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Biomedical subjects

P C Pang

Publications and source records attributed to P C Pang.

18 recordsLinked to original sources
PubMed2001

The repeatability and accuracy of axial length and anterior chamber depth measurements from the IOLMaster .

BACKGROUND: Axial length and anterior chamber depth have been measured clinically using conventional ultrasound biometry. Recently, a non-contact device has become available to measure these parameters. This study evaluated the repeatability and accuracy of this device. METHODS: The axial length and anterior chamber depth were measured by two practitioners on a group of young subjects using the IOLMaster followed by a conventional ultrasound biometer operated by a third practitioner. The accommodation was controlled in ultrasound biometry through a full correction on the non-measured eye and a distant fixation target. RESULTS: There was good repeatability and accuracy of axial length assessment. The mean difference between the IOLMaster and ultrasound biometry was -0.099 mm, with 95% limits of agreement between 0.66 and -0.85 mm. The axial length was slightly shorter from the IOLMaster and the difference was not significant. The anterior chamber depth was repeatable but was shown to be deeper than the ultrasound results. The mean difference in anterior chamber depth between the IOLMaster and ultrasound biometry was 0.15 mm, with 95% limits of agreement between 0.34 and -0.03 mm. It is suggested that the former device is not measuring the axial anterior chamber depth. CONCLUSIONS: The IOLMaster is a non-contact 'optical' A-scan which is simple to use and good for axial length assessment. The anterior chamber depth assessment should be further evaluated.

Adult↗
PubMed2001

Nasopharyngectomy for recurrent nasopharyngeal carcinoma: an innovative transnasal approach through a mid-face deglove incision with stereotactic navigation guidance.

Traditional approaches to nasopharyngectomy for the treatment of recurrent nasopharyngeal carcinoma carry considerable complications. This paper presents an innovative transnasal approach with stereotactic navigation guidance through a mid-face deglove incision which has been done for 15 patients with minimal morbidity. All patients had resumed their oral diet within a week, and were discharged within 10 days. The intraoral wound had healed within a week. The only complications were a mild degree of saddling of the nasal dorsum in one patient and temporary facial numbness that resolved within six weeks in three. Tumour had been resected with clear margins in 12/15, in the other three being stuck to the carotid artery.

Adult↗
PubMed2001

A prospective study of the effect of botulinum toxin A on masseteric muscle hypertrophy with ultrasonographic and electromyographic measurement.

We evaluated the effect of botulinum toxin A on masseteric muscle hypertrophy by using ultrasound and electromyography. Five patients (four with bilateral and one with unilateral masseteric muscle hypertrophy) were studied prospectively. In each patient, ultrasound-guided percutaneous intramuscular injection of botulinum toxin A was carried out. The change in muscle bulk was evaluated using serial ultrasonography and the electrical activity was assessed with electromyography. All five patients (nine hypertrophic muscles) showed a good response, with the maximal effect of a 31% reduction in muscle bulk seen 3 months after treatment. The effect remained stable one year after injection for six of the hypertrophic muscles, whereas three muscles needed a second injection to maintain the atrophy. This preliminary prospective study suggests that botulinum toxin A is a safe alternative method of treating masseteric muscle hypertrophy. However, the effect may be temporary and further intramuscular injection may be required to maintain atrophy.

Adolescent↗
PubMed2001

Subcranial anterior skull base dural repair with galeal frontalis flap.

The pericranial flap has been widely used to repair surgically created anterior skull base defects during craniofacial resection. This report describes a technique of subcranial dural repair with a galeal frontalis flap after resection of an ethmoidal adenoid cystic carcinoma.

Carcinoma, Adenoid Cystic↗
PubMed2001

Fibromatosis of the head and neck region.

OBJECTIVE: Five cases of head and neck fibromatosis were analyzed. The imaging and pathologic findings, surgical management, and clinical outcome were discussed. STUDY DESIGN AND SETTING: A retrospective study of 5 adult head and neck fibromatosis cases, evaluating long-term follow-up results of conservative treatment. RESULTS: The 5 patients (2 male and 3 female) ranged in age from 16 to 51 years. The lesion size ranged from 1 to 8 cm. Four cases had limited surgical resection; 1 case was followed only. One of the surgically treated cases had a recurrence that was irradiated. All patients were well for a follow-up period of 2 to 8 years. CONCLUSION: Aggressive excision of head and neck fibromatosis cannot be achieved easily. Vigilant follow-up with or without conservative surgical excision achieves good disease control. Low dose radiotherapy can be used for inoperable cases. SIGNIFICANCE: Judicious conservative treatment should be attempted for head and neck fibromatosis to achieve optimal functional preservation.

Adolescent↗
PubMed2001

Necrosis of the nasal ala after improper taping of a nasogastric tube.

Inserting a nasogastric tube during various abdominal procedures is a common maneuver to decompress the upper gastrointestinal tract. Improper placement and taping of the nasogastric tube results in excessive pulling on the nasal ala and subsequent pressure necrosis. This complication not only carries serious cosmetic morbidity, it is also preventable if a proper taping technique is employed.

Adult↗
PubMed2001

A case of parotid mucoepidermoid carcinoma complicated by fatal gastrointestinal bleeding.

Mucoepidermoid carcinoma is one of the most common of the salivary gland neoplasms. Histologically, it is classified as either a low-, intermediate-, or high-grade tumor, and there are significant differences in prognosis among the different grades. Patients with low-grade disease have an excellent chance of survival. High-grade tumors behave aggressively, and they frequently manifest as local recurrences and distant metastases. We describe a case of a high-grade mucoepidermoid carcinoma of the parotid gland that had metastasized to the skin, stomach, and liver. The disease culminated in a rapidly fatal bleeding from the stomach metastasis. Such a complication is unusual and to our knowledge has not been previously reported. We briefly discuss the clinical features, biologic behavior, and treatment of this tumor.

Carcinoma↗
PubMed1995

Monitoring respiratory activity in neonates using diaphragmatic electromyograph.

The monitoring of the development of respiratory function in low-birth-weight or sick neonates is important in its overall treatment. The most direct approach to obtaining information on respiratory function is to monitor the activity of the diaphragmatic muscular system rather than measure the resultant change in lung volume or ventilator output, which cannot be guaranteed to be directly related to the neonate's own respiratory activity. The system was designed to assess the feasibility of monitoring respiratory activity in such neonates by measuring the diaphragmatic electromyograph. It is hoped that this system can be used to monitor the development of lung function and possibly, if reliability proves adequate, the synchronisation and control of ventilator assistance. To monitor the EMG, the dominant effect of the ECG was removed using a digital processor. Initial clinical measurements indicate that neonatal respiratory activity can be monitored by measuring the diaphragmatic EMG. Comparative measurements show the EMG method is faster in detecting the inspiratory phase of a breath. Measurements on ventilated neonates showed the presence of intermittent respiratory activity. It also is proposed that clinically relevant information may be deduced from the analysis of the morphology of the detected EMG waveform.

Diaphragm↗