Significant Anatomical Variations Research Articles

1046 URETHRAL ATROPHY DOES NOT OCCUR AFTER IMPLANTATION OF AN ARTIFICIAL URINARY SPHINCTER

INTRODUCTION AND OBJECTIVES: Sacral Neuro Stimulation (SNS) is an FDA approved treatment for urgency/frequency, urge incontinence, urinary retention, and fecal incontinence. Successful outcome is predicated on accurate location of the lead based on anatomy and physiologic response. Adjacent foramina S2, S3, and S4 may have sufficient locational overlap to cause unintended clinical localization of the wrong foramina. Detailed anatomic imaging and analysis may provide relevant information regarding lead placement effecting patient response. METHODS: DICOM images from a de-identified, IRB-approved database of 1mm slice pelvic CT images were rendered into 3D models using Mimics (Materialise) software. Images with bony deformity were excluded. Points of interest, tagged throughout each pelvis, were used to measure angles and distances of interest on the rendered 3D volumetric models. Both male and female pelvic CT images were included. The medial-lateral distance from the medial edge of the S2-S4 foramina to the sacral spinous processes were measured, along with the caudad-cephalad distances from the cephalad edge of S2-S4 foramina to the dorsal aspect of the sacro-iliac (SI) joints. The position of S2, S3, and S4 relative to the sacral spinous processes and inferior SI joints were determined, with sub-populations (clusters) of S2, S3, and S4 foramina identified. Statistical analysis was performed using SPSS 18.0 (IBM, Somers, NY). RESULTS: Of the 150 pelvises enrolled, 133 met criteria for inclusion. The greatest adjacent population overlap occurs bilaterally between the most caudad cluster of S2 and the most cephalad cluster of S3, regarding which up to 9% (12/133) of the left and up to 14% (18/133) of the right S2 foramina may be errantly localized during a clinical attempt to locate S3. Overlap between the most caudad S3 cluster with the two most cephalad S4 clusters represents insignificant clinic impact ( 4%). 20% of the total population had a fifth left sacral foramen, and 22% had a fifth right sacral foramen. CONCLUSIONS: Significant anatomic variation exists in regard to foramen location. Reliance on anatomic landmarks alone or unreliable physiologic responses may hinder accurate lead placement. Further investigation, such as cadaveric or clinical trial, is necessary to obtain more conclusive data regarding the true clinical incidence of errant foramen localization.

Does Anatomy of the Pubic Arch Interfere with the Maintaining of Erection?

There are men who suffer from unsustainable erections without any identified cause of erectile dysfunction, raising the question if anatomical alterations could be involved. Since early anatomical studies, it has been proposed that to achieve full penile rigidity, the blood must be blocked inside the penis by compression of the deep dorsal vein (DDV), the main venous collector under pubic symphysis. Using a recently developed caverno computed tomography (CT) scan technique, allowing the evaluation of the venous drainage of the corpora cavernosa (CC) during erection, we have studied some anatomical conditions of this important part of the erectile phenomenon. Puboischial rami angles were measured in axial CT images and calculated strictly on the upper insertion point of the CC, using axial submillimeter slices in 37 patients divided into 3 groups depending on the results of the caverno CT scan: (i) no leak; (ii) superficial veins leaking; and (iii) drainage through the DDV and/or preprostatic plexus. In addition same angles were measured in two randomly unselected populations of men (N = 30), and women (N = 23) who underwent pelvic CT scan for various reasons, unrelated to their sexual or genital condition. The angles made by both puboischial rami were measured in patients with and without veno-occlusive dysfunction and in unselected samples of men and women. There is a significantly wider angle made by both puboischial rami in men without complete erection and without evidence of anomalous venous drainage (group 3) (72.2° ± 4.7° standard deviation [SD]), compared with both men with normal erection (group 1) (57.5 ± 5° SD) P < 0.00001, and men with incomplete erection and evidence of anomalous drainage (group 2) (57.7 ± 6° SD) P < 0.00001. If confirmed in larger samples, these results raise new questions on the mechanism and the role of these significant anatomical variations, yet unknown, in maintaining or not full rigid erections.

