Matthias Rab

Anatomic variability of the ilioinguinal and genitofemoral nerve : Implications for the treatment of groin pain

&NA; The differential diagnosis of groin pain must consider problems of the ilioinguinal and/or genitofemoral nerve. These nerves may become injured during hernia surgery or lower quadrant surgical procedures. To treat injury to these nerves, it is critical to understand their anatomic variability. In the present study the pattern of cutaneous nerve branches in the inguinal region was investigated through dissection in 64 halves of 32 human embalmed anatomic specimens. In contrast to usual textual descriptions, four different types of cutaneous branching patterns are identified: type A, with a dominance of genitofemoral nerve in the scrotal/labial and the ventromedial thigh region. In type A, the ilioinguinal nerve gives no sensory contribution to these regions (43.7 percent). In type B, with a dominance of ilioinguinal nerve, the genitofemoral nerve shares a branch with the ilioinguinal and gives motor fibers to cremaster muscle in the inguinal canal, but has no sensory branch to the groin (28.1 percent). In type C, with a dominance of genitofemoral nerve, the ilioinguinal nerve has sensory branches to the mons pubis and inguinal crease together with an anteroproximal part of the root of the penis or labia majora. The nerve was found to share a branch with the iliohypogastric nerve (20.3 percent). In type D, cutaneous branches emerge from both the ilioinguinal and the genitofemoral nerves. Additionally, the ilioinguinal nerve innervates the mons pubis and inguinal crease together with a very anteroproximal part of the root of the penis or labia majora (7.8 percent). The described patterns of innervation were bilaterally symmetric in 40.6 percent of the cadavers. The anatomic variability of both nerves has implications for all surgeons operating in the groin region and for those caring for the patient with groin pain. (Plast. Reconstr. Surg. 108: 1618, 2001.)

The precision of ultrasound imaging and its relevance for carpal tunnel syndrome.

The carpal tunnel syndrome (CTS) is the most common peripheral entrapment neuropathy in human. The diagnosis is based on symptoms and on physical examination and is supported by nerve conduction tests. The aim of this study was to evaluate the precision and the valence of ultrasound (US) for CTS. An anatomic study was performed on 40 wrists of 20 unfixed human cadavers. The carpal tunnel and its important structures and contents were imaged and measured by ultrasound (7.5-MHz high resolution probe). The dorsopalmar diameter (DPD), the radioulnar diameter (RUD), the perimeter (P) and the cross-sectional area (A) were determined for the carpal canal and for the median nerve. These US images and measurements were directly compared with anatomic cross-sections gained from the same wrists at the same level. Our results showed that ultrasound is a very precise method to display the anatomy of the carpal tunnel and of the median nerve and thus the conditions of the median nerve. Significant differences could not be detected for each of these parameters either for the carpal tunnel or the median nerve. (Ultrasound cross-sectional area of carpal tunnel 162.4 ± 29.3 mm2 and of the median nerve 9.2 ± 2.4 mm2 anatomy cross-sectional area of carpal tunnel 168.4 ± 31.2 mm2 and of median nerve 9.4 ± 2.2 mm2).

Functional and morphometric evaluation of end-to-side neurorrhaphy for muscle reinnervation.

This study was undertaken to quantify the effect of motor collateral sprouting in an end-to-side repair model allowing end organ contact. Besides documentation of the functional outcome of muscle reinnervation by end-to-side neurorrhaphy, this experimental work was performed to determine possible downgrading effects to the donor nerve at end organ level. In 24 female New Zealand White rabbits, the motor nerve branch to the rectus femoris muscle of the right hindlimb was dissected, cut, and sutured end-to-side to the motor branch to the vastus medialis muscle after creating an epineural window. The 24 rabbits were divided into two groups of 12 each, with the second group receiving additional crush injury of the vastus branch. After a period of 8 months, maximum tetanic tension in the reinnervated rectus femoris and the vastus medialis muscles was determined. The contralateral healthy side served as control. The reinnervated rectus femoris muscle showed an average maximum tetanic force of 24.9 N (control 26.2 N, p = 0.7827), and the donor vastus medialis muscle 11.0 N (control 7.3 N, p = 0.0223). There were no statistically significant differences between the two experimental groups (p = 0.9914). The average number of regenerated myelinated nerve fibers in the rectus femoris motor branch was 1185 ± 342 (control, 806 ± 166), and the mean diameter was 4.6 ± 0.6 &mgr;m (control, 9.4 ± 1.0 &mgr;m). In the motor branch to the vastus medialis muscle, the mean fiber number proximal to the coaptation site was 1227 (±441), and decreased distal to the coaptation site to 795 (±270). The average difference of axon counts in the donor nerve proximal to distal regarding the repair site was 483.7 ± 264.2. In the contralateral motor branch to the vastus medialis muscle, 540 (±175) myelinated nerve fibers were counted. In nearly all cross-section specimens of the motor branch to the vastus medialis muscle, altered nerve fibers could be identified in one fascicle distal and proximal to the repair site. The results show a relevant functional reinnervation by end-to-side neurorrhaphy without functional impairment of the donor muscle. It seems to be evident that most axons in the attached segment were derived from collateral sprouts. Nonetheless, the present study confirms that end-to-side neurorrhaphy is a reliable method of reconstruction for damaged nerves, which should be applied clinically in a more extended manner. (Plast. Reconstr. Surg. 106: 383, 2000.)

