Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “SCALP”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 1,531 records · Page 85Linked to original sources
PubMed1980

Spatio-temporal visually evoked scalp potentials in response to partial-field patterned stimulation.

Visually evoked scalp potentials (VESP) have been recorded at 40 electrode sites from each of 3 subjects. Pattern appearance/disappearance was used for whole field and partial field stimulation. The data are displayed as equipotential maps. The topographical features of the equipotential maps show periods of stable organization followed by periods of relatively rapid change. The structure of the maps changes in a consistent pattern with the region of the retina stimulated; the first peak fits well within the framework of the cruciform model of striate cortex. The first and second peaks of the VESP appear to be caused by independent neural generators. The work reported in this paper shows major agreement with other authors and reconciles some points of disagreement between them.

Electroencephalography↗
PubMed1981

Mechanically and electrically evoked somatosensory potentials in human: scalp and neck distributions of short latency components.

Short latency somatosensory potentials evoked by electrical stimulation of the median nerve as well as by mechanical stimulation on the nail of the index finger were recorded from 10 normal adults using a noncephalic reference (the forearm contralateral to the stimulus). Potentials were recorded from 15 electrode locations extending from the level of the 4th thoracic through the 7th, 4th and 2nd cervical vertebrae to the scalp at Oz, P4, P3, A2, A1, C4, Cz, C3, F4, F3 and Fpz. In general, all the components of potentials evoked by mechanical stimulation had electrically evoked counterparts with comparable surface distributions and variations between subjects. Some of the electrically evoked components, which were low in amplitude and variable in occurrence between subjects, did not have mechanically evoked counterparts. Possible generators of the components detected are discussed based on their surface distribution and polarity reversals. A comparable study on patients with well localized lesions must be performed in order to support or disprove the generators proposed.

Adolescent↗
PubMed1987

High frequency scalp potentials evoked by a reaction time task.

'Bursts' of high frequency (20-80 Hz) extracellular electrical activity are the signature of the brain mechanism mediating recognition of odors in rabbits and cats. To test the hypothesis that a similar mechanism may be functional in man outside the olfactory system, relationships were studied between bursts of 20-150 Hz scalp EEG and parameters of performance during visual reaction time tasks. Specific findings indicated that (1) muscle artifacts were not the primary source of identified EEG bursts, (2) the mechanism which produces the bursts may be similar in both rabbit olfactory bulb and human neocortex, (3) visual task performance may be mediated by the brain areas which produced the bursts, and (4) burst activity varied with changes in performance which may be associated with attention and learning.

Adult↗
PubMed1987

Mapping of scalp potentials by surface spline interpolation.

Evoked potentials and EEGs record punctate electrical activity at electrode sites. To represent the overall potential distribution on the entire scalp it is necessary to interpolate between these sampled values. Surface splines are mathematical tools for interpolating functions of two variables. In comparison to the classical methods of interpolation, based on linear combination of the potentials of the 4 nearest electrodes, spline methods are smoother, give more precisely located extrema and converge faster toward the 'true' potential surface when the number of recording electrodes is increased. These advantages are at the expense of lengthier computation time.

Brain Mapping↗
PubMed1996

Estimation of interpolation errors in scalp topographic mapping.

Topographic maps are commonly constructed from electrical scalp recordings (such as EEGs and ERPs) using several different interpolation methods. It is important to determine the accuracy of such maps. Previous assessments of interpolation methods have been based on global error measures and the visual appearance of the topographic maps. However, the relationship of interpolation error to local contributing factors requires a more detailed analysis. In this paper, we use simulations to explore and quantify the relationship of error to global and local factors for different interpolation methods. We find that among the best interpolation methods, adequate electrode density is more important than the method used. For shallow sources, we show that local interpolation error is most correlated with potential gradient, and has a lesser correlation with distance to nearest electrode. The greatest correlation, however, is with the product of gradient and distance. Thus, interpolation error can be controlled locally by making the interelectrode distance inversely proportional to the expected potential gradient. With shallow sources, areas far from any electrode and having high apparent gradient are likely to have high interpolation error. Moreover, all areas far from any electrode may contain high interpolation errors, and should be interpreted with caution.

Brain Mapping↗
PubMed1989

Staples versus sutures in the closure of scalp wounds: a prospective, double-blind, randomized trial.

Over a 6-month period, patients attending the Accident and Emergency Department of the Mater Infirmorum Hospital with scalp wounds were randomly allocated to one of two groups for closure of their wounds with either nylon sutures or metal staples. Each group contained 100 patients. Patients were reviewed at 5 days (95 per cent) after the removal of sutures or staples and again at 3 weeks (61 per cent). The two groups were similar for age, sex, aetiology and wound characteristics. There was no difference in morbidity or rate of wound infection but stapling was significantly faster and less painful. The use of staples carries no risk of accidental needle-stick injury and should therefore be safer than suturing for the user.

Double-Blind Method↗
PubMed1983

Distribution of scalp somatosensory potentials evoked by stimulation of the tibial nerve in man.

