Marko Schulze

Variation in the hypothenar muscles and its impact on ulnar tunnel syndrome

Compression of the ulnar nerve at Guyon’s canal can be caused not only by tumor-like structures, a fibrotic arch, a ganglion, lipoma, aneurysm or thrombosis but also by anomalous hypothenar muscles which are reviewed here. For the search of relevant papers, PubMed and crucial anatomical textbooks were consulted. The abductor digiti minimi is the most variable hypothenar muscle. It can possess one to three muscle bellies. Additional heads can arise from the flexor retinaculum, the palmaris longus tendon, the pronator quadratus tendon or the deep fascia of the palmar side of the forearm. Our own case of an aberrant abductor digiti minimi appearing like connective tissue and originating in the antebrachial fascia is included here. Hematoxylin and eosin staining revealed that macroscopically non-muscle-like tissue contained skeletal muscle tissue. The muscle itself resembled other described cases. In addition, at the flexor digiti minimi accessory heads with origin from the flexor retinaculum, the antebrachial fascia or the long flexor muscles of the forearm can be detected. By contrast, the opponens digiti minimi mostly lacks variations and is sometimes missing. In our opinion, this is due to its hidden location. However, in few cases an additional head can arise from the lower arm aponeurosis. Furthermore, additional (fourth) hypothenar muscles might be expressed. These muscles are characterized by origins in the forearm and insertions on the head of the 5th metacarpal bone or on the 5th proximal phalanx. It must be noted that accessory hypothenar muscles might look like connective tissue at first glance. Often their origin extends to the antebrachial fascia. This can be explained by the phylogenetic fact that all intrinsic muscles of the hand are derived from muscle masses that originated in the forearm. In the opinion of several authors, ulnar nerve compression mostly is evoked by hyper trophied variant hypothenar muscles due to overuse as for example in carpenters. In some rare cases, an aberrant hypothenar muscle can also evoke median nerve compression.

[Ultrasound-guided intermediate cervical plexus block. Anatomical study].

BACKGROUND AND OBJECTIVES The innervation of the human cervical region is complex and subject to relevant anatomical variability involving sections of the cervical plexus, brachial plexus and cranial nerves. AIM The objective was to demonstrate the dissemination of injected dye solution by anatomical preparation and to define a suitable target compartment for an ultrasound-guided block technique. MATERIAL AND METHODS Own anatomical preparations are compared to recent review articles on the subject. The focus is on clinically relevant conclusions for performing cervical plexus blocks. In three non-embalmed cadavers six intermediate ultrasound-guided blocks of the cervical plexus were carried out, each with 20 ml methylene blue. Following preparation of the cervical plexus photographic documentation of the spread of the injected marker was performed. RESULTS In five cases the target compartment was correctly identified. In these cases, a cranio-caudal spread of the injectate within the double layer of the cervical fascia was observed. In addition, the superficial layer was permeable to the injected methylene blue. The injection solution disseminated with the sensitive terminal branches of the cervical plexus below the platysma. In all cases an anastomosis (superficial cervical ansa) between the facial nerve (ramus colli) and the cervical plexus (transverse cervical nerve) could be demonstrated. The prevertebral lamina proved to be impermeable to injected methylene blue and no evidence of a porous structure of the prevertebral lamina was found. CONCLUSION The compartment between the superficial and the prevertebral layer of the cervical fascia is a suitable target for cervical plexus blocks. This injection site describes an intermediate cervical plexus block. As the compartment contains the sensory terminal branches of the spinal nerves C2-4, it may be referred to as C2-C4 compartment. The cranio-caudal spread of the injectate allows lateromedial needle guidance in the horizontal plane. As the superficial lamina is not a barrier to the injectate an additional subcutaneous infiltration of the nerve area appears dispensable. The prevertebral lamina proved to be impermeable to injected methylene blue. Whether phrenic nerve blocks are preventable with more distal intermediate cervical plexus blocks (selective block of the supraclavicular nerves, e.g. for surgery of the clavicle) must be investigated in clinical trials. The permanent anastomosis (superficial cervical ansa) between the cervical plexus and the ramus colli of the facial nerve provides an anatomically reasonable explanation for inadequate cervical plexus blocks.

