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At least 1,369 records · Page 76Linked to original sources
PubMed1991

Principles for transformation of scalp EEG from potential field into source distribution.

Tracings representing simultaneously recorded values of EEG potentials from different positions on the scalp surface describe how the instantaneous potential field over the scalp surface changes with time. Each instantaneous distribution of potential can be seen as resulting from spatial integration of primary components into the potential field. These components may be derived by means of the reverse procedure: subjecting the data from the potential field to spatial differentiation as provided by the Laplacian source operator. The result is a "deblurred," i.e., a more differentiated, distribution of source components hypothetically associated with the generators of the potential field. The Laplacian source operator can be implemented as a linear combination of the instantaneous potential values, either by means of very simple electronic circuitry or in a computer. The linear combination is a standard operation in matrix algebra and is widely applied in signal processing. The formalism of matrix algebra simplifies a precise evaluation of the method in relation to conventional derivation techniques and provides further methods for analysis of the EEG data.

Brain↗
PubMed1978

Square scalp grafts, combined with strip grafts, for the treatment of male pattern baldness.

In the treatment of male pattern baldness, the use of square scalp grafts permits one to obtain the same number of larger grafts from a much smaller donor area--with immediate primary closure leaving only one linear scar. Suitable instruments for marking and cutting the square scalp grafts have been a problem, but a new square marker and a square knife (with disposable blades, in either the 5 mm or 3.5 mm size) have been designed and are available.

Alopecia↗
PubMed1990

Island scalp flap for superior forehead reconstruction.

An island scalp fasciocutaneous flap, based on the posterior superficial temporal vessels, is described for single-stage reconstruction of full-thickness forehead and scalp defects. The hairline can be precisely determined and tailored to restore symmetry. By removing the hair-bearing dermis of the forehead portion of the flap and placing a full-thickness skin graft, aesthetic reconstitution of the forehead skin is achieved. This flap is especially useful when exposed calvarium limits other techniques.

Adult↗
PubMed1996

The expanded forehead scalping flap: a new method of total nasal reconstruction.

The challenge of total nasal reconstruction is particularly formidable in the pediatric patient. Forehead skin is taut, and conventional methods of reconstruction, such as the midline forehead flap, provide a paucity of tissue in this age group. Tissue expansion is well-suited modification to overcome this limitation, but as applied to the midline forehead flap, it does not address the resulting vertical forehead scar. We present a new technique for total nasal reconstruction using an expanded, transversely oriented forehead scalping flap in a pediatric patient. This approach not only provides a generous amount of forehead skin but also limits donor-site morbidity and scarring by orienting incisions transversely at the hairline and within the scalp.

Child↗
PubMed2007

Hemodynamic changes due to infiltration of the scalp with epinephrine-containing lidocaine solution: a hypotensive episode before craniotomy.

Epinephrine-containing lidocaine solution is commonly infiltrated on the scalp before craniotomy. But the hemodynamic changes caused by epinephrine-containing lidocaine solution have been less intensely studied. A prospective randomized double blind control study was designed to observe hemodynamic changes caused by epinephrine-containing lidocaine solution in neurosurgical operations under general anesthesia. One hundred twenty patients undergoing scheduled craniotomy were allocated randomly to 4 groups. All the patients received 1% lidocaine 16 mL with different dose (concentration) epinephrine: group 1 with 40 microg (2.5 microg/mL); group 2 with 80 microg (5 microg/mL); group 3 with 160 microg (10 microg/mL); and group 4 (control group) without epinephrine. mean arterial pressure (MAP) and heart rate were recorded at 30-second interval in 5 minutes after the beginning of local infiltration. In group 1, group 2, and group 3, the lowest MAP and the highest MAP during this period also were recorded. Bleeding was assessed after raising the craniotomy flap. Compared with the baseline, significant hemodynamic changes, particularly decrease in MAP with increase in heart rate at 1.5 minutes after the beginning of local infiltration, were observed in group 1, group 2, and group 3 (P<0.001), but not in group 4. The highest MAP increased significantly compared with the baseline in group 3 (P<0.05), but not in group 1 or group 2. Epinephrine-containing lidocaine solution reduced bleeding significantly (P<0.01). Infiltration with epinephrine-containing lidocaine solution elicits temporary but significant hemodynamic changes including hypotension before craniotomy. Commonly clinically used concentrations of epinephrine (2.5 to 10 microg/mL) can reduce the bleeding on the scalp.

