Hypofractionated CyberKnife stereotactic radiosurgery for acoustic neuromas with and without association to neurofibromatosis Type 2

CyberKnife stereotactic radiosurgery (CKSRS) has been proved effective in treating intra-cranial lesions. To treat acoustic neuroma (AN) patients with or without neurofibromatosis Type 2 (NF2) associations, the functional preservation of hearing, trigeminal nerve, and facial nerve are important. Twenty-one patients were treated with hypofractionated CKSRS. Fourteen non-NF2 and seven NF2 patients were enrolled. Cranial nerve function, audiograms, and magnetic resonance images (MRI) were monitored. Mean follow-up was 15 month. Tumors with volumes ranging from 0.13 to 24.8 cm3 (mean 5.4 cm3) were irradiated with the marginal dose 1800-2000 cGy/3 fractions. Tumors were treated with an 80 to 89% isodose line (mean 83%) and mean 97.9% tumor coverage. Two patients experienced hearing deterioration (16.7%) in the non-NF2 group, and 3 patients (50%) in the NF2 group. No facial or trigeminal dysfunction, brain stem toxicity, or cerebellar edema occurred. Tumor regression was seen in 9 patients (43%) and stable in 12 patients (57%). 100% tumor control rate was achieved. Hypofractionated CKSRS was not only effective in tumor control but also excellent in hearing preservation for non-NF2 AN. But for NF2 patients, although the tumor control was remarkable, hearing preservation was modest as in non-NF2 patients.

A knowledge-based system for patient image pre-fetching in heterogeneous database environments--modeling, design, and evaluation

When performing primary reading on a newly taken radiological examination, a radiologist often needs to reference relevant prior images of the same patient for confirmation or comparison purposes. Support of such image references is of clinical importance and may have significant effects on radiologists' examination reading efficiency, service quality, and work satisfaction. To effectively support such image reference needs, we proposed and developed a knowledge-based patient image pre-fetching system, addressing several challenging requirements of the application that include representation and learning of image reference heuristics and management of data-intensive knowledge inferencing. Moreover, the system demands an extensible and maintainable architecture design capable of effectively adapting to a dynamic environment characterized by heterogeneous and autonomous data source systems. In this paper, we developed a synthesized object-oriented entity- relationship model, a conceptual model appropriate for representing radiologists' prior image reference heuristics that are heuristic oriented and data intensive. We detailed the system architecture and design of the knowledge-based patient image pre-fetching system. Our architecture design is based on a client-mediator-server framework, capable of coping with a dynamic environment characterized by distributed, heterogeneous, and highly autonomous data source systems. To adapt to changes in radiologists' patient prior image reference heuristics, ID3-based multidecision-tree induction and CN2-based multidecision induction learning techniques were developed and evaluated. Experimentally, we examined effects of the pre-fetching system we created on radiologists' examination readings. Preliminary results show that the knowledge-based patient image pre-fetching system more accurately supports radiologists' patient prior image reference needs than the current practice adopted at the study site and that radiologists may become more efficient, consultatively effective, and better satisfied when supported by the pre-fetching system than when relying on the study site's pre-fetching practice.

A knowledge-based patient image prefetching system: design, evaluation and management

One fundamental clinical role of radiologists is to provide attending physicians with interpretations of an individual patient's radiological images essential to a treatment plan or overall patient management. Interpreting images from a newly taken radiological examination often requires reference to prior images of the same patient to establish a baseline from which to confirm a suspected pathological process or injury or to evaluate the progression of one that has been identified. Such image references are crucial to the radiologist's examination reading and when inappropriately supported can result in prolonged reading time, decreased report quality, and frustration. To address the problem of inadequate image prefetching methods used by many health care organizations, we took a knowledge-based approach and developed Image Retrieval Expert System (IRES), which incorporates relevant medical/radiological knowledge and contains image retrieval heuristics commonly shared by radiologists. This article describes the design of IRES, highlights its preliminary evaluation results, and discusses issues important for managing this and similar technologies in a health care organization.

