Search PubMed⌕ Search

Biomedical subjects

C Teo

Publications and source records attributed to C Teo.

At least 19 recordsLinked to original sources
PubMed2006

Central neurocytoma in third and fourth ventricles with aqueductal involvement.

Central neurocytomas are characterized by their intraventricular locations, usually arising from the lateral ventricles and their benign clinical course. Variations in location, histology and clinical behaviour have been reported in recent years. The authors present two cases of central neurocytomas arising in the third and fourth ventricles with aqueductal involvement. The atypical features in their location and behaviour are discussed. The cases represent the extended spectrum of central neurocytomas.

Adult↗
PubMed2005

Resolution of trigeminal neuralgia following third ventriculostomy for hydrocephalus associated with Chiari I malformation: case report.

OBJECTIVE AND IMPORTANCE: Cranial nerve dysfunction, including trigeminal neuralgia, has been associated with Chiari I malformations. In such cases, trigeminal neuralgia is thought to be related to tonsillar compression of the brainstem or to traction on the cranial nerves. Hydrocephalus may be a contributing factor. CLINICAL PRESENTATION: A 38-year-old woman had right-sided lancinating facial pain typical of trigeminal neuralgia but was otherwise neurologically intact. Magnetic resonance imaging showed no evidence of a compressing vessel. Moderate hydrocephalus and a Chiari I malformation were noted incidentally. The visibility of the aqueduct was poor. INTERVENTION: The patient underwent a third ventriculostomy and her symptoms resolved completely. CONCLUSION: This is the first case in which trigeminal neuralgia was treated with a third ventriculostomy and one of only four cases of isolated trigeminal neuralgia associated with a Chiari malformation. Acquired aqueductal stenosis may have caused the hydrocephalus which, in turn, caused the Chiari malformation configuration that caused the trigeminal neuralgia. The rationale for the treatment modality and possible causes of Chiari I-induced trigeminal neuralgia are discussed.

Adult↗
PubMed2005

Disaster relief and initial response to the earthquake and tsunami in Meulaboh, Indonesia.

The Singapore Humanitarian Assistance Support Group deployed a team of 32 medical relief workers to Meulaboh, Indonesia to provide medical assistance for victims of the 26 December earthquake and tsunami disaster. The team was deployed at a primary healthcare clinic at an internally displaced persons' (IDP) camp and at the sole hospital's emergency and surgical departments. The team saw a total of 1841 patients, 1371 at the clinic and 446 at the hospital's emergency department, and performed surgery on 24 patients. Tsunami-related trauma cases accounted for 31.8% (142) of cases at the emergency department, 1.6% (22) of cases at the clinic, and 91.7% (22) of surgeries. This paper details the difficulties and lessons learnt by the team, including the lack of important resources for healthcare delivery. Water, sanitation, hygiene, and vector control were some of the problems faced, with the goal to provide the most effective public health for the greatest number of people given the limited resources available.

Disasters↗
PubMed2004

Endoscopic-assisted sciatic nerve exploration.

A sciatic nerve lesion is uncommon. We report the utility of the endoscope in an 18-year-old female with multiple lesions of her sciatic nerve. Somatosensory evoked potentials and MRI were indicative of a sciatic nerve lesion. We describe a simple technique of endoscopic exploration of the sciatic nerve to assist intraoperative decision making.

Adolescent↗
PubMed2003

Multiple schwannomas of the sciatic nerve.

Schwannomas are rare benign tumours of nerve sheath cells of neural crest origin. Often these tumours are solitary and encapsulated. Multiple schwannomas can arise from the peripheral nervous system including cranial nerves, spinal roots, the brachial and lumbar-sacral plexus or major peripheral nerves. We report an extremely rare case of schwannomatosis of the sciatic nerve in a young female and include a comprehensive literature review. Treatment options are discussed.

Adolescent↗
PubMed2001

Endoscopic assisted posterior fossa decompression.

Technical advances in neurosurgery follow a general philosophy favouring less invasive means of managing surgical disease. We describe a patient with a symptomatic type I Chiari malformation managed by posterior fossa decompression using endoscopic techniques. Technical considerations, including drawbacks of the procedure, are discussed.

Adult↗
PubMed2000

Disorders of CSF hydrodynamics.

This article reviews the range of hydrodynamic disorders affecting the CSF circulation. Initially consideration is given to questions of definition and classification. A scheme for the practical, clinical analysis for the diagnosis of such disorders is then presented. The physiology and pathophysiology of the CSF circulation is reviewed, with particular emphasis on issues that remain unresolved. This provides a background to consideration of the adverse consequences of abnormal CSF hydrodynamics, again focusing on areas where further information is required. Methods of clinical investigation of CSF hydrodynamics are reviewed, followed by general considerations of treatment. Finally, each of the main, clinically important, forms of disordered CSF hydrodynamics is briefly considered, with particular emphasis, again, on areas where current knowledge is deficient. The conditions considered include hydrocephalus of various forms (childhood, adult, arrested, multi-compartment), infantile macrocephaly, arachnoid and glioependymal cysts, syringo- and hydromyelia, pseudotumour cerebri, impaired cranial venous outflow, altered CSF composition, shunt obstruction without ventricular enlargement and low-CSF-pressure states.

Adolescent↗
PubMed2000

Complete resolution of hypertension after decompression of Chiari I malformation.

The Chiari I malformation has not been previously linked to sustained hypertension. Other forms of medullary compression have, however, been shown to be associated with elevated arterial pressure. This association has been demonstrated through numerous studies that have implicated compression of the rostral ventrolateral medulla, usually by vascular structures, as a factor responsible for hypertension. We present a case of a young man with a 2-year history of hypertension who was found to have a Chiari I malformation. No other cause for hypertension was found. After subsequent surgical decompression, his hypertension resolved immediately. No other therapeutic options were activated. This is the first reported case linking Chiari I malformation and sustained hypertension. This case presents further evidence linking medullary compression and elevation of hemodynamic tone.

Case Reports↗
PubMed2000

Cerebrospinal fluid pharmacokinetics of cefpodoxime proxetil in piglets.

Cefpodoxime is an oral third-generation cephalosporin used for the treatment of acute upper-respiratory tract infections caused by susceptible bacteria in children. Although not indicated for the treatment of bacterial meningitis, it is used to treat other infections produced by organisms associated with meningitis and may obscure the result of cerebrospinal fluid (CSF) cultures in children who develop meningitis while receiving oral antibiotics if sufficient concentrations are achieved in the CSF. This study evaluated the disposition of cefpodoxime and penetration into CSF in piglets. Fifteen Landacre-Camborough cross piglets (10-20 days old) received cefpodoxime proxetil oral suspension (10 mg/kg). Repeated plasma and CSF samples were collected over 24 hours for quantitation of cefpodoxime by HPLC. Pharmacokinetic analysis was performed on both plasma and CSF data. The plasma concentration versus time data for cefpodoxime were best characterized using a one-compartment model with first-order absorption. The mean (+/- SD) pharmacokinetic parameters for Cmax, tmax, and AUC0-infinity were 23.3 +/- 12.9 mg/L, 3.9 +/- 1.4 h, and 237 +/- 129 mg/L.h, respectively. CSF/plasma ratios for AUC0-infinity demonstrated a mean cefpodoxime penetration of approximately 5%. CSF penetration of cefpodoxime was evident following a single oral dose of cefpodoxime proxetil suspension. Despite the small percentage of total cefpodoxime dose distributing into the CSF, the resultant concentrations approached or exceeded the MIC90 for many bacterial pathogens considered susceptible to cefpodoxime. Accordingly, clinicians should use caution in the interpretation of CSF cultures in patients who develop clinical signs and symptoms consistent with meningitis and who have been previously treated with cefpodoxime.

Animals↗
PubMed1999

Endoscopic management of hydrocephalus secondary to tumors of the posterior third ventricle.

Management of the obstructive hydrocephalus that accompanies tumors located in the third ventricle has traditionally involved either urgent tumor resection, with resultant ventricular decompression, or cerebrospinal fluid diversion that requires either ventriculostomy or shunt placement prior to tumor removal. Although this approach has worked well for the better part of a century, it has both short- and long-term sequelae that can possibly be avoided. Beacause a number of lesions in this area are benign or are amenable to radiotherapy, a less invasive approach to their treatment is desirable. The advances in both instrumentation and techniques of endoscopic surgery have established alternatives to the traditional treatment of third ventricular tumors and resultant hydrocephalus. The authors review the treatment of 19 patients with posterior third ventricular tumors who presented to Arkansas Children's Hospital over a 5-year period (September 1993-July 1999). In 11 patients signs and/or symptoms of hydrocephalus were demonstrated and were treated with endoscopic third ventriculostomy, additionally, a biopsy procedure, resection, or fenestration of the tumor was performed in a number of patients. Endoscopy was believed to have been of benefit in all patients, despite the eventual failure of the ventriculostomy in one patient. There were no complications in this series. The algorithm thus developed by the authors provides both a diagnostic and therapeutic pathway that may ultimately reduce the morbidity associated with the treatment of patients with posterior third ventricular lesions.

Journal Article↗
PubMed1999

Application of skull base techniques to pediatric neurosurgery.

Techniques for skull base surgery have become well established over the last 10 years. Most of these techniques are used in adult patients for skull base tumors and neurovascular diseases. There are very few large series of pediatric patients in whom skull base approaches have been used, because of the rarity of these conditions. The authors would like to present a relatively large series of 26 pediatric patients who underwent skull base approaches for tumor resection. These tumors involved the anterior cranial base in 5 patients, the medial cranial skull base in 4 patients, and the posterior cranial base in 12 cases. Five patients had tumors that involved two or more fossae. The overall complication rate was 57%, which included temporary cranial nerve palsies, CSF leak and infection. Patients with permanent complications were 8 in number (37%). There was 1 postoperative death from pneumonia approximately 6 weeks after surgery. Complete tumor removal was achieved in 24 of the 26 patients. Skull base tumors in children are often extensive and present significant surgical challenges. Although complete tumor extirpation is the goal in most pediatric patients, this is often achieved only with some morbidity. This paper demonstrates the effectiveness of skull base approaches for these tumors and underscores the high stakes involved.