Patent ductus arteriosus closure using the amplatzer® vascular plug II for all anatomic variants

To evaluate the safety and efficacy of the Amplatzer® Vascular Plug II (AVPII) for closure of the patent ductus arteriosus (PDA). The PDA has significant anatomic variation. No device has proven applicable to all PDAs. Previous case reports and small series have documented limited use of the AVPII for some PDA types. We describe the largest and most diverse experience using the AVPII. A retrospective analysis of patients undergoing percutaneous PDA closure between 01/01/2009 and 05/01/2012 was performed. The PDA was characterized, measured, and the device chosen was listed. Deployment technique, complications and procedural results were recorded. Sixty-seven procedures were performed. The AVPII was utilized for 43 (64.2%), 15 (20.9%) had coils, 7 (10.4%) had the AGA duct occluder, and 3 (4.5%) were referred for surgery. The AVPII was placed in infants as young as 2 months and 4.2 kg. AVPII size ranged from 4 to 10 mm. All PDA types were closed. Retrograde and antegrade deployments were performed, using the outer disc as a "retention skirt" to secure the device and improve occlusion. Three patients were up-sized prior to release. All deployments were successful; 89% "in-lab" and 100% closure on postprocedural echocardiogram. There were no complications. We report the largest experience with the AVPII for PDA closure. The device was used in all morphologic types and small patients. It is low profile, easily repositioned, and had excellent results without complications. We contend that this is the most versatile device currently available.

Diagnosis and Treatment of Rudimentary Uterine Horn with Severe Dysmenorrhea and Acute Abdomen

A unicornuate uterus is a rare congenital anomaly of Müllerian duct, characterized by significant anatomic variation. Coexisting rudimentary horn is the common type of variation; such horn may not communicate with the unicornuate uterus and may have functional endometrium. In the study, we suggest the proper diagnostic modality and treatment of symptomatic unicornuate uterus.

Normal Tibiofibular Relationships at the Syndesmosis on Axial CT Imaging

Computed tomography (CT) is reported to be superior to plain radiography for imaging the syndesmosis, but CT criteria differentiating normal from abnormal tibiofibular relationships do not exist. The purpose of this study was to define normal tibiofibular relationships at the syndesmosis on axial CT imaging and to report the reliability of these measurements. Thirty healthy volunteers underwent CT evaluation of bilateral ankles. Axial CT measurements consisted of tibiofibular clear space, tibiofibular overlap, anterior tibiofibular interval, and fibular rotation (θ(fib)). To assess reliability, 3 investigators independently made each CT measurement on 2 separate occasions. Sixty ankles were included for analysis. CT measurements demonstrated excellent intrarater and interrater reliability. There was significant anatomic variability between individuals. Specifically, statistically significant gender differences were discovered in CT measurements of tibiofibular overlap and anterior tibiofibular interval. Variance between ankles of each subject was calculated. In an uninjured population, tibiofibular intervals do not vary by more than 2.3 mm, and the rotation of the fibula does not vary by more than 6.5° between ankles of the same person. Measurements of tibiofibular relationships made on axial CT images are reliable. Because of significant anatomic variation between individuals, using a patient's contralateral ankle for comparison provides a precise definition of normal tibiofibular relationships. These criteria allow for the detection of subtle variations in the tibiofibular relationships indicating instability and provide a tool for postoperatively assessing the reduction of the injured syndesmosis.

Location, number and morphology of parathyroid glands: results from a large anatomical series

Surgical management of parathyroid gland disease may sometimes be difficult, due mainly to the surgeon's failure to successfully detect parathyroids in unusual locations. The records of 942 cadavers (574 men and 368 women) who underwent autopsy in the Department of Forensic Medicine in Athens during the period 1988-2009 were reviewed. In total, 3,796 parathyroid glands were resected and histologically verified. Parathyroid glands varied in number. In 47 cases (5 %), one supernumerary (fifth) parathyroid was found, while in 19 cases (2 %) three parathyroid glands found. Superior glands were larger than inferior ones. However, there was no significant difference between the genders with respect to gland size. In 324 (8.5 %) out of 3,796, the glands were detected in an ectopic location: 7 (0.2 %) in the thyroid parenchyma, 79 (2 %) in different sites in the neck and 238 (6.3 %) in the mediastinum, 152 (4.1 %) of which were found in the upper and 86 (2.2 %) in the lower mediastinum. Significant anatomical variations of normal parathyroid glands may exist regarding number and location-knowledge that is essential for their successful identification and surgical management.