Adolescent↗
PubMed2004

Scalp lesions in Turner syndrome: a result of lymphoedema?

Lymphoedema and skin naevi are common in children with Turner syndrome (TS). Lymphoedema in the early stages of fetal life is thought to cause several of the phenotypic characteristics in patients with TS such as nuchal folds and pterygium colli. We present two patients with TS who have unusual lesions on the scalp. The first patient had an oval circumscribed lesion. Two biopsies were obtained from the lesion. Increased numbers of collagen fibres were seen in the reticular dermis suggesting the diagnosis of connective tissue naevus. The second patient presented with an area with skin folds on the scalp, similar to cutis verticis gyrata. Although unusual in TS, both lesions could be considered as resolving stages of lymphoedema. We suggest that karyotyping should be performed in cases of female infants presenting with similar lesions.

Child, Preschool↗
PubMed2002

The intractability of scaling scalp distributions to infer neuroelectric sources.

ERP researchers use differences in scalp distributions to infer differences in spatial configurations of neuroelectric generators. Since McCarthy and Wood (1985) demonstrated that a spatially fixed current source varying only in strength can yield a significant Condition x Electrode interaction in ANOVA, the recommended approach has been to normalize ERP amplitudes, for example, by vector length, prior to testing for interactions. The assumptions of this procedure are examined and it is shown via simulations that this application of vector scaling is both conceptually flawed and unsound in experimental practice. Because different spatial configurations of neural generators cannot reliably be inferred from different scalp topographies even after amplitude normalization, it is recommended that the procedure no longer be used for this purpose.

Analysis of Variance↗
PubMed2004

Very fast rhythmic activity on scalp EEG associated with epileptic spasms.

PURPOSE: Very fast activity was investigated on the ictal EEGs of epileptic spasms to elucidate the pathophysiology of West syndrome (WS) and related disorders from a novel point of view. METHODS: The traces of scalp ictal EEG of spasms temporally were expanded in 11 patients whose clinical diagnosis was symptomatic WS in six, cryptogenic WS in two, Aicardi syndrome in one, and symptomatic generalized epilepsy after WS in the remaining two. Time evolution of averaged power spectra of the ictal fast activity also was analyzed in each patient. RESULTS: Rhythmic gamma activity with frequency ranging from 50 to 100 Hz was detected in a total of 345 of 537 spasms. Fast activity was seen bilaterally in nine patients, was lateralized to one hemisphere in another, and appeared independently on each hemisphere in the remaining infant with Aicardi syndrome. Power spectra showed a clear peak corresponding to spasm-associated gamma rhythm, with frequency centering approximately 65 Hz and ranging from 51 to 98 Hz. The morphology and spectral characteristics of ictal gamma rhythm were completely different from those of muscle activity or alternating current (AC) artifacts. CONCLUSIONS: Spasm-associated gamma activity was clearly detected on the scalp. This observation may provide a clue to the pathophysiology of spasms.

Cerebral Cortex↗
PubMed2004

Limitations of human occipital scalp hair follicle organ culture for studying the effects of minoxidil as a hair growth enhancer.

