Search PubMed⌕ Search

Biomedical subjects

F L Chan

Publications and source records attributed to F L Chan.

At least 109 records · Page 6Linked to original sources
PubMed1991

Cranial nerve involvement and base of the skull erosion in nasopharyngeal carcinoma.

In a prospective study of 262 consecutive patients with nasopharyngeal carcinoma (NPC), using computed tomography (CT) as their baseline evaluation, erosion of the base of the skull and intracranial extension into the middle cranial fossa were found in 31.3% and 12.2% of patients, respectively. Thirty-four of these patients had cranial nerve involvement at presentation; 30 of them had involvement of one or more of the third to sixth cranial nerves. Most cases of intracranial extension of tumor were accompanied by erosion of the base of the skull, but the reverse was not true. All patients with cranial nerve palsy involving the third to sixth cranial nerves had associated erosion of the ipsilateral base of the skull. The CT evaluation of patients with cranial nerve involvement who are believed to harbor NPC should include thin cuts of the base of the skull for detection of subtle bone erosion. This may be the only clue to the presence of a small NPC. The prognostic significance of cranial nerve involvement, base of the skull erosion, and intracranial extension of the tumor on the survival of the group of 84 patients who had T4 tumors was evaluated with regression analysis using the Cox model. Only cranial nerve involvement was found to be a significant factor influencing survival.

Cranial Nerve Neoplasms↗
PubMed1991

Biliary cystadenoma and cystadenocarcinoma: some unusual features.

Biliary cystadenoma and cystadenocarcinoma are rare tumours which have a good prognosis after complete surgical removal. Correct pre-operative diagnosis depends on the imaging characteristics of the tumours. We have observed some unusual features including multifocal tumours with attachment to other abdominal organs, tumour presenting as cholangitic abscess, and distant metastasis after apparently complete resection by hemihepatectomy.

Adult↗
PubMed1990

Ascending aortic dissection complicating syphilitic aortitis, late after aortic valve replacement.

A 54-year-old man underwent aortic valve replacement for syphilitic aortic regurgitation. Eight years later, he was admitted with sudden precordial discomfort and symptoms of superior vena caval obstruction. Ascending aortic dissection was diagnosed by echocardiography and computed tomography of the thorax. The patient succumbed rapidly after admission. Postmortem findings and histological features were compatible with syphilitic aortitis, without significant atherosclerosis. This case report adds to the sparse literature on aortic dissection complicating syphilitic aortitis, and illustrates that, at certain stages of the disease process, syphilitic aortitis can lead to such a degree of mechanical instability of the aortic wall as to predispose to dissection.

Aortic Rupture↗
PubMed1990

Role of computed tomography in the management of recurrent pyogenic cholangitis.

A retrospective analysis was performed to define the indications and usefulness of computed tomography (CT) in the management of 62 patients with recurrent pyogenic cholangitis. When performed in 18 patients in the acute phase for persistent fever inexplicable by ultrasonography and cholangiography, CT scans identified the cause of sepsis to be liver abscesses (n = 7), impacted stones in left lateral segments (n = 3) and right posterior inferior duct (n = 1). When performed in 44 patients during remission, CT scans detected impacted intrahepatic stones as the cause of non-opacification of segmental bile ducts on cholangiograms (n = 15), demonstrated liver volume changes (segmental atrophy, n = 31; hypertrophy, n = 5), differentiated intrahepatic stones from pneumobilia (n = 5) and revealed stones in segregated intrahepatic bile ducts (n = 4). Overall 75.8% of CT scans showed valuable intrahepatic findings which were useful in guiding the appropriate treatment for the intrahepatic pathology. In the others without demonstrable intrahepatic pathology on CT, patients were adequately treated for common bile duct pathology alone. It is recommended that CT should be performed when ultrasonography and cholangiography cannot elucidate the cause of persistent fever, when the cholangiogram shows non-opacification of segmental bile ducts, or fails to demonstrate the cause of recurrent acute cholangitis, particularly in patients who have had previous bilio-enteric drainage procedures.