P.1.029 Multimodal neuroimaging with PET and MRI to investigate the relation between serotonergic neurotransmission and regional brain volumes

Population-based studies indicate that between 5 and 9 percent of US children exhibit significant deficits in mathematical reasoning, yet little is understood about the brain morphological features related to mathematical performances. In this work, deformation-based morphometry (DBM) analyses have been performed on magnetic resonance images of the brains of 79 third graders to investigate whether there is a correlation between brain morphological features and mathematical proficiency. Group comparison was also performed between Math Difficulties (MD-worst math performers) and Normal Controls (NC), where each subgroup consists of 20 age and gender matched subjects. DBM analysis is based on the analysis of the deformation fields generated by non-rigid registration algorithms, which warp the individual volumes to a common space. To evaluate the effect of registration algorithms on DBM results, five nonrigid registration algorithms have been used: (1) the Adaptive Bases Algorithm (ABA); (2) the Image Registration Toolkit (IRTK); (3) the FSL Nonlinear Image Registration Tool; (4) the Automatic Registration Tool (ART); and (5) the normalization algorithm available in SPM8. The deformation field magnitude (DFM) was used to measure the displacement at each voxel, and the Jacobian determinant (JAC) was used to quantify local volumetric changes. Results show there are no statistically significant volumetric differences between the NC and the MD groups using JAC. However, DBM analysis using DFM found statistically significant anatomical variations between the two groups around the left occipital-temporal cortex, left orbital-frontal cortex, and right insular cortex. Regions of agreement between at least two algorithms based on voxel-wise analysis were used to define Regions of Interest (ROIs) to perform an ROI-based correlation analysis on all 79 volumes. Correlations between average DFM values and standard mathematical scores over these regions were found to be significant. We also found that the choice of registration algorithm has an impact on DBM-based results, so we recommend using more than one algorithm when conducting DBM studies. To the best of our knowledge, this is the first study that uses DBM to investigate brain anatomical features related to mathematical performance in a relatively large population of children.

Colour Doppler Assessment of the Perforators of Anterolateral Thigh Flap and its Usefulness in Preoperative Planning

The role of the anterolateral thigh flap (ALTF) in reconstructive microsurgery grows systematically from mid-eighties of the twenty century until now. Significant anatomic variability of the perforators supplying the ALTF was described in literature. THE AIM OF THE STUDY was ultrasonographic assessment of the ALTF perforators in terms of localization, symmetry, diameter and flow velocity. The study was performed using ultrasound machine with 12 MHz linear transducer. Both thighs of 30 healthy volunteers (15 men and 15 women) aged from 18 to 60 (mean 37.9) were examined. The line from anterior superior iliac spine (ASIS) to lateral border of the patella was traced, and divided into 10 equal segments. Point where perforator pierces the deep fascia was marked and its diameter was measured and recorded. Maximal flow velocity was measured and recorded. Symmetry of perforator location was confirmed as positive if difference in position of two perforators on both thighs was less than 1.5 cm in diameter. Total number of 119 perforators supplying skin of 60 thighs was found (mean 1.98 perforator per thigh). No perforators were found in 4 thighs (6.6%). Perforators were most abundant in segments from 5 to 7 (74.6%). Perforators with largest diameters and maximal flow velocity reaching 30-47 cm/s were localized in segments 5 and 6. Perforators in segments 4 and 5 were more abundant in men (50.9%) than in women (36.7%). Septal perforators make up to 26.9% of the total. Eighty percent of the septal perforators were localized in segments 5 and 6. Perforator distribution was elicited in the middle of the ASIS--patella line. In the range of ±1.5 cm from the midpoint of the line 33.6% of the perforators were found. 1. Most of perforators with large diameter and big flow velocity are located in segments 5 and 6. 2. Perforators are more common in men in segments 4 and 5 than in women. 3. No perforators found in 4 thighs suggests that preoperative perforator mapping should become a preoperative routine, which can spare intraoperative dilemmas.

High resolution MR anatomy of the subthalamic nucleus: Imaging at 9.4T with histological validation

Using conventional MRI the subthalamic nucleus (STN) is not clearly defined. Our objective was to define the anatomy of the STN using 9.4 T MRI of post mortem tissue with histological validation. Spin-echo (SE) and 3D gradient-echo (GE) images were obtained at 9.4 T in 8 post mortem tissue blocks and compared directly with corresponding histological slides prepared with Luxol Fast Blue/Cresyl Violet (LFB/CV) in 4 cases and Perl stain in 3. The variability of the STN anatomy was studied using internal reference points. The anatomy of the STN and surrounding structures was demonstrated in all three anatomical planes using 9.4 T MR images in concordance with LFB/CV stained histological sections. Signal hypointensity was seen in 6/8 cases in the anterior and medial STN that corresponded with regions of more intense Perl staining. There was significant variability in the volume, shape and location of the borders of the STN. Using 9.4 T MRI, the internal signal characteristics and borders of the STN are clearly defined and significant anatomical variability is apparent. Direct visualisation of the STN is possible using high field MRI and this is particularly relevant, given its anatomical variability, for planning deep brain stimulation.

