Lukas Reissig

High-resolution episcopic microscopy (HREM): a tool for visualizing skin biopsies.

We evaluate the usefulness of digital volume data produced with the high-resolution episcopic microscopy (HREM) method for visualizing the three-dimensional (3D) arrangement of components of human skin, and present protocols designed for processing skin biopsies for HREM data generation. A total of 328 biopsies collected from normally appearing skin and from a melanocytic nevus were processed. Cuboidal data volumes with side lengths of ~2×3×6 mm3 and voxel sizes of 1.07×1.07×1.5 µm3 were produced. HREM data fit ideally for visualizing the epidermis at large, and for producing highly detailed volume and surface-rendered 3D representations of the dermal and hypodermal components at a structural level. The architecture of the collagen fiber bundles and the spatial distribution of nevus cells can be easily visualized with volume-rendering algorithms. We conclude that HREM has great potential to serve as a routine tool for researching and diagnosing skin pathologies.

The surgical anatomy of the supraclavicular lymph node flap: A basis for the free vascularized lymph node transfer

Vascularized lymph node transfer is an effective surgical method in reducing lymphedema. This study provides the first detailed description of the surgical anatomy of the supraclavicular lymph node flap in regard to pedicle length, pedicle diameter, and the number of lymph nodes and their exact location inside the flap.

Highly variable penetrance of abnormal phenotypes in embryonic lethal knockout mice.

Background: Identifying genes that are essential for mouse embryonic development and survival through term is a powerful and unbiased way to discover possible genetic determinants of human developmental disorders. Characterising the changes in mouse embryos that result from ablation of lethal genes is a necessary first step towards uncovering their role in normal embryonic development and establishing any correlates amongst human congenital abnormalities. Methods: Here we present results gathered to date in the Deciphering the Mechanisms of Developmental Disorders (DMDD) programme, cataloguing the morphological defects identified from comprehensive imaging of 220 homozygous mutant and 114 wild type embryos from 42 lethal and subviable lines, analysed at E14.5. Results: Virtually all mutant embryos show multiple abnormal phenotypes and amongst the 42 lines these affect most organ systems. Within each mutant line, the phenotypes of individual embryos form distinct but overlapping sets. Subcutaneous edema, malformations of the heart or great vessels, abnormalities in forebrain morphology and the musculature of the eyes are all prevalent phenotypes, as is loss or abnormal size of the hypoglossal nerve. Conclusions: Overall, the most striking finding is that no matter how profound the malformation, each phenotype shows highly variable penetrance within a mutant line. These findings have challenging implications for efforts to identify human disease correlates.

Longitudinal Gliding of the Median Nerve in the Carpal Tunnel: Ultrasound Cadaveric Evaluation of Conventional and Novel Concepts of Nerve Mobilization

OBJECTIVE To evaluate median nerve excursion during conventional nerve gliding exercises and newly developed exercises, primarily comprising abduction and adduction of the fingers. DESIGN Descriptive study. SETTING Anatomical dissection facility. CADAVERS Random sample of upper extremities of fresh whole-body human cadavers (N=18). Cadavers with neuromuscular diseases in the medical record or anatomic variations were excluded. INTERVENTION Conventional and new nerve gliding exercises. MAIN OUTCOME MEASURES Distances between markers applied into the nerve and markers in the periosteum were visualized with ultrasound and measured. Comparisons of nerve excursions between different exercises were performed. RESULTS Conventional exercises led to substantial nerve gliding proximal to the carpal tunnel and between the head of the pronator teres (12 and 13.8mm, respectively), but it led to far less in the carpal tunnel (6.6mm). With our novel exercises, we achieved nerve gliding in the carpal tunnel of 13.8mm. No substantial marker movement could be detected during lateral flexion of the cervical spine. CONCLUSIONS Although conventional nerve gliding exercises only lead to minimal nerve excursions in the carpal tunnel, our novel exercises with the abduction and adduction of the fingers result in substantial longitudinal gliding throughout the arm. Clinical trials will have to deliver the clinical evidence.

Surgical anatomy of the vascularized submental lymph node flap: Anatomic study of correlation of submental artery perforators and quantity of submental lymph node.

Harvesting the submental flap for vascularized lymph node transfer (VLNT) presents a challenging procedure because of, the topographic variation of the submental artery (SA) and the marginal mandible nerve (MMN) and the limited pedicle length for a free tissue transfer. The aim of this study was to evaluate surgical anatomical landmarks and variations of the submental lymph node flap (SLNF).

A staging system for correct phenotype interpretation of mouse embryos harvested on embryonic day 14 (E14.5)

We present a simple and quick system for accurately scoring the developmental progress of mouse embryos harvested on embryonic day 14 (E14.5). Based solely on the external appearance of the maturing forelimb, we provide a convenient way to distinguish six developmental sub‐stages. Using a variety of objective morphometric data obtained from the commonly used C57BL/6N mouse strain, we show that these stages correlate precisely with the growth of the entire embryo and its organs. Applying the new staging system to phenotype analyses of E14.5 embryos of 58 embryonic lethal null mutant lines from the DMDD research programme (https://dmdd.org.uk) and its pilot, we show that homozygous mutant embryos are frequently delayed in development. To demonstrate the importance of our staging system for correct phenotype interpretation, we describe stage‐specific changes of the palate, heart and gut, and provide examples in which correct diagnosis of malformations relies on correct staging.