Adolescent↗
PubMed1999

Endoscopic treatment of the trapped fourth ventricle

OBJECTIVE: To propose endoscopic treatment as an effective initial alternative for patients with a trapped fourth ventricle. METHODS: We reviewed the records of the last 16 consecutive patients with a symptomatic trapped fourth ventricle seen at the Arkansas Children's Hospital. The first eight patients underwent a shunt procedure; the next eight had endoscopic procedures. The shunt procedures consisted of either separate shunts or combined supra- and infratentorial shunts with shared distal catheters. The endoscopic procedures consisted of either fenestration into the lateral ventricle or aqueductal plasty with or without a stent. RESULTS: All patients underwent successful procedures with good outcomes, although the patients with shunts appeared to have a higher-than-expected rate of revision (50%). Seven revisions were performed on four patients, with a complication rate of 25%. Of the patients who had endoscopic procedures, one eventually required a shunt. The overall complication rate for patients who had endoscopic procedures was also 25%. CONCLUSION: Endoscopic treatment of the trapped fourth ventricle is effective in most cases. In view of the higher-than-expected revision rate with fourth ventricular shunts and an equivalent complication rate, endoscopic treatment is a reasonable initial treatment option for patients with a trapped fourth ventricle.

Journal Article↗
PubMed1998

Disinhibition of the sleep state-dependent p1 potential in Parkinson's disease-improvement after pallidotomy.

We previously reported that the P1 or P50 midlatency evoked potential underwent decreased habituation or disinhibition in patients with Parkinson's Disease. This sleep state-dependent response appears to be generated by cholinergic elements of the reticular activating system. We attempted to determine if the decreased habituation or disinhibition of the P1 potential would be altered by bilateral pallidotomy. Twenty-three patients who met inclusion criteria for surgery underwent pre- and post-operative evaluation using a Modified United Parkinson's Disease Rating Scale (UPDRS) and P1 potential recordings. Decreased habituation of the P1 potential was determined using a paired stimulus paradigm in which click stimuli were presented at 250, 500 and 1000 msec interstimulus intervals (ISI). Pre-operatively, patients showed disinhibition of the P1 potential at the 250 msec ISI (60 37% vs. 21 20%) and 500 msec ISI (78 47% vs. 43 31%) compared to age-matched control subjects. Post-operatively, the same patients showed a significant improvement in habituation of the P1 potential at the same ISIs (250 msec 37 21%; 500 msec 43 32%). UPDRS scores for these patients pre-operatively were 59 18 and 24 11 post-operatively, resulting in a significant reduction in symptom severity. We conclude that bilateral pallidotomy resulted in a significant improvement in symptom ratings and reduced the disinhibition of the P1 midlatency evoked response.

Analysis of Variance↗
PubMed1997

Decreased habituation of midlatency auditory evoked responses in Parkinson's disease.

The P1 midlatency auditory evoked potential was studied in patients with Parkinson's disease and compared to that in age-matched controls. Habituation of the potential was determined by using a two-click stimulus paradigm in which the stimuli were presented at 250-, 500-, and 1,000-ms interstimulus intervals. Results showed that habituation of the P1 potential had a statistically significant decrease at the 250-ms and 500-ms interstimulus intervals in patients with Parkinson's disease compared to normal controls. The degree of decreased habituation was found to increase with severity of the disease such that stage 5 patients showed greater decreases in habituation compared to stage 4, as did stage 4 compared to stage 3. These findings may be explained by the presence of a dysregulation of sensory processing, possibly by elements of the reticular activating system, including the pedunculopontine nucleus, in Parkinson's disease.

Aged↗
PubMed1997

Prior fluoridation in childhood affects dental caries and tooth wear in a south east Queensland population.

Fluoride exposure in early life has an effect on dental caries experience, but does it affect tooth wear in later life? Ninety-six South East Queensland subjects were studied. Their histories revealed three groups; a fluoride (F-) in water supply, a F- by supplement, and a non-fluoridated (non F-) group. Significantly higher caries experience was found in the non-F- group compared with F- in water group and the F- supplement group. No statistically significant difference in caries experience was found between the F- in water and F- supplement groups. Overall, tooth wear affected more sextants of the dentitions of non-fluoridated, high-caries subjects than of fluoridated low-caries subjects. Comparisons of wear patterns on sextants of the dentitions, between the fluoridated and non-fluoridated groups, revealed that in sextants where attrition was present no marked differences were discernible between the two groups. However, in most sextants where incisal, palatal, occlusal or non-occlusal erosion was found, this type of wear was commoner in non-fluoridated subjects. The exceptions were the mandibular molar sextants, where prior fluoride-exposure did not appear to protect against occlusal erosion patterns. This study showed that fluoride exposure during the first 12 years of life, which reduced dental caries in this population, may also protect teeth from wear to some extent.

Adolescent↗