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Biomedical subjects

R C Burgess

Publications and source records attributed to R C Burgess.

At least 19 recordsLinked to original sources
PubMed2002

Complications of invasive video-EEG monitoring with subdural grid electrodes.

OBJECTIVE: To evaluate the risk factors, type, and frequency of complications during video-EEG monitoring with subdural grid electrodes. METHODS: The authors retrospectively reviewed the records of all patients who underwent invasive monitoring with subdural grid electrodes (n = 198 monitoring sessions on 187 patients; median age: 24 years; range: 1 to 50 years) at the Cleveland Clinic Foundation from 1980 to 1997. RESULTS: From 1980 to 1997, the complication rate decreased (p = 0.003). In the last 5 years, 19/99 patients (19%) had complications, including two patients (2%) with permanent sequelae. In the last 3 years, the complication rate was 13.5% (n = 5/37) without permanent deficits. Overall, complications occurred during 52 monitoring sessions (26.3%): infection (n = 24; 12.1%), transient neurologic deficit (n = 22; 11.1%), epidural hematoma (n = 5; 2.5%), increased intracranial pressure (n = 5; 2.5%), and infarction (n = 3; 1.5%). One patient (0.5%) died during grid insertion. Complication occurrence was associated with greater number of grids/electrodes (p = 0.021/p = 0.052; especially >60 electrodes), longer duration of monitoring (p = 0.004; especially >10 days), older age of the patient (p = 0.005), left-sided grid insertion (p = 0.01), and burr holes in addition to the craniotomy (p = 0.022). No association with complications was found for number of seizures, IQ, anticonvulsants, or grid localization. CONCLUSIONS: Invasive monitoring with grid electrodes was associated with significant complications. Most of them were transient. Increased complication rates were related to left-sided grid insertion and longer monitoring with a greater number of electrodes (especially more than 60 electrodes). Improvements in grid technology, surgical technique, and postoperative care resulted in significant reductions in the complication rate.

Adolescent↗
PubMed2001

Design and evolution of a system for long-term electroencephalographic and video monitoring of epilepsy patients.

The impact of technology, especially computer technology, on clinical neurophysiology instrumentation has yielded more than automation of paper-based electroencephalography. The new features now available as standard components of digital EEG/video have actually transformed practice (e.g., post hoc remontaging or filtering). At the same time, however, the fact that the signals are digital has led to a panoply of "tools in search of a problem." To incorporate appropriate tools in a practical and cost-effective fashion is a challenge that requires detailed, interdisciplinary knowledge, as well as concentrated effort. Although it is in the nature of research and development to follow a few blind alleys, too many projects are never productively implemented because excessive attention is focused on the obscure and not enough on whether and how the technique can actually help patients. In addition, a long-term view requires making the correct technology choices, to benefit from the consumer cost cycle and to ensure a continuous migration pathway. The lessons learned and principles established while bringing together the space, the people, and the equipment into an efficient, high-volume epilepsy monitoring unit are instructive.

Biophysical Phenomena↗
PubMed2001

Brachydactyly type C.

Brachydactyly type C is an autosomal dominant disorder with markedly variable penetrance. A patient with limited gene expression has shortening limited to the middle phalanges and the first metacarpal and an elongation of the radial side of the base of the second proximal phalanx. When completely expressed the characteristic radiographic findings are shortening of all the metacarpals, greatest in the thumb, followed by the little, ring, middle, and index fingers; brachymesophalangy (shortening of the middle phalanges); shortening of the proximal phalanges of the index and middle fingers, with the proximal phalanges of the ring and small fingers of normal length; elongation of the radial side of the base of the second proximal phalanx resulting in a trapezoidal shaped epiphysis; ulnar deviation at the second and third metacarpophalangeal joints; and hypersegmentation (extra phalanx) of the index and middle fingers. The ulnar deviation of the index and middle fingers may result in scissoring and require surgical correction. The hand deformities of 10 patients with brachydactyly type C are presented to characterize the hand abnormalities in the syndrome and its variable presentation.

Adult↗
PubMed2001

An arrhythmia detector and heart rate estimator for overnight polysomnography studies.

We present an algorithm for automatic on-line analysis of the electrocardiography (ECG) channel acquired during overnight polysomnography (PSG) studies. The system is independent of ECG morphology, requires no manual initialization, and operates automatically throughout the night. It highlights likely occurrences of arrhythmias and intervals of bad signal quality while outputting a continual estimate of heart rate. Algorithm performance is validated against standard ECG databases and PSG data. Results demonstrate a minimal false negative rate and a low false positive rate for arrhythmia detection, and robustness over a wide range of noise contamination.

Algorithms↗
PubMed2000

The polysomnogram assay: a method to represent the overnight polysomnogram in a condensed format.

