Intramedullary spinal schwannoma: case report and review of preoperative magnetic resonance imaging features.

Intramedullary schwannomas are rare spinal cord tumours. Correct preoperative diagnosis is essential for proper surgical planning and complete resection. We present a case of cervical intramedullary schwannoma followed by discussion on its preoperative magnetic resonance imaging features and review of the literature.

Effect of WEB 2086 on myocardial infarct size and regional blood flow in the dog.

OBJECTIVE: Systemic administration of platelet activating factor (PAF, 1-O-alkyl-2-acetyl-sn-glycero-phosphocholine) produces hypotension and decreased cardiac output; in isolated heart preparations PAF increases coronary vascular resistance and depresses inotropic state. A precursor of PAF bioactivity has been found early in myocardial ischaemia and other reports have suggested that PAF antagonists can reduce myocardial damage and ventricular arrhythmia. This study concerns the effects of WEB 2086, a PAF antagonist, on myocardial infarct size and coronary blood flow after total coronary artery occlusion. METHODS: Open chest anaesthetised dogs (n = 26) were pretreated with either WEB 2086 (5 mg.kg-1) or saline before proximal occlusion of the circumflex artery and constant infusion of WEB 2086 (1 mg.kg-1.h-1) or saline was maintained for 5 h. Cardiac output and regional myocardial flow were measured with radiolabelled microspheres (46Sc, 57Co, and 113Sn) before and immediately after occlusion and 5 h later. In the 22 dogs surviving occlusion, infarct size was determined by planimetry of cross sectional slices after exposure to triphenyltetrazolium chloride. RESULTS: Infarct size was not different between treated and control groups, at 23.6(SEM 2.3)% v 24.8(3.7)% of left ventricle, and was not different between groups when related to vasculature at risk and to collateral blood flow determined with microspheres. CONCLUSIONS: No beneficial effect of a relatively large dose of the potent PAF antagonist, WEB 2086, on myocardial infarct size or collateral blood flow was found after relatively short duration of myocardial ischaemia in the dog.

Plasma platelet activating factor degradation and serum lipids after coronary bypass surgery.

OBJECTIVE: Platelet activating factor (PAF) is a potent mediator in inflammatory responses and maybe involved in various disease states. Degradation of PAF in plasma results from the action of a specific, lipoprotein associated, acetylhydrolase. The aim was to determine plasma acetylhydrolase activity under optimised conditions, PAF half life, phospholipase A2 activity, the lyso-derivative of PAF (lyso-PAF), and lipids in patients undergoing coronary artery bypass grafting. METHODS: The study variables were determined 3 d and 7 d following coronary artery surgery and compared to presurgical values in 15 males, age 55(SEM 4) years. RESULTS: Three days following coronary bypass grafting, total, LDL and HDL cholesterol fell significantly by 30%, 45%, and 15% respectively (p less than 0.001), all decreases correlating with bypass time (p less than 0.025). Concentrations remained low at 7 d (p less than 0.005). Acetylhydrolase activity fell by 38% (p less than 0.001) at 3 d post-surgery and remained depressed, but plasma PAF half life did not change after surgery. The inverse relationship between acetylhydrolase activity and plasma PAF half life preoperatively (p less than 0.01) was not evident after surgery. There was a direct linear relationship between acetylhydrolase activity and both total (p less than 0.002) and LDL cholesterol (p less than 0.001) before surgery. The fall in acetylhydrolase activity correlated with the fall in these lipids (p less than 0.01) but not with that of HDL cholesterol. Plasma lyso-PAF decreased by 65% (p less than 0.001) at 3 d and remained depressed (p less than 0.001). Plasma phospholipase A2 activity increased by 60% (p less than 0.01) and remained raised (p less than 0.05), the increase at 3 d being related to bypass time (p less than 0.05). CONCLUSIONS: The large fall in plasma acetylhydrolase activity after coronary bypass grafting is consistent with the fall in plasma lipids. However, the absence of a significant change in the measured PAF half life in plasma raises questions as to the pathophysiological significance of the decrease in acetylhydrolase activity.

A case-controlled MRI/MRA study of neurovascular contact in hemifacial spasm.