Minoxidil induces new hair growth in approximately one-third of patients with androgenetic alopecia after 1 year of treatment. With several conflicting reports in the literature based on small-scale studies, the current study aimed to clarify whether organ culture of human scalp anagen VI hair follicles is a suitable in vitro test system for reproducing, and experimentally dissecting, the recognized in vivo hair-growth-promoting capacity of minoxidil. Hair shaft elongation was studied in terminal anagen VI hair follicles microdissected from the occipital scalp of 36 healthy adults. A total of 2300 hair follicles, approximately 65 per individual, were tested using modifications of a basic organ culture protocol. It is shown here that minoxidil does not significantly increase hair shaft elongation or the duration of anagen VI in ex vivo culture despite several enhancements on the conventional methodology. This disparity to what is seen clinically in minoxidil responders may be explained by the following: (i) use of occipital (rather than frontotemporal or vertex) hair follicles; (ii) use of, already maximally growing, anagen VI hair follicles; (iii) a predominance of hair follicles from minoxidil unresponsive-donors; (iv) use of minoxidil rather than its sulfate metabolite; and/or (v) use of a suboptimal minoxidil dosage. This disparity questions the usefulness of standard human hair follicle organ culture in minoxidil research. Unexpectedly, minoxidil even inhibited hair shaft elongation in the absence of insulin, which may indicate that the actual hair-growth-modulatory effects of minoxidil depend on the concomitant local presence/absence of other growth modulators.

Adult↗
PubMed2005

Recent findings with computerized methods for scalp hair growth measurements.

Sensitive tools have been developed in order to monitor hair loss and treatment responses. Recently the Tricho-Scan was presented (by RH) as such a method which combines epiluminescence microscopy (ELM) with automatic digital image analysis. Herewith new TrichoScan data obtained from 10 women and 21 men with androgenetic hair loss after 6 mo of treatment with 5%-minoxidil are presented. Even in this small cohort of patients, we noticed a significant increase of hair density, cumulative hair thickness and terminal hair counts. Alternative methods were developed during a human alopecia investigation and research technology (HAIR Technology) programme at Skinterface. This involves contrast-enhancement, image acquisition, and processing by qualified technicians followed by computer-assisted image analysis. The specific identification of exogen hair, further adds to this very refined non-invasive investigative method for hair follicle function investigation. Regional variations of hair growth dynamics do exist in the human scalp such as in female patients complaining of hair loss, scalp hair density and growth on top of the head differs significantly from the occipital site. Finally, from transversal studies and from detailed monitoring of subsequent hair cycles during longitudinal studies, data were obtained that support the fact that shortening of hair cycle, slowing down of growth rates and thinning of hair shafts are heralding hair miniaturisation. In the workshop the TrichoScan, the method of Canfield and Skinterface have been shown.

Adult↗
PubMed2005

A non-sense mutation in the corneodesmosin gene in a Mexican family with hypotrichosis simplex of the scalp.

BACKGROUND: Hypotrichosis simplex of the scalp (HSS; MIM 146520) is a rare autosomal dominant form of non-syndromic alopecia that affects men and women equally. Up to now, only a small number of families with HSS have been reported. The affected individuals experience a diffuse progressing hair loss from childhood to adulthood that is confined to the scalp. Recently, HSS has been mapped to the short arm of chromosome 6 (6p21.3), allowing mutations in the corneodesmosin gene (CDSN) to be identified as the cause of the disorder. To date, two stop mutations have been found in three unrelated families with HSS of different ethnic origin. OBJECTIVES: To describe the first HSS-family with Latin American (Mexican) background comprising 6 generations and to identify a mutation in the CDSN gene. PATIENTS/METHODS: The patients were examined by a clinician and blood samples were taken. After DNA extraction, sequencing analysis of the CDSN gene and restriction enzyme analysis with PsuI were performed. RESULTS: By direct sequencing of the two exons of the CDSN gene, a nonsense mutation was identified in the index patient in exon 2, resulting in a premature stop codon (Y239X). The mutation co-segregates perfectly in the family with the disease and was not found in 300 control chromosomes using a restriction enzyme analysis with PsuI. CONCLUSIONS: A nonsense mutation was identified in the first family with HSS of Latin American ethnical background. Our data provide molecular genetic evidence for a 3rd stop mutation in exon 2 of the CDSN gene being responsible for HSS. All to date known nonsense mutations responsible 3 for HSS are clustered in a region of 40 amino acids which is in accordance with a dominant negative effect conferred by aggregates of truncated CDSN proteins.

Adolescent↗
PubMed1989

Fungal kerion--total scalp involvement due to Microsporum canis infection.