Adult↗
PubMed1990

Cerebrovascular disease in Hong Kong Chinese.

Our prospective study of cerebrovascular disease in Hong Kong confirms a previous clinical impression that stroke in the Chinese has a pattern different from that in Caucasians. We studied 540 patients (aged 20-70 years) with stroke. Computed tomography or autopsy was obtained in 86.1% and showed an increase in the proportion with lacunar infarction, striatocapsular infarction, and parenchymal hemorrhage relative to the frequencies in Caucasians. This increase in the incidence of cerebral hemorrhage occurs not only in semicomatose and comatose patients but also in alert patients (16.9%) and those with a lacunar syndrome (12.5%). Our findings suggest that cerebrovascular disease in the Chinese selectively affects small vessels, causing lacunes and hemorrhages. In future community studies on stroke prevalence, researchers should be cautious about interpreting similar prevalence rates as reflecting similar risk factors or pathologies.

Adult↗
PubMed1990

Nasopharyngeal carcinoma: pattern of skeletal metastases.

The records of 153 nasopharyngeal carcinoma patients with skeletal metastases were reviewed. The skeletal system was the most common site of distant metastases. The patients who developed skeletal metastases were significantly younger than those without skeletal metastases, although there was no difference between sexes. The pattern of skeletal involvement conforms to the general pattern, the spine and pelvis being the common sites. The first region of involvement was lumbar spine (28.4%), then dorsal spine (27.7%), sacrum and pelvis (16.3%), femur (9.9%), rib and sternum (7.8%), humerus (5.0%), cervical spine (3.5%) and skull vault (1.4%). Radiologically, the lesions were lytic in 66.0%, mixed lytic and sclerotic in 12.8% and sclerotic in 21.2%. The time to development of symptomatic skeletal metastases of mixed or sclerotic nature was significantly longer than lytic lesions, and patients with mixed or sclerotic metastases also had better survival.

Adolescent↗
PubMed1989

Pancreatic phlegmon: what is it?

In a retrospective study of 264 patients with acute pancreatitis, 22 were identified as having phlegmon by combined radiologic and clinical criteria. The radiologic criteria consisted of demonstration of abnormal lesion on computed tomography scan which was composed of masses of mixed density, free of extraluminal gas and lacking a well-defined wall. The clinical criteria was that the clinical course was free of sepsis. Half of the group thus identified had severe pancreatitis as defined as having three or more poor prognostic signs. Fever, leukocytosis, and serum amylase elevation persisted for a longer period than usual. Complication was infrequent but the lesion could persist for 3 to 4 months without producing symptoms. This is a relatively benign condition and surgery should be avoided.

Abscess↗
PubMed1989

Primary mediastinal endodermal sinus tumors: CT evaluation.

Five patients with primary mediastinal endodermal sinus tumor have been evaluated by computed tomography (CT). The tumors were all located in the anterior mediastinum. Prechemotherapy CT demonstrated large, irregularly enhancing inhomogeneous masses without fat components. Calcification was visualized in two tumors. Some parts of the pleura-lung interface were irregular in four cases. Obliteration of fat planes to pericardium and chest wall was evident in all cases, and there was infiltration of intercostal muscles in four. Postchemotherapy CT in two patients who responded to chemotherapy showed either newly developed cystic lesions or cystic change of the original mediastinal mass. The cystic masses had more regular borders, a homogeneous hypodense center, and a smooth peripheral rim of contrast-enhancing tissue.

Adolescent↗
PubMed1989

Pediatric pyeloplasty: 50 patients with 59 hydronephrotic kidneys.