BACKGROUND: Neurovascular contact (NVC) with the root exit zone (REZ) of the ipsilateral facial nerve is associated with hemifacial spasm (HFS), but unresolved issues remain. OBJECTIVES: To 1) determine the frequency of symptomatic and nonsymptomatic NVC, 2) determine the features of NVC associated with HFS, and 3) correlate severity of HFS to these features. METHODS: Two independent, blinded, prospective assessments of high-resolution MR and MR angiography (MRA) images were performed on Chinese cases (HFS: n = 44; age-matched control subjects: n = 20). RESULTS: Over 88% of 44 symptomatic sides in patients with HFS had NVC of the ipsilateral facial nerve. At least 80% of symptomatic sides involved NVC at the anterior aspect of the REZ [REZ(ant.)]. Although NVC was observed in approximately half of nonsymptomatic sides, at least 70% of them were not at REZ(ant.). NVC at the cisternal and intracanalicular portions of the facial nerve were not associated with HFS. Half of our patients with HFS had bilateral NVC, but none had bilateral symptoms. Most of our MR/MRA images showed that the size and position of the arterial branches of the vertebrobasilar system were markedly asymmetric. Of patients with bilateral NVC, over 83% had asymmetric NVC sites. The anterior inferior cerebellar artery was the most common vessel involved in NVC, but was not significantly associated with HFS. Most of the NVC involved one vessel at one contact point with no indentation. The development of HFS was significantly associated with nerve indentation in NVC. The development and severity of HFS were not associated with multiple contact points in NVC. No significant interobserver variability existed between the blinded assessments. CONCLUSIONS: MRI/MR angiography are accurate, fast, and safe in characterizing neurovascular contact (NVC) at the brainstem. The site of NVC and ipsilateral facial nerve indentation in NVC are significant determinants for the development of hemifacial spasm (HFS). The lack of bilateral NVC at the anterior aspect of the root exit zone of the facial nerve could explain in part the lack of bilateral symptoms. The development and severity of HFS are not associated with a specific blood vessel or multiple contact points in NVC.

Ultrasonographic measurement of subarachnoid space in normal infants and children.

This study was undertaken to evaluate the sonographic measurement of subarachnoid spaces in normal children and its relationship with age and to define a normal range in a Chinese population and to differentiate normal variant findings from pathologic dilatation. The subarachnoid spaces in 278 normal term neonates, infants, and children were studied with real-time ultrasound using a 7.5-MHz vector transducer. The craniocortical width, sinocortical width, and interhemispheric width were measured in the coronal plane at the level of the foramen of Monro, on either side of the hemispheres. Correlation of sonographic measurements with age was made. The mean widths were plotted against age. A correlation with age was found in all three spaces, with an increasing trend with age until 28 weeks of gestation. Thereafter, a decreasing trend was noted. The normal upper limit of subarachnoid spaces for children is proposed to be the values on the ninety-fifth percentile of the regression curve. Correlation of measurement with age must be considered to decide whether an increase in subarachnoid space is pathologic or not.

Prominent periportal echogenicity: its sonographic evaluation and its significance.

Prominent periportal echogenicity was detected during sonographic examination of patients suffering from recurrent pyogenic cholangitis, hepatocellular carcinoma and acute cholecystitis. To document the finding, 140 normal individuals were studied to establish a norm for the evaluation of the periportal echogenicity. The significance of this sonographic finding and its possible aetiology are discussed.

Ileoileocolic intussusception in children: diagnosis and significance.

The ileoileocolic type of childhood intussusception is difficult to diagnose pre-operatively and is associated with increased morbidity. This study describes the clinical and imaging features of 10 consecutive ileoileocolic intussusceptions diagnosed ultrasonically in 10 patients over a 36 month period. Ultrasound-guided hydrostatic reduction using Hartmann's solution was attempted in all 10 patients. Clinical and imaging features were compared with those of 28 ileocolic intussusceptions in 25 patients diagnosed and treated using the same methods during the same period. Most of the clinical and plain radiographic features of the patients with the ileoileocolic and ileocolic types of intussusception were similar. The two types of intussusception had the classical doughnut or pseudokidney, or both, signs on pre-reduction ultrasound scans. During the reduction process, when surrounded by fluid within the caecal lumen, the ileoileocolic type of intussusception had a typical complex appearance due to frond-like loops of intussuscepted small bowel. This finding was present in all cases. The hydrostatic reduction rate was only 10% (1/10) for ileoileocolic intussusception, compared with 92.9% (26/28) for the ileocolic type. All unsuccessfully-reduced cases underwent surgery, with surgical confirmation of the intussusception type in all cases. Only one patient was found to have a lead point, caused by a Meckel's diverticulum. In conclusion, the diagnosis of ileoileocolic intussusception can be made pre-operatively and these patients require surgical management.

Quantitative SPECT imaging: influence of object size.

In positron emission tomography (PET) the measured radionuclide concentration or recovery coefficient (RC) in the transverse plane has been shown to be dependent on source size. The RC dependence on object size was therefore experimentally measured for gamma camera SPECT system to determine the influence of additional factors such as: (a) geometrical spatial resolution of each collimator type, (b) scattering effects at each photon energy due to surrounding background, (c) influence of choice of reconstruction filter and (d) photon penetration through the collimator septa. Data were acquired for different collimator types using 99Tcm (140 keV) and 131I (364 keV) to partly differentiate between photon scattering and collimator penetration effects. Results obtained demonstrated that thick septa collimators with low penetration fraction (theoretical leakage less than 3%) are required to minimize the measured response dependence on source size and to obtain a relatively unique relationship independent of photon energy and background activity. Measurements of this type are important for quantitative SPECT imaging in radioimmunoimaging or radioimmunotherapy.

