Scalp thickness as a predictor of wound complications after cerebral revascularization using the superficial temporal artery: a risk factor analysis.

OBJECTIVE: Cerebral revascularization using the superficial temporal artery diverts some of the blood supply from the scalp to the brain. This may compromise the blood supply to the scalp and could result in more wound complications. OBJECTIVE: This retrospective chart review aimed to identify the incidence of, and independent risk factors for, wound complications after cerebral revascularization using the superficial temporal artery. METHODS: Patients who underwent cerebral revascularization using the superficial temporal artery between January 2003 and February 2017 were studied. Minor wound complications included superficial skin necrosis, and mild wound dehiscence, while major wound complications included full-thickness skin necrosis, deep infection, and osteomyelitis that required additional surgical treatment. RESULTS: A total of 482 cerebral revascularization procedures using the superficial temporal artery were included. Wound complications developed in 32 cases (6.6% of the total), including 7 classified as major in severity (1.5% of the total). The multivariate analysis revealed diabetes mellitus (odds ratio 4.058, p = 0.001), low body mass index (odds ratio 1.21, p = 0.009), and thin scalp (odds ratio 1.82, p < 0.001) as the main risk factors for wound complications. Every 1-mm increase in scalp thickness was associated with a protective effect on wound complications (odds ratio 0.549). CONCLUSION: Cerebral revascularization using the superficial temporal artery was associated with a relatively high incidence of wound complications. Diabetes mellitus, low body mass index, and thin scalp were found to be independent risk factors for wound complications. The thickness of the scalp could be a useful predictor of wound complications.

Tissue biomechanics of the human head are altered by Thiel embalming, restricting its use for biomechanical validation.

Thiel embalming is a well-known method of anatomical fixation giving lifelike optical and haptic tissue properties. Beyond these characteristics, Thiel embalming may also be a promising method to provide lifelike tissues for validation purposes of human head biomechanics. Recent investigations using Thiel-embalmed human tissues of the upper and lower limb yielded contradicting biomechanical results on fixation-induced changes in the tissues' load-deformation behavior. It is to date unclear if Thiel embalming may have a softening or stiffening effect on human soft tissues or no global effect on biomechanics compared to the fresh state, with the latter being the most desirable outcome. The given study aimed at assessing the effects of Thiel embalming on the uniaxial tensile properties of human head soft tissues. Age-matched fresh and Thiel-embalmed dura mater, temporalis muscle, temporalis muscle fascia, and scalp samples were examined. Dura, fascia, and scalp samples showed significantly different elastic moduli compared to fresh tissues (all P < 0.01). The observed ultimate tensile strength supports the theory of an increased collagen crosslinking of the embalmed tissues when compared to the fresh state. Thiel-embalmed muscles failed any tensile testing approach as a result of the muscles dissolving due to the embalming. Furthermore, collagen integrity seems altered in scanning electron microscopy by the Thiel embalming, limiting their use for ultrastructural failure analyses. Thiel-embalmed soft tissues may consequently not serve to reflect the biomechanical properties of the human head. Consequently, the application of Thiel embalming should be limited to preliminary tests for biomechanical purposes. Clin. Anat. 32:903-913, 2019. © 2019 Wiley Periodicals, Inc.

Hairline Lowering Surgery With Bone Tunneling Suture Fixation: Effectiveness and Safety in 91 Patients.

BACKGROUND: People with a wide forehead often look older. Hairline lowering surgery is a good treatment option, which is generally performed utilizing Endotine. OBJECTIVES: We describe our hairline lowering surgical technique involving bone tunneling without Endotine, a method designed to produce comparable outcomes with fewer side effects. We evaluated the effectiveness and safety of our technique. METHODS: Charts of 91 patients who underwent hairline lowering surgery without Endotine were reviewed retrospectively. We utilized standardized preoperative and postoperative photographs to measure the proportions of 3 face parts and the length of the forehead. We also determined changes in forehead length at various times after surgery, occurrence of postoperative complications, and overall patient satisfaction with their surgical results. RESULTS: Of the 91 patients, 80 were female and the mean age was 28.67 ± 7.15 years. Preoperatively, the mean forehead length was 8.09 ± 0.69 cm and ratio of facial part lengths was 1.08:1:0.99 (cranial to caudal). The hairline was advanced 18.37 ± 2.90 mm. One month postoperatively, the mean forehead length was 6.57 ± 0.52 cm and facial parts ratio was 1:1:0.99. Compared with preoperatively, forehead length was significantly reduced at 1, 3, 6, and 12 months postoperatively. Forehead length was not significantly different at 1 and 12 months postoperatively. All patients were satisfied or very satisfied with their overall surgical results. CONCLUSIONS: Hairline lowering surgery with bone tunneling was effective and safe, and patients were satisfied with the results. The effects appeared immediately following surgery and were sustained over time.