Diffusion tensor imaging tractography to visualize the relationship of the optic radiation to epileptogenic lesions prior to neurosurgery

SummaryPurpose: About one-third of patients with epilepsy are refractory to medical treatment and may be amenable to surgery. However, in patients with lesions on or near the presumed course of the optic radiation, the potential benefits of resection must be balanced against the risk of a visual field deficit. This study demonstrates the utility of diffusion tensor imaging (DTI) tractography in delineating the course of the optic radiation and its relationship to the epileptogenic lesion prior to epilepsy surgery.Methods: Anatomic and DTI scans were acquired on 10 patients with medically refractory epilepsy undergoing presurgical evaluation at the National Hospital for Neurology and Neurosurgery. Five patients underwent surgery and repeat scans postoperatively. The optic radiation was delineated and visualized in relation to the lesions on anatomic images and in three-dimensional (3D) reconstructions. Preoperative and postoperative visual fields were acquired by Goldmann perimetry.Key Findings: The entire optic radiation was reliably delineated bilaterally in all patients. The results provide helpful additional information in informing the patient of the risks of surgery and in planning the surgical procedure and approach. Postoperative imaging findings correlated with the visual field data.Significance: The optic radiation shows significant anatomic variability, but can be reliably delineated by tractography. Because surgical disruption of the optic radiation has serious consequences for the patient, DTI tractography is a useful technique in this population. Future integration with real-time neuronavigation will minimize the risks of neurosurgery.

03 Tractography to visualise the relationship of the optic radiation to epileptogenic lesions prior to neurosurgery

BackgroundA third of patients with epilepsy are refractory to medical treatment and may be amenable to surgery. A major concern is to avoid causing new deficits. As conventional MR imaging...

Radiographic study of the hip joint to determine anthropometric parameters for Indian population

Hip replacement surgeries are on the rise in India. However, for these surgeries, most of the implants used are imported and manufactured entirely to suit the geometrical considerations of the western population. Studies in the past have shown that there are anatomical variations in the hip joint for different ethnic backgrounds and geographical locations. There is paucity of anthropometric hip joint data related to Indian population and anthropometric variations in skeletal geometry between Asian and Western counterparts have not yet been thoroughly reviewed and considered for implant manufacturing. The purpose of this anthropometric study is to determine any anatomical variations in the normal hip joint among the Indian population and to statistically compare the mean values with the existing data on western population. 422 Hip radiographs of 211 individuals (141 males and 70 females) with normal and healthy hip joints were evaluated to obtain the horizontal offset, vertical offset and neck shaft angle. For males, mean neck shaft angle was 127.68° (SD = 3.94), horizontal offset was 34.60mm (SD=6.55) and vertical offset was 39.17 mm (SD = 5.86). For females, mean neck shaft angle was 125.92° (SD = 4.75), horizontal offset was 32.96 mm (SD = 7.04) and vertical offset was 36.38 mm (SD = 6.28). When these parameters were compared to the data available from western world, there were significant anatomical variations and it was evident that there is a need to evaluate existing implants in relation to this data and possibly design the implants suited and relevant to Indian population.

It Is Time to Abandon Atlanto-Axial Joint Injections: Do No Harm!

It Is Time to Abandon Atlanto-Axial Joint Injections: Do No Harm!

Characterisation of additional mental foramina through cone beam computed tomography

Variations in jaw bone neurovascularisation must be identified to decrease the potential risk for haemorrhages and neural disturbances during surgical procedures such as implant placement and orthognatic surgeries. The aim of this study is to characterise additional mental foramina (AMF) through cone beam computed tomography (CBCT) images, by describing their frequency, size, location and direction of their associated bony canals, as well as to assess their corresponding ipsilateral and contralateral mental foramina (MF). CBCT images from 285 patients were analysed. Prevalence of AMF was 9·4%. From 0 to 2 AMF were observed, with two bilateral cases. Two cases of unilateral absence of MF were registered. Patients presenting AMF did not differ significantly from those without AMF regarding gender, age or ethnicity. Diameters of AMF and their corresponding ipsilateral and contralateral MF were 1·9 mm (±0·7 mm), 3·8 mm (±0·6 mm) and 4·1 mm (±0·6 mm), respectively. Ratios between diameters of AMF and corresponding ipsilateral MF ranged between 0·24 and 0·99. Location of AMF was variable, with most cases located posteriorly, posterior-inferiorly, posterior-superiorly or anterior-superiorly to their respective MF. Significant anatomical variability regarding neurovascularisation was observed among patients and CBCT examinations presented as a valuable tool for individually assessing these anatomical features.