Childhood intussusception: ultrasound-guided Hartmann's solution hydrostatic reduction or barium enema reduction?

A comparison was made of the efficacy of ultrasound guided Hartmann's solution hydrostatic reduction on 23 patients (US group) with the same number of consecutive patients in whom hydrostatic reduction was done by barium enema (BE group) under fluoroscopy for childhood intussusception. The US group was diagnosed by ultrasound scan and reduction was attempted under the guidance of ultrasonography with Hartmann's solution at 100 mm Hg pressure. Excluded were patients older than 12 years, patients in shock, patients with peritonitis, bowel perforation, and gross abdominal distension as well as recurrent intussusception of more than three episodes. There were three patients excluded in this group. The diagnosis of intussusception and complete reduction were confirmed by gastrografin enema. This US group had three recurrences (3 of 26, 11.5%), one lead point (1 of 23, 4.4%), and 19 successful reductions (19 of 26, 73%). Incidentally, there were also three patients excluded in this period of barium enema reduction. There was only one recurrence (1 of 24, 4.2%), one leadpoint (1 of 23, 4.4%), and 12 successful reductions (12 of 24, 50%) in these 23 BE patients. The success rates for the ileo-colic intussusceptions with Hartmann's solution reduction and barium enema reduction were 91% (19 of 21) and 55% (12 of 22), respectively (P = .00865). There was no complication in either group, and the accuracy of diagnosing a complete reduction was 100% in both forms of reduction. Hence, ultrasound-guided hydrostatic reduction for childhood ileocolic intussusception is preferred because it is safe, accurate, has a higher success rate, and can avoid radiation exposure risk.

Modern imaging in the evaluation of hepatolithiasis.

Hepatolithiasis is a primary disease of the biliary ducts, presenting with recurrent pyogenic cholangitis, complicated by parenchymal infection, obstructive cholangiopathy and subsequent parenchymal destruction. Cholangiocarcinoma is a rarer complication. Modern imaging aims at accurate delineation of biliary ducts and liver parenchyma. It directs planning of surgical or interventional treatment, and serves to guide these procedures. The characteristic features comprise varying combinations of ductal dilatation, intrahepatic/extrahepatic ductal stones, segmental ductal strictures and lobar/segmental atrophy; and in acute exacerbation parenchymal or ductal contrast enhancement, abscess and biliary obstruction. Ultrasonography is the preferred primary examination. Further imaging depends on the ultrasonography findings, the patient's symptomatology, the clinical problems and the intended mode of treatment. Contrast cholangiography is warranted preceding biliary intervention. Computed tomography evaluates ductal stones, extent of disease, acute parenchymal complications and prior to hepatic resection. Magnetic resonance imaging is less accessible, but obtains cross-sectional findings similar to computed tomography. It comprehensively evaluates the liver and portal venous system, for prognostic indication and contemplation of liver resection. For diagnostic purposes, magnetic resonance cholangiography promises to replace the more invasive contrast cholangiography. Therapeutic approaches tailored to the results of strategically applied imaging helps to improve the outcome of patients with hepatolithiasis.

MRI features of spinal ganglioglioma.

Spinal cord ganglioglioma is a rare tumor most often encountered in the first three decades. Scanty computed tomography (CT) reports on the tumor describe it as a hypodense or cerebrospinal fluid (CSF) dense area with little contrast enhancement despite its solid nature. We report two cases of spinal ganglioglioma both involving almost the whole spinal cord. On magnetic resonance imaging (MRI), the tumors appear hypointense to the spinal cord on T1 and hyperintense to the cord on T2 images, and were mainly solid at exploration. It is important to recognize these tumors as long survival can be achieved after surgical resection.

Health promotion board-ministry of health clinical practice guidelines: treating tobacco use and dependence.

The Health Promotion Board (HPB) has updated the clinical practice guidelines on Treating Tobacco Use and Dependence to provide health professionals in Singapore with evidence-based interventions for smoking cessation. This article reproduces the introduction and executive summary of key guideline recommendations (with recommendations from the guidelines) from the HPB-MOH Clinical Practice Guidelines on Treating Tobacco Use and Dependence, for the information of SMJ readers. Chapters and page numbers mentioned in the reproduced extract refer to the full text of the guidelines, which are available from the Health Promotion Board website: http://www.hpb.gov.sg/cpg-smoking-cessation. The recommendations should be used with reference to the full text of the guidelines. Following this article are multiple choice questions based on the full text of the guidelines.

