C M Chan

Queen Elizabeth Hospital, Hong Kong, Hong Kong

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Publications (27)36.12 Total impact

  • JPK Chan · SMS Lo · CM Chan · WL Poon · YL Cheung · KW Shek · KW Tang · PH Wong
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    ABSTRACT: Direct carotid cavernous sinus fistula is a common delayed complication of head trauma, particularly in patients with skull base fractures. When carotid cavernous sinus fistula occurs together with carotid artery dissection, it poses a big challenge regarding successful treatment. Endovascular treatment options include occlusion with detachable balloons, coils, and Pipeline flow diverters (Chestnut Medical Technologies, Menlo Park [CA], USA). Here we describe the successful management of a patient with dual pathology with traumatic carotid cavernous sinus fistula and internal carotid artery dissection with multiple pseudoaneurysms using flow diverters and detachable coils.
    No preview · Article · Sep 2015 · Hong Kong Journal of Radiology
  • JB Chiang · SSM Lo · LC Ho · CM Chan · WL Poon · KW Tang · YL Cheung
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    ABSTRACT: Neurenteric cyst is a notably rare epithelium-lined cystic lesion found in the central nervous system. Malignant transformation of the neurenteric cyst is infrequent, with only six cases reported in the English literature. We report the case of a 74-year-old patient with recurrent neurenteric cyst in the posterior cranial fossa that underwent malignant transformation 2 years after initial surgery. Histologically, the initial lesion was compatible with benign neurenteric cyst, whereas the recurrent lesion illustrated features of adenocarcinoma.
    No preview · Article · Dec 2014 · Hong Kong Journal of Radiology
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    Calvin HK Mak · K M Cheng · YL Cheung · C M Chan
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    ABSTRACT: OBJECTIVES. To evaluate the efficacy and complications of endovascular treatment for ruptured internal carotid artery pseudoaneurysms following irradiation of nasopharyngeal carcinoma. DESIGN. Retrospective case series. SETTING. Tertiary neurosurgical referral unit of a Hong Kong public hospital. PATIENTS. Patients with ruptured radiation-induced internal carotid artery pseudoaneurysms that were treated endovascularly from October 1999 to October 2011 at Queen Elizabeth Hospital were reviewed. Hospital records, imaging, and angiographic data were studied. RESULTS. During the study period, 15 such nasopharyngeal carcinoma patients were treated by endovascular means at Queen Elizabeth Hospital. Ten presented with epistaxis, three with otorrhagia (bleeding from the ear), and two with both. Therapeutic occlusion of the affected internal carotid artery was performed in four patients, and stenting of the artery (with or without coil obliteration of the pseudoaneurysm) was performed in 11. Immediate haemostasis was achieved in all cases. One (7%) of the 15 patients endured symptomatic recurrence of the pseudoaneurysm, and in another an asymptomatic residual pseudoaneurysm was noted in the follow-up angiogram. Three patients suffered clinically significant procedure-related complications, including cerebral infarction (n=2) and brain abscess (n=1). In the angiograms obtained after a mean post-treatment interval of 13 (range, 0.7-60) months, the stent patency rate was 67%. All three patients with occluded stents were asymptomatic. CONCLUSIONS. Ruptured internal carotid artery pseudoaneurysms following radiotherapy is a rare but life-threatening condition. Endovascular treatment by occlusion or reconstruction of the internal carotid artery with stents provides immediate haemostasis and obliteration of the pseudoaneurysms, with a low recurrence rate. Long-term follow-up is necessary to look out for delayed post-treatment complications.
    Preview · Article · May 2013 · Hong Kong medical journal = Xianggang yi xue za zhi / Hong Kong Academy of Medicine
  • J Cw Kong · K M Cheng · Y L Cheung · C M Chan
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    ABSTRACT: Vein of Galen aneurysmal malformation is a rare entity in the paediatric population. However, it is being recognised with increasing frequency due to better diagnostic techniques. Neonates usually present with congestive heart failure, while in older infants and children it tends to manifest with seizures, hydrocephalus, intracerebral or subarachnoid haemorrhages. We present a case of ruptured vein of Galen aneurysmal malformation in a 3-month-old baby boy treated by transarterial embolisation using Guglielmi detachable coils.