The scalp distribution of the response to stimulation of the tibial nerve at the medial malleolus was systematically analysed. The somatosensory evoked potential (SEP) was recorded with electrodes placed in a transversal line over the ipsilateral and contralateral postcentral gyri and in a sagittal line over the longitudinal brain fissure. The SEPs recorded over the ipsilateral hemisphere and along the sagittal line were similar to the F response (the response over the foot primary somatosensory region). Over the contralateral hemisphere the waveform of the responses changed obviously from point F to the point C (contralateral hand primary somatosensory region). The C response started with N37, P40 had a longer latency, N50 was not present and the subsequent waves were also considerably different. Mathematical simulation of the responses recorded from the electrodes between points F and C has shown that they represent an electrical algebraic summation of the activity over points F and C. Although the F and C responses may be 2 potentials arising from the opposite sides of a single dipole generator which is located in the medial fissure, it is more probable that the somatosensory evoked potential on tibial nerve stimulation reflects the activity of 2 separate generators.

Adolescent↗
PubMed1987

The influence of signal loss on the comparison between computer analyses of the fetal heart rate in labour using pulsed Doppler ultrasound (with autocorrelation) and simultaneous scalp electrocardiogram.

A comparison between the computer analyses of records of the fetal heart rate (FHR) obtained simultaneously by pulsed doppler ultrasound with autocorrelation and by fetal scalp electrocardiogram (ECG) in labour showed no statistical differences when signal loss was less than 2%. Increasing signal loss, due to maternal movement, correlated significantly with greater differences between ultrasound and ECG values for mean FHR variation (r = 0.58, p less than 0.005). With higher signal loss (average 15.6%) the mean FHR variation measured by ultrasound was significantly lower than that measured by ECG (T = 3.83, p less than 0.005) but this reduction was not of clinical significance.

Diagnosis, Computer-Assisted↗
PubMed1988

Correlation clusters in the accumulation of metals in human scalp hair: effects of age, community of residence, and abundances of metals in air and water supplies.

Scalp hair samples taken from 122 children and 27 adults from three native Indian villages in northern Alberta, Canada were analyzed for 32 metals, in an attempt to trace industrial pollution into the human population. One of the villages has been exposed since 1967 to increased levels of several metals due to its proximity to the world's first two oil sands petroleum extraction plants (Suncor and Syncrude), which release large amounts of metals into the environment. Metal-enriched particulates are emitted at a rate of 547-780 kg h-1 for Suncor, and 713-1067 kg h-1 for Syncrude. To test the hypothesis that hair content reflected accumulation of environmental metals, water and aerometric samples were collected and analyzed for their metal content. These analyses demonstrated that elevated levels of nine metals in hair from children in one of the control villages (Garden River) are (with the exception of Al) correlated with increased levels of metals in water and air. Moreover, increased levels of Cu, but lowest levels of all other metals were found in hair and environmental samples from one control village (Fort Chipewyan). Correlation matrices for metals in the hair samples revealed three sets of highly intercorrelated metals ('correlation clusters'): (i) Pb/Cd; (ii) Al/V/Fe; (iii) Ca/Mg/Sr/Ba. These groups of metals were significantly intercorrelated (r greater than 0.6, p less than 0.001) in the total population, and in both children and adults, or both males and females, as well as when the population was compared according to community of residence. The robustness of the clusters is particularly noteworthy in view of large differences in the proportions and absolute amounts of the various metals in hair from children in the three villages. Plots of metal levels in hair as a function of age of subject reveal a dramatic decrease in concentrations of Al, V, and Fe during the first years of life. The high levels of Al and V in hair from very young children may reveal a lower selectivity in metal absorption, and a higher risk of toxicity during a period of rapid growth when need for nutritionally essential metals is particularly high.

Adult↗
PubMed1984

Contiguous scalp, skull, and epidural Hodgkin's disease.

A patient with Hodgkin's disease of the nodular sclerosing subtype presented with recurrent disease at the site of a previous blunt trauma to the head. The tumor involved the scalp and subjacent skull and epidural space. This particular presentation of Hodgkin's disease is probably unique, and involvement of the skull and cranial cavity by this subtype of Hodgkin's disease is rare.

Adult↗
PubMed1988

Intraoperative monitoring of evoked potentials with a spiral scalp electrode. Technical note.

Monitoring evoked potentials from the brain for prolonged periods during neurosurgical procedures ideally requires attached scalp electrodes that may be placed in a sterile field. The limitations of conventional surface and percutaneous electrodes in the operating room environment have led to the development of a disposable curved-needle electrode which is inherently self-retaining. Clinical results have demonstrated the advantages of this new electrode over other electrodes currently used for intraoperative neurophysiological monitoring.

Electrodes↗
PubMed1988

Preservation of craniotomy bone flaps under the scalp.

Bone flaps are occasionally not replaced because of brain swelling or for other reasons. Various methods for preserving the free bone flaps have been described. Reimplantation of a free bone flap after a period of preservation outside the body, however, may be complicated by infection, and facilities for proper preservation under sterile conditions may not be available. We present a new technique for preserving the bone flap under the scalp until brain swelling has resolved. The bone flap is reimplanted 12-48 days later. No serious complications related to this technique have been encountered in the 37 patients in which it was used.

Adolescent↗
PubMed1994

Scalp hibernoma: case report and literature review.

Hibernomas are uncommon, benign neoplasms derived from the remnants of fetal brown adipose tissue. A review of the world literature revealed 105 cases, with the interscapular location the most common. Typically, hibernomas are asymptomatic and slow-growing. Adequate treatment usually consists of simple excision. We describe the second documented case of a scalp hibernoma.

Humans↗