Ultraschallgesteuerte intermediäre zervikale Plexusanästhesie

BACKGROUND AND OBJECTIVES The innervation of the human cervical region is complex and subject to relevant anatomical variability involving sections of the cervical plexus, brachial plexus and cranial nerves. AIM The objective was to demonstrate the dissemination of injected dye solution by anatomical preparation and to define a suitable target compartment for an ultrasound-guided block technique. MATERIAL AND METHODS Own anatomical preparations are compared to recent review articles on the subject. The focus is on clinically relevant conclusions for performing cervical plexus blocks. In three non-embalmed cadavers six intermediate ultrasound-guided blocks of the cervical plexus were carried out, each with 20 ml methylene blue. Following preparation of the cervical plexus photographic documentation of the spread of the injected marker was performed. RESULTS In five cases the target compartment was correctly identified. In these cases, a cranio-caudal spread of the injectate within the double layer of the cervical fascia was observed. In addition, the superficial layer was permeable to the injected methylene blue. The injection solution disseminated with the sensitive terminal branches of the cervical plexus below the platysma. In all cases an anastomosis (superficial cervical ansa) between the facial nerve (ramus colli) and the cervical plexus (transverse cervical nerve) could be demonstrated. The prevertebral lamina proved to be impermeable to injected methylene blue and no evidence of a porous structure of the prevertebral lamina was found. CONCLUSION The compartment between the superficial and the prevertebral layer of the cervical fascia is a suitable target for cervical plexus blocks. This injection site describes an intermediate cervical plexus block. As the compartment contains the sensory terminal branches of the spinal nerves C2-4, it may be referred to as C2-C4 compartment. The cranio-caudal spread of the injectate allows lateromedial needle guidance in the horizontal plane. As the superficial lamina is not a barrier to the injectate an additional subcutaneous infiltration of the nerve area appears dispensable. The prevertebral lamina proved to be impermeable to injected methylene blue. Whether phrenic nerve blocks are preventable with more distal intermediate cervical plexus blocks (selective block of the supraclavicular nerves, e.g. for surgery of the clavicle) must be investigated in clinical trials. The permanent anastomosis (superficial cervical ansa) between the cervical plexus and the ramus colli of the facial nerve provides an anatomically reasonable explanation for inadequate cervical plexus blocks.

Variations in brachial plexus with respect to concomitant accompanying aberrant arm arteries

INTRODUCTION Variations in the brachial plexus are the rule rather than the exception. This fact is of special interest for the anesthetist when planning axillary block of brachial plexus. MATERIAL AND METHODS 167 cadaver arms were evaluated for variations in brachial plexus, with focus on the cords of the plexus, the loop of the median nerve, and the course of the median, musculocutaneous, ulnar, axillary and radial nerves. In addition, concomitant arterial variations were recorded. RESULTS In 167 arms, variations were detected in 60 cases (36%). With 46 arms (28%) most variations concern the median nerve, followed by 13 cases (8%) which involved the musculocutaneous nerve. Ulnar, axillary and radial nerve variations were rare, amounting to 1.2% for each nerve. In median nerve conditions with a shifted loop of median nerve (12%), a hidden position of the loop or a hidden course of the beginning median nerve (8%) and a doubled loop of median nerve (17%) were observed. In musculocutaneous nerve conditions with a non-perforated coracobrachialis (1.8%), a doubled origin of the nerve (1.2%) and a giving back of branches to the median nerve (1.8%) were noted. Variations in ulnar, axillary and radial nerves concerned lower than normal diameters. CONCLUSIONS It must be stressed that cases which showed a hidden position or a doubled expression of the loop of the median nerve, a hidden course of its beginning and variable interconnections between musculocutaneous and median nerves are of special interest for anesthetists and surgeons. Hence, it is important to note that variations of arm arteries can be associated with brachial plexus variations. For example, a common trunk of axillary artery followed by a hidden loop and course of the median nerve may result in incomplete axillary block of brachial plexus.

Does the approach influence the success rate for ultrasound-guided rectus sheath blocks? An anatomical case series

The anterior cutaneous branches of the thoracolumbar spinal nerves enter the rectus sheath at its lateral border and perforate the muscle after travelling a short distance in the ventral direction. In this anatomical case series, we show that dye injection at the medial margin did not lead to reliable impregnation of the target nerves. The local anesthetic should therefore be injected at the lateral edge of the rectus sheath. Preceding surgical procedures to the ventral abdominal wall may affect the craniocaudal spread of local anesthetic.

Neointimal fibrotic lead encapsulation – Clinical challenges and demands for implantable cardiac electronic devices

Every tenth patient with a cardiac pacemaker or implantable cardioverter-defibrillator implanted is expected to have at least one lead problem in his lifetime. However, transvenous leads are often difficult to remove due to thrombotic obstruction or extensive neointimal fibrotic ingrowth. Despite its clinical significance, knowledge on lead-induced vascular fibrosis and neointimal lead encapsulation is sparse. Although leadless pacemakers are already available, their clinical operating range is limited. Therefore, lead/tissue interactions must be further improved in order to improve lead removals in particular. The published data on the coherences and issues related to lead associated vascular fibrosis and neointimal lead encapsulation are reviewed and discussed in this paper.