    No preview · Article · Oct 2012 · Hong Kong medical journal = Xianggang yi xue za zhi / Hong Kong Academy of Medicine
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    H K Leung · Y Lam · K M Cheng · C M Chan · Y L Cheung
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    ABSTRACT: Intracranial aneurysm in twins is a rare clinical disease entity. Only 15 cases have been described in the literature. We report on a pair of identical twins with intracranial aneurysms. One presented with subarachnoid haemorrhage; digital subtraction angiography showed a left posterior communicating artery aneurysm, which was treated by coiling. The patient's twin sister was called for screening, whereupon digital subtraction angiography revealed a right ophthalmic internal carotid artery aneurysm that was treated conservatively.
    Preview · Article · Apr 2011 · Hong Kong medical journal = Xianggang yi xue za zhi / Hong Kong Academy of Medicine
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    ABSTRACT: It is hypothesized that a venographic-based operational classification of dural carotid-cavernous fistula (DCCF) will facilitate early selection of the optimal venous route and enhance the efficacy of transvenous catheterization and embolization of the cavernous sinus. This was a retrospective study on 97 patients who presented with symptomatic DCCF. Definition of classification type 1: both the anterior and posterior compartments of the cavernous sinus were opacified, type 2: only the anterior compartment was opacified, type 3: only the posterior compartment was opacified. Subtype a: the facial vein (FV) draining the superior ophthalmic vein (SOV) was opacified, subtype b: only the inferior petrosal sinus (IPS) was opacified, subtype c: neither the FV nor the IPS were opacified, subtype d: both the FV and the IPS were opacified. The SOV route was recommended for subtype 1a and type 2. The IPS route was recommended for subtype 1b, 1c, 1d, and type 3. Success rates of catheterization by the recommended routes and non-recommended routes were calculated. Number of DCCF lesions were 20 (1a), 28 (1b), 23 (1c), 26 (1d), 16 (2a), 10 (2c), 2 (3b). Of 145 attempted catheterization, 91 and 54 were performed with a recommended route and un-recommended route, respectively. Success rate for catheterization and embolization performed with the recommended route and un-recommended route was 71/91 (78%) and 20/54 (37%), respectively (Chi-Square test Pā€‰=ā€‰0.0024). Venographic operational classification is useful for guiding the selection of optimal venous route which enhances the efficacy of transvenous embolization of the DCCF.
    No preview · Article · Dec 2010 · Neuroradiology
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    ABSTRACT: Objectives: Malignant spinal cord compression is an uncommon complication in patients with cancer. It is frequently diagnosed late and causes irreversible damage to spinal cord. Malignant spinal cord compression is an oncological emergency, requiring a prompt imaging diagnosis and immediate treatment. Magnetic resonance imaging has a vital role in the management of such patients. Our audit was to assess whether patients with malignant spinal cord compression were recognised, investigated, and treated appropriately in our hospital. Large international audits of malignant spinal cord compression, such as clinical resource and audit group, were used as our reference standards. We also compared the level of spinal cord compression inferred clinically and based on magnetic resonance imaging findings, and evaluated whether localised spinal magnetic resonance imaging based on clinical assessment as adopted in our routine magnetic resonance imaging protocol was appropriate. Methods: From January to December 2008, 1087 patients underwent magnetic resonance imaging scans of the spine in our hospital. Of these, 106 patients presented with clinical features suspicious of malignant spinal cord compression and urgent magnetic resonance imaging spine was performed. The demographic factors, primary tumour pathology, Tokuhashi score, clinical symptoms, clinical suspicion of the level of cord compression, magnetic resonance imaging findings, treatment response, and prognosis were assessed retrospectively from the medical records, the electronic Patient Record, and imaging reports from the Radiology Information System. Results: Among the patients with a clinical suspicion of malignant spinal cord compression, prevalence rates were higher in males (61%) and older persons (mean age, 63 years; standard deviation, 14 years). Lung cancer was the most common responsible primary tumour in males (38%), whereas breast cancer was the most common primary tumour in females (32%). Spinal cord compression was the initial presentation of malignancy in 6 (8%) patients. Most patients showed evidence of bone metastasis (53%) and metastasis in major internal organs (51%) prior to the clinical presentation of malignant spinal cord compression. The most common clinical symptoms of malignant spinal cord compression were back pain (77%), limb weakness (94%) and numbness (90%). Of the 106 patients, 43% showed a low Tokuhashi score (<5) during admission. 