High-resolution Episcopic Microscopy (HREM) - Simple and Robust Protocols for Processing and Visualizing Organic Materials

We provide simple protocols for generating digital volume data with the high-resolution episcopic microscopy (HREM) method. HREM is capable of imaging organic materials with volumes up to 5 x 5 x 7 mm3 in typical numeric resolutions between 1 x 1 x 1 and 5 x 5 x 5 µm3. Specimens are embedded in methacrylate resin and sectioned on a microtome. After each section an image of the block surface is captured with a digital video camera that sits on the phototube connected to the compound microscope head. The optical axis passes through a green fluorescent protein (GFP) filter cube and is aligned with a position, at which the bock holder arm comes to rest after each section. In this way, a series of inherently aligned digital images, displaying subsequent block surfaces are produced. Loading such an image series in three-dimensional (3D) visualization software facilitates the immediate conversion to digital volume data, which permit virtual sectioning in various orthogonal and oblique planes and the creation of volume and surface rendered computer models. We present three simple, tissue specific protocols for processing various groups of organic specimens, including mouse, chick, quail, frog and zebra fish embryos, human biopsy material, uncoated paper and skin replacement material.

The surgical anatomy of the vascularized lateral thoracic artery lymph node flap—A cadaver study

One promising surgical treatment of lymphedema is the VLNT. Lymph nodes can be harvested from different locations; inguinal, axillary, and supraclavicular ones are used most often. The aim of our study was to assess the surgical anatomy of the lateral thoracic artery lymph node flap.

The Spinal Accessory Nerve for Functional Muscle Innervation in Facial Reanimation Surgery: An Anatomical and Histomorphometric Study.

IntroductionFacial reanimation surgery is performed in severe cases of facial palsy to restore facial function. In a 1-stage procedure, the spinal accessory nerve can be used as a donor nerve to power a free gracilis muscle transplant for the reanimation of the mouth. The aim of this study was to describe the surgical anatomy of the spinal accessory nerve, provide a guide for reliable donor nerve dissection, and analyze the available donor axon counts. MethodsDissections were performed on 10 nonembalmed cadavers (measurements of 20 nerves). Surgical anatomy of the spinal accessory nerve was described and distances to important landmarks were measured. Nerve biopsies were obtained of the main nerve trunk distal to the skull base, caudoposterior to the sternocleidomastoid muscle, proximal to the trapezius muscle and at the level of donor nerve harvest to analyze the myelinated axon count throughout the course of the spinal accessory nerve. The donor nerve length and available donor nerve axon count were the primary outcome parameters in this study. ResultsThe mean donor nerve length was 11.6 cm. The spinal accessory nerve was transferred to the mandibular angle without tension for ideal coaptation to the free muscle transplant. After retraction of the trapezius muscle, a small distal nerve branch that leaves the main nerve trunk at a 90-degree angle medially was used as a landmark to indicate the level of donor nerve transection. On average, 1400 myelinated donor axons were available for innervation of the gracilis muscle transplant. ConclusionsThis study gives a practical guide for spinal accessory nerve dissection for its application in facial reanimation as a motor source for the innervation of a free muscle transplant.

Ultrasound of the Hypoglossal Nerve in the Neck: Visualization and Initial Clinical Experience with Patients.

BACKGROUND AND PURPOSE: The hypoglossal nerve, providing motor innervation for the tongue, can be affected in many diseases of the neck and skull base, leading to dysarthria, dysphagia, and ultimately atrophy of the tongue. We determined the feasibility of direct visualization of the hypoglossal nerve in the neck with ultrasound, testing this technique on healthy volunteers and evaluating it in clinical practice. MATERIALS AND METHODS: The study consisted of 4 parts: first, ultrasound-guided perineural ink injections along the course of the hypoglossal nerve at 24 sides of 12 fresh, nonembalmed cadaver necks. Subsequently, the specimens were dissected to confirm the correct identification of the nerve. The second part was examination of healthy volunteers with ultrasound and measurement of cross-sectional areas for generating reference data. The third part was scanning of healthy volunteers by 2 resident physicians with little and intermediate experience in ultrasound. Fourth was examination with ultrasound of patients with motor symptoms of the tongue. RESULTS: The hypoglossal nerve was correctly identified bilaterally in all cadaveric specimens (24/24) and all volunteers (33/33). The cross-sectional area ranged from 1.9 to 2.1 mm2. The resident physicians were able to locate the nerve in 19 of 22 cases, demonstrating that locating the nerve is reproducible and feasible even with intermediate experience in ultrasound. Finally, alterations of the hypoglossal nerve in disease states could be depicted. CONCLUSIONS: Direct, reliable, and reproducible visualization of the extracranial hypoglossal nerve with ultrasound is feasible.