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Biomedical subjects

M Rayport

Publications and source records attributed to M Rayport.

At least 19 recordsLinked to original sources
PubMed1997

Computer analysis of human depth EEG in different sleep stages.

This study compares delta (< 4 Hz), theta (4-8 Hz), alpha (8-12 Hz) and beta (12-20 Hz) band EEG signals during wakefulness, rapid-eye-movement (REM) sleep, and stage 1 and stage 2 non-REM sleep recorded from both surface and depth electrodes in patients with drug-resistant partial seizures. Computer analysis utilizing Fast Fourier Transforms (FFT) was performed with the Neurovision software developed for this purpose. Mean amplitudes were calculated for each of the frequency bands. Preliminary analysis was performed with emphasis on the presence and characteristics of theta activity in the hippocampus of the brain. Results demonstrate theta wave activity in the hippocampus with an increase of theta activity in REM sleep as compared to non-REM sleep (stages 1 and 2).

Adult↗
PubMed1992

New head-prone position for posterior fossa surgery in infants with severe hydrocephalus.

A new head-prone position is described for posterior cranial fossa surgery on infants whose cerebral cortical mantle has been markedly thinned by severe hydrocephalus. The new position furnished a direct line of sight to the apex of the IV ventricle corresponding to that provided by the classic high sitting position, without the latter's risks of air embolism and of acute subdural hematoma secondary to tearing of corticodural bridging vessels due to escape of gravity-impelled CSF from the large ventricles. The anesthesiologic technique, the positioning of the patient, and the surgeon's posture presented no unusual problems.

Anesthesia, Inhalation↗
PubMed1991

Abdominal cerebrospinal fluid pseudocyst: occurrence after intraperitoneal urological surgery in children with ventriculoperitoneal shunts.

Increasingly, children with ventriculoperitoneal shunts are undergoing urinary tract reconstructive surgery with bowel. The peritoneal end of the ventriculoperitoneal shunt tubing usually is exposed during the procedure, making the system vulnerable to infections and malfunction. The records of 103 myelomeningocele children with ventriculoperitoneal shunts and bowel-bladder reconstructive surgical procedures (27) were reviewed for evidence of an abdominal cerebrospinal fluid pseudocyst (6). Pseudocyst formation occurred in only 1 of 76 ventriculoperitoneal shunt patients (1.3%) who had not undergone versus 6 of 27 (22%) who had undergone an intra-abdominal procedure. The 6 children had a total of 8 pseudocysts, including 7 pseudocysts that developed 8 days to 47 months (average 15.1 months) after the reconstructive surgery and 1 that developed before reconstructive surgery. All patients had abdominal symptoms (pain or mass) or symptoms of increased intracranial pressure. Treatment included computerized tomography-guided needle aspiration or abdominal exploration with cyst evacuation and shunt repositioning or replacement. The walls of the pseudocyst were formed by matted loops of bowel. Additional shunt surgery was required in 5 patients with conversion to ventriculoatrial shunts. We conclude that the development of an abdominal cerebrospinal fluid pseudocyst is at least in part related to the prior abdominal surgery. Thus, pediatric urological and general surgeons caring for children with ventriculoperitoneal shunts should be aware of this complication.

Abdomen↗
PubMed1989

Magnetic resonance imaging in the evaluation of a gunshot wound to the cervical spine.

A patient in the second trimester of pregnancy sustained a gunshot wound of the upper cervical spine with a partial Brown-Séquard syndrome. The patient's condition was evaluated by conventional roentgenography, computed axial tomography (CT), and magnetic resonance imaging (MRI). The MRI alone clearly demonstrated the relationship of the bullet and the spinal cord, whereas the CT image was obliterated by metal artifacts. The bullet was removed from the spinal canal by a posterior approach with the patient in the sitting position and in skeletal cervical traction. The neurological status of the patient improved markedly after the surgery.

Adult↗
PubMed1987

Computed tomography-guided intracranial biopsy and cyst aspiration: accumulated experience in 60 patients.

We have reviewed our continued experience with computed tomography guided freehand percutaneous brain biopsy using a needle guide sheath of our own devising. The guide sheath is equipped with small metallic marker beads and throws no artifacts. It is useful in demonstrating the exact tip of the guide biopsy sheath in relation to the wall of the intracerebral lesion. The deforming response of the target lesion wall to the guide sheath and the biopsy needle is easily seen using our technique and is highly correlated to obtaining a satisfactory pathologic specimen. Combination of this guide sheath with a suitable computed tomography compatible head frame may represent a highly accurate and reliable but relatively simple guidance system.

Biopsy, Needle↗
PubMed1983

Outcomes and indications of corpus callosum section for intractable seizure control.

Callosotomy (CCS) was performed in 9 cases of rigorously classified drug-refractory epilepsy not eligible for focal cortical resection. Complete CCS was carried out in two stages in 8 patients. 1 case had an anterior CCS only. None of the 9 patients has become seizure free. In 7, seizure frequency has diminished by a factor of 3-60 for at least one seizure type. Drop attacks in 2 cases have ceased. Clinical seizure patterns appeared more helpful in predicting outcome than preoperative EEG and stereoelectroencephalographic studies. Complete CCS may result in prolonged behavioral disturbances in the areas of language, hemisphere competition and attention-memory sequencing with impact on the sphere of daily living.

Adolescent↗
PubMed1982

Computed tomography-guided intracranial biopsy and cyst aspiration.

A coordinated series of instruments has been developed for use in computed tomography (CT)-guided brain lesion biopsy and cyst aspiration: a plastic guide needle that is relatively free of CT artifacts, a ball-and-socket holding device for multidirectional sampling, and an aspiration-cutting biopsy needle that reliably produces consistent cores of tissue. Twenty-six biopsy and/or aspiration procedures have been performed on 24 patients with an overall biopsy success rate of 79%. The method is most reliable with highly malignant astrocytomas and least reliable with metastases and unusual primary tumors. There were 3 complications: 2 intratumoral hematomas and 1 death due to hemorrhage. A survey of published CT biopsy series shows an overall success rate of 85%. The rate of serious complications is 3.5% (including 3 deaths). The incidence of intratumoral hematomas that are clinically silent or associated with relatively minor clinical problems is 9%. CT-guided intracranial biopsy is more reliable than the earlier freehand methods and simpler than stereotactic techniques. It is the procedure of choice for percutaneous biopsy of superficial and deep hemispheric lesions.

Biopsy, Needle↗
PubMed1981

Variability in right hemisphere language function after callosal section: evidence for a continuum of generative capacity.

Two recent patients in our behavioral series investigating the psychological effects of callosal section exhibit right hemisphere language. Using lateralized visual and auditory stimulation, semantic, phonetic, and expressive linguistic functions were examined. While the right hemisphere language systems in both patients were shown to be capable of semantic information processing, they differed in their abilities to process phonetic information, follow verbal commands, and produce linguistic responses. It is argued that the differences between left and right hemisphere language systems are quantitative and are best characterized along a continuum of generative capacity. It is the variability in such capacity that appears to be responsible for the variability in right hemisphere language function within the split-brain population.

Adult↗