77% of patients with a clinical suspicion of malignant spinal cord compression had magnetic resonance imaging spine in our hospital within 24 hours; the upper thoracic spine was the most common level of cord compression among these patients, and multilevel compression occurred in 8% of them. There was considerable discrepancy between the level of spinal cord compression inferred clinically and that determined by magnetic resonance imaging (57%); the average level of discrepancy being 5 vertebral bodies (95% confidence interval, 4-6). A greater degree of discrepancy was evident in patients with multiple spinal metastases (p < 0.05). 89% of patients with a clinical suspicion of malignant spinal cord compression had received steroids. The mean time required for starting definitive treatment after confirmation of the diagnosis by magnetic resonance imaging was 1.3 (standard deviation, 0.5) days; 74% were treated within 24 hours of the imaging. Patients with malignant spinal cord compression had an unsatisfactory survival rate of 75% at hospital discharge; the median survival time from first clinical presentation was 37 days (range, 9-884 days). The majority (57%) of patients showed clinical improvement after radiotherapy. Conclusion: Patients with malignant spinal cord compression in our hospital were recognised, investigated, and treated appropriately. Our results were comparable to those reported in the literature. We found a great discrepancy between the level of spinal cord compression inferred clinically and by magnetic resonance imaging, particularly when multiple spinal metastases were present. We concluded that localised magnetic resonance imaging of the spine based on clinical findings was inadequate. Our magnetic resonance imaging protocol for malignant spinal cord compression patient was modified based on the results of this study.
    No preview · Article · Jan 2010 · Journal of the Hong Kong College of Radiologists
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    ABSTRACT: To review the pattern of ruptured intracranial aneurysms in terms of size, location, and the prevalence of multiple aneurysms in the Hong Kong Chinese population with subarachnoid haemorrhage. Retrospective study. Three public hospitals in Hong Kong. A total of 267 Chinese patients with subarachnoid haemorrhage from ruptured intracranial aneurysms between July 1998 and June 2002 were reviewed retrospectively. The patients had a mean age of 59 (range, 13-96) years, with a female-to-male ratio of 2:1. Concerning the age at presentation, males presented with ruptured intracranial aneurysms at a younger age (P=0.001) than females. Ruptured aneurysms were more commonly located in the anterior than posterior circulation (84% vs 16%). The posterior communicating artery (26%) and anterior communicating artery (22%) were the most common sites of rupture. As a whole, 64% of the aneurysms had a size of 5 mm or less. The anterior communicating artery had a higher proportion with a size of 5 mm or less compared to other locations (P<0.05). In this cohort, the prevalence of multiple aneurysms was 17%. There was no significant difference in the prevalence of multiple aneurysms between men and women (P=0.30). In patients with multiple aneurysms, the sizes of ruptured aneurysms were greater than those of the largest unruptured aneurysms (P<0.001). When compared with the group with single aneurysms, patients with multiple aneurysms had a smaller proportion of small aneurysms, sized 5 mm or less (P<0.05). The pattern of ruptured intracranial aneurysms in the Hong Kong Chinese population was different from western and Japanese populations. Although the distribution of locations for ruptured aneurysms was similar, Hong Kong Chinese had a larger proportion of small aneurysms sized 5 mm or less. The prevalence of multiple aneurysms in Hong Kong is comparable to that in the Japanese population, but lower than that in the western populations.
    Full-text · Article · Sep 2009 · Hong Kong medical journal = Xianggang yi xue za zhi / Hong Kong Academy of Medicine
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    ABSTRACT: Developmental venous anomaly (also known as venous angioma or venous malformation) is one of the 4 main vascular malformations. Developmental venous anomaly is usually benign and clinically silent. This report is of a patient with cerebellar developmental venous anomaly with draining vein thrombosis, complicated by non-haemorrhagic venous infarct of the midbrain.
    No preview · Article · Jan 2009 · Journal of the Hong Kong College of Radiologists
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    ABSTRACT: Neurilemmoma (schwannoma) is a benign peripheral nerve sheath tumour that rarely occurs in the nasal cavity. Lesions that present in the paranasal sinuses and nasal cavity account for approximately 4% of head and neck neurilemmomas. In patients with a known history of neurofibromatosis, computed tomography and magnetic resonance imaging can give a clue to this diagnosis, which requires confirmation by histology. This report is of a patient with nasal neurilemmoma and neurofibromatosis 2.
