Back Pain : Pathophysiology, Diagnosis, and Treatment

Although back pain is one of the most common medical conditions [1], with a reported general population prevalence close to 50% along their lifetime in a long-term British survey [2], it does not attract the interest it should from the general population [3], political powers [4,5] and scientific community [6]. Patients keep coming to our offices for a surgical solution to their back pain, hoping that a miraculous operation will solve all their problems [3,7]. Yet, the surgical procedure sometimes does not solve the problem, and it can be the cause of a new nightmare in one third of patients [8,9]. A Japanese study found that 95% of their patients had persistent back pain after surgery at the same level or worse than before the operation [10]. Often patients have little or no information on how they reached this situation and how to take an active part in the treatment process to achieve a successful result [11]. For many, a costly and painful operation seems the fastest way to eliminate this unpleasant condition [12]. Yet, the problem starts much earlier, and we must stress how things begin and progress to prevent the problem from happening and to avoid treating it [13,14]. For example, some have reported a recent worrisome relationship between adolescents' sedentary lifestyle and obesity and the rise in low back pain prevalence in the European population [14]. We must concentrate on what patients know about their back pain and its prevalence in each country. We need to obtain reliable data on the actual incidence of this medical condition to attract the politicians' interest [15]. Then, they are the ones that can pass laws that reduce the weight that children have to carry on their way to school or the amount of time that adults have to stand in their jobs. We also need to concentrate on awakening the general population to how their lifestyle habits should be the first thing to change if we want to reduce the number of people with back pain [16]. The first step is to discover the prevalence of back pain in each country and in each job, social group, and community. Sadly, the general data about the general population are of limited help. To do this, we need questionnaires that help us to gather this information. Unfortunately, most questionnaires designed to evaluate the incidence of back pain are provided in English [17]. However, translating and adapting them to other languages and cultural and social environments is essential for worldwide validity and use [18,19]. Therefore, we aim to focus on this aspect in the Special Issue. Another vital step is to make the population aware of the importance of healthy lifestyle habits to avoid back pain [20]; for example, everybody knows about refraining from smoking, avoiding being overweight, and exercising. Still, perhaps we should focus more on primary school for children and adolescents to acquire healthy habits and prevent future problems [14]. However, families and social environments also have a crucial role to play, besides that of the school. A final consideration is of conservative treatments. For example, in the present opioid pandemic, back muscle strengthening [21], perhaps with regular swimming [22], is a step that should be encouraged before considering medical treatment with medication, not to say before any surgical procedure. To conclude, this Special Issue is devoted to adapting back pain questionnaires to other languages to find the prevalence of this medical condition worldwide, as well as to those aspects that will prevent, minimize, and correct it to make it less common and easier to handle

ICR in human cadaveric specimens: An essential parameter to consider in a new lumbar disc prosthesis design

[EN] Study design Biomechanical study in cadaveric specimens. Background The commercially available lumbar disc prostheses do not reproduce the intact disc's Instantaneous centre of Rotation (ICR), thus inducing an overload on adjacent anatomical structures, promoting secondary degeneration. Aim To examine biomechanical testing of cadaveric lumbar spine specimens in order to evaluate and define the ICR of intact lumbar discs. Material and Methods Twelve cold preserved fresh human cadaveric lumbosacral spine specimens were subjected to computerized tomography (CT), magnetic resonance imaging (MRI) and biomechanical testing. Kinematic studies were performed to analyse range of movements in order to determine ICR. Results Flexoextension and lateral bending tests showed a positive linear correlation between the angle rotated and the displacement of the ICR in different axes. Discussion ICR has not been taken into account in any of the available literature regarding lumbar disc prosthesis. Considering our results, neither the actual ball-and-socket nor the withdrawn elastomeric nucleus models fit the biomechanics of the lumbar spine, which could at least in part explain the failure rates of the implants in terms of postoperative failed back syndrome (low back pain). It is reasonable to consider then that an implant should also adapt the equations of the movement of the intact ICR of the joint to the post-surgical ICR. Conclusions This is the first cadaveric study on the ICR of the human lumbar spine. We have shown that it is feasible to calculate and consider this parameter in order to design future prosthesis with improved clinical and biomechanical characteristics.Vanaclocha-Saiz, A.; Atienza Vicente, CM.; Vanaclocha, V.; Belloch, V.; Santabarbara, JM.; Jordá-Gómez, P.; Vanaclocha, L. (2020). ICR in human cadaveric specimens: An essential parameter to consider in a new lumbar disc prosthesis design. North American Spine Society Journal. 2:1-8. https://doi.org/10.1016/j.xnsj.2020.100016S18

Seminari 7 Neurocirurgia

Es el seminari 7 de NeurocirurgiaIt is the Neurosurgery seminar number

Bionate biocompatibility: in vivo study in rabbits

Response to foreign materials includes local tissue reaction, osteolysis, implant loosening, and migration to lymph nodes and organs. Bionate 80A human explants show minor wear and slight local tissue reaction, but we do not know the response at the spinal cord, nerve roots, lymph nodes, or distant organs. This study aims to figure out reactions against Bionate 80A when implanted at the spinal epidural space of 24 20-week-old New Zealand white rabbits. In one group of 12 rabbits, we implanted Bionate 80A on the spinal epidural space, and another group of 12 rabbits was used as the control group. We studied tissues, organs, and tissue damage markers on blood biochemistry, urine tests, and necropsy. The animals' clinical parameters and weight showed no statistically significant differences. At 3 months, the basophils increased slightly in the implant group, platelets decreased in all, and at 6 months, implanted animals showed slight eosinophilia, but none of these changes was statistically significant. External, organ, and spinal tissue examination showed neither toxic reaction, inflammatory changes, or noticeable differences between groups or survival periods. Under microscopic examination, the Bionate 80A particles induced a chronic granulomatous response always outside the dura mater, with giant multinucleated cells holding phagocytized particles and no particle migration to lymph nodes or organs. Thus, it was concluded that Bionate particles, when implanted in the rabbit lumbar epidural space, do not generate a significant reaction limited to the surrounding soft tissues with giant multinucleated cells. In addition, the particles did not cross the dura mater or migrate to lymph nodes or organs

Treatment of Neuropathic Pain in Brachial Plexus Injuries

Brachial plexus injuries are commonly followed by chronic pain, mostly with neuropathic characteristics. This is due to peripheral nerve lesions, particularly nerve root avulsions, as well as upper limb amputations, and complex regional pain syndrome (CRPS). The differential diagnosis between CRPS and neuropathic pain is essential as the treatment is different for each of them. Medical treatments are the first step, but for refractory cases there are two main types of surgical alternatives: ablative techniques and neuromodulation. The first group involves destruction of the posterior horn deafferented neurons and usually provides a better pain control but has a 10% complication rate. The second group provides pain control with function preservation but with limited effectiveness. Each case has to be thoroughly evaluated to apply the treatment modality best suited for it

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

Finite Element Analysis of a Bionate Ring-Shaped Customized Lumbar Disc Nucleus Prosthesis

[EN] Study design: Biomechanical study of a nucleus replacement with a finite element model. Objective: To validate a Bionate 80A ring-shaped nucleus replacement. Methods: The ANSYS lumbar spine model made from lumbar spine X-rays and magnetic resonance images obtained from cadaveric spine specimens were used. All materials were assumed homogeneous, isotropic, and linearly elastic. We studied three options: intact spine, nucleotomy, and nucleus implant. Two loading conditions were evaluated at L-3-L-4, L-4-L-5, and L-5-S-1 discs: a 1000 N axial compression load and this load after the addition of 8 Nm flexion moment in the sagittal plane plus 8 Nm axial rotation torque. Results: Maximum nucleus implant axial compression stresses in the range of 16-34 MPa and tensile stress in the range of 5-16 MPa, below Bionate 80A resistance were obtained. Therefore, there is little risk of permanent implant deformation or severe damage under normal loading conditions. Nucleotomy increased segment mobility, zygapophyseal joint and end plate pressures, and annulus stresses and strains. All these parameters were restored satisfactorily by nucleus replacement but never reached the intact status. In addition, annulus stresses and strains were lower with the nucleus implant than in the intact spine under axial compression and higher under complex loading conditions. Conclusions: Under normal loading conditions, there is a negligible risk of nucleus replacement, permanent deformation or severe damage. Nucleotomy increased segmental mobility, zygapophyseal joint pressures, and annulus stresses and strains. Nucleus replacement restored segmental mobility and zygapophyseal joint pressures close to the intact spine. End plate pressures were similar for the intact and nucleus implant conditions under both loading modes. Manufacturing customized nucleus implants is considered feasible, as satisfactory biomechanical performance is confirmed.This project received funding from the European Union's 6th Framework Programme under project number IP 026599-s.Vanaclocha-Saiz, A.; Vanaclocha, V.; Atienza Vicente, CM.; Clavel, P.; Jorda-Gomez, P.; Barrios, C.; Vanaclocha, L. (2022). Finite Element Analysis of a Bionate Ring-Shaped Customized Lumbar Disc Nucleus Prosthesis. ACS Applied Bio Materials. 5(1):172-182. https://doi.org/10.1021/acsabm.1c01027S1721825

Nerve Root Reimplantation in Brachial Plexus Injuries

Nerve root avulsion is the most severe form of brachial or lumbosacral plexus injury. Spontaneous recovery is extremely rare, and when all the nerve roots of the affected plexus are avulsed, the therapeutic options are very limited. Nerve root reimplantation has been attempted since the 1990s, first in experimental animal models and afterwards in human beings. Currently, only partial recovery of the proximal limb muscles has been achieved. New therapeutic strategies have been developed to improve motor neuron survival and axonal regeneration, with promising results. Neurotrophic factors and some drugs have been used successfully to improve the regenerating ability, but long-term studies in humans are needed to develop complete recovery of the affected limb