We report the case of a 5-year-old girl who developed a remarkably extensive kerion of the scalp due to Microsporum canis infection. Total scalp involvement of this severity and prolonged duration is now unusual, but there has been surprisingly little residual cicatricial alopecia. Microsporum canis does not respond well to ketoconazole, and griseofulvin remains the drug of choice for dermatophyte infections involving hair; a prolonged course may be necessary. This case also demonstrates the benefit of corticosteroids for certain cases of inflammatory ringworm where the host's response to the fungus is exceptionally marked.

Administration, Topical↗
PubMed1977

Six and 14/sec positive spikes with widespread distribution over the scalp as a seizure pattern.

Five patients with either "diencephalic" or "brainstem" epilepsy or "diencephalosis" were examined EEGcally during the course of their hospitalization. The significant changes were detected, mainly by diphenhydramine activation as to the distribution of the 6-14/sec positive spike pattern on the scalp. When the patients were relatively free from their symptoms, the positive spikes were recorded partially on only one or very fre areas, and when they were experiencing clinical paroxysms, the spikes were detected diffusely in almost all areas of the scalp. Chronological EEG observations paralleling the clinical course of illness of a paroxysmal nature are unpopular. However, the necessity of efforts to record EEG's of patients during clinical paroxysms seems important and has been briefly discussed concerning the question as to whether the 6-14/sec positive spike pattern is an abnormal EEG change or perhaps a "seizure pattern".

Adolescent↗
PubMed1996

Scalp flaps in the treatment of baldness. Long-term results.

BACKGROUND: Scalp flaps have been used as a treatment for male pattern baldness for many years. OBJECTIVE: To assess the long-term results of these flaps. METHODS: Twenty patients who underwent a total of 31 temporo-parieto-occipital and temporo-parietal flaps 10-20 years ago were reviewed. RESULTS: Consistent maintaining of the initially obtained coverage and a low incidence of complications was demonstrated. Universally, the male pattern baldness progressed, requiring in some patients subsequent procedures. CONCLUSIONS: Scalp flaps, when performed properly with anticipation of further hair loss, are an effective treatment of male pattern baldness in the appropriately selected patient.

Adult↗
PubMed1998

Ictal scalp EEG in unilateral mesial temporal lobe epilepsy.

PURPOSE: We wished to determine the predictive significance of unilateral hippocampal atrophy and interictal spikes on localization of ictal scalp EEG changes and assess whether ictal EEG provides information that might change treatment or influence prognosis in patients with such characteristics of epilepsy. METHODS: We analyzed EEG seizure patterns in 118 seizures in 24 patients with unilateral mesial temporal lobe epilepsy (MTLE) defined by typical clinical seizure semiology, unilateral hippocampal atrophy on magnetic resonance imaging (MRI) and unitemporal spikes on interictal EEG. Two blinded electroencephalographers independently determined morphology, location, and time course of ictal EEG changes. RESULTS: Lateralization was possible in 88.4-92.0% of seizures and always corresponded to the side of the interictal spike focus and of hippocampal atrophy on MRI. Although only 30.4-33.9% of seizures were lateralized at onset, a later significant pattern emerged (12.6-13.3 s after EEG seizure onset) that allowed lateralization in 82.4-91.0% of seizures with nonlateralized onset. Interobserver reliability for lateralization was excellent, with a K-value of 0.85. In most patients, either all (79.2-83.3%) or >50% (8.3-16.7%) of seizures were lateralized. In only a small proportion of patients (4.2-8.3%) were <50% of seizures lateralized. In 1 patient, no seizure could be lateralized by 1 electroencephalographer. The results of ictal EEG recordings did not alter the surgical approach and did not correlate with surgical outcome. CONCLUSIONS: We conclude that unilateral hippocampal atrophy on MRI and unitemporal interictal spikes can predict localization of ictal scalp EEG changes with a high degree of reliability and that ictal EEG provides no additional localizing information in this particular patient group.

Adult↗
PubMed1998

Predictive value of interictal epileptiform discharges during non-REM sleep on scalp EEG recordings for the lateralization of epileptogenesis.