    No preview · Article · Jan 2008 · Journal of the Hong Kong College of Radiologists
  • H.S. Fung · S. Lau · J.C.W. Siu · C.M. Chan · S.C.H. Chan
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    ABSTRACT: Objective: To determine the utility and accuracy of ultrasonography for the diagnosis of acute appendicitis. Methods: In this retrospective study, 242 of 286 patients undergoing ultrasonography of the appendix from 1 June 2006 to 31 December 2006 were included. The ultrasonography report, pathology report, and clinical notes were reviewed. The pathology report was used as the gold standard for a diagnosis of acute appendicitis. Results: The overall rate of visualisation of the appendix was 41.7%. Fifty six patients (23%) had a positive diagnosis of acute appendicitis by ultrasonography, 45 (19%) had a negative diagnosis, and 141 (58%) had an inconclusive diagnosis; 17 patients (7%) had an alternative diagnosis suggested by ultrasonography. Twenty nine patients (12%) underwent computed tomography on the basis of the ultrasonography report, 6 of whom had a positive diagnosis for acute appendicitis, 5 had a negative diagnosis, and 18 had an alternative diagnosis suggested by computed tomography. The sensitivity, specificity, positive predictive value, and negative predictive value of ultrasonography for acute appendicitis were 75.9%, 89.7%, 73.2%, and 91.0%, respectively, after adjusted calculation for the group with an inconclusive ultrasonography diagnosis. Conclusions: The performance of ultrasonography for investigation of acute appendicitis at the Queen Elizabeth Hospital, Hong Kong, is comparable to the data reported in the literature. Ultrasonography is a useful and safe imaging modality for investigation of acute appendicitis, and computed tomography has a complementary role for the diagnosis of acute appendicitis and management of patients with right lower quadrant pain.
    No preview · Article · Jan 2008 · Journal of the Hong Kong College of Radiologists
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    H Y Chan · K M Cheng · M W Lo · C M Chan · Y L Cheung
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    ABSTRACT: Dementia is a common medical problem that affects elderly patients. We report on a 77-year-old man with an intracranial dural arteriovenous fistula who presented with dementia that was initially thought to be irreversible and degenerative. Subsequent neuroendovascular intervention resulted in significant functional and cognitive improvement.
    Preview · Article · Mar 2006 · Hong Kong medical journal = Xianggang yi xue za zhi / Hong Kong Academy of Medicine
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    ABSTRACT: Intracranial involvement of Rosai-Dorfman disease is rare. Central nervous system involvement occurs in less than 5% of patients. To date, there have only been 52 patients with this condition reported in 41 articles. This report is of a patient with a 13-year history of intracranial Rosai-Dorfman disease experiencing occlusion of the internal carotid artery. The clinical, pathological, and radiological features of the disease are discussed, together with a review of the literature.
    No preview · Article · Jan 2003 · Journal of the Hong Kong College of Radiologists
  • K.F. Chan · T.W. Fan · C.M. Chan · Y.L. Cheung · S.C.H. Chan
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    ABSTRACT: A 4-year-old boy presented with motor weakness and was subsequently found to have intraspinal extramedullary arteriovenous malformation (type IV C arteriovenous malformation) at the cervical region. Angiographic embolisation was performed. This patient illustrates the clinical inconspicuousness of spinal arteriovenous malformation in young patients and the importance of making the correct diagnosis so as to facilitate further interventional therapy.
    No preview · Article · Jan 2003 · Journal of the Hong Kong College of Radiologists
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    ABSTRACT: Patients with dural arteriovenous fistula (DAVF) are at higher risk of developing neurological deficits when there is retrograde leptomeningeal venous drainage. Our aim is to demonstrate the presence of dilated deep medullary veins in the brain on magnetic resonance imaging (MR) in this group of patients, and to assess their clinical significance. Nine patients with angiographically proven DAVF associated with leptomeningeal venous drainage who had MR before treatment were studied.MR was performed in at least two orthogonal planes before and after gadolinium administration. The dural fistula was located at the cavernous sinus in five patients, at the transverse-sigmoid sinus in three and at the tentorium in one. Dilated deep medullary veins were noted in six patients. Of these, four showed parenchymal abnormalities which included intracerebral haematoma, venous infarction, brain oedema and T2 hyperintensity in brainstem. Venous varix was present in one patient. No neurological complication or parenchymal change was observed in the three patients without dilated deep medullary veins. Therefore, in patients with intracranial DAVF associated with leptomeningeal venous recruitment, the MR finding of dilated deep medullary veins suggests a more severe degree of venous hypertension and congestion in the brain. This subgroup of patients has a much higher chance of neurological complications and warrants urgent intervention.