A report of 59 hydronephrotic kidneys due to pelviureteric junction (PUJ) obstruction in 50 children less than 12 years of age is presented. Thirty-two percent of the patients were less than 1 year of age, with their main presenting feature being an abdominal mass (88%). For older children, loin or abdominal pain was the chief presenting symptom (68%). During infancy, the left and right sides were equally affected, followed closely by bilateral involvement. On the other hand, in older children, the left side was predominantly affected, being twice as common as the right, and the latter again was twice as common as bilateral involvement. Dismembered pyeloplasty was the procedure used in most cases (88%); the nephrectomy rate was 8% for grossly dilated or dysplastic kidneys. During follow-up (of 6 months to 10 years) of 54 pyeloplasties, improvement was seen in 36 (67%), 12 were unchanged (22%), and one reverted to normal (2%) after the initial operation. Two (4%) worsened initially but achieved stabilization after reoperation; the remaining 3 patients (6%) showed unsatisfactory results. Stents were used in 65% of the cases and nephrostomies in 53%.

Child↗
PubMed1989

Imaging for adrenal tumours.

Modern medical imaging has transformed the diagnosis and management of adrenal disease. The various types of adrenal tumours bear different aspects of problems in diagnostic imaging. The investigation used must be determined and monitored individually, as directed by the clinical and biochemical findings. CT plays a central role in the localization of the functioning adrenal tumours. It is regarded as the imaging modality of choice because it combines safety with a high rate of detection. It is highly sensitive in the localization of the large adrenal tumours that account for Cushing's syndrome and phaeochromocytomas, as well as the small tumours that account for primary hyperaldosteronism. It is, however, not reliable for the detection of adrenal hyperplasia, and does not yield functional imaging information. For small tumours not detectable by CT, and for ectopic tumours, complementary investigations with appropriate application of venous sampling, radionuclide scintigraphy and occasionally arteriography, will be very useful. CT-guided percutaneous biopsy is employed for the incidentalomas in oncologic patients. MRI appears to hold a great potential for the diagnosis of adrenal disorders, but this modality is awaiting wider availability of instrumentation and clearer documentation of techniques.

Adrenal Gland Neoplasms↗
PubMed1989

Treatment of precocious puberty using an intranasal luteinizing hormone-releasing hormone analogue: Buserelin.

Fourteen patients with precocious puberty were treated for 1-3 years with 900-1800 micrograms/day of intranasal (i.n.) Buserelin. The peak luteinizing hormone and follicle-stimulating hormone responses to intravenous luteinizing hormone-releasing hormone were reduced significantly 4 weeks after starting treatment and remained suppressed while the patients were on treatment. Two patients were withdrawn because of drug non-compliance. Three patients showed regression of pubertal changes, four patients showed no progression and five patients showed progression of breast size or pubic hair staging after 1.5-2 years of treatment. Treatment was changed to the subcutaneous route in two patients because of hormonal escape and accelerated skeletal maturation. The mean growth velocity decreased from 10.78 cm/year (s.e.m. = 0.64) to 7.06 cm/year (s.e.m. = 0.85) after 1 year of treatment (P less than 0.005). After an increase in dosage (from 900 micrograms/day to 1800 micrograms/day) in most patients, further significant falls in growth velocity to 5.29 cm/year (s.e.m. = 0.45), 4.63 cm/year (s.e.m. = 0.8) and 5.06 cm/year (s.e.m. = 0.5) were observed at 18, 24 and 30 months, respectively, compared with the pretreatment value (P less than 0.001). With treatment, the increased rate of skeletal maturation normalized. In 10 patients who had completed 2 years of treatment, the height standard deviation score for bone age improved from a pretreatment value of -2.42 +/- 0.42 to -1.6 +/- 0.42 after 2 years of treatment (P less than 0.01), indicating an improvement in height prognosis. It is concluded that i.n. Buserelin at a dose of 1800 micrograms/day is effective in the treatment of most but not all patients with precocious puberty.

Administration, Intranasal↗
PubMed1989

Evaluation of recurrent pyogenic cholangitis with CT: analysis of 50 patients.

