Redundant nerve roots of the cauda equina: review of the literature

In imaging diagnosis, redundant nerve roots of the cauda equina are characterized by the presence of elongated, enlarged and tortuous nerve roots in close relationship with a high-grade lumbar spinal canal stenosis. This is not an independent entity, but it is believed to be a consequence of the chronic compression at the level of the lumbar canal stenosis and thus may be part of the natural history of lumbar spinal stenosis. The present paper is aimed at reviewing the histopathological, electrophysiological and imaging findings, particularly at magnetic resonance imaging, as well as the clinical meaning of this entity. As the current assessment of canal stenosis and root compression is preferably performed by means of magnetic resonance imaging, this is the imaging method by which the condition is identified. The recognition of redundant nerve roots at magnetic resonance imaging is important, particularly to avoid misdiagnosing other conditions such as intradural arteriovenous malformations. The literature approaching the clinical relevance of the presence of redundant nerve roots is controversial. There are articles suggesting that the pathological changes of the nerve roots are irreversible at the moment of diagnosis and therefore neurological symptoms are less likely to improve with surgical decompression, but such concept is not a consensus.

Spatiotemporal neuromodulation therapies engaging muscle synergies improve motor control after spinal cord injury.

Electrical neuromodulation of lumbar segments improves motor control after spinal cord injury in animal models and humans. However, the physiological principles underlying the effect of this intervention remain poorly understood, which has limited the therapeutic approach to continuous stimulation applied to restricted spinal cord locations. Here we developed stimulation protocols that reproduce the natural dynamics of motoneuron activation during locomotion. For this, we computed the spatiotemporal activation pattern of muscle synergies during locomotion in healthy rats. Computer simulations identified optimal electrode locations to target each synergy through the recruitment of proprioceptive feedback circuits. This framework steered the design of spatially selective spinal implants and real-time control software that modulate extensor and flexor synergies with precise temporal resolution. Spatiotemporal neuromodulation therapies improved gait quality, weight-bearing capacity, endurance and skilled locomotion in several rodent models of spinal cord injury. These new concepts are directly translatable to strategies to improve motor control in humans.

Etude du nerf phrenique chez le cobaye (Cavia porcellus, L., 1756)

The aim of the present study to ascertain the mode of origin of the phrenic nerve and to provide a morphological basis for experimental studies of this nerve in the guinea pig. In sketches made of the dissections, in 10 male and 10 female guinea pigs adults, the modes of origin of the phrenic roots were demonstrated to arise from the fourth to the seventh cervical nerves. Four types of origin could be distinguished. The phrenic nerve of the guinea pig has three or four roots.

Tumor maligno da bainha de nervo periférico envolvendo raízes nervosas do terceiro segmento medular lombar em um cão

Malignant peripheral nerve sheath tumors (MPNST) involving spinal nerve roots are uncommon in dogs. A nine-year old, intact, mixed-breed dog, demonstrated clinical signs of incoordination in the pelvic limbs and micturition for approximately one week. Clinical examination revealed proprioceptive deficits and bilateral patellar hyperreflexia. During exploratory celiotomy a mass was observed adhered to the lumbar vertebral segments. Medical therapy was initiated, but neurological signs were progressive, and the owner opted for euthanasia. Gross examination showed that the mass in the abdominal cavity was attached to the lumbar segments L3 and L4, causing bone lysis in L3, but showed no tumor invasion into the spinal canal. Microscopic features were characterized by prominent proliferation of ovoid and fusiform cells with poorly defined cytoplasm arranged in interlacing bundles and concentric whorls. The cells were embedded in a delicate to moderate collagenous stroma and moderate anisokariose and high mitotic activity were noted. The immunohistochemical assay showed positive staining for GFAP, S-100 protein and vimentin, and negative staining for factor VIII, α-actin and citokeratine. The definitive diagnosis of malignant peripheral nerve sheath tumor was made on the basis of the histological and immunohistochemical findings.

Cytokine inhibition and time-related influence of inflammatory stimuli on the hyperalgesia induced by the nucleus pulposus

The symptoms of lumbar disc herniation, such as low back pain and sciatica, have been associated with local release of cytokines following the inflammatory process induced by the contact of the nucleus pulposus (NP) with the spinal nerve. Using an animal experimental model of intervertebral disc herniation and behavioral tests to evaluate mechanical (electronic von Frey test) and thermal (Hargreaves Plantar test) hyperalgesia in the hind paw of rats submitted to the surgical model, this study aimed to detect in normal intervertebral disc the cytokines known to be involved in the mechanisms of inflammatory hyperalgesia, to observe if previous exposure of the intervertebral disc tissue to specific antibodies could affect the pain behavior (mechanical and thermal hyperalgesia) induced by the NP, and to observe the influence of the time of contact of the NP with the fifth lumbar dorsal root ganglion (L5-DRG) in the mechanical and thermal hyperalgesia. The cytokines present at highest concentrations in the rat NP were TNF-alpha, IL-1 beta and CINC-1. Rats submitted to the disc herniation experimental model, in which a NP from the sacrococcygeal region is deposited over the right L5-DRG, showed increased mechanical and thermal hyperalgesia that lasted at least 7 weeks. When the autologous NP was treated with antibodies against the three cytokines found at highest concentrations in the NP (TNF-alpha, IL-1 beta and CINC-1), there was decrease in both mechanical and thermal hyperalgesia in different time points, suggesting that each cytokine may be important for the hyperalgesia in different steps of the inflammatory process. The surgical remotion of the NP from herniated rats 1 week after the implantation reduced the hyperalgesia to the level similar to the control group. This reduction in the hyperalgesia was also observed in the group that had the NP removed 3 weeks after the implantation, although the intensity of the hyperalgesia did not decreased totally. The removal of the NP after 5 weeks did not changed the hyperalgesia observed in the hind paw, which suggests that the longer the contact of the NP with the DRG, the greater is the possibility of development of chronic pain. Together our results indicate that specific cytokines released during the inflammatory process induced by the herniated intervertebral disc play fundamental role in the development of the two modalities of hyperalgesia (mechanical and thermal) and that the maintenance of this inflammation may be the most important point for the chronification of the pain.

Contrast-enhanced MR myelography in spontaneous intracranial hypotension: description of an artefact imitating CSF leakage

In contrast-enhanced (CE) MR myelography, hyperintense signal outside the intrathecal space in T1-weighted sequences with spectral presaturation inversion recovery (SPIR) is usually considered to be due to CSF leakage. We retrospectively investigated a hyperintense signal at the apex of the lung appearing in this sequence in patients with SIH (n = 5), CSF rhinorrhoea (n = 2), lumbar spine surgery (n = 1) and in control subjects (n = 6). Intrathecal application of contrast agent was performed in all patients before MR examination, but not in the control group. The reproducible signal increase was investigated with other fat suppression techniques and MR spectroscopy. All patients and controls showed strongly hyperintense signal at the apex of the lungs imitating CSF leakage into paraspinal tissue. This signal increase was identified as an artefact, caused by spectroscopically proven shift and broadening of water and lipid resonances (1-2 ppm) in this anatomical region. Only patients with SIH showed additional focal enhancement along the spinal nerve roots and/or in the spinal epidural space. In conclusion CE MR myelography with spectral selective fat suppression shows a reproducible cervicothoracic artefact, imitating CSF leakage. Selective water excitation technique as well as periradicular and epidural contrast collections may be helpful to discriminate between real pathological findings and artefacts.

High-resolution vascular imaging of the rat spine using liposomal blood pool MR agent.

BACKGROUND AND PURPOSE: High-resolution, vascular MR imaging of the spine region in small animals poses several challenges. The small anatomic features, extravascular diffusion, and low signal-to-noise ratio limit the use of conventional contrast agents. We hypothesize that a long-circulating, intravascular liposomal-encapsulated MR contrast agent (liposomal-Gd) would facilitate visualization of small anatomic features of the perispinal vasculature not visible with conventional contrast agent (gadolinium-diethylene-triaminepentaacetic acid [Gd-DTPA]). METHODS: In this study, high-resolution MR angiography of the spine region was performed in a rat model using a liposomal-Gd, which is known to remain within the blood pool for an extended period. The imaging characteristics of this agent were compared with those of a conventional contrast agent, Gd-DTPA. RESULTS: The liposomal-Gd enabled acquisition of high quality angiograms with high signal-to-noise ratio. Several important vascular features, such as radicular arteries, posterior spinal vein, and epidural venous plexus were visualized in the angiograms obtained with the liposomal agent. The MR angiograms obtained with conventional Gd-DTPA did not demonstrate these vessels clearly because of marked extravascular soft-tissue enhancement that obscured the vasculature. CONCLUSIONS: This study demonstrates the potential benefit of long-circulating liposomal-Gd as a MR contrast agent for high-resolution vascular imaging applications.

Increased intraoperative epidural pressure in lumbar spinal stenosis patients with a positive nerve root sedimentation sign

Purpose The sedimentation sign (SedSign) has been shown to discriminate well between selected patients with and without lumbar spinal stenosis (LSS). The purpose of this study was to compare the pressure values associated with LSS versus non-LSS and discuss whether a positive SedSign may be related to increased epidural pressure at the level of the stenosis. Methods We measured the intraoperative epidural pressure in five patients without LSS and a negative SedSign, and in five patients with LSS and a positive SedSign using a Codman TM catheter in prone position under radioscopy. Results Patients with a negative SedSign had a median epidural pressure of 9 mmHg independent of the measurement location. Breath and pulse-synchronous waves accounted for 1–3 mmHg. In patients with monosegmental LSS and a positive SedSign, the epidural pressure above and below the stenosis was similar (median 8–9 mmHg). At the level of the stenosis the median epidural pressure was 22 mmHg. A breath and pulse-synchronous wave was present cranial to the stenosis, but absent below. These findings were independent of the cross-sectional area of the spinal canal at the level of the stenosis. Conclusions Patients with LSS have an increased epidural pressure at the level of the stenosis and altered pressure wave characteristics below. We argue that the absence of sedimentation of lumbar nerve roots to the dorsal part of the dural sac in supine position may be due to tethering of affected nerve roots at the level of the stenosis.

Clinical and Histological Effects of the Intrathecal Administration of Methylprednisolone in Dogs

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Arranjos configurados pelos nervos do plexo braquial no urubu (Coragyps atratus foetens - Linnaeus, 1758)

The anatomical study of the origin and distribution of brachial plexus in vulture (Coragyps atratus foetens) was performed in 14 animals, adults, males and females, deriving of the region of Araçatuba (SP). After fixed in watery solution of formaldehyde 10,00%, became dissected bilateral of the origin of the brachial plexus, and yours distribution. The analysis allowed verify that brachial plexus of vulture, four root possess, which originate from the ventral branches of cervical spinal nerves eleven (C11), twelve (C12) and thirteen (C13) and of the ventral branches of thoracic spinal nerve one (T1) and (T2) in both sides (100%). The first root part of C11 in the right and left side, and of the edge skull of the dorsal lace the nerves subescapular, subcoracoescapular e supracoracóide in both antímeros (100%). As the root originates from C12 in both sides, giving origin to the dorsal lace, giving the axilar, radial and anconeal nerves (100%). The third root of plexus originates solely from C13 (100%) and the root of T1 in both sides (100%). The roots of C12, C13 and T1 was united the ventral lace originates, which breaks the nerves to medianoulnar that divided in medium and to ulnar and the pectoral nerves (100%). T2 emits filaments that join it root nervous of T1, being one filament (35,55%) and two filaments (64,29%) in side right, while that in the left one filament (42,85%), two filaments (50%) and three filaments (7,15%).

Efeitos determinados pela metilprednisolona, administrada pela via subaracnóidea, sobre a medula espinhal e as meninges: estudo experimental em cães

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Espondilomielopatia cervical caudal em cães: diagnóstico por imagem

The Caudal Cervical Spondylomyelopathy, also known as “Wobbler syndrome” is a neurological disorder that affects mainly breeds of large and giant size, especially Doberman pinsher and Great danes. Its aetiology is multifactorial and leads to a narrowing of the spinal canal by morphological and positional caudal cervical vertebrae (C5, C6 and C7), causing compression of the spinal cord and nerve roots. The clinical signs presented by the affected animals are progressive ataxia of hindlimbs and, later, the forelimbs, sometimes progressing to tetraparesis. Neck pain may be present. The diagnosis is made through the association of clinical signs and diagnostic imaging such as radiography, myelography, computed tomography and magnetic resonance imaging. According to the classification of the lesion obtained by imaging examinations, the conservative or surgical treatment is established and the prognosis is variable in accordance with the degree of affection of the spinal cord

Functional neurologic recovery in two dogs diagnosed with severe luxation of the vertebral column

Traumatic injuries to the vertebral column, spinal cord, and cauda equina nerve roots occur frequently in human and veterinary medicine and lead to devastating consequences. Complications include partial or complete loss of motor, sensory, and visceral functions, which are among the main causes of euthanasia in dogs. The present case report describes neurological functional recovery in two dogs that were treated surgically for severe spinal fracture and vertebral luxation. In the first case, a stray, mixed breed puppy was diagnosed with thoracolumbar syndrome and Schiff-Scherrington posture, as well as a T13 caudal epiphyseal fracture with 100% luxation between vertebrae T13 and L1; despite these injuries, the animal did show deep pain sensation in the pelvic limbs. Decompression through hemilaminectomy and spinal stabilization with vertebral body pins and bone cement were performed, and the treatment was supplemented with physiotherapy and acupuncture. In the second case, a mixed breed dog was diagnosed with a vertebral fracture and severe luxation between L6 and L7 after a vehicular trauma, but maintained nociception and perineal reflex. Surgical stabilization of the spine was performed using a modified dorsal segmental fixation technique Both patients showed significant recovery of neurological function. Complete luxation of the spinal canal observed radiographically does not mean a poor prognosis, and in some cases, motor, sensory, and visceral functions all have the potential for recovery. In the first case the determining factor for good prognosis was the presence of deep pain perception, and in the second case the prognosis was determined by the presence of sensitivity and anal sphincter tone during the initial neurological examination.

Rapid assessment of internodal myelin integrity in central nervous system tissue

Monitoring pathology/regeneration in experimental models of de-/remyelination requires an accurate measure not only of functional changes but also of the amount of myelin. We tested whether X-ray diffraction (XRD), which measures periodicity in unfixed myelin, can assess the structural integrity of myelin in fixed tissue. From laboratories involved in spinal cord injury research and in studying the aging primate brain, we solicited "blind" samples and used an electronic detector to record rapidly the diffraction patterns (30 min each pattern) from them. We assessed myelin integrity by measuring its periodicity and relative amount. Fixation of tissue itself introduced +/-10% variation in periodicity and +/-40% variation in relative amount of myelin. For samples having the most native-like periods, the relative amounts of myelin detected allowed distinctions to be made between normal and demyelinating segments, between motor and sensory tracts within the spinal cord, and between aged and young primate CNS. Different periodicities also allowed distinctions to be made between samples from spinal cord and nerve roots and between well-fixed and poorly fixed samples. Our findings suggest that, in addition to evaluating the effectiveness of different fixatives, XRD could also be used as a robust and rapid technique for quantitating the relative amount of myelin among spinal cords and other CNS tissue samples from experimental models of de- and remyelination.