    No preview · Article · Sep 2002 · Interventional Neuroradiology
  • C. K. Law · C. M. Chan · P. T. Leung · M. C. Chu
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    ABSTRACT: A Reply to the Comment by Mourad Haddad and Vincent Hakim.
    No preview · Article · Nov 2001 · Physical Review Letters
  • C. K. Law · C. M. Chan · P. T. Leung · M.-C. Chu
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    ABSTRACT: We investigate the dynamic stability of two interacting Bose-Einstein condensates moving through each other with a relative velocity vr. We show that there exists a critical velocity vr(c) such that for vr>vr(c) the condensate mixture becomes unstable. We construct an analytic expression of the critical relative velocity and determine the unstable collective modes. We also discuss how our results can be applied to matter-wave-mixing processes.
    No preview · Article · May 2001 · Physical Review A
  • T C Tan · C M Chan · H M Chiu
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    ABSTRACT: An anterior cerebral artery traumatic aneurysm in a 15-month-old infant is described. The diagnosis was confirmed by computed tomographic angiography. The patient recovered fully after successful clipping of the aneurysm. As the signs of traumatic intracranial aneurysm may be subtle especially in young children, a high degree of suspicion is essential in patients presenting with delayed neurological deterioration after head trauma.
    No preview · Article · May 2001 · British Journal of Neurosurgery
  • K M Cheng · C M Chan · YL Cheung · H M Chiu · K W Tang · C K Law
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    ABSTRACT: Haemorrhage from rupture of petrous ICA aneurysm can be life threatening and emergency treatment is required. We report 2 cases of radiation-induced petrous internal carotid artery (ICA) aneurysm presenting with acute haemorrhage (epistaxis and otorrhagia) after radiotherapy (RT) for nasopharyngeal carcinoma (NPC). Both patients had a history of RT treatment for NPC. The first patient, a 54-year-old man, presented with sudden severe epistaxis and haemorrhagic shock. The second patient, a 35-year-old man, presented with episodes of severe otorrhagia. The first patient was immediately resuscitated. Obliteration of the aneurysm was performed by endovascular occlusion of the ICA with Guglielmi detachable coils and fibered platinum coils. For the second patient, the aneurysm was treated by deploying a self-expandable stent across the aneurysm neck. In an emergency situation, ruptured petrous ICA aneurysm can be treated with endovascular occlusion of the ICA with microcoils if there is a good collateral blood flow. Alternatively, the aneurysm can be treated by deployment of a stent, which can induce stasis and eventual thrombosis of the aneurysm.
    No preview · Article · Feb 2001 · Acta Neurochirurgica
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    ABSTRACT: Meningiomas are rare in childhood and they constitute 1.5% of intracranial meningiomas. We report a case of a left middle cranial fossa meningioma in a 11-year-old boy who presented with left-sided facial weakness and deafness. Neurological examination showed left lower motor neuron facial nerve palsy with sensori-neural deafness of his left ear. Computed tomography demonstrated a contrast enhancing extra-axial tumour in the left middle cranial fossa with calcification. Magnetic resonance imaging confirmed the presence of an extra-axial tumour measuring 3 Ɨ 3.5 Ɨ 2.7 cm. The mass was isointense to gray matter on T1-weighted images, with a markedly hypointense rim on T2-weighted images. The lesion exhibited homogeneous enhancement with gadolinium. It eroded the petrous base, extending into the left internal auditory meatus and cerebello-pontine cistern. The preoperative diagnosis was trigeminal schwannoma. Intraoperatively, a firm tumour was seen arising from the middle cranial fossa attached to the petrous temporal bone. Near-total excision of tumour was achieved. The histological diagnosis was xanthomatous meningioma. The patient recovered uneventfully without additional neurological deficit. He underwent linac radiosurgery for the 1 cm tumour remnants in the internal acoustic meatus and the left cerebellopontine angle. Follow-up MRI scans 14 months after radiosurgery showed shrinkage of the remaining tumour. At follow up 20 months after operation the child was well and had resumed his education. Conclusion: While surgery remains the main therapeutic modality, complete excision is not always possible in skull base meningiomas as it carries significant postoperative morbidity. Radiosurgery is a valuable complementary measure for local control in case of residual or recurrent tumour.
    No preview · Article · Feb 2001 · Annals of the College of Surgeons Hong Kong