Atypical central neurocytoma: report of a case

Central neurocytomas are rare, relatively benign intraventricular neoplasms composed of uniform round cells with neuronal differentiation. The majority of previously reported central neurocytomas did not recurr after tumor removal and the patients had favorable postoperative outcomes. Only a few cases with malignant histopathology or malignant behavior have been noted. Atypical central neurocytoma is a new entity that was first described in the literature in 1997. The tumors have been noted to exhibit a Ki-67 labeling index of 2% or more, or vascular proliferation, mitoses, and necrosis, or both. Atypical histologic findings are usually associated with a somewhat less favorable clinical course and requires postoperative radiotherapy. We report a unique case of a 33-year-old man with a large intraventricular central neurocytoma. The characteristic histopathologic picture, the immunoreactivity for both synaptophysin and neuron-specific enolase, and the ultrastructural features of neuronal differentiation distinguished it from ependymoma and oligodendroglioma. The mitotic activity (up to 3 mitoses/10 high power field) and the high percentage of Ki-67-staining tumor cells (labeling index, 5.0%) in our case were consistent with the atypical variant of central neurocytoma. The patient underwent craniotomy and partial resection of the tumor. Unfortunately, he died of hydrocephalus and brain edema, the next day.

A survey of physicians' acceptance of telemedicine

Physicians' acceptance of telemedicine is an important managerial issue facing health-care organizations that have adopted, or are about to adopt, telemedicine. Most previous investigations of the acceptance of telemedicine have lacked theoretical foundation and been of limited scope. We examined technology acceptance and usage among physicians and specialists from 49 clinical departments at eight public tertiary hospitals in Hong Kong. Out of the 1021 questionnaires distributed, 310 were completed and returned, a 30% response rate. The preliminary findings suggested that use of telemedicine among clinicians in Hong Kong was moderate. While 18% of the respondents were using some form of telemedicine for patient care and management, it accounted for only 6.3% of the services provided. The intensity of their technology usage was also low, accounting for only 6.8% of a typical telemedicine-assisted service. These preliminary findings have managerial implications.

Holocord intramedullary spinal cord astrocytoma: report of one case

Intramedullary spinal cord astrocytoma in infants is relatively uncommon. Its occurrence is usually confined to the cervical and cervicothoracic regions. In this paper, we report on the case of a 4-month old male infant with low grade holocord intramedullary spinal cord astrocytoma. He had developed progressive weakness of the lower extremities over a month period. Neurological examination revealed flaccid paraplegia as well as complete loss of all modalities of sensation below the T10 level. MRI revealed a large intramedullary mass which was found to be an intramedullary astrocytoma at surgery. This case report presents the clinical features, radiographic findings, and treatment and outcome for this patient together with a review of relevant literature.

Urban teleradiology in Hong Kong

We investigated four major teleradiology programmes in Hong Kong. We analysed the overall organizational background of each programme, the context of its implementation, the choice of technology and the decision-making process, and the subsequent dissemination of the technology. Our review suggests that the success of a telemedicine programme is contingent not only on good technology but also on effective management of issues pertaining to human and organizational factors. At the departmental level, the context of the implementation of telemedicine is crucial. At the institutional level, success depends on planning and management. At the professional level, continued education, periodic meetings and seminars are all effective means of promoting telemedicine among health-care professionals and administrators. At the national level, the Hong Kong experience suggests that telemedicine can be effectively developed by starting with urban-based programmes.

Magnetic resonance imaging of radiation necrosis after radiotherapy for acromegaly: report of a case

A total 5,600 cGy in 28 fractions in 44 days was delivered to a 53-year-old woman with acromegaly after transsphenoid removal of a pituitary adenoma. Sixteen months later, she suffered a progressive loss of vision. Radiation optic neuropathy was diagnosed. A T1-weighted imaging showed gadolinium-enhanced lesions in the optic chiasm, pituitary stalk and hypothalamus. Magnetic resonance imaging is uniquely suited to detect radiation injury to the sellar region. The complications of radiation therapy for benign tumor can be severe even by current standard procedures.

Treatment of cerebellar infarction by decompressive suboccipital craniectomy

BACKGROUND AND PURPOSE

We present an anecdotal series of 11 patients without past history of stroke with progressive neurological deterioration while on medical therapy for large cerebellar infarctions. Clinical signs of brain stem compression developed in these patients. Computerized tomography of the head confirmed mass effect from brain edema. It was the clinical judgment of the neurologists and neurosurgeons that each of these 11 patients would expire without surgical intervention.

METHODS

All 11 patients (seven men, four women; mean age, 54 years) were treated with suboccipital craniectomy for decompression and temporary ventriculostomy for cerebrospinal fluid pressure monitoring and drainage.