We present the polysomnogram assay (PSGA), a new representation format for the polysomnogram (PSG), designed to assist in the interpretation of overnight PSG studies. The technique condenses the PSG record by a factor of 30 while preserving the ability to portray PSG features of diagnostic relevance, including sleep architecture, arousals, movement, leg jerks, cyclic alternating pattern, and increased breathing effort. The PSGA patterns associated with these events are described and illustrated by examples. The new format considerably reduces the effort required to evaluate sleep quality and continuity, making it more practicable for the polysomnographer to interpret the entire overnight PSG study. The compressed time scale also facilitates analysis of relatively long PSG episodes and allows assessment of signal activity surrounding critical PSG events. The PSGA appears capable of improving identification of arousals, leg jerks, and upper airway resistance, and may be especially amenable for automatic analysis of PSG data.

Airway Resistance↗
PubMed1998

How competent do our graduates feel?

As part of a review of the undergraduate curriculum to assess its relevance for a future general practitioner, a survey of self-perceived competency at graduation based on the competency list developed by the Association of Canadian Faculties of Dentistry was circulated to recent graduates and the graduating class. The overall response was 67.5 percent, and revealed that approximately 70 percent of the respondents felt well prepared in approximately 69 percent of the competencies. These were the common "bread and butter" items of dentistry, such as basic restorative dentistry, examination, diagnosis, treatment planning, local anaesthesia, and scaling. Those areas reported as less well-prepared for included financial and personnel management, performance of soft-tissue biopsies, and management of chronic orofacial pain. Clarification of the raw survey results in focus groups was needed to uncover specific details that could lead to remedial action in problem areas.

Analysis of Variance↗
PubMed1997

Peak detection in auditory and somatosensory evoked potentials by means of the zero-crossings wavelet representation.

A feature detection algorithm for detecting singularity-like features in a one-dimensional signal has been developed. It is based on the zero-crossings wavelet representation introduced by Mallat [1], and involves a variance-weighted cross-correlation of the appropriate wavelet transform of the signal in the various frequency bands with an averaged template characterizing the particular feature. The algorithm was developed for the purpose of automatic feature detection in averaged evoked potentials. It successfully detects waves I to V in the auditory evoked potential and the N20 and P25 peaks in the median nerve stimulated somatosensory evoked potential, in normal and delayed-latency cases. The performance of the algorithm is plotted as a function of the signal-to-noise ratio. A priori knowledge of the expected feature amplitudes and latencies is not necessary, but may be incorporated into the model. By feeding the feature amplitude and latency estimates back into the algorithm as a priori knowledge, it is configured to track the changing characteristics of a feature over time.

Algorithms↗
PubMed1996

Subdural potentials at orbitofrontal and mesial prefrontal areas accompanying anticipation and decision making in humans: a comparison with Bereitschaftspotential.

Field potentials associated with the execution of a warned choice Go/No-Go reaction task were recorded from prefrontal supplementary (SMA) and primary motor cortex (MI) by using subdural electrodes in 5 epileptic patients during presurgical evaluation. The choice was between a Go and a No-Go imperative stimulus (S2) in the S1-S2 paradigm. Orbitofrontal and mesial prefrontal areas generated a slow preceding potential before S2 (most likely late CNV), and bilateral mesial prefrontal areas generated a transient potential, most likely related to decision making, upon S2 in both Go and No-Go conditions. In self-paced, repetitive movement, the Bereitschaftspotential was seen only at SMA and MI, but not in the prefrontal area. The present result, therefore, suggests that in humans orbitofrontal and mesial frontal areas play an important role in preparation for cognition and in decision making, whereas SMA and MI do so in motor preparation.

Adult↗
PubMed1996

Ilizarov treatment of pilon fractures.

The authors retrospectively reviewed 13 pilon fractures in 12 patients treated with a diaphyseal-epiphyseal technique of Ilizarov external fixation. Clinical followup averaged 16 months (range, 12-25 months). Eighty-four percent of the fractures had healed within 16 weeks after surgery. Average range of motion of the ankle was 12 degrees dorsiflexion and 25 degrees plantar flexion. One delayed union was treated with bone grafting and eventually healed; 1 nonunion was treated with ankle arthrodesis. Most patients (91%) experienced mild or no pain. There were no deep infections. This technique is an effective treatment option for tibial pilon fractures.

Adult↗
PubMed1996

Subdural recording of ictal DC shifts in neocortical seizures in humans.

PURPOSE: Invasive ictal EEG recording is often necessary to delineate epileptogenic areas in patients with intractable partial epilepsy, but even intracranial ictal recordings often reveal ill-defined onset zones in neocortical epilepsy. We studied the physiologic significance of ictal direct current (DC) potentials recorded intracranially in human epilepsy. METHODS: We made intracranial ictal EEG recordings in three patients with intractable partial seizures arising from frontal, lateral temporal, and parietal neocortical areas by using closely spaced subdural electrodes (platinum in two patients and stainless steel in one patient) with both standard (1.5 Hz) and open (0.016 Hz) low-frequency filter (LFF) settings. RESULTS: The initial ictal pattern was localized to two to nine subdural electrodes and characterized by very low voltage and high-frequency rhythmic activity ("electrodecremental pattern"). A slow-rising negative potential (DC potential) was seen in a slightly more restricted area (two to six electrodes) and occurred 1-10 s before the initial ictal EEG discharges in two patients. CONCLUSIONS: These results agree with those of previous studies of ictal DC shifts in animals and suggest that ictal DC shifts may be helpful in delineating the epileptogenic area more precisely in human epilepsy.