An efficient method for eccrine gland isolation from human scalp.

We describe a simple and efficient method to isolate eccrine sweat glands from the human scalp. This method is inspired by the hair graft harvesting method used in hair transplantation. Based on the recently described anatomical relationship between the scalp hair follicle and the eccrine gland, we have found that scalp follicular unit grafts are an excellent eccrine gland isolation source, especially for the coiled component. In order to make the gland visible for stereoscopic microdissection, the follicular units need to be previously stained with a vital dye like methylene blue or neutral red. The simplicity and efficiency of this isolation method should encourage further research into human eccrine sweat gland function which has always been hindered by the difficulty of gland isolation.

Eccrine sweat glands associate with the human hair follicle within a defined compartment of dermal white adipose tissue.

BACKGROUND: Eccrine sweat glands (ESGs) are critical for thermoregulation and are involved in wound healing. ESGs have traditionally been considered as separate skin appendages without connection to the pilosebaceous unit (PSU). However, recent preliminary evidence has encouraged the hypothesis that the PSU and ESG are more interconnected than previously thought. OBJECTIVES: To re-evaluate the morphology of human skin adnexa with an integrated three-dimensional (3D) perspective in order to explore the possible interconnections that the PSU and the ESG may form. METHODS: A systematic 3D reconstruction method of skin sections, direct visualization of human scalp follicular unit transplant grafts and a scalp strip ex vivo were used to validate and further explore the hypothesis. RESULTS: We demonstrate that the coiled portion of most ESGs is morphologically integrated into the PSU of human scalp skin and forms a structural unit that is embedded into a specific, hair follicle-associated region of dermal white adipose tissue (dWAT). This newly recognized unit is easily accessible and experimentally tractable by organ culture of follicular units and can be visualized intravitally. CONCLUSIONS: We propose a model of functional human skin anatomy in which ESGs are closely associated with the PSU and the dWAT to form a common homeostatic tissue environment, which may best be encapsulated in the term 'adnexal skin unit'. The challenge now is to dissect how each component of this superstructure of human skin functionally cooperates with and influences the other under physiological conditions, during regeneration and repair and in selected skin diseases.

Study on Hair Distribution in Healthy Males for Hair Restoration Design.

BACKGROUND: The incidence of hair loss among Chinese male has increased to 21.3 per hundred. Hair restoration has been an effective technique. Detailed hair distribution has a tremendous impact on the surgery design. OBJECTIVE: To investigate the pattern of hair distribution in Chinese young adult males. METHODS: A total of 1000 males without hair disease were enrolled. We evaluated the locations of the main anatomical marks at different sites on the scalp and analyzed the hair density and follicular unit structure using the standard photographs and trichoscope. RESULTS: The hairline shapes were classified as: linear (48.7%), linear with central protrusion (27.9%), round (9.8%), round with central protrusion (13.7%). The average height of the median line was 6.78 ±â€Š0.75 cm, the ratio of the median line and the forehead height was 0.333. The average distance from the parietal whorl to the vertical bimeatal line was 7.05 ±â€Š3.32 cm, and most of the PWs were on the right (51.4%) and had a clockwise pattern (73.3%). The hair density was 171.12 ±â€Š18.32 hairs/cm in the vertex. 1-hair follicular units were (75.90% and 56.39%) in anterior hairline and temporal area. CONCLUSION: Our study clearly assisted understanding of scalp anatomy and hair distribution in Chinese young adult males.

Hairline Restoration: Difference in Men and Woman-Length and Shape.

