Nerve Transfers in the Treatment of Peripheral Nerve Injuries

Successful re-innervation of proximal limb peripheral nerve injuries is rare. Axons regenerate at ~1 mm/day, reaching hand muscles by 24 months, finding them atrophied and fibrosed. Peripheral nerve injury repair is often delayed waiting for spontaneous recovery. This waiting time should not be longer than 6 months as after 18 months reinnervation will not achieve effective muscular function. When spontaneous recovery is impossible, referral too late or damage too severe, other options like a transfer from a nearby healthy nerve to the injured one must be considered. They are very successful, and the deficit in the donor site is usually minimal. The most common nerve transfers are a branch of the spinal nerve to the trapezius muscle to the suprascapular nerve, a branch of the long head of the triceps to the axillary nerve, a fascicle of the ulnar nerve to the motor branch of the biceps muscle, two branches of the median nerve to the posterior interosseous nerve and the anterior interosseous nerve to the ulnar nerve. There are many more options that can suit particular cases. Introduced in brachial plexus injury repair, they are now also applied to lower limb, to stroke and to some spinal cord injuries

Peripheral Nerve Entrapment and their Surgical Treatment

Nerves pass from one body area to another through channels made of connective tissue and/or bone. In these narrow passages, they can get trapped due to anatomic abnormalities, ganglion cysts, muscle or connective tissue hypertrophy, tumours, trauma or iatrogenic mishaps. Nearly all nerves can be affected. The clinical presentation is pain, paraesthesia, sensory and motor power loss. The specific clinical features will depend on the affected nerve and on the chronicity, severity, speed and mechanism of compression. Its incidence is higher under some occupations and is some systemic conditions: diabetes mellitus, hypothyroidism, acromegaly, alcoholism, oedema and inflammatory diseases. The diagnosis is suspected with the clinical presentation and provocative clinical test, being confirmed with electrodiagnostic and/or ultrasonographic studies. Magnetic Resonance Studies (MRI) rule out ganglion cysts or tumours. Conservative medical treatment is often sufficient. In refractory ones, surgical decompression should be performed before nerve damage and muscle atrophy are irreversible. The ‘double crash’ syndrome happens when a peripheral nerve is compressed at more than one point along its trajectory. In cases with marked muscle atrophy, a ‘supercharge end‐to‐side’ nerve transfer can be added to the decompression. After decompression in those few cases with refractory pain, a nerve neurostimulator can be applied

Chronic Headache and Neuromodulation

The immense majority of patients with chronic headaches can be controlled with medical treatments. However, there is a subset of them with poor response, and it is for those patients that new therapeutic strategies are being designed. Neuromodulation has been used for chronic pain management in many areas for the past 50 years. The application of these techniques to the treatment of the most refractory chronic headache disorders has offered hope to these patients. There is a large variety of different techniques, each of them particularly suitable to specific types of chronic headaches. The surgically implanted devices are still in use in some particularly recalcitrant cases. Nevertheless, new percutaneous devices allow new treatment strategies. Percutaneous devices do not always show the same effectivity as surgically implanted stimulating devices, but they are user-friendly and have no serious adverse effects. Thus, they are becoming the treatment of choice once the pharmacological means are no longer effective. In case of failure, the surgical procedures would still be available as a last resort

Selective T3-T4 sympathicotomy versus gray ramicotomy on outcome and quality of life in hyperhidrosis patients : a randomized clinical trial

Compensatory hyperhidrosis is the leading cause of patients' dissatisfaction after thoracic sympathicotomy. The study aimed to reduce compensatory hyperhidrosis to increase patients' satisfaction. A prospective randomized study on palmar hyperhidrosis, May 2016-September 2019. Twenty-one patients T3- T4 sympathicotomy and 21 T3- T4 gray ramicotomy. Data prospectively collected. Analysis at study's end. Focus on the sweating, temperature, quality of life baseline and postoperatively, compensatory hyperhidrosis, hand dryness, patients' satisfaction, and if they would undergo the procedure again and recommend it. No baseline differences between groups. Hyperhidrosis was controlled postoperatively in all patients. No mortality, serious complications, or recurrences. Sympathicotomy worse postoperative quality of life (49.05 (SD: 15.66, IR: 35.50-63.00) versus ramicotomy 24.30 (SD: 6.02, IR: 19.75-27.25). After ramicotomy, some residual sweating on the face, hands, and axillae. Compensatory sweating worse with sympathicotomy. Satisfaction higher with ramicotomy. Better results with ramicotomy than sympathicotomy regarding hand dryness, how many times a day the patients had to shower or change clothes, intention to undergo the procedure again or recommend it to somebody else, and how bothersome compensatory hyperhidrosis was. T3-T4 gray ramicotomy had better results than T3-T4 sympathicotomy, with less compensatory sweating and higher patients' satisfaction

Barbed Dental Ti6Al4V Alloy Screw : Design and Bench Testing

Background context. Dental implants are designed to replace a missing tooth. Implant stability is vital to achieving osseointegration and successful implantation. Although there are many implants available on the market, there is room for improvement. Purpose. We describe a new dental implant with improved primary stability features. Study design. Lab bench test studies. Methods. We evaluated the new implant using static and flexion-compression fatigue tests with compression loads, 35 Ncm tightening torque, displacement control, 0.01 mm/s actuator movement speed, and 9-10 Hz load application frequency, obtaining a cyclic load diagram. We applied variable cyclic loadings of predetermined amplitude and recorded the number of cycles until failure. The test ended with implant failure (breakage or permanent deformation) or reaching five million cycles for each load. Results. Mean stiffness was 1151.13 ± 133.62 SD N/mm, mean elastic limit force 463.94 ± 75.03 SD N, and displacement 0.52 ± 0.04 SD mm, at failure force 663.21 ± 54.23 SD N and displacement 1.56 ± 0.18 SD mm, fatigue load limit 132.6 ± 10.4 N, and maximum bending moment 729.3 ± 69.43 mm/N. Conclusions. The implant fatigue limit is satisfactory for incisor and canine teeth and between the values for premolars and molars for healthy patients. The system exceeds five million cycles when subjected to a 132.60 N load, ensuring long-lasting life against loads below the fatigue limit

High frequency of lumbar fusion in patients denied surgical treatment of the sacroiliac joint

Purpose: Effective treatment of medical conditions relies on proper diagnosis. Clinical trials show the safety and effectiveness of sacroiliac joint (SIJ) fusion in patients with chronic SI joint dysfunction. To what extent is the condition under recognised? Objective: To determine whether under recognition of SIJ pain affects healthcare trajectories in Spanish patients with low back pain. Methods: Retrospective study of characteristics and consequences of 189 patients with persistent SIJ pain seen in an outpatient neurosurgery clinic. Results: Patients with SIJ pain who were denied surgical treatment had a longer pain duration, higher likelihood of prior lumbar fusion, and a high rate (63%) of lumbar fusion within 2 years prior to SIJ pain diagnosis, which, in most cases, provided little benefit. Conclusions: Lack of knowledge of the role of the SIJ in chronic low back pain probably results in diagnostic confusion and may lead to misdirected treatment

Bionate Lumbar Disc Nucleus Prosthesis : Biomechanical Studies in Cadaveric Human Spines

Design: cadaveric spine nucleus replacement study. Objective: determining Bionate 80A nucleus replacement biomechanics in cadaveric spines. Methods: in cold preserved spines, with ligaments and discs intact, and no muscles, L3-L4, L4-L5, and L5-S1 nucleus implantation was done. Differences between customized and overdimensioned implants were compared. Flexion, extension, lateral bending, and torsion were measured in the intact spine, nucleotomy, and nucleus implantation specimens. Increasing load or bending moment was applied four times at 2, 4, 6, and 8 Nm, twice in increasing mode and twice in decreasing mode. Spine motion was recorded using stereophotogrammetry. Expulsion tests: cyclic compression of 50-550 N for 50,000 cycles, increasing the load until there was extreme flexion, implant extrusion, or anatomical structure collapse. Subsidence tests were done by increasing the compression to 6000 N load. Results: nucleotomy increased the disc mobility, which remained unchanged for the adjacent upper level but increased for the lower adjacent one, particularly in lateral bending and torsion. Nucleus implantation, compared to nucleotomy, reduced disc mobility except in flexion-extension and torsion, but intact mobility was no longer recovered, with no effect on upper or lower adjacent segments. The overdimensioned implant, compared to the customized implant, provided equal or sometimes higher mobility. Lamina, facet joint, and annulus removal during nucleotomy caused more damaged than that restored by nucleus implantation. No implant extrusion was observed under compression loads of 925-1068 N as anatomical structures collapsed before. No subsidence or vertebral body fractures were observed under compression loads of 6697.8-6812.3 N. Conclusions: nucleotomized disc and L1-S1 mobility increased moderately after cadaveric spine nucleus implantation compared to the intact status, partly due to operative anatomical damage. Our implant had shallow expulsion and subsidence risks

Nucleus disc replacement : designs and material selection FEA analysis

Study design. Material selection, implant design and Finite Element Analysis (FEA) studies. Background. Nucleus disc replacements, implanted since 1960, have undergone continuous evolution in materials and designs, but subsidence, extrusion, and in vivo degradation limit widespread use. Aim: To create a new nucleus disc replacement that avoids the abovementioned drawbacks. Material and Methods. We created eighteen designs with varied materials and analyzed them with FEA in compression and shear tests in a lumbar spine model programmed in Ansys Parametric Design Language. Results. Bionate® 80A had the closest mechanical characteristics to the intact disc nucleus. Monobloc designs bore the physiological stresses correctly but suffered significant deformations with permanent damage during surgical insertion through the annulus opening. In addition, sandwich designs were too rigid and had an unreliable curing process. Therefore, we chose an oval doughnut-like 5 mm wall monobloc Bionate® 80A nucleus replacement. It minimized implant stress in loading, distributed the loads uniformly, and tolerated the lateral compression during implantation. Conclusions. Out of the eighteen designs we analyzed with FEA, we found that the monobloc oval doughnut-like Bionate 80A nucleus replacement reproduced best the biomechanics of the natural disc nucleus and had the lowest subsidence risk as it transmits the load to the ring apophysis. Furthermore, due to its elasticity implanting it through the average annulotomy required to perform a lumbar microdiscectomy should be possible

ADDISC lumbar disc prosthesis : Analytical and FEA testing of novel implants

The intact intervertebral disc is a six-freedom degree elastic deformation structure with shock absorption. 'Ball-and-socket' TDR do not reproduce these properties inducing zygapophyseal joint overload. Elastomeric TDRs reproduce better normal disc kinematics, but repeated core deformation causes its degeneration. We aimed to create a new TDR (ADDISC) reproducing healthy disc features. We designed TDR, analyzed (Finite Element Analysis), and measured every 500,000 cycles for 10 million cycles of the flexion-extension, lateral bending, and axial rotation cyclic compression bench-testing. In the inlay case, we weighted it and measured its deformation. ADDISC has two semi-spherical articular surfaces, one rotation centre for flexion, another for extension, the third for lateral bending, and a polycarbonate urethane inlay providing shock absorption. The first contact is between PCU and metal surfaces. There is no metal-metal contact up to 2000 N, and CoCr28Mo6 absorbs the load. After 10 million cycles at 1.2-2.0 kN loads, wear 140.96 mg (35.50 mm3), but no implant failures. Our TDR has a physiological motion range due to its articular surfaces' shape and the PCU inlay bumpers, minimizing the facet joint overload. ADDISC mimics healthy disc biomechanics and Instantaneous Rotation Center, absorbs shock, reduces wear, and has excellent long-term endurance

Treatment of Brachial Plexus Injuries

Despite immense advancements, brachial plexus injuries continue to be an area where improvement is much needed. While some problems have been solved, there remain difficult situations where patients desperately need the neurosurgeon's help. This book is an attempt to put the state of the art in some of these less known areas, to provide the reader with an insight into what is currently being done today and what might be the possible therapeutic strategies for the future. We attempt not only to provide information but also more importantly to awake the interest of as many researchers as possible to find new solutions to old problems