Adolescent↗
PubMed1995

Movement-related potentials associated with bilateral simultaneous and unilateral movements recorded from human supplementary motor area.

To clarify the differences of movement-related potentials (MRPs) among ipsilateral, contralateral and simultaneous bilateral movements, MRPs with finger, thumb or foot movements were recorded from subdural electrodes chronically implanted on the supplementary motor area (SMA) in 3 patients, and also from the primary sensorimotor area in two of them being evaluated for epilepsy surgery. As a result: (1) SMA generated clear pre-movement potentials regardless of the type of movement. Its amplitude was almost identical between contralateral and bilateral movements except for the motor potential (MP). The pre-movement potentials associated with ipsilateral movements were relatively smaller than those with contralateral or bilateral movements. (2) The primary sensorimotor area generated clear pre-movement potentials in contralateral and bilateral movements with similar amplitude. With ipsilateral hand movements, however, only a small Bereitschaftspotential (BP) and no negative slope (NS') or MP was seen, and ipsilateral foot movements were not preceded by any BP. It is, therefore, most likely that, as far as the preparation for simple voluntary self-paced movement is concerned, the SMA plays an equally important role in unilateral and bilateral movements, whereas the primary sensorimotor area is involved predominantly in the preparation of contralateral movements.

Adult↗
PubMed1995

Generator locations of movement-related potentials with tongue protrusions and vocalizations: subdural recording in human.

Movement-related potentials (MRPs) associated with tongue protrusions and vocalizations were recorded from chronically implanted subdural electrodes over the lower perirolandic area in 7 patients being evaluated for epilepsy surgery. In 3 patients, tongue protrusions elicited a clearly defined, well localized slow negative Bereitschaftspotential (BP) at the motor tongue area, and a positive BP at the sensory tongue area. At the motor tongue area the negative BP was followed by a negative slope (NS') and a motor potential (MP), and at the sensory tongue area the positive BP and a positive reafferent potential (RAP) were seen but no NS' and MP could be identified. In the other 4 patients, tongue protrusions elicited positive BP, NS' and MP at the motor and sensory tongue area, and positive RAP at the sensory area. It was concluded that BPs, NS' and MPs are mainly generated in the motor cortex involving the crown as well as the anterior bank of the central fissure. The sensory cortex (areas 3a and 3b) also participated in the generation of BPs but to a lesser degree. Different degree of involvement of these multiple generators most likely explains the interindividual variability of polarity and distribution of the MRPs. RAPs most likely arise from primary sensory areas 1 and 2. Brain potentials were also recorded at the motor (2 patients) and sensory (2 patients) language areas, but no specific language-related potentials could be identified. Evoked potentials to lip stimulation were investigated in 4 patients. In 3 patients, the responses at the sensory tongue area (P16, N21 and P30) had the same latency but opposite polarity to those at the motor tongue area. In the other patient, the responses (P16, N21 and P30) at the motor and sensory tongue areas were of the same polarity. The MRPs to tongue protrusions in those 4 patients revealed the same polarity relationship between the pre- and postcentral potentials. However, the maximal amplitude of evoked potentials and MRPs was seen at almost the same electrodes, suggesting that the main generators for these MRPs and evoked potentials must be located at contiguous areas in the anterior and posterior bank, respectively, of the central fissure.

Adolescent↗
PubMed1995

Delayed high median neuropathy after supracondylar humeral fracture. A case report and review of the literature.

Compression neuropathy of the median nerve around the elbow is an uncommon yet well-recognized clinical entity. Acute compression can occur after trauma to the elbow, whereas prolonged compression neuropathy usually involves compression under a normal or aberrant anatomic structure. The authors present a case of severe median nerve compression neuropathy above the elbow that occurred several months after a supracondylar humeral fracture in a previously asymptomatic adolescent with aberrant soft tissue anatomy.

Child↗
PubMed1995

Symptomatic lunate-triquetral coalition.

Carpal coalitions are an uncommon anatomic anomaly caused by the failure of segmentation of the carpal cartilaginous anlage. The most common carpal coalition is between the lunate and triquetrum. Previously considered completely asymptomatic, carpal coalition and associated degenerative arthritis of the incompletely involved joints has been proven as a cause of occult wrist pain.

Adolescent↗
PubMed1994

Polymerase chain reaction amplification of herpes simplex viral DNA from the geniculate ganglion of a patient with Bell's palsy.

Bell's palsy is the most common cause of facial paralysis. In this study, we demonstrate the presence of herpes simplex viral type 1 (HSV-1) genomic DNA in the geniculate ganglion of a patient who had Bell's palsy. This association suggests that in this patient, HSV-1 may have caused Bell's palsy. If HSV-1 is a cause of Bell's palsy, treatment with acyclovir may be beneficial. Additional studies should be done to establish the prevalence of HSV-1 as an etiologic agent of Bell's palsy.

Aged↗