Recurrent pyogenic cholangitis: ultrasound evaluation compared with endoscopic retrograde cholangiopancreatography.

Fifty cases of recurrent pyogenic cholangitis among Chinese in Hong Kong were studied by ultrasound and compared with endoscopic retrograde cholangiopancreatography. The sensitivity of ultrasound detection of both dilated intrahepatic biliary ducts and intrahepatic calculi is 67% as compared with endoscopic retrograde cholangiopancreatography. A negative study, therefore, does not rule out the presence of such pathological features. A dilated common duct is present in virtually every case of recurrent pyogenic cholangitis and ultrasound is very accurate in its detection. Furthermore, ultrasound is able to provide additional information which can be missed with endoscopic retrograde cholangiopancreatography. Prominent periportal echogenicity, concomitant abscesses and tumours are examples in this series. Such findings bear significance on the management of patients with recurrent pyogenic cholangitis.

Short term vitamin E supplementation has no effect on platelet function, plasma phospholipase A2 and lyso-PAF in male volunteers.

1. Based largely upon in vitro studies, vitamin E has been reported to inhibit phospholipase A2 activity, to alter phospholipid metabolism and reduce platelet aggregation. 2. The effect of dietary supplementation with D-alpha-tocopherol (1500 iu/day for 14 days) was studied in nine males, 41-63 years old, comparing active treatment with a preceding placebo period. 3. Despite an increase from 2.6 +/- 0.8 (s.d.) x 10(-5) mol/L to 6.0 +/- 1.8 10(-5) mol/L in plasma vitamin E there were no significant changes in the aggregation of diluted whole blood or platelet rich plasma to adenosine diphosphate (ADP) or collagen, in plasma phospholipase A2 activity or plasma lyso-platelet-activating factor (lyso-PAF) (bioassay after in vitro acetylation to PAF). 4. High dose vitamin E dietary supplementation had no effect on these phospholipid and platelet parameters.

Variant of the Triple A syndrome.

The Triple A syndrome is a rare condition comprising achalasia, alacrima and adrenocorticotrophic hormone (ACTH) insensitivity. A 12 year old Chinese girl with a variant of this syndrome (achalasia and alacrima), presenting with failure to thrive, is reported. Typical appearances of achalasia on barium swallow subsequently led to the correct diagnosis. The radiologist may be the first to recognize this syndrome and hence help anticipate its potentially life-threatening sequelae.

Computed tomography of paranasopharyngeal spaces: normal variations and criteria for tumour extension.

In 137 normal CT scans of the nasopharynx, the parapharyngeal spaces at the nasopharynx level were asymmetrical in 30%. Their difference in width and distance from the midline was greater than 1 mm in 51% and 44% respectively. Fat was absent in the interpterygoid fascia in 20%, in the alar fascia in 28%, in the prevertebral space in 35%, and in the retropharyngeal space in 99% of patients. Assessment of tumour extension to the paranasopharyngeal space usually relies on symmetry and fascial fat planes. As either feature may not be present in the normal person, the relation of the tumour to two lines representing two fascial planes is proposed as a complementary method for the evaluation of tumour extension.

Plasma phospholipase A2 activity in clinical acute myocardial infarction.

1. Phospholipase A2 (PLA2) cleaves phospholipids to produce a lyso-phospholipid and free fatty acid and, in view of the biological activity of the products, PLA2 may play a role in many disease states. Lyso-phospholipids and free arachidonic acid increase in ischaemic myocardium, indicating that ischaemia activates the enzyme. 2. Plasma PLA2 activity was measured in patients with acute myocardial infarction, based on the release of labelled arachidonic acid from Escherichia coli cell membrane. Fourteen males (peak serum creatine phosphokinase (CK) above twice upper normal) were studied on day 1 (within 6 h of chest pain onset), days 2-4, and days 6-9. Normal age matched males (n = 13) were also studied. 3. Plasma PLA2 in patients with uncomplicated myocardial infarction (n = 12) was, initially, 1.14 +/- 0.10 (s.e.m.) nmol/min per mL plasma, similar to that in the normal group (1.52 +/- 0.14). On days 2-4, PLA2 activity increased to 1.94 +/- 0.18 (P less than 0.001) and this activity was correlated with the earlier peak CK level (P less than 0.02). On days 6-9, PLA2 activity was 1.49 +/- 0.13 while in two patients who developed complications and underwent open-heart surgery between the last two measurements, there were further increases to 4.22 and 4.04 nmol/min per mL. 4. The increase in plasma PLA2 in uncomplicated myocardial infarction is likely to be due to release from the damaged myocardium; whether it contributes to pathophysiology is uncertain.

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.