The use of computed tomography (CT) was investigated in 50 patients with recurrent pyogenic cholangitis, 22 of whom had undergone prior choledochoenterostomy or sphincteroplasty. A spectrum of pathologic features was noted, including intrahepatic ductal dilatation (n = 50), common duct dilatation (n = 34), strictures (n = 11), intrahepatic calculi (n = 37), common duct calculi (n = 15), pneumobilia (n = 26), segmental atrophy (n = 18), and splenomegaly (n = 7). Unilobar disease existed in 14 patients. The left lateral segment was predominantly affected, with ductal dilatation (n = 23) and segmental atrophy (n = 13). During acute exacerbation, additional manifestations were observed: ductal wall enhancement (n = 4), segmental parenchymal enhancement (n = 9), hepatic abscess (n = 9), and biloma (n = 2). CT enables sensitive, complete evaluation of this disorder. It is valuable when results of ultrasonography are non-diagnostic and for planning hepatic resection, evaluating associated mass lesions, and guiding complex interventional procedures.

Adult↗
PubMed1989

Comparison of the effectiveness of 2-hourly versus 8-hourly subcutaneous injections of a somatostatin analog (SMS 201-995) in the treatment of acromegaly.

To determine whether sc injections of a somatostatin analog (SMS 201-995) every 2 h (q2h) is more effective than sc injections every 8 h (q8h) in achieving a constant suppression of GH levels and a more satisfactory clinical response, we studied 10 patients with acromegaly (4 newly diagnosed and 6 previously treated with bromocriptine/pituitary irradiation/transfrontal hypophysectomy). The dose of SMS 201-995 was increased from 300 micrograms/day to a maximum of 600 micrograms/day when the mean serum GH (hourly samples for 12 h) failed to be suppressed to undetectable levels in over 75% of the samples. Five patients received a 200-micrograms sc injection q8h (600 micrograms/day), and the other 5 received sc injections q2h [418 +/- 46 micrograms/day (mean +/- SE); range, 288-504 micrograms/day]. In the group receiving q2h sc SMS 201-995 there was a marked suppression of mean GH from a basal level of 77.3 +/- 24.7 mU/L to less than 5 mU/L in all five subjects. In the group receiving q8h sc SMS 201-995, mean GH was suppressed from a basal level of 82.2 +/- 21.7 to 15.4 +/- 3.3 mU/L after 6 months of therapy, and none of the patients had a mean GH level consistently less than 5 mU/L. Despite the difference in the level of GH suppression, mean serum somatomedin-C levels were decreased promptly in both groups of subjects. Associated with the decrease in somatomedin-C levels there was a marked clinical response in both groups, but improvement in clinical features and decreases in hand volumes and ring size occurred earlier in the group receiving SMS 201-995 q2h. Significant tumor shrinkage (25% to greater than 50% reduction) was observed in two patients receiving q2h injections, while a 25-50% reduction in tumor size was noted in another patient receiving q8h injections. Because of the small doses of SMS 201-995 used side-effects of abdominal discomfort and flatulence were mild and rapidly disappeared. Our results show that increasing the frequency of sc administration of the somatostatin analog from q8h to q2h leads to more marked and consistent suppression of GH levels and more rapid improvement of clinical signs. Increasing the frequency of delivery of SMS 201-995 may be an alternative to increasing the dose in some patients with acromegaly.

Acromegaly↗
PubMed1989

Interrupted aortic arch in an asymptomatic adult.

Isolated interrupted aortic arch is a rare congenital cardiac disorder believed at one time to be incompatible with life once the ductus arteriosus closed. To our knowledge, only 12 cases have been reported in the literature and mostly in children. The diagnosis was made in all of them by catheterization. We report the first adult patient with an asymptomatic interrupted aortic arch diagnosed by computed tomography.

Adult↗
PubMed1989

Postsurgical recurrent stress fracture in the spine affected by ankylosing spondylitis.

Stress fracture in the dorsolumbar region is a well-known complication of the rigid spine usually occurring at the end stages of ankylosing spondylitis. When indicated, surgical treatment by anterior spinal fusion is prescribed. Three cases illustrating the appearance of new stress fractures in different parts of the spine after the successful anterior surgical fusion of a previous lesion indicate the possibility of recurrence. This explains the persistence of back pain postoperatively. These stress fractures seem unrelated to spinal deformities. External bracing is useful, but additional surgical fusions may become necessary.

Adult↗