RESULTS

Seven patients demonstrated neurological improvement on the first postoperative day. Two patients returned to their previous jobs 3 months after surgery. The Barthel Index indicated that six individuals were functioning with minimal assistance within a follow-up period of 16-60 months. The remaining three were functionally dependent. No mortality was noted in this series.

CONCLUSIONS

These results suggest that decompressive suboccipital craniectomy may be an effective, lifesaving procedure for malignant cerebellar edema after a large infarction.

Cryptococcal infection presenting with lumbosacral polyradiculopathy: report of a case

Cryptococcal infection presenting primarily as lumbosacral polyradiculopathy is rare. We report on a 57-year-old man with lumbosacral polyradiculopathy, and in which a culture from the cerebrospinal fluid grew Cryptococcus neoformans. A serum cryptococcal antigen study showed a positive reaction. Biopsy specimens from the spinal nerve rootlet showed evidence of arachnoiditis and direct involvement of the nerve root by Cryptococcus neoformans. It is important to remember that localized lumbosacral polyradiculopathy can be the sole initial manifestation of cryptococcosis.

[Ventriculo-peritoneal shunt in the treatment of schizencephaly with infantile spasm: report of one case]

Schizencephaly is a rare congenital cerebral malformation, which usually produces static neurological symptoms. Occasionally, mass effect on the schizencephalic cavity may cause progressive neurological deficit. Surgical intervention is, therefore, needed to relieve the increased intracranial pressure. This article presents a 7-month-old girl who had suffered from right hemiparesis since birth, and head nodding of four weeks' duration. A brain CT revealed a cleft, along the left Sylvian fissure, which communicated with the lateral ventricle. The septum pellucidum was absent. Midline structures had shifted to the right hemisphere. The CT finding was consistent with a diagnosis of schizencephaly with mass effect. The infant received a ventriculo-peritoneal shunt operation. At postoperative follow-up which has continued for eight months, no further head nodding, an improvement of hemiparesis and psychomotor development were noted.

Upper lumbar disc herniation

Herniations of the upper lumbar disc have often been overlooked due to a relatively low incidence we had 457 lumbar disc surgeries from January 1978 to June 1987. Twenty-two of them were of the upper three lumbar discs. We analyzed these patients according to their clinical syndromes, radiological findings and surgical results. The characteristic features of anterior thigh pain from upper lumbar disc herniation were different from the more commonly seen fourth and fifth lumbar disc herniation which resulted in sciatica. The incidence of cauda equina syndrome was relatively high in our series (36%). All the 22 cases had correlated X-ray findings. Satisfactory operative results for upper lumbar disc herniation were achieved in 20 of 22 (90%).

Site of ocular hydrolysis of a prodrug, dipivefrin, and a comparison of its ocular metabolism with that of the parent compound, epinephrine

Dipivefrin is a prodrug of epinephrine which is hydrolyzed to epinephrine after absorption into the eye. The major site of this hydrolysis is shown to be the cornea. Some dipivefrin is absorbed unchanged into ocular tissues, but most appears as epinephrine and its metabolites within 15 min after topical application. Metanephrine is the major metabolite of epinephrine found in ocular tissues. It is found as soon as 15 min aftter application of either dipivefrin or epinephrine and appears in all the tissues tested. The data indicate that the peinephrine which is liberated by hydrolysis of topically applied dipivefrin is metabolized similarly to topically applied epinephrine. The monoamine oxidase metabolites of epinephrine appear 1 to 3 hr after treatment and are found mainly in the aqueous humor. After ocular application of either compound there appear to be uptake and storage of the exogenous epinephrine in the iris plus ciliary body. There is also some storage of unmetabolized epinephrine in the cornea.

Ocular absorption and metabolism of topically applied epinephrine and a dipivalyl ester of epinephrine

An analogue of epinephrine (EPI), dipivalyl epinephrine (DPE), has been found to reduce intraocular pressure (IOP) significantly at lower concentrations than EPI itself. In order to understand the reason for this increased activity, the ocular penetration, distribution, and metabolism of these two compounds were compared. About 10 times as much DPE as EPI was absorbed by rabbit eyes, with the cornea as the major repository for the increased amount of drug absorbed. Comparison of the partition coefficients of the two compounds showed DPE to be from 100 to 600 times as lipophilic as EPI. The radioactive materials found in the aqueous humor after treatment with either compound had the same mobility in a thin-layer chromatographic system. The data indicate that following the increased penetration of the lipophilic prodrug, DPE is hydrolyzed to EPI in the eye.