Hair restoration has become increasingly popular in recent years with both men and women. New technologies such as follicular unit extraction and grafting have made it possible for patients to get a natural looking result with minimal downtime. Men usually experience hairline recession as a result of androgenic alopecia, while women most commonly experience thinning of the crown and vertex, with the preservation of the hairline. However, there is a growing population of women who wish to advance their hairline forward because of congenital high hairline, traction alopecia, or previous facial cosmetic surgery. There are several key differences between the female and male hairline. Understanding such differences and following certain guidelines will help the facial plastic surgeon to obtain beautiful and natural appearing results.

Study of frontal hairline patterns for natural design and restoration.

OBJECTIVE: Hair loss is one of the most noticeable esthetic problems of the mankind. Hair transplantation has been a highly effective technique in reducing wide foreheads and recontouring the hairline. Creating a natural hairline is one of the most important elements of a successful hair transplant. This study aims at the requirements which are essential in designing hairline morphometrics and natural frontline. METHODS: Standard photographs of the forehead region were obtained from two hundred young Turkish adults participated in this study. The hairline contour was classified into five groups as round, M-shaped, rectangular, bell-shaped and triangular. Measurements of the forehead region, such as the height of the forehead, widths of the forehead and supraorbital region were calculated as reference points. RESULTS: In women, the average height of the forehead was 58.3 ± 6.6 mm, the average width of the forehead and the supraorbital region was 129 ± 14.4 mm and 125.3 ± 13.5 mm, respectively. The incidence of the hairline shapes was seen as; round (28%), M-shaped (19%), rectangular (30%), bell-shaped (5%), or triangular (18%). In men, the average height of the forehead was 61.4 ± 9.7 mm, the average width of the forehead and supraorbital region was 137.1 ± 18 mm and 133.9 ± 15.9 mm, respectively. The hairline contour among young male adults was classified as round in 27%, M-shaped in 46%, rectangular in 31%, bell-shaped in 4% and triangular in 2%. The rectangular and M-shaped hairlines resemble a more masculine appearance, whereas round shaped hairline resembles femininity. CONCLUSION: Ideal reconstruction of scalp defects relies on a comprehensive understanding of scalp anatomy and detailed information of patient factors. The classification of the hairline and measured forehead reference lengths will be beneficial in the correction of wide foreheads. There were significant gender differences in the esthetic rankings of the hairline contour. Compared to women, both of the measured average forehead reference lengths displayed a significantly greater value in men. Our results clearly showed that sex difference affected the predominance of the contour type. The M shape was the most common, and the triangular type was poorly classified in men, whereas the rectangular hairline was the most common type among women.

Is the eccrine gland an integral, functionally important component of the human scalp pilosebaceous unit?

The pilosebaceous unit (PSU) and the eccrine sweat gland (ESG) are classically described as completely independent skin appendages. However, careful inspection of scalp follicular units reveals that the secretory segment of the ESG spatially approximates the hair follicle in a position below the sebaceous gland and the insertion of the arrector pili muscle. Therefore, we propose here that, contrary to conventional wisdom, the PSU and the ESG should not be viewed in isolation, and may form instead, along with the arrector pili muscle and the apocrine gland (where present),one functional unit. For this, we suggest the more inclusive term of 'Hair Cluster' (HC). If confirmed, e.g. by 3D imaging techniques, the novel concept of a functional HC, whose individual components may communicate via secreted molecules and may share selected progenitor cell populations for HC repair/regeneration, has major physiological and pathological implications, which are briefly discussed.

Algorithmic Approach to Overcome Scalp Deficiency in the Setting of Secondary Cranial Reconstruction.