Diagnosis and laparoscopic management of a rudimentary uterine horn in a teenage girl, presenting with haematometra and severe endometriosis: Our experience and review of literature

SummaryA unicornuate uterus is a rare congenital malformation of the female genital tract, which appears in about 1/1000 women and is characterized by significant anatomic variability. In the most common type, a noncommunicating rudimentary horn coexists with the unicornuate uterus. The diagnosis of this anomaly is usually delayed, as it remains asymptomatic until adolescence and its initial symptoms are atypical. As a result, it is often diagnosed after the appearance of severe complications, such as haematometra, endometriosis, infertility and ectopic pregnancy. We report a case of a teenage girl presenting with dysmenorrhoea, endometriosis and haematometra secondary to a noncommunicating rudimentary horn. The diagnosis of the anomaly was based on magnetic resonance imaging (MRI) and laparoscopy. The excision of the symptomatic rudimentary horn and the ipsilateral fallopian tube was also performed laparoscopically. A review of the literature follows, focusing mainly on the diagnosis and laparoscopic management of a unicornuate uterus and its complications in adolescence. Laparoscopy is an accurate diagnostic tool, which also carries significant advantages in effective surgical management of congenital uterine anomalies, especially in young women.

Measurement of Skull Bone Thickness for Bone-Anchored Hearing Aids

A-mode ultrasound scanning with coded signals allows bone thickness measurements at the site of bone-anchored hearing aid surgery as compared to computed tomographic scanning and mechanical measurements. Adequate bone thickness is a prerequisite for successful, long-lasting osseointegration of titanium fixtures for bone-anchored hearing aids. Computed tomography can be used to measure bone thickness but has several drawbacks. Bone thickness was measured at the site of bone-anchored hearing aids surgery in 28 formaldehyde-preserved human cadaver temporoparietal bones. Four blinded investigators used a hand-held, A-mode ultrasound system with direct coupling at 2.25 MHz transducer using coded signals (SonoPointer) and repeated the measurements twice. Comparisons were made with high-resolution computed tomographic scanning and mechanical micrometer caliper measurements. There was significant anatomical variation in the temporoparietal bones. Computed tomography was in good agreement with the mechanical reference. All specimens could be measured by the SonoPointer. The mean difference between the mechanical control and ultrasound scanning averaged for all measurements by all investigators was 0.3 mm (standard deviation, 1.2 mm). Trained ultrasound experts yielded better results (mean difference, 0.3 mm; standard deviation, 1.0 mm). Agreement was best for bone thickness up to 5 mm. Outliers occurred in bones thicker than 7.5 mm. The SonoPointer is a promising, noninvasive, hand-held tool for real-time measurement of bone thickness in bone-anchored hearing aid surgery, especially for children. Even disregarding the absolute thickness reading, the SonoPointer could be used to search intraoperatively for a local maximum of bone thickness.

What is the role of intra-operative fluoroscopic measurements to determine tibial tunnel placement in anatomical anterior cruciate ligament reconstruction?

The hypothesis for this study was that intra-operative fluoroscopic measurements can be used to determine tibial tunnel placement during anatomic anterior cruciate ligament (ACL) reconstruction. The anteromedial (AM) and posterolateral (PL) bundle insertion sites were marked with a thermal device and measured in a consecutive cohort of 67 patients undergoing anatomical ACL reconstruction. For double bundle reconstruction, guide pins were passed in the center of the AM and PL tibial footprints. For single bundle (SB) reconstruction a guide wire was placed between the center of AM and PL footprints. Subsequently, the position of the centers of the AM and PL insertion sites were measured on standardized lateral intra-operative fluoroscopic images. The center for the AM bundle was found to be at 31% (range 20-42%) of the AP distance on the medial joint line and at 35% (range 23-42%) of the AP distance on the Amis and Jakob line. The center of the PL bundle was at 48% (range 37-59%) of the AP distance on the medial joint line and 48% (range 39-58%) of the AP distance on the Amis and Jakob line. The center of the tibial tunnel in the SB group (n = 15) was at 42 and 41% in relation to the medial joint line and the Amis and Jakob line, respectively. Because a significant anatomic variation exists between patients, the decision with respect to tunnel placement should not be merely based on intra-operative fluoroscopic images.