Human Femoral Vein Diameter and Topography of Valves and Tributaries: A Post Mortem Analysis: Femoral Vein Dimensions, Tributaries, and Valves

The femoral vein (FV) is a clinically important vessel. Failure of its valves can lead to chronic venous insufficiency (CVI) with severe manifestations such as painful ulcers. Although they are crucial for identifying suitable implant sites for therapeutic valves, studies on the topography of FV tributaries and valves are rare. Moreover, the femoral vein diameter (FVD) must be known to assess the morphometric requirements for valve implants. To reassess the anatomical requirements for valve implants, 155 FVs from 82 human corpses were examined. FVDs and tributary and valve topographies were assessed using a laboratory straightedge. The FVD increased from 6 mm in the distal femoropopliteal vein to 11 mm in the iliofemoral vein proximal to the saphenofemoral junction (SFJ). Diameters were significantly bigger in males than females. Height correlated positively with FVD. Distal to the SFJ, within a distance of 38 cm, one to eight valves were present. Up to two valves were present within 10 cm proximal to the SFJ. Individual tributary and valve topography must be considered to ensure appropriate design and successful implantation of a venous valve for CVI therapy in the FV. A suitable implant site would be proximal to the SFJ via an infrainguinal transfemoral access. Clin. Anat. 31:1065–1076, 2018.

Fast and reliable dissection of porcine parathyroid glands — A protocol for molecular and histological analyses

As calcium and phosphorus are of vital importance for life, physiological activity of the parathyroid glands (PTGs) is crucial to maintain mineral homeostasis and bone mineralization. However, PTG-specific molecular routes in response to environmental factors and intrinsic hormonal responses are not yet fully understood. Since nutrient requirements, pathophysiology and functional genomics of pigs are similar to those of humans, pigs might be a suitable model to study the holistic gene expression and physiological aspects of the parathyroid gland, which could be used in both animal sciences and biomedical research. However, due to their small size and hidden location, the dissection of the PTGs, particularly in pigs, is difficult. Therefore, a protocol for untrained dissectors has been established that allows a fast and reliable identification of the PTGs in domestic pigs. Based on their localization within the cranial thymus near the carotid bifurcation, sampling was verified by histological staining and mRNA expression pattern. Analyses revealed the prominence of parathyroid hormone (PTH)-producing chief cells. Moreover, the copy numbers of PTH differed substantially between the PTGs and their surrounding thymus tissue, as PTH was expressed virtually exclusively in the PTGs. The developed protocol will substantially facilitate a fast and reliable dissection of porcine PTGs which is essential for studies characterizing the molecular mechanisms of parathyroid glands, e.g. when applying new feeding strategies in pigs.

Ultraschallgesteuerte intermediäre zervikale Plexusanästhesie@@@Ultrasound-guided intermediate cervical plexus block: Anatomische Untersuchung@@@Anatomical study

BACKGROUND AND OBJECTIVES The innervation of the human cervical region is complex and subject to relevant anatomical variability involving sections of the cervical plexus, brachial plexus and cranial nerves. AIM The objective was to demonstrate the dissemination of injected dye solution by anatomical preparation and to define a suitable target compartment for an ultrasound-guided block technique. MATERIAL AND METHODS Own anatomical preparations are compared to recent review articles on the subject. The focus is on clinically relevant conclusions for performing cervical plexus blocks. In three non-embalmed cadavers six intermediate ultrasound-guided blocks of the cervical plexus were carried out, each with 20 ml methylene blue. Following preparation of the cervical plexus photographic documentation of the spread of the injected marker was performed. RESULTS In five cases the target compartment was correctly identified. In these cases, a cranio-caudal spread of the injectate within the double layer of the cervical fascia was observed. In addition, the superficial layer was permeable to the injected methylene blue. The injection solution disseminated with the sensitive terminal branches of the cervical plexus below the platysma. In all cases an anastomosis (superficial cervical ansa) between the facial nerve (ramus colli) and the cervical plexus (transverse cervical nerve) could be demonstrated. The prevertebral lamina proved to be impermeable to injected methylene blue and no evidence of a porous structure of the prevertebral lamina was found. CONCLUSION The compartment between the superficial and the prevertebral layer of the cervical fascia is a suitable target for cervical plexus blocks. This injection site describes an intermediate cervical plexus block. As the compartment contains the sensory terminal branches of the spinal nerves C2-4, it may be referred to as C2-C4 compartment. The cranio-caudal spread of the injectate allows lateromedial needle guidance in the horizontal plane. As the superficial lamina is not a barrier to the injectate an additional subcutaneous infiltration of the nerve area appears dispensable. The prevertebral lamina proved to be impermeable to injected methylene blue. Whether phrenic nerve blocks are preventable with more distal intermediate cervical plexus blocks (selective block of the supraclavicular nerves, e.g. for surgery of the clavicle) must be investigated in clinical trials. The permanent anastomosis (superficial cervical ansa) between the cervical plexus and the ramus colli of the facial nerve provides an anatomically reasonable explanation for inadequate cervical plexus blocks.