Neuroma Prevention by End-to- Side Neurorraphy: An Experimental Study in Rats

PURPOSE The successful treatment of painful neuromas remains a difficult goal to attain. In this report we explore the feasibility of neuroma prevention by insertion of the proximal end of a nerve through an end-to-side neurorraphy into an adjacent mixed nerve to provide a pathway and target for axons deprived of their end organ. METHODS Experiments were performed on a total of twenty 250-g Sprague-Dawley rats. Two groups of 10 animals were prepared. Group A served as an anatomic control. In group B the right saphenous nerve was transected and implanted end-to-side through an epineurial window into the tibial nerve distal to the trifurcation of the sciatic nerve. After 12 weeks the corresponding sensory neurons were identified by retrograde labeling techniques and histomorphometric analysis of the proximal and distal tibial nerve segments, and regular histology of the end-to-side site were performed. RESULTS The results of the retrograde labeling of the corresponding sensory neuron pool of the saphenus nerve showed extensive labelling of the L1 to L3 spinal ganglions after intracutaneous tracer application of the planta pedis. The morphology of the end-to-side coaptation site and histomorphologic analysis prove that sensory neurons penetrate the perineurial sheath and axons regenerate along the tibial Schwann cell tubes toward their targets. CONCLUSIONS Axons of a severed peripheral nerve that are provided with a pathway and target through an end-to-side coaptation will either be pruned or establish some type of end-organ contact so that a neuroma can be prevented. Whether these axons will lead to disturbing sensations such as paresthesia or dysesthesia in the newly found environment or remain silent codwellers, this experiment cannot answer. Long-term results of future clinical work will have to decide whether the prevention of the neuroma through end-to-side coaptation will be an appropriate therapy for this difficult problem.

Impact of early high caloric duodenal feeding on the oxygen balance of the splanchnic region after severe burn injury

Early enteral nutrition is recommended in burned patients. Depending on the amount administered, enteral feeding causes an increase of intestinal oxygen-demand. Although early moderate enteral nutrition has been shown to be beneficial, early high calorie enteral nutrition might lead to an imbalance of the O(2)-balance of the gut since intestinal perfusion is decreased after major burns. In 20 severely burned patients during the first 48 h of early high caloric duodenal feeding an assessment of the CO(2)-gap between the arterial and the gastric CO(2), as parameter for the intestinal O(2)-balance, was performed. Time points were prior to starting the enteral nutrition (BASE) subsequently every 30 min after increasing the amount of nutrition administered and from the 11th to the 48th h after beginning of nutrition in intervals of 6 h. In none of the patients was the CO(2)-gap increased during the rapid increase of enteral nutrition. On the contrary the CO(2)-gap decreased significantly. We conclude that high caloric duodenal feeding in the early hypodynamic postburn phase does not have adverse effects on the oxygen balance of the intestine.

The axillary vein central venous catheter in severely burned patients

In severely burned patients the approach to the central vein is often difficult due to concomitant edema, but also due to the fact that the skin area, where commonly used approaches are performed, is burned as well, whereas the axillary region is often not involved. In order to perform an axillary approach to the central vein as an alternative to the commonly used approaches in patients, an anatomical dissection in fresh human cadavers was carried out. Considering the anatomical landmarks which were found during dissection of the axillary region, the axillary approach to the central vein was used in 35 patients in our intensive burn care unit with unaffected axillary skin. In three cases the only complication observed was an occasional puncture of the axillary artery without major hematoma. The infection rate of the catheters was similar to the commonly used puncture sites. This approach to the central venous line in severely burned patients can be recommended.

Impact of duodenal feeding on the oxygen balance of the splanchnic region during different phases of severe burn injury

Enteral nutrition is recommended in burned patients. Depending on the amount administered, enteral feeding causes an increase of intestinal oxygen-demand. Since intestinal perfusion is decreased after major burns the aim of this study was to evaluate, whether duodenal feeding might be a cofactor for the development of a splanchnic O(2)-imbalance. In 15 severely burned patients during duodenal feeding starting within 6 h after injury the assessment of the CO(2)-gap between arterial and gastric CO(2), as a parameter for the measurement of intestinal O(2)-balance was performed. Beginning prior to enteral nutrition CO(2)-gap measurements were carried out to show when the CO(2)-gap increased above 30 mmHg during the whole critical illness phase of the patients. When the CO(2)-gap increased above 30 mmHg enteral nutrition was reduced by 50% and the CO(2)-gap was measured 1 h later. In none of the patients the CO(2)-gap increased during increase of enteral nutrition. In seven patients, the CO(2)-gap increased between the 6th and 13th day above 30 mmHg and fell significantly 1 h after reduction of enteral nutrition. Contrary to the early postburn phase, enteral feeding might have adverse effects on the oxygen balance of the intestine in the later stages of the critical illness phase.