Complex Percutaneous Resections for Upper-Tract Urothelial Carcinoma

Percutaneous endoscopic resection is a viable treatment option for upper-tract urothelial carcinoma (UC) in selected patients. We present our experience with patients who underwent percutaneous resections for complex urothelial tumors. Patients who were undergoing percutaneous treatment for UC were identified within a prospectively maintained database at a single institution. Charts were reviewed to identify complex patients (n = 16) who met the following criteria: (a) tumor size >2.5 cm (n = 8), (b) preoperative creatinine level >3.0 mg/dL (n = 3), or (c) anatomic variant (cystectomy/urinary diversion [n = 2]; autotransplanted kidney [n = 1]; ipsilateral partial nephrectomy [n = 1]; distal ureterectomy [n = 1]). Demographic, operative, and oncologic data were captured. Recurrence-free, cancer-specific, and overall survivals were calculated and compared with a control group of noncomplex cases (n = 23). No difference was found in mean age (69.7 +/- 10.8 years vs 69.8 +/- 11.2 years), complication rate (6.3% vs 7.1%), or change in creatinine level (1.53 mg/dL to 1.51 mg/dL vs 1.88 mg/dL to 1.57 mg/dL) between noncomplex and complex cases. The incidences of high-grade tumors (55% vs 71%), invasive tumors (15% vs 20%), solitary kidney (82% vs 92%), contralateral nephroureterectomy (52% vs 60%), and history of bladder cancers (47% vs 38%) were similar between the two groups. Median follow-up was 36 months. No difference was seen in cancer-specific survival (P = 0.98) or recurrence-free survival (P = 0.39). An improved trend in overall survival (P = 0.20) was seen in the noncomplex patients when compared with the complex group. These findings suggest that patients with large tumors, poor renal function, and significant anatomic variations may be well served by endoscopic treatment for upper-tract UC when indicated.

Cricothyroidotomy: Comparison of three Different Techniques on a Porcine Airway

We compared three different cricothyroidotomy techniques on a cadaveric porcine airway model to determine the most rapid, successful and safe method in emergency situations. In this observational comparative bench-test, surgical or scalpel cricothyroidotomy (ST), Cook Melker Cricothyrotomy Kit (CM) and Portex Cricothyroidotomy Kit (PCK) were evaluated. After a familiarisation program, four operators performed five procedures using each of the techniques. A dissected pig airway was housed in an airway training manikin. Time to successful completion of the procedure, complications and anatomical variations in the pig larynx were recorded. A patent airway was established in 20 of 20 (100%) attempts with CM technique, 11 of 20 (55%) with ST and six of 20 (30%) with PCK technique. The CM technique was associated with a higher success rate (P <0.001). There was no significant difference (P=0.4) in the median time (interquartile range) taken to achieve a patent airway; CM 50 seconds (40 to 57), ST 47 seconds (41 to 55) and PCK 63 seconds (41 to 150). There was a higher rate of posterior tracheal wall injury with the PCK technique (n=11) and ST technique (n=5). No complications were observed with CM technique. There were no significant anatomical variations in the pig larynxes. We conclude that the CM technique is safe, rapid and has a significantly higher success rate in achieving an artificial airway in this airway model. Overall, all the participants in our study preferred to use this kit in an emergency situation.

The relationship between transepidermal water loss and skin permeability

Transepidermal water loss (TEWL) is a measure of the steady-state water vapour flux crossing the skin to the external environment and it has been used extensively to characterise skin barrier function. We have previously hypothesised that in vivo TEWL is directly related to the reciprocal of the diffusional permeation pathlength through the stratum corneum (SC). The aim of the present paper is to validate experimentally this hypothesis. Ninety volunteers were recruited and TEWL and corneocyte surface areas were measured for six anatomic sites. The number of cell layers in the SC was calculated for each anatomic site in order to estimate the geometric pathlength for water efflux. Significant anatomic site variability was found for both TEWL and corneocyte surface area which were inversely correlated. A direct reciprocal relationship between TEWL and pathlength was determined, with TEWL values tending to zero when corneocytes are infinitely large. In general, skin sites with smaller corneocytes have fewer cell layers, with shorter permeation pathlengths and higher TEWL values. The results confirm our previous hypothesis and suggest that TEWL may be used to characterise the permeation routes for different anatomic sites.