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The spinal cord and brain stem are connected to the autonomic target cells by two-neuron chains of the peripheral sympathetic and parasympathetic nervous systems. These chains consist of populations of preganglionic neurons and postganglionic neurons that are synaptically connected in the autonomic ganglia. They transmit messages from the central nervous system to the target cells are called "final autonomic pathways." These pathways are the building blocks of the peripheral autonomic nervous system. The main difference between the final somatomotor pathways and the final autonomic pathways is that the central messages may undergo quantitative changes in the autonomic ganglia, and that some effector cells are innervated by more than one type of functional autonomic pathway. The impulse pattern transmitted by peripheral autonomic pathways to the target cells is the result of integration in the spinal cord, brain stem, hypothalamus and telencephalon. Reflex patterns that are generated by afferent stimuli in peripheral autonomic neurons may serve as physiological markers to analyze the functional structure of the autonomic circuits in the neuraxis. Using this approach of neurophysiological recording from single autonomic neurons in vivo, detailed knowledge has accumulated about the organization of the autonomic nervous system in animals and humans.
Teleosts exhibit enormous heterogeneity in brain morphology, especially in the patterns of the organization of cerebellum. The cerebellum of a red-tail shark that we analyzed was well-developed and included three main divisions: the valvula cerebelli, the corpus cerebelli, and the vestibulolateral lobe. Characteristically, the cerebellar cortex contained three well-distinct layers: an outer molecular, intermediate ganglionic, and inner granular layer. The ganglionic layer possessed irregularly arranged Purkinje cells and eurydendroid cells that extended their processes into the molecular layer. Both Purkinje cells and eurydendroid cells showed immunoreactivity for iNOS2. Moreover, astrocytes in the cerebellum showed the expression of glial fibrillary acidic protein. The most striking observation in the cerebellum of shark was the lack of deep cerebellar nuclei and a well-identified white matter. On the other hand, the gray substance in the spinal cord displays a characteristic pattern in its organization, in which the dorsal horns lie quite close together, giving the gray substance the shape of an inverted Y and possessing large neurons. Notably, the white matter possessed myelinated nerve fibers. The current study provides the first report on the organization of layers and neurons in the cerebellum and spinal cord of red-tail shark. This research will contribute to the neuroanatomy and evolutionary studies of the brain of Cyprinidae.
A previously healthy 48-year-old female presented to the emergency department with a 2-week history of low back pain, progressive lower extremities weakness, and right leg numbness. There were no bowel or bladder dysfunction symptoms. Spine magnetic resonance imaging (MRI) showed an intradural cystic lesion dorsal to the spinal cord at the level of L1 measuring 1.6 × 2.1 × 4.1 cm, which was T1 hypointense and T2 hyperintense, with a small soft tissue component and no gadolinium enhancement (Figure 1). A small lipomatous component was also noted. There were no associated vertebral anomalies. The patient underwent a T12-L2 laminectomy and cyst resection, which was subtotal due to the cyst adherence to the conus medullaris. Histopathology showed characteristic features of a neurenteric cyst, with respiratory-type epithelium in the cyst wall (Figure 2). Eight months later, follow-up MRI showed no evidence of recurrence. The patient reported improved sensation in the lower extremities; however, there was some residual weakness predominantly in the proximal hip flexors bilaterally.
Currently, the types and distribution of the lesions induced in the central nervous system (CNS) by Trypanosoma cruzi remain unclear as the available evidence is based on fragmented data. Therefore, we developed a systematic review to analyse the main characteristics of the CNS lesions in non-human hosts infected. From a structured search on the PubMed/Medline and Scopus platforms, 32 studies were retrieved, subjected to data extraction and methodological bias analysis. Our results show that the most frequent alterations in the CNS are the presence of different forms of T. cruzi and intense lymphocytes infiltrates. The encephalon is the main target of T. cruzi, and inflammatory changes in the CNS are more frequent and severe in the acute phase of infection. The parasite's genotype and phenotype are associated with the tropism and severity of the CNS lesions. The methodological limitations found in the studies were divergences in inoculation pathways, under-reporting of animal age and weight, sample calculation strategies and histopathological characterization. Since the changes were dependent on the pathogenicity and virulence of the T. cruzi strains, the genotype and phenotype characterization of the parasite are extremely relevant to predict changes in the CNS and the neurological manifestations associated with Chagas’ disease.
Background: Spinal cord stimulation (SCS) is a well-established treatment for chronic neuropathic pain in the lower limbs. Upper limb pain comprises a significant proportion of neuropathic pain patients, but is often difficult to target specifically and consistently with paresthesias. We hypothesized that the use of dorsal nerve root stimulation (DNRS), as an option along with SCS, would help us better relieve pain in these patients. Methods: All 35 patients trialed with spinal stimulation for upper limb pain between July 1, 2011, and October 31, 2013, were included. We performed permanent implantation in 23/35 patients based on a visual analogue scale pain score decrease of ≥50% during trial stimulation. Results: Both the SCS and DNRS groups had significant improvements in average visual analogue scale pain scores at 12 months compared with baseline, and the majority of patients in both groups obtained ≥50% pain relief. The majority of patients in both groups were able to reduce their opioid use, and on average had improvements in Short Form-36 quality of life scores. Complication rates did not differ significantly between the two groups. Conclusions: Treatment with SCS or DNRS provides meaningful long-term relief of chronic neuropathic pain in the upper limbs.
Prostate cancer is associated with vertebral metastasis in up to 10% of
patients; however, intradural spinal cord metastases (ISCM) are much less
frequent. We present the clinical and histopathological findings of a
patient with ISCM arising from prostate. A PubMed literature search for ISCM
from the prostate yielded a total of nine additional cases. ISCM of the
prostate occurs at a late stage of systemic disease and the prognosis is
generally poor. Decompressive surgery followed by adjuvant radiation therapy
may help reduce intractable pain and stabilize neurological symptoms,
thereby improving quality of life.
The aim of the work was to analyse changes in the location and morphological characteristics of calbindin (CB)-immunoreactive (IR) neurons of the thoracic spinal cord of C57BL/6N male mice after completion of a 30-day space flight on board the BION-M1 biosatellite (Russia, 2013). Space flight induced multidirectional changes of the number and morphological parameters of CB-positive neurons. The number of IR neurons increased in laminae I (from 10 to 17 neurons per section), II (from 42 to 67 cells per section) and IX (from two neurons per segment to two neurons per section), but CB disappeared in neurons of lamina VIII. Weightlessness did not affect the number of CB-IR neurons in laminae III–V and VII, including preganglionic sympathetic neurons. The cross-sectional area of CB-IR neurons decreased in lamina II and VII (group of partition cells) and increased in laminae III–V and IX. After a space flight, few very large neurons with long dendrites appeared in lamina IV. The results obtained give evidence about substantial changes in the calcium buffer system and imbalance of different groups of CB-IR neurons due to reduction of afferent information under microgravity.
The hypothesis that the central nervous system (CNS) generates movement as a shift of the limb's equilibrium posture has been corroborated experimentally in studies involving single- and multijoint motions. Posture may be controlled through the choice of muscle length-tension curve that set agonist-antagonist torque-angle curves determining an equilibrium position for the limb and the stiffness about the joints. Arm trajectories seem to be generated through a control signal defining a series of equilibrium postures. The equilibrium-point hypothesis drastically simplifies the requisite computations for multijoint movements and mechanical interactions with complex dynamic objects in the environment. Because the neuromuscular system is springlike, the instantaneous difference between the arm's actual position and the equilibrium position specified by the neural activity can generate the requisite torques, avoiding the complex “inverse dynamic” problem of computing the torques at the joints. The hypothesis provides a simple, unified description of posture and movement as well as contact control task performance, in which the limb must exert force stably and do work on objects in the environment. The latter is a surprisingly difficult problem, as robotic experience has shown. The prior evidence for the hypothesis came mainly from psychophysical and behavioral experiments. Our recent work has shown that microstimulation of the frog spinal cord's premotoneural network produces leg movements to various positions in the frog's motor space. The hypothesis can now be investigated in the neurophysiological machinery of the spinal cord.
It is increasingly clear that spinal reflex systems cannot be described in terms of simple and constant reflex actions. The extensive convergence of segmental and descending systems onto spinal interneurons suggests that spinal interneurons are not relay systems but rather form a crucial component in determining which muscles are activated during voluntary and reflex movements. The notion that descending systems simply modulate the gain of spinal interneuronal pathways has been tempered by the observation that spinal interneurons gate and distribute descending control to specific motoneurons. Spinal reflex systems are complex but current approaches will continue to provide insight into motor systems. During movement, several neural mechanisms act to reduce the functional complexity of motor systems by inhibiting some of the parallel reflex pathways available to segmental afferents and descending systems. The flexion reflex system is discussed as an example of the flexibility of spinal interneuron systems and as a useful conceptual construct. Examples are provided of the kinds of experiments that can be developed using current approaches to spinal interneuronal systems.
Afferent nerve endings in the bladder wall are important in conveying the sensations associated with degrees of bladder fullness and also bladder pain to the spinal cord. This chapter discusses the peripheral control of micturition, cellular signaling pathways in normal bladder function, spinal control of bladder function, and interoceptive sensations. Acetylcholine (ACh) and adenosine triphosphate (ATP) are released by the bladder urothelium during urine storage, in increasing concentrations as the bladder wall distends. Muscarinic, nicotinic and purinergic receptors have been identified in the bladder urothelium and/or suburothelium in human or animal studies. In normal adults information about the bladder is passed from the periaqueductal gray (PAG) to higher regions of the brain. This type of interoception is mediated by afferent input through small-diameter fibers in lamina 1 of the spinal cord. A number of spinal reflex mechanisms are involved in the control of the urethro-vesical unit.
Our sensory and motor capacities depend on more than just the workings of the brain and spinal cord; they also depend on the workings of other parts of the body, such as the sensory organs, the musculoskeletal system, and relevant parts of the peripheral nervous system (e.g., sensory and motor nerves). It seems natural to think of cognition as an interaction effect: the result, at least in part, of causal processes that span the boundary separating the individual organism from the natural, social, and cultural environment. One thing to say that cognitive activity involves systematic causal interaction with things outside the head, and it is quite another to say that those things instantiate cognitive properties or undergo cognitive processes. Bridging this conceptual gap remains a major challenge for defenders of the extended mind. Situated cognition is a many-splendored enterprise.
Spina bifida meningomyelocele with hydrocephalus (SBM) is commonly associated with anomalies of the corpus callosum (CC). We describe MRI patterns of regional CC agenesis and relate CC anomalies to functional laterality based on a dichotic listening test in 90 children with SBM and 27 typically developing controls. Many children with SBM (n = 40) showed regional CC anomalies in the form of agenesis of the rostrum and/or splenium, and a smaller number (n = 20) showed hypoplasia (thinning) of all CC regions (rostrum, genu, body, and splenium). The expected right ear advantage (REA) was exhibited by normal controls and children with SBM having a normal or hypoplastic splenium. It was not shown by children with SBM who were left handed, missing a splenium, or had a higher level spinal cord lesion. Perhaps the right hemisphere of these children is more involved in processing some aspects of linguistic stimuli. (JINS, 2008, 14, 771–781.)
By
Patrick Mertens, Professor of Neurosurgery Hôpital Neurologique et Neuro-Chirurgical Pierre Wertheimer, Lyon, France,
Marc Sindou, Professor of Neurosurgery Hôpital Neurologique et Neuro-Chirurgical Pierre Wertheimer, Lyon, France
Spasticity is one of the commonest sequelae of neurological diseases. In most patients spasticity is useful in compensating for lost motor strength. Nevertheless, in a significant number of patients it may become excessive and harmful, leading to further functional losses. Stimulation of spinal cord was developed in the 1970s on the basis of the 'gate-control theory' of Melzach and Wall for the treatment of neurogenic pain. This method has been found to be partially effective in the treatment of spastic syndromes, such as those encountered in multiple sclerosis or spinal cord degenerative diseases, such as Strumpell-Lorrain syndrome. Orthopaedic procedures can reduce spasticity by means of muscle relaxation that results from tendon lengthening and may help in restoring articular function when deformities have become irreducible. Current techniques for correcting excessive shortness of the muscle tendon assembly are muscular desinsertion, myotomy, tenotomy and lengthening tenotomy.
Controlling neuropathic pain is an unmet medical need and we set out to identify new therapeutic candidates. AV411 (ibudilast) is a relatively nonselective phosphodiesterase inhibitor that also suppresses glial-cell activation and can partition into the CNS. Recent data strongly implicate activated glial cells in the spinal cord in the development and maintenance of neuropathic pain. We hypothesized that AV411 might be effective in the treatment of neuropathic pain and, hence, tested whether it attenuates the mechanical allodynia induced in rats by chronic constriction injury (CCI) of the sciatic nerve, spinal nerve ligation (SNL) and the chemotherapeutic paclitaxel (Taxol¯). Twice-daily systemic administration of AV411 for multiple days resulted in a sustained attenuation of CCI-induced allodynia. Reversal of allodynia was of similar magnitude to that observed with gabapentin and enhanced efficacy was observed in combination. We further show that multi-day AV411 reduces SNL-induced allodynia, and reverses and prevents paclitaxel-induced allodynia. Also, AV411 cotreatment attenuates tolerance to morphine in nerve-injured rats. Safety pharmacology, pharmacokinetic and initial mechanistic analyses were also performed. Overall, the results indicate that AV411 is effective in diverse models of neuropathic pain and support further exploration of its potential as a therapeutic agent for the treatment of neuropathic pain.
Spinal cord ependymomas are relatively rare tumours and their management is not well established. This retrospective analysis was performed to examine the outcome of patients treated for this malignancy at our institution between 1982 and 2004.
Hospital charts of 14 consecutive patients (10 men and four women) aged 8 to 58 years (median 32 years) were retrospectively analysed. This series included nine extramedullary and five intramedullary well differentiated (eight – G1, six – G2) ependymomas. All patients were treated with primary surgery. Postoperative radiotherapy was administered in 12 patients after subtotal excision. Total dose ranged from 35Gy in 17 fractions to 50.4Gy in 28 fractions. One patient experienced spinal axis failure despite complete resection of the primary tumour and was managed with salvage radiotherapy and chemotherapy following surgical excision of the relapse. There have been no radiotherapy-related serious side effects.
One patient was lost to follow-up. Of the remaining 13 patients, at a median follow-up of 5.5 years (3 months to 20 years), 12 were alive including 11 without progression.
Conclusion: In our group of patients radiotherapy following subtotal resection or used as a single modality was well tolerated and resulted in 92% long-term survival.