Experimental development of an electrically stimulated biological skeletal muscle ventricle for chronic aortic counterpulsation

OBJECTIVE The chronic shortage of donor organs for cardiac transplantation and the high costs for mechanical assist devices demand the development of alternative cardiac assist devices for the treatment of severe heart failure. Cardiac assistance by stimulated skeletal muscles is currently investigated as such a possible alternative. The goal of the presented study was to construct a newly designed biological skeletal muscle ventricle and to evaluate its possible hemodynamic efficacy in an acute sheep model. METHODS A total of 14 adult sheep were used for acute experiments. The entire thoracic aorta including the aortic root was excised from a donor sheep. An aorto-pericardial pouch conduit (APPC) was created by enlarging the aortic circumference in its middle section with two strips of pericardium. This biological conduit was anastomosed in parallel to the descending aorta of a recipient sheep, using the aortic root as an inflow valve to the conduit. Stimulation electrodes were applicated to the thoracodorsal nerve and the latissimus dorsi muscle was detached from the trunk and wrapped around the pouch. ECG-triggered functional electrical stimulation was applied during cardiac diastole to simulate aortic counterpulsation. Stimulation was performed during various hemodynamic conditions. RESULTS A standardised surgical procedure suitable for long term studies was established during six experiments. An APPC, with 70-80 mm filling volume, was found to be of optimal size. In another eight experiments, hemodynamic measurements were performed. Under stable hemodynamic conditions the stimulation of the biological skeletal muscle ventricle induced a significant increase of mean arterial pressure by 14% and mean diastolic pressure by 26%. During pharmacologically induced periods of cardiac failure, the stimulation of the APPC increased mean arterial pressure by 13% and mean diastolic pressure by 19%. In all eight experiments, the diastolic peak pressure reached supra-systolic values during stimulation. CONCLUSIONS The results demonstrate the hemodynamic efficacy of this newly designed biological skeletal muscle ventricle as an aortic counterpulsation device. Chronic experiments using a preconditioned fatigue-resistant muscle will further help to evaluate its possible clinical significance.

The use of allogeneic cultivated keratinocytes for the early coverage of deep dermal burns - indications, results and problems.

Since 1995, keratinocytes are grown into cultures and used as allografts for the coverage of deep dermal defects in our burn unit. Donor skin samples are mostly acquired from other burn patients. In addition, special methods of skin preservation allow us the use of skin, which has been taken in redundancy for split thickness skin grafting from nonburned patients.Thirty five patients with deep partial thickness burns in the face were treated since 1996 according to the following concept: Dermabrasion or tangential excision was performed before the 5th day following trauma. If viable dermis was present, the wounds were covered with sheets of allogeneic cultivated keratinocytes. In cases of deeper defects, autologous skin grafts were applied. In 23 cases, epithelialisation was achieved within 10 days, in 8 patients, a prolonged duration until complete healing was observed. In 5 faces, coverage of residual defects with skin grafts was necessary. The mentioned problems of wound healing occurred from infection, incomplete excision of burn eschar and a depth of the wound which was retrospectively seen too deep for the treatment with keratinocytes. At follow up, patients were examined clinically and functionally with Freys faciometer®, which is an instrument for quantification of mimic movements. In cases of uncomplicated healing, a nearly complete restitution was found.Other indications include deep dermal burns in children and the coverage of early excised wounds in adults, with a reasonable amount of viable dermis remaining, both resulting in a significant reduction of donor-site morbidity. In severely burned adults with limited donor sites, it offers the possibility of immediate definite coverage of large areas.

The impact of a muscle target organ on nerve grafts with different lengths—A histomorphological analysis

The present study was done in order to evaluate the influence of a target muscle on the regenerative processes in long nerve grafts. In 21 rabbits the saphenous nerve was used as a nerve graft and coapted to the cut motor nerve of vastus medialis. The animals were separated into three groups with different graft lengths, namely 3, 5, and 7 cm. In a second stage the distal end of the graft (Graft.dist.) was coapted to the motor branch of rectus femoris. Cross sections of the normal vastus nerve and the Graft.dist. before and 7 months after the connection to rectus femoris were analyzed histomorphometrically. Before coaptation to the target organ mean fiber number in the Graft.dist. of the 3‐cm‐long grafts was 3380 and decreased to 2413 in the 7‐cm‐long grafts. Seven months after coaptation the results showed a statistically significant decrease of fibers in the Graft.dist. of group two and three and a distinct decrease of the fibers in group one. Summarizing, in a two‐stage nerve grafting procedure the reinnervation of the muscle target organ leads to a down‐regulation of fibers in the distal end of short and long nerve grafts.