Anatomy and Imaging of the Spinal Cord: An Overview.

The spinal cord comprises the part of the central nervous system located within the vertebral canal, extending from the foramen magnum to approximately the second lumbar vertebra. The spinal cord is covered by 3 meninges: dura mater, arachnoid mater, and pia mater (arranged from the outermost layer inward). A cross-section of the spinal cord reveals gray and white matter. Ascending and descending pathways have defined locations in the matter of the spinal cord. This article aims to review the spinal cord anatomy and demonstrate the imaging aspects, which are essential for the interpretation and understanding of spinal cord injuries.

Hypertension and sympathetic nervous system overactivity rely on the vascular tone of pial vessels of the rostral ventrolateral medulla in spontaneously hypertensive rats.

NEW FINDINGS: What is the central question of this study? Is purinergic signalling in the pial vessels involved in the control of vascular tone in the ventral surface of the brainstem, affecting high blood pressure and sympathetic overactivity in spontaneously hypertensive rats? What is the main finding and its importance? The regulation of vascular tone in the ventral surface of the brainstem is tailored to support neuronal functions, arterial pressure and sympathetic activity. This adds one more piece in the complex puzzle to understand the central mechanisms underlying the genesis of hypertension. ABSTRACT: Evidence suggests the rostral ventrolateral medulla (RVLM) region is chronically hypoperfused and hypoxic in spontaneously hypertensive rats (SHR), which can facilitate ATP release throughout the brainstem. Thus, we hypothesized that purinergic signalling plays a key role in the increased vascular tone in the RVLM region, which in turn could be responsible for the high sympathetic tone and blood pressure in the SHR. The application of an antagonist of P2 receptors, pyridoxalphosphate-6-azophenyl-2',4'-disulfonic acid (10 µm), or of P2Y1a receptors, MRS2179 (100 µm), on the surface of RVLM pial vessels of SHR produced an increase in the diameter of blood vessels (PPADS: 31 ± 1.4 µm or MRS2179: 32 ± 0.78 µm vs. saline: 27 ± 1.2 µm), an effect not observed in normotensive Wistar rats. In addition, the antagonism of P2 receptors was able to evoke a significant decrease in the arterial pressure, heart rate and splanchnic nerve activity in SHR, but not in Wistar rats. Our data show that SHR have higher vascular tone of pial vessels in the RVLM region when compared to the normotensive Wistar rats, a mechanism that relies on purinergic signalling through P2 receptors, suggesting a possible association with higher activity of sympathoexcitatory neurones, and sustained increases in blood pressure.

Salvinorin A preserves cerebral pial artery autoregulation after forebrain ischemia via the PI3K/AKT/cGMP pathway.

This study aimed to investigate the protective effect of salvinorin A on the cerebral pial artery after forebrain ischemia and explore related mechanisms. Thirty Sprague-Dawley rats received forebrain ischemia for 10 min. The dilation responses of the cerebral pial artery to hypercapnia and hypotension were assessed in rats before and 1 h after ischemia. The ischemia reperfusion (IR) control group received DMSO (1 µL/kg) immediately after ischemia. Two different doses of salvinorin A (10 and 20 µg/kg) were administered following the onset of reperfusion. The 5th, 6th, and 7th groups received salvinorin A (20 µg/kg) and LY294002 (10 µM), L-NAME (10 µM), or norbinaltorphimine (norBIN, 1 µM) after ischemia. The levels of cGMP in the cerebrospinal fluid (CSF) were also measured. The phosphorylation of AKT (p-AKT) was measured in the cerebral cortex by western blot at 24 h post-ischemia. Cell necrosis and apoptosis were examined by hematoxylin-eosin staining (HE) and TUNEL staining, respectively. The motor function of the rats was evaluated at 1, 2, and 5 days post-ischemia. The dilation responses of the cerebral pial artery were significantly impaired after ischemia and were preserved by salvinorin A treatment. In addition, salvinorin A significantly increased the levels of cGMP and p-AKT, suppressed cell necrosis and apoptosis of the cerebral cortex and improved the motor function of the rats. These effects were abolished by LY294002, L-NAME, and norBIN. Salvinorin A preserved cerebral pial artery autoregulation in response to hypercapnia and hypotension via the PI3K/AKT/cGMP pathway.