PURPOSE: EEG recording during sleep is widely used in the assessment of epilepsy, particularly in candidates for surgery, yet the diagnostic value of this procedure is not well established. We evaluated the predictive reliability of interictal epileptiform discharges (IEDs) for localization in presurgical patients with temporal lobe epilepsy (TLE) during non-REM sleep. METHODS: Preoperative scalp EEG recordings with waking and sleep states were assessed in 83 patients with TLE in whom localization of the epileptogenic zone was subsequently confirmed by successful surgical treatment (patient seizure-free >1 year). RESULTS: The accuracy of EEG recordings for prediction of lateralization significantly changed from 51.8% during waking to 78.3% during sleep. After exclusion of patients who showed no discharges, the predictive value changed from 74.1 to 86.7%. However, in patients in whom the waking scalp EEG lateralized incorrectly, no improvement in reliability was achieved by sleep recording. CONCLUSIONS: Our results suggest that IEDs occurring in non-REM sleep provide more accurate information for lateralization of epileptogenesis than do those occurring during waking. This gain of diagnostic information was obtained in patients who showed either bilateral or no discharges in waking records, because unilateral discharges arising de novo in sleep were always correctly lateralizing. On the other hand, in patients who showed unilateral discharges in the awake state, whether ipsilateral or contralateral to the epileptogenic zone, the findings were generally unchanged during sleep.

Adult↗
PubMed1996

The measurement of caffeine concentration in scalp hair as an indicator of liver function.

Caffeine concentration in plasma and scalp hair has been determined for subjects consuming normal daily amounts of caffeine and the results used as an indicator of individual hepatic metabolic capacity. Daily exposure to caffeine was assessed in six healthy Japanese volunteers by direct HPLC measurement of the concentrations of caffeine in aliquots of all caffeine-containing beverages consumed by the subjects. The measurements were repeated on three different occasions for each subject and caffeine consumption (mean +/- s.d.) was calculated as 178.0 +/- 84.3 mg day-1 with an intra-individual variability of 23.8 +/- 6.3% as coefficient of variation. A survey of daily caffeine consumption in 121 adult Japanese by means of a questionnaire revealed a similar value (231.8 +/- 177.8 mg day-1). Caffeine concentration in the plasma sampled during an overnight caffeine-free interval was measured by HPLC and a comparison made between healthy subjects and patients with liver disease (0.71 +/- 0.32, 0.77 +/- 0.45 and 3.92 +/- 1.91 micrograms mL-1 for healthy volunteers (n = 6), patients with hepatitis (n = 11) and those with liver cirrhosis (n = 4), respectively). Strands of scalp hair were collected from six healthy subjects and six patients with liver cirrhosis. Caffeine in hair was identified and measured by gas chromatography-mass spectrometry after digestion of the hair matrix with protease and extraction of the caffeine with chloroform. Caffeine concentration in hair collected from patients with liver cirrhosis (26.5 +/- 5.04 ng mg-1 hair) was significantly higher than that in hair sampled from healthy subjects (7.21 +/- 3.11 ng mg-1). These findings suggest that the determination of caffeine concentration in the plasma and hair of subjects consuming normal daily amounts of caffeine-containing beverages provides a practical assessment of individual liver metabolic capacity.

Adult↗
PubMed1991

Cell cycle kinetics of human anagen scalp hair bulbs in thyroid disorders determined by DNA flow cytometry.

In both, 6 hyperthyroid and 6 hypothyroid patients as well as 10 healthy volunteers, cell cycle kinetics of dissected anagen scalp hair bulbs were determined by means of DNA flow cytometry (DNA-FCM). Compared with the healthy control group in patients with thyroid disorders striking differences of cell kinetic data were evaluated. In hyperthyroidism a significant increase (30%) and in hypothyroidism a significant decrease (15%) of S and G2+M phase cell percentages was found. The proliferation index (S+G2+M %) calculated revealed similar results. A correlation between the height of S phase percentages and plasma T3 levels was recognizable but could not be proven statistically. By means of DNA-FCM the study demonstrates for the first time the influence of thyroid hormones on in vivo cell cycle kinetics of human scalp hair bulbs.

Adult↗