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Displaying publications 1 - 20 of 52 in total

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Failed magnetic resonance imaging examinations due to claustrophobia

Sarji SA, Abdullah BJ, Kumar G, Tan AH, Narayanan P

Australas Radiol, 1998 Nov;42(4):293-5.
PMID: 9833363

A recognized cause of incomplete or cancelled MRI examinations is anxiety and claustrophobic symptoms in patients undergoing MR scanning. This appears to be a problem in many MRI centres in Western Europe and North America, where it is said to be costly in terms of loss of valuable scan time, and has led to researchers suggesting several anxiety-reducing approaches for MRI. To determine the incidence of failed MRI examination among our patients and if there are any associations with a patient's sex, age and education level, we studied claustrophobia that led to premature termination of the MRI examination in the University Malaya Medical Centre (UMMC) in 3324 patients over 28 months. The incidence of failed MRI examinations due to claustrophobia in the UMMC was found to be only 0.54%. There are associations between claustrophobia in MRI with the patients' sex, age and level of education. The majority of those affected were male patients and young patients in the 25-45-years age group. The patients' education level appears to be the strongest association with failed MRI examinations due to claustrophobia, where the majority of the affected were highly educated individuals. Claustrophobia in MRI is more of a problem among the educated individuals or patients from a higher socio-economic group, which may explain the higher incidence in Western European and North American patients.
Harm reduction in Asia: a successful response to hidden epidemics. The Asian Harm Reduction Network

Crofts N, Costigan G, Narayanan P, Gray J, Dorabjee J, Langkham B, et al.

AIDS, 1998;12 Suppl B:S109-15.
PMID: 9679636
Neglected laryngeal foreign body

Ambu VK, Narayanan P, Ratnasingam V

J Laryngol Otol, 2001 Sep;115(9):740-2.
PMID: 11564306

Laryngeal foreign bodies, especially in children, mostly present as an acute emergency. Few cases of long-standing laryngeal foreign bodies have been reported in the literature. This case illustrates one of the sequelae of a neglected laryngeal foreign body, resulting in significant granulation tissue formation in the larynx, and its management.
Efficacy of relocation of submandibular duct in cerebral palsy patients with drooling

Puraviappan P, Dass DB, Narayanan P

Asian J Surg, 2007 Jul;30(3):209-15.
PMID: 17638641

The efficacy of relocating the submandibular duct to treat drooling in children with cerebral palsy was studied.
Fulltext Juvenile nasopharyngeal angiofibroma in a tertiary centre: ten-year experience

Tang IP, Shashinder S, Gopala Krishnan G, Narayanan P

Singapore Med J, 2009 Mar;50(3):261-4.
PMID: 19352568

This is a retrospective study that aimed to examine the outcomes of patients presenting with juvenile nasopharyngeal angiofibroma (JNA) at a tertiary centre in Malaysia.
HPLC determination of imatinib in plasma and tissues after multiple oral dose administration to mice

Teoh M, Narayanan P, Moo KS, Radhakrisman S, Pillappan R, Bukhari NI, et al.

Pak J Pharm Sci, 2010 Jan;23(1):35-41.
PMID: 20067864

Imatinib inhibits Bcr-Abl, c-KIT and PDGFR kinases. It is approved for the treatment of chronic myeloid leukemia (CML), gastrointestinal stromal tumors (GIST) and has further therapeutic potential. Male ICR mice were given imatinib PO (50 or 25 mg/kg, 5 doses every 2 h); euthanized 2 h after the last dose administration; plasma, liver, brain, spleen and kidney were collected and imatinib concentration measured by an optimized HPLC method for quantification in tissues. Methanol (1:1 v/v plasma) and pH 4, 40:30:30 (v/v/v) water-methanol-acetonitrile at 5 ml/g (brain) and 10 ml/g (spleen, kidney, liver) ratio was added to the samples, homogenized, sonicated, centrifuged (15,000 rpm, 5 min, 2 degrees C) and the supernatant injected into an Inertsil CN-3 column (4.6 mm x 150 mm, 5 microm) using 64:35:1 (v/v/v) water-methanol-triethylamine (pH 4.8), flow rate 1 ml/min, 25 degrees C. Imatinib eluted at 7.5 min (268 nm). Linearity: 0.1-50 microg/ml; precision, accuracy, inter- and intra-day variability was within 15%. Recovery was above 95% (plasma), 80% (brain) and 90% (kidney, liver, spleen). Imatinib tissue concentrations were 6-8 folds higher than plasma except brain, where the ratio decreased from 0.24 to 0.08 suggesting limited brain penetration, likely due to blood brain barrier efflux transporters. The extensive distribution supports the expansion of therapeutic applications.
Disposition and tissue distribution of imatinib in a liposome formulation after intravenous bolus dose to mice

Moo KS, Radhakrishnan S, Teoh M, Narayanan P, Bukhari NI, Segarra I

Yao Xue Xue Bao, 2010 Jul;45(7):901-8.
PMID: 20931790

Imatinib is an efficacious anticancer drug with a spectrum of potential antitumour applications limited by poor biodistribution at therapeutic concentrations to the tissues of interest. We assess the pharmacokinetic and tissue distribution profile of imatinib in a liposome formulation. Its single dose (6.25 mg x kg(-1)) in a liposome formulation was administered iv to male mice. Imatinib concentration was measured in plasma, spleen, liver, kidney and brain using a HPLC assay. Non-compartmental pharmacokinetic approach was used to assess the disposition parameters. The plasma disposition profile was biphasic with a plateau-like second phase. The AUC(0-->infinity) was 11.24 microg x h x mL(-1), the elimination rate constant (k(el)) was 0.348 h(-1) and the elimination half life (t(1/2)) was 2.0 h. The mean residence time (MRT) was 2.59 h, V(SS) was 1.44 L x kg(-1) and clearance was 0.56 L x h x kg(-1). Liver achieved the highest tissue exposure: CMAX = 18.72 microg x mL(-1); AUC(0-->infinity)= 58.18 microg x h x mL(-1) and longest t(1/2) (4.29 h) and MRT (5.31 h). Kidney and spleen AUC(0-->infinity) were 47.98 microg x h x mL(-1) and 23.46 microg x h x mL(-1), respectively. Half-life was 1.83 h for the kidney and 3.37 h for the spleen. Imatinib penetrated into the brain reaching approximately 1 microg x g(-1). Upon correction by organ blood flow the spleen showed the largest uptake efficiency. Liposomal imatinib presented extensive biodistribution. The drug uptake kinetics showed mechanism differences amongst the tissues. These findings encourage the development of novel imatinib formulations to treat other cancers.
A haemostatic agent delivery system for endoscopic neurosurgical procedures

Waran V, Sek K, Bahuri NF, Narayanan P, Chandran H

Minim Invasive Neurosurg, 2011 Oct;54(5-6):279-81.
PMID: 22278798 DOI: 10.1055/s-0031-1297997

In endoscopic neurosurgery problems with haemostasis due to poor access exist. We have developed a system which allows the delivery of a variety of haemostatic agents in a more efficacious manner. The system has been used successfully in endoscopic skull base surgery and endoscopic surgery within the parenchyma of the brain using tube systems.
Do the prevalence and components of metabolic syndrome differ among different ethnic groups? A cross-sectional study among obese Malaysian adolescents

Narayanan P, Meng OL, Mahanim O

Metab Syndr Relat Disord, 2011 Oct;9(5):389-95.
PMID: 21718129 DOI: 10.1089/met.2011.0014

OBJECTIVE: The aim of this study was to determine the prevalence of metabolic syndrome and the most common combination of cardiometabolic disorders among different ethnic groups of obese adolescents in Malaysia.
RESEARCH DESIGN AND METHODS: A cross-sectional study among 335 obese adolescent boys and girls aged 12-18 years from 10 randomly selected schools was conducted. After recording blood pressure and waist circumference (WC), a fasting blood sample was obtained and analyzed for glucose and lipids. Metabolic syndrome was diagnosed on the basis of adolescent metabolic syndrome criteria specified by National Cholesterol Education Program Adult Treatment Panel III if three of the five risk factors--hypertriglyceridemia, hyperglycemia, hypertension, low high-density lipoprotein C, and increased WC--were present. The prevalence among different ethnic groups was analyzed.
RESULTS: The obesity rate among adolescents was 8.4%, and nearly one-third of the obese adolescents had metabolic syndrome. More than 90% of obese adolescents had at least one metabolic abnormality. Metabolic syndrome was more prevalent among obese boys (40.2%) compared to obese girls (17%). Boys had significantly higher mean WC and triglycerides and lower HDL-C (P value 0.0001). Increased WC and triglycerides and high blood pressure comprised the most prevalent (34.3%) risk factor combination followed by WC, low HDL, and high blood pressure (22.5%). Over all, Indians had the highest prevalence of metabolic syndrome (36.4%), followed by Chinese (33.8%) and Malays (27.4%). Elevated triglyceride levels were more prevalent among Chinese, hypertension among Malays, and the other three abnormalities among Indians.
CONCLUSION: Indians had the highest prevalence of metabolic syndrome. Increased WC and triglycerides and high blood pressure comprised the most prevalent risk factor combination.
Nasal allergies in the Asian-Pacific population: results from the Allergies in Asia-Pacific Survey

Katelaris CH, Lai CK, Rhee CS, Lee SH, Yun WD, Lim-Varona L, et al.

Am J Rhinol Allergy, 2011 Sep-Oct;25 Suppl 1:S3-15.
PMID: 22185687 DOI: 10.2500/ajra.2011.25.3674

The Allergies in Asia-Pacific Survey describes the symptoms, impact, and treatment of allergic rhinitis (AR) across Australia, China, Hong Kong, Malaysia, Singapore, Taiwan, Vietnam, and the Philippines. The Allergies in Asia-Pacific Survey was undertaken to further clarify the prevalence of physician-diagnosed nasal allergies (NAs), impact on quality-of-life (QOL), existing treatment paradigms and gaps, and NA medications currently used in treatment.
Fulltext Retropharyngeal abscess - A complication of laryngeal mask airway

Lynn E, Ping T, Keng Y, Singh R, Kwong W, Soon T, et al.

J Surg Case Rep, 2012 Oct 01;2012(10):7.
PMID: 24960747 DOI: 10.1093/jscr/2012.10.7

Retropharyngeal or parapharyngeal abscesses developing after intubation are rare. This can present as surgical emergency post extubation. We report a case of retropharyngeal abscess that probably occurred as a complication of laryngeal mask insertion.
Base of tongue tuberculosis: a case report

Hussaini J, Mutusamy S, Omar R, Rajagopalan R, Narayanan P

Acta Med Iran, 2012;50(2):151-2.
PMID: 22359087

We report a rare case of base of tongue tuberculosis following pulmonary tuberculosis. Patient presented to us with chief complaints of sore throat and pain on swallowing for period of 3 months. On examination with 70 degree telescope, we observed an ulcer on right side of base of tongue. The edges of the ulcer appeared to be undermined with whitish slough at the centre of the ulcer. Examination of neck showed a multiple small palpable middle deep cervical lymph nodes on right side of neck. Biopsy of the ulcer was taken, which showed granulomatous inflammation, suggestive of tuberculosis. Laboratory investigations revealed a raise in erythrocyte sedimentation rate, sputum for acid fast bacilli was strongly positive. Chest X ray was performed for patient showed multiple areas of consolidation. Patient was referred to chest clinic for further management of tuberculosis and was started on anti-tuberculous drugs. In conclusion tuberculosis of oral cavity is rare, but should be considered among one of the differential diagnosis of the oral lesions and biopsy is necessary to confirm the diagnosis.
Randomized controlled trial to compare the efficacy and safety of oral paricalcitol with oral calcitriol in dialysis patients with secondary hyperparathyroidism

Ong LM, Narayanan P, Goh HK, Manocha AB, Ghazali A, Omar M, et al.

Nephrology (Carlton), 2013 Mar;18(3):194-200.
PMID: 23311404 DOI: 10.1111/nep.12029

The objective of the study was to compare the efficacy and safety of oral paricalcitol with oral calcitriol for treating secondary hyperparathyroidism.
Velopharyngeal and choanal stenosis after radiotherapy for nasopharyngeal carcinoma

Hussein J, Tan TS, Chong AW, Narayanan P, Omar R

Auris Nasus Larynx, 2013 Jun;40(3):323-6.
PMID: 22652485 DOI: 10.1016/j.anl.2012.05.004

Choanal stenosis is a well recognized late complication of radiotherapy for nasopharyngeal carcinoma. However velopharyngeal stenosis post radiotherapy for nasopharyngeal carcinoma is rare. We present here a case of bilateral choanal stenosis and velopharyngeal stenosis in a patient treated with radiotherapy for nasopharyngeal carcinoma. A 58-year-old woman presented to our otolaryngology clinic with a one year history of nasal obstruction. She was diagnosed to have nasopharyngeal carcinoma 12 years ago for which she received radiotherapy. Clinical examination revealed bilateral choanal stenosis and velopharyngeal stenosis. Treatment of choanal stenosis and velopharyngeal stenosis is challenging due to high incidence of recurrence and patients frequently require multiple procedures. The patient underwent a transnasal endoscopic excision of velopharyngeal scar tissue and widening of posterior choana using Surgitron®, mitomycin-C applied topically to the surgical wound and bilateral stenting under general anesthesia. The stents were kept for two weeks, and 3 years post operation velopharyngeal aperture and posterior choana remained patent. As illustrated in this case velopharyngeal stenosis can occur after radiotheraphy and should not be overlooked. Combine modality of transnasal endoscopic excision of velopharyngeal scar tissue, widening of choanal stenosis with Surgitron® followed by the application of mitomycin-C and stenting has been shown to be an effective option.
Study site: ENT clinic, University Malaya Medical Centre (UMMC), Kuala Lumpur, Malaysia
Stroke incidence in the South West District of the Penang Island, Malaysia: PEARLs: Penang Acute Stroke Research Longitudinal Study

Neelamegam M, Looi I, Cheah WK, Narayanan P, Hamid AM, Ong LM

Prev Med, 2013;57 Suppl:S77-9.
PMID: 23295169 DOI: 10.1016/j.ypmed.2012.12.022

This community based incidence study aims to report the stroke incidence in the south-west region of the Penang Island.
The effectiveness of transmeatal low-power laser stimulation in treating tinnitus

Ngao CF, Tan TS, Narayanan P, Raman R

Eur Arch Otorhinolaryngol, 2014 May;271(5):975-80.
PMID: 23605244 DOI: 10.1007/s00405-013-2491-3

The aim of this study is to examine the effectiveness of transmeatal low-power laser stimulation (TLLS) in treating tinnitus. This is a prospective, double-blinded, randomized, placebo-controlled trial. Patients with persistent subjective tinnitus as their main symptom were recruited into the study from the outpatient clinics. The recruited patients were randomized into the experimental group or TLLS+ group (patients in this group were prescribed to use TLLS at 5 mW at 650 nM wavelength for 20 min daily and oral betahistine 24 mg twice per day for a total of 10 weeks) and the control group or TLLS- group (patients in this group were prescribed with a placebo device to use and oral betahistine 24 mg twice per day for 10 weeks). All patients were required to answer two sets of questionnaires: the Tinnitus handicap inventory (THI) and visual analogue scales (VAS) symptoms rating scales, before starting the treatment and at the end of the 10-week treatment period. The total score of the THI questionnaire was further graded into five grades, grade 1 being mild and grade 5 being catastrophic. Wilcoxon-signed ranks test and Mann-Whitney test were used to compare and analyze the THI and VAS scores before and after treatment for each group. Changes with p value of <0.05 were considered as statistically significant. Chi square test was used to analyze the change of parameters in categorical forms (to compare between TLLS+ and TLLS-). Changes with p value of <0.05 were considered as statistically significant. Forty-three patients successfully and diligently completed their treatment. It was noted that using any condition of the device, TLLS+ or TLLS-, patient's tinnitus symptoms improved in terms of THI scores (TLLS+, p value = 0.038; TLLS-, p value = 0.001) or VAS scores with a change of at least one grade (TLLS+, p value = 0.007; TLLS-, p value = 0.002) at p value <0.05 significant level. In contrast when TLLS+ group was compared with TLLS- group, no statistically significant result was obtained. In term of VAS scores, there seems to be no statistically significant improvement in patients' annoyance, sleep disruption, depression, concentration and tinnitus loudness and pitch heard between the two groups. Transmeatal low-power laser stimulation did not demonstrate significant efficacy as a therapeutic measure in treating tinnitus.
Study site: Otorhinolaryngology clinic, University Malaya Medical Centre (UMMC), Kuala Lumpur, Malaysia
Fulltext Maxillary Sinus Mucopyocele in a Fifty-eight-year-old man: A Possible Late Complication of Irradiation to Head and Neck

Sharouny H, Narayanan P

Iran Red Crescent Med J, 2014 Jul;16(7):e17133.
PMID: 25237579 DOI: 10.5812/ircmj.17133

INTRODUCTION: A mucocele is an epithelial-lined, mucus-containing sac that can fill the sinus completely and expand gradually. Mucopyocele is an infected mucocele.
CASE REPORT: We presented a case of left maxillary mucopyocele in a 58-year-old man that developed after radiotherapy for nasopharyngeal carcinoma. Computed tomography scan showed opacification of the left maxillary sinus expanding through the medial wall of the antrum with thinning and destruction of the adjacent structures. Endoscopic marsupialization of the lesion and left partial maxillectomy were performed. The cystic mass had yellowish thick mucopurulent fluid that was completely drained.
CONCLUSIONS: A few cases of sphenoid sinus mucocele as a late complication of radiation therapy have been reported. Maxillary mucocele and mucopyocele can be considered as one of the late complications of radiotherapy to head and neck as a result of occlusion of sinus ostia by scarred mucosa.
Fulltext Endoscopic marsupialisation of the lateral frontal sinus mucocele with orbital extension: a case report

Sharouny H, Narayanan P

Iran Red Crescent Med J, 2015 Jan;17(1):e17104.
PMID: 25763256 DOI: 10.5812/ircmj.17104

INTRODUCTION: Frontal sinus mucoceles are the commonest among all paranasal mucoceles. With introduction of functional endoscopic sinus surgery, surgeons prefer endoscopic management of sinus mucoceles, but lesions that appear in the lateral part of the frontal sinus can be difficult to access and often need external approaches.
CASE PRESENTATION: We described a lateral frontal sinus mucocele with intra-orbital extension, which was successfully managed by endoscopic sinus surgery.
CONCLUSIONS: Endoscopic sinus surgery is the treatment of choice in most frontal sinus mucoceles including lateral frontal mucoceles.
Endoscopic skull base training using 3D printed models with pre-existing pathology

Narayanan V, Narayanan P, Rajagopalan R, Karuppiah R, Rahman ZA, Wormald PJ, et al.

Eur Arch Otorhinolaryngol, 2015 Mar;272(3):753-7.
PMID: 25294050 DOI: 10.1007/s00405-014-3300-3

Endoscopic base of skull surgery has been growing in acceptance in the recent past due to improvements in visualisation and micro instrumentation as well as the surgical maturing of early endoscopic skull base practitioners. Unfortunately, these demanding procedures have a steep learning curve. A physical simulation that is able to reproduce the complex anatomy of the anterior skull base provides very useful means of learning the necessary skills in a safe and effective environment. This paper aims to assess the ease of learning endoscopic skull base exposure and drilling techniques using an anatomically accurate physical model with a pre-existing pathology (i.e., basilar invagination) created from actual patient data. Five models of a patient with platy-basia and basilar invagination were created from the original MRI and CT imaging data of a patient. The models were used as part of a training workshop for ENT surgeons with varying degrees of experience in endoscopic base of skull surgery, from trainees to experienced consultants. The surgeons were given a list of key steps to achieve in exposing and drilling the skull base using the simulation model. They were then asked to list the level of difficulty of learning these steps using the model. The participants found the models suitable for learning registration, navigation and skull base drilling techniques. All participants also found the deep structures to be accurately represented spatially as confirmed by the navigation system. These models allow structured simulation to be conducted in a workshop environment where surgeons and trainees can practice to perform complex procedures in a controlled fashion under the supervision of experts.
3 Tesla magnetic resonance imaging noise in standard head and neck sequence does not cause temporary threshold shift in high frequency

Lim EY, Tang IP, Peyman M, Ramli N, Narayanan P, Rajagopalan R

Eur Arch Otorhinolaryngol, 2015 Nov;272(11):3109-13.
PMID: 25205300 DOI: 10.1007/s00405-014-3232-y

High acoustic noise level is one of the unavoidable side effects of 3 T magnetic resonance imaging (MRI). A case of hearing loss after 3 T MRI has been reported in this institution and hence this study. The objective of this study was to determine whether temporary threshold shift (TTS) in high frequency hearing occurs in patients undergoing 3 T MRI scans of the head and neck. A total of 35 patients undergoing head and neck 3 T MRI for various clinical indications were tested with pure tone audiometry in different frequencies including high frequencies, before and after the MRI scan. Any threshold change from the recorded baseline of 10 dB was considered significant. All patients were fitted with foamed 3 M earplugs before the procedure following the safety guidelines for 3 T MRI. The mean time for MRI procedure was 1,672 s (range 1,040-2,810). The noise dose received by each patient amounted to an average of 3,906.29% (1,415-9,170%). The noise dose was derived from a normograph used by Occupational Noise Surveys. This was calculated using the nomograph of L eq, L EX, noise dose and time. There was no statistically significant difference between the hearing threshold before and after the MRI procedures for all the frequencies (paired t test, P > 0.05). For patients using 3 M foamed earplugs, noise level generated by 3 T MRI during routine clinical sequence did not cause any TTS in high frequency hearing.

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