BACKGROUND: Multidisciplinary approaches have shown improved outcomes in secondary cranial reconstruction, however, scalp deficiency remains a common obstacle for tension-free scalp closure during cranioplasty. Therefore, our objective was to create an algorithmic approach using a novel concept of "component separation" to help minimize potential complications. METHODS: The authors tested the hypothesis of achieving greater scalp mobility by way of "component separation" in a half-scalp, bilateral cadaver study, and describe within 2 clinical examples. Pterional-sized (N = 2) and hemicraniectomy-sized (N = 2) scalp flaps were dissected on 2 cadaveric heads using an internal control for each scenario. All flaps (N = 4) were created with (experimental group) and without (control group) "retaining ligament release." Total amounts of scalp mobility were measured bilaterally and compared accordingly. RESULTS: Scalp flap mobility was calculated from the sagittal midline using identical arcs of rotation. With zero tension, we observed an increased distance of movement equaling 1 cm for the "experimental" pterional flap, compared with the contralateral "control." Similarly, we found an increase of additional 2 cm in scalp mobility for the "experimental" hemicraniectomy-sized flap. CONCLUSIONS: Tension free scalp closure is most critical for achieving improved outcomes in secondary cranial reconstruction. In this study, we show that a range of 1 to 2 additional centimeters may be gained through a component separation, which is of critical value during scalp closure following cranioplasty. Therefore, based on our high volume cranioplasty experience and cadaver study presented, we offer some new insight on methods to overcome scalp deficiency accompanying secondary cranial reconstruction.

Gradient rotating outer volume excitation (GROOVE): A novel method for single-shot two-dimensional outer volume suppression.

PURPOSE: To introduce a new outer volume suppression (OVS) technique that uses a single pulse and rotating gradients to accomplish frequency-swept excitation. This new technique, which is called gradient rotating outer volume excitation (GROOVE), produces a circular or elliptical suppression band rather than suppressing the entire outer volume. METHODS: Theoretical and k-space descriptions of GROOVE are provided. The properties of GROOVE were investigated with simulations, phantom, and human experiments performed using a 4T horizontal bore magnet equipped with a TEM coil. RESULTS: Similar suppression performance was obtained in phantom and human brain using GROOVE with circular and elliptical shapes. Simulations indicate that GROOVE requires less SAR and time than traditional OVS schemes, but traditional schemes provide a sharper transition zone and less residual signal. CONCLUSION: GROOVE represents a new way of performing OVS in which spins are excited temporally in space on a trajectory that can be tailored to fit the shape of the suppression region. In addition, GROOVE is capable of suppressing tailored regions of space with more flexibility and in a shorter period of time than conventional methods. GROOVE provides a fast, low SAR alternative to conventional OVS methods in some applications (e.g., scalp suppression).

N400-like responses to three-chord harmonic sequences with unexpected out of key endings: scalp topography, cortical sources, and perspectives for a clinical use.

A series of ERP components, each provided with both a precise timing with respect to stimulation and a specific cortical localization, reflects the temporal succession of processing stages of music information. This makes the musical stimulus potentially usable to probe residual brain functions in non-communicating patients with disorders of consciousness. In an attempt to find a simple stimulation protocol that was suitable for use in a clinical setting, the purpose of this study was to verify whether a minimum-length musical stimulus, provided with a definite music-syntactic connotation, was still able to elicit musical ERPs in a group of eight healthy subjects. The stimulus was composed of the minimum number of chords necessary and sufficient to enable the subject to predict a plausible closure of the sequence (priming) and, at the same time, to provide him/her with the closing chord of the sequence (target), either congruous (probable closing) or not (improbable closing) to the tonal context. The subject's task was to discriminate and recognize the irregular targets. The components that were expected to be elicited, in this experimental situation, were ERAN, N5, P600/LPC. Conversely, in addition to these former components, we unexpectedly observed a N400-like component. To determine whether this component was a real N400, we submitted our data to a sLORETA analysis in order to identify its cortical generators. Irregular chords showed higher current densities with respect to regular ones on the right-sided medial and superior temporal gyri, superior and inferior parietal lobules, fusiform and parahippocampal gyri, and on the bilateral posterior cingulate cortex. In particular, the N400-like wave seems to share with the word-primed music-elicited N400 certain generators that are located in cortical areas BA 21/37 and BA 22. This suggests that even chord-primed chord targets can convey extra-musical meanings and that, consequently, they might be useful in assessing residual higher-order information-processing capabilities in non-communicating patients with disorders of consciousness.

Anatomical correlations of the international 10-20 sensor placement system in infants.

Developmental research, as well as paediatric clinical activity crucially depends on non-invasive and painless brain recording techniques, such as electroencephalography (EEG), and near infrared spectroscopy (NIRS). However, both of these techniques measure cortical activity from the scalp without precise knowledge of the recorded cerebral structures. An accurate and reliable mapping between external anatomical landmarks and internal cerebral structures is therefore fundamental to localise brain sources in a non-invasive way. Here, using MRI, we examined the relations between the 10-20 sensor placement system and cerebral structures in 16 infants (3-17 weeks post-term). We provided an infant template parcelled in 94 regions on which we reported the variability of sensors locations, concurrently with the anatomical variability of six main cortical sulci (superior and inferior frontal sulcus, central sulcus, sylvian fissure, superior temporal sulcus, and intraparietal sulcus) and of the distances between the sensors and important cortical landmarks across these infants. The main difference between infants and adults was observed for the channels O1-O2, T5-T6, which projected over lower structures than in adults. We did not find any asymmetry in the distances between the scalp and the brain envelope. However, because of the Yakovlean torque pushing dorsally and frontally the right sylvian fissure, P3-P4 were not at the same distance from the posterior end of this structure. This study should help to refine hypotheses on functional cognitive development by providing an accurate description of the localization of standardised channels relative to infants' brain structures. Template and atlas are publicly available on our Web site (http://www.unicog.org/pm/pmwiki.php/Site/InfantTemplate).

Scalp and skull influence on near infrared photon propagation in the Colin27 brain template.

Near-infrared neuromonitoring (NIN) is based on near-infrared spectroscopy (NIRS) measurements performed through the intact scalp and skull. Despite the important effects of overlying tissue layers on the measurement of brain hemodynamics, the influence of scalp and skull on NIN sensitivity are not well characterized. Using 3555 Monte Carlo simulations, we estimated the sensitivity of individual continuous-wave NIRS measurements to brain activity over the entire adult human head by introducing a small absorption perturbation to brain gray matter and quantifying the influence of scalp and skull thickness on this sensitivity. After segmenting the Colin27 template into five tissue types (scalp, skull, cerebrospinal fluid, gray matter and white matter), the average scalp thickness was 6.9 ± 3.6 mm (range: 3.6-11.2mm), while the average skull thickness was 6.0 ± 1.9 mm (range: 2.5-10.5mm). Mean NIN sensitivity - defined as the partial path length through gray matter divided by the total photon path length - ranged from 0.06 (i.e., 6% of total path length) at a 20mm source-detector separation, to over 0.19 at 50mm separations. NIN sensitivity varied substantially around the head, with occipital pole exhibiting the highest NIRS sensitivity to gray matter, whereas inferior frontal regions had the lowest sensitivity. Increased scalp and skull thickness were strongly associated with decreased sensitivity to brain tissue. Scalp thickness always exhibited a slightly larger effect on sensitivity than skull thickness, but the effect of both varied with SD separation. We quantitatively characterize sensitivity around the head as well as the effects of scalp and skull, which can be used to interpret NIN brain activation studies as well as guide the design, development and optimization of NIRS devices and sensors.

Spatial registration for functional near-infrared spectroscopy: from channel position on the scalp to cortical location in individual and group analyses.

Functional near-infrared spectroscopy (fNIRS) has now become widely accepted as a common functional imaging modality. In order for fNIRS to achieve genuine neuroimaging citizenship, it would ideally be equipped with functional and structural image analyses. However, fNIRS measures cortical activities from the head surface without anatomical information of the object being measured. In this review article, we will present a methodological overview of spatial registration of fNIRS data to overcome this technical drawback of fNIRS. We first introduce and explore the use of standard stereotaxic space and anatomical labeling. Second, we explain different ways of describing scalp landmarks using 10-20 based systems. Third, we describe the simplest case of fNIRS data co-registration to a subject's own MRI. Fourth, we extend the concept to fNIRS data registration of group data. Fifth, we describe probabilistic registration methods, which use a reference-MRI database instead of a subject's own MRIs, and thus enable MRI-free registration for standalone fNIRS data. Sixth, we further extend the concept of probabilistic registration to three-dimensional image reconstruction in diffuse optical tomography. Seventh, we describe a 3D-digitizer-free method for the virtual registration of fNIRS data. Eighth, we provide practical guidance on how these techniques are implemented in software. Finally, we provide information on current resources and limitations for spatial registration of child and infant data. Through these technical descriptions, we stress the importance of presenting fNIRS data on a common platform to facilitate both intra- and inter-modal data sharing among the neuroimaging community.

Intraoperative continuous monitoring of facial motor evoked potentials in acoustic neuroma surgery.

The preservation of facial nerve function is one of the primary objectives in acoustic neuroma surgery. We detail our method of continuous intraoperative facial motor evoked potential (MEP) monitoring and present criteria for the preservation of facial nerve function to avoid postoperative facial nerve palsy. Our study population was comprised of 15 patients who did not (group 1), and 20 who did (group 2) undergo facial MEP monitoring during surgery to remove acoustic neuromas. In group 2, we continuously stimulated the facial motor cortex at 5- or 10-s intervals throughout surgery. Electromyograms (EMGs) were recorded from the contralateral orbicularis oculi- and orbicularis oris muscles. Optimal anode and cathode placement was at the facial motor cortex and the vertex, respectively. Postoperative facial palsy occurred in 8 of the 15 group 1 patients; in 2 it improved to grade II at 6 months after the operation. Of the 20 group 2 patients, 7 suffered postoperative facial palsy. At 6 months after the operation, their facial nerve function was normal. At the end of the operation, the ratio of the amplitude of the supramaximal EMG to the amplitude at the dural opening was 39.6 % in patients with- and 94.3 % in patients without transient postoperative facial palsy. Continuous facial MEP monitoring not only alerts to surgical invasion of the facial nerves but also helps to predict postoperative facial nerve function. To preserve a minimum amplitude ratio of 50 %, even transient postoperative facial palsy must be avoided. MEP monitoring is an additional useful modality for facial nerve monitoring during acoustic neuroma surgery.

New system for tracking a device for diagnosing scalp skin.

In scalp skin examinations, it is difficult to find a previously treated region on a patient's scalp through images captured by a camera attached to a diagnostic device because the zoom lens on camera has a small field of view. Thus, doctors manually record the region on a chart or manually mark the region. However, this process is slow and inconveniences the patient. Thus, we propose a new system for tracking the diagnostic device for the scalp skin of patients. Our research is novel in four ways. First, our proposed system consists of two cameras to capture the face and the diagnostic device. Second, the user can easily set the position of camera to capture the diagnostic device by manually moving a frame to which the camera is attached. Third, the position of patient's nostrils and corners of the eyes are detected to align the position of his/her head more accurately with the recorded position from previous sessions. Fourth, the position of the diagnostic device is continuously tracked during the examination through images that help detect the position of the color marker attached to the device. Experimental results show that our system has a higher performance than conventional method.

Hair in newborns and infants: clinical and dermoscopic evaluation of 45 cases.

BACKGROUND: The literature still lacks comprehensive assessments on the features of neonatal hair and scalp characteristics. OBJECTIVES: To evaluate the clinical and dermoscopic features of scalp hair in newborns, including measurement of hair density, length and diameter. METHODS: Forty-five newborns were recruited for the study. For each patient, data regarding sex, age at consultation, delivery method, gestational age and maternal age at delivery were collected. A clinical score of hair density was created by investigators in order to divide the neonates into two groups: group 1 included neonates with poor and slightly poor hair density and group 2 included neonates with quite good and good hair density. Each patient underwent scalp videodermatoscopy. RESULTS: Based on their clinical score, 15 newborns had good hair density, while 30 had poor hair density. Among the parameters evaluated by the investigators, only weight at birth significantly correlated with neonatal hair density. Two neonates presented a frontal-temporal pattern of hair loss. Videodermatoscopy revealed that nine neonates, all in the poor hair density group, had a particular hair shaft dermoscopic feature, characterized by the presence of widespread thin hair. CONCLUSION: On the basis of the results obtained from our study, we propose a new classification of transient neonatal hair loss. We have found two different hair types: 'neonatal type', rarely observed, that appears in the first 4 weeks of life with a frontal-temporal pattern; and 'classic type', more frequently observed, appearing at 8-12 weeks of life with a predominant occipital pattern.