Endovascular occlusion of pial arteriovenous macrofistulae, using pCANvas1 and adenosine-induced asystole to control nBCA injection.

Background In large-caliber pial macrofistulae (pMF), the combination of high blood flow velocity and large efferent artery diameter makes control over the endovascular vessel occlusion difficult and may result in the inadvertent venous passage of occlusive devices or embolic agents. Case descriptions Patient 1: A 27-year-old man presented with headache and ataxia. An infratentorial pMF supplied by both superior cerebellar arteries with venous ectasia was found. The first treatment attempt using balloons and coils failed since the position of either device could not be controlled because of a distal diameter of the feeding artery of 8 mm. In a second session a pCANvas1 (phenox) was deployed at the level of the arteriovenous connection and adenosine-induced asystole allowed the controlled injection of nBCA/Lipiodol with partial occlusion of the pMF. A remaining arteriovenous shunt was occluded under asystole in a third session. The procedures were well tolerated, the patient returned to normal and DSA confirmed the occlusion of the fistula. Patient 2: A 13-year-old boy with hereditary hemorrhagic teleangiectasia presented with an intracerebral hemorrhage from an aneurysm of the left MCA. Twelve weeks after the aneurysm treatment a feeding MCA branch (diameter 4.5 mm) of a right frontal pMF was catheterized. The macrofistula was occluded by deployment of a pCANvas1, followed by the injection of nBCAl/Lipiodol under adenosine-induced asystole. Conclusion pCANvas1 and adenosine-induced asystole allow a controlled injection of nBCA/Lipiodol for the endovascular occlusion of high-flow pMF without venous passage of the embolic agent.

Macroscopic aspects of Saimiri sciureus dura mater / Aspectos macroscópicos da dura mater de Saimiri sciureus

Saimiri sciureus is a small New World primate (NHP) commonly called macaco-de-cheiro that inhabits the tropical forests of the Amazon basin. Anatomical features are not well studied in most primates, and the encephalic morphology and related structures are still quite unknown. Comparative anatomy of the meninges in South American primates is still scarce. Dura mater, arachnoid and pia mater are a group of stratified layers that surrounds and promotes protection to the medulla spinalis. This study aimed to shed light on the anatomy of dura mater in Samiri sciureus in order to contribute to the neuroscience in primates. We investigated three young females and two males of S. sciureus. Specimens were fixed through perfusion with a 10 percent formaldehyde aqueous solution. In S. sciureus encephalus few gyrus and circunvolutions, and a very delicate system consisting of eight sinus venosus was found between the dura mater layers. Based on our findings, we can conclude that the Saimiri sciureus dura mater is quite similar to other mammals, however we detected a new sinus venosus formation at the level of parietal bone, named sinus parietalis, what appears to be its first description.

Saimiri sciureus, com nome comum de macaco-de-cheiro, é um pequeno primata do Novo Mundo (PNM) que habita as florestas tropicais da Bacia Amazônica. Os detalhes anatômicos de primatas são pouco conhecidos e a anatomia comparada de animais selvagens da América do Sul é escassa, mais especificamente, sobre as meninges de PNM. Meninges pertencem a um sistema de membrana responsável por envolver e proteger o Sistema Nervoso Central; consiste em três membranas: dura mater, aracnoide e pia mater. Este estudo objetivou a elucidação do comportamento anatômico da dura mater de S. sciureus com o intuito de contribuir para a área de neurociências em primatas. Foram investigados três fêmeas e dois machos jovnes de S. sciureus. Os espécimes de meninges foram fixados por perfusão usando solução aquosa 10 por cento de formaldeído. O encéfalo de S. sciureus demonstrou um número baixo de giros e circunvoluções, e um sistema delicado de oito seios venosos foi verificado entre as camadas da dura mater. Baseados em nossos achados podemos concluir que a dura mater de S. sciureus é similar aos de outros mamíferos, no entanto, apresenta a formação de um novo seio venoso em nível ao osso parietal, sendo denominado de seio parietal. Isto parece ser a primeira descrição deste seio.

Macroscopic aspects of Saimiri sciureus dura mater / Aspectos macroscópicos da dura mater de Saimiri sciureus

Saimiri sciureus is a small New World primate (NHP) commonly called macaco-de-cheiro that inhabits the tropical forests of the Amazon basin. Anatomical features are not well studied in most primates, and the encephalic morphology and related structures are still quite unknown. Comparative anatomy of the meninges in South American primates is still scarce. Dura mater, arachnoid and pia mater are a group of stratified layers that surrounds and promotes protection to the medulla spinalis. This study aimed to shed light on the anatomy of dura mater in Samiri sciureus in order to contribute to the neuroscience in primates. We investigated three young females and two males of S. sciureus. Specimens were fixed through perfusion with a 10 percent formaldehyde aqueous solution. In S. sciureus encephalus few gyrus and circunvolutions, and a very delicate system consisting of eight sinus venosus was found between the dura mater layers. Based on our findings, we can conclude that the Saimiri sciureus dura mater is quite similar to other mammals, however we detected a new sinus venosus formation at the level of parietal bone, named sinus parietalis, what appears to be its first description.(AU)

Saimiri sciureus, com nome comum de macaco-de-cheiro, é um pequeno primata do Novo Mundo (PNM) que habita as florestas tropicais da Bacia Amazônica. Os detalhes anatômicos de primatas são pouco conhecidos e a anatomia comparada de animais selvagens da América do Sul é escassa, mais especificamente, sobre as meninges de PNM. Meninges pertencem a um sistema de membrana responsável por envolver e proteger o Sistema Nervoso Central; consiste em três membranas: dura mater, aracnoide e pia mater. Este estudo objetivou a elucidação do comportamento anatômico da dura mater de S. sciureus com o intuito de contribuir para a área de neurociências em primatas. Foram investigados três fêmeas e dois machos jovnes de S. sciureus. Os espécimes de meninges foram fixados por perfusão usando solução aquosa 10 por cento de formaldeído. O encéfalo de S. sciureus demonstrou um número baixo de giros e circunvoluções, e um sistema delicado de oito seios venosos foi verificado entre as camadas da dura mater. Baseados em nossos achados podemos concluir que a dura mater de S. sciureus é similar aos de outros mamíferos, no entanto, apresenta a formação de um novo seio venoso em nível ao osso parietal, sendo denominado de seio parietal. Isto parece ser a primeira descrição deste seio.(AU)

Inflammatory changes in the central nervous system are associated with behavioral impairment in Plasmodium berghei (strain ANKA)-infected mice.

Experimental cerebral malaria is a neuroinflammatory condition that results from the host immune response to the parasite. Using intravital microscopy, we investigated leukocyte recruitment in the brain microcirculation and the temporal relationship of this process to the behavioral changes observed in Plasmodium berghei (strain ANKA)-infected C57Bl/6 mice. We found that leukocyte recruitment was increased from day 5 post-infection (p.i.) onwards. Histopathological changes and increased levels of inflammatory cytokines in the brain were also observed. Behavioral performance evaluated by the SHIRPA protocol showed functional impairment from day 6 p.i. onwards. Thus, early leukocyte migration into the brain and associated inflammatory changes may be involved in neurological impairment in parasite-infected C57Bl/6 mice.

Aracnoides trabecular, piamadre espinal humana y anestesia subaracnoidea / Trabecular arachnoid membrane, human spinal piamater and subarachnoid anesthesia

En los textos de anestesiología se aportan pocos detalles sobre la aracnoides trabecular y la piamadre espinal humana, a pesar de ser estructuras íntimamente relacionadas con los anestésicos locales administrados en una anestesia subaracnoidea. Complicaciones tales como el síndrome de cauda equina y el síndrome de irritación radicular transitorio posterior a la realización de bloqueos subaracnoideos, sumado a la alta permeabilidad que ha sido asociada con la piamadre, nos ha motivado a investigar sobre la ultraestructura de estas meninges. Método. Las muestras estudiadas se tomaron de cadáveres recientes y fueron examinadas por microscopía electrónica de transmisión y de barrido. Resultados. El trabeculado aracnoideo rodeaba a las raíces nerviosas, a la médula y a los vasos que se encontraban dentro del espacio subaracnoideo, limitando zonas. La piamadre estaba formada por un plano celular y por un compartimiento subpial. En el plano celular existían perforaciones naturales, especialmente en la región del cono medular y en las raíces nerviosas. Conclusiones. La inyección accidental de anