopic transnasal approach and minimally invasive techniques the fistulae were successfully repaired in all 5 patients.
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Twenty patients with chronic refractory sinusitis or rhinitis were identified to have immune defects on the basis of total immunoglobulin level, immunoglobulin G subclass, and vaccine response. Eight patients were immunoglobulin A deficient, five had low immunoglobulin levels with vaccine hyporesponse, and four had low immunoglobulin levels with normal vaccine responses. Three subjects showed isolated immunoglobulin G1 deficiency. Demographic variables such as age, sex, infection pattern, and any other related disorders were studied retrospectively, which may have contributed to the diagnosis. An immunologic screen was essential for the diagnosis of immunodeficiency in these patients. Treatment options included prophylactic antibiotics, management of associated allergies, functional endoscopic sinus surgery, and replacement therapy with immunoglobulin in selected patients.
An endoscopic study of the sphenoid sinus was carried out, on 30 cadavers, to understand the important anatomical relationships of the sphenoid sinus, and the sella turcica. The aim was to study the endoscopic anatomy and the variants, and to determine if endoscopic instrumentation and techniques, could play a beneficial role in endoscopic management of sellar lesions. The results of this study are discussed, with particular reference to the important surgical anatomical features of the sphenoid sinus. A surgical technique for the endoscopic transsphenoid approach to the sella turcica was developed. Anatomical variants can be identified endoscopically, and endoscopic techniques have the advantages of improved visualization, magnification, angled vision, and a panoramic perspective of the intrasphenoid anatomy, compared to currently employed methods of pituitary/sellar surgery, using the operating microscope.
The excellent visualization and minimally invasive surgical technique of endoscopic sinus surgery was applied to the management of 40 patients with sellar lesions. Endoscopic management of sellar lesions offers, not only the advantage of improved visualization, but also magnification, and a panoramic perspective of the important relationships of the sella turcica. In the past year, we have managed 40 subjects with sellar lesions, endoscopically: 38 patients had pituitary adenomas and two a craniopharyngioma. At our hospital, the endoscope has replaced the operating microscope for surgery for pituitary adenomas and other sellar lesions. The endoscopic approach to the sphenoid sinus and the sella is performed by an ENT surgeon and the ablative surgery performed by a neurosurgeon. Our experiences, using the endoscope to perform surgery on sellar and parasellar lesions, are reported and the advantages, over the operating microscope, which is traditionally used are discussed. The technique for endoscopic management of sellar lesions is described.
A retrospective review was conducted of 64 patients with deep neck abscesses. Based on clinical and operative findings, these abscesses were categorized as retropharyngeal abscess (29 patients), parapharyngeal abscess (10 patients), Ludwig's angina (19 patients), or necrotizing cervical fasciitis (six patients). Regional trauma from an ingested foreign body was the cause for 59 per cent of the patients with a retropharyngeal abscess. In 90 per cent of subjects with Ludwig's angina, an odontogenic cause was established; however, in the majority of cases of parapharyngeal abscess (80 per cent) and necrotizing fasciitis of the neck (85 per cent), aetiology was unknown. Fifty-five patients (86 per cent) required open neck drainage. In the remaining nine (14 per cent) endoscopic drainage of the abscess was possible. Eight patients (12 per cent) needed a tracheotomy for airway control. The overall mortality was eight per cent despite aggressive anti-microbial therapy and early surgical intervention. Thirty-four cultures grew aerobic organisms. Seventy-six per cent of these were gram-negative microorganisms. The bacteriological pattern of deep neck abscesses is changing and may be responsible for the considerable mortality rate with which the abscesses are still associated despite anti-microbial therapy.
Synovial sarcoma of the hypopharynx is a rare neoplasm. To date only 23 cases of synovial sarcoma of the hypopharynx have been reported in the literature. An additional case in an 18-year-old male is presented. This is the first case of synovial sarcoma in the hypopharynx to be reported in Singapore. The presentation was that of a mass in the hypopharynx; progressive dysphagia, intermittent hoarseness and gradual airway compromise. A CT scan was valuable in determining the site of origin and extent of the lesion. Histopathology was diagnostic. Treatment comprised of wide surgical excision of the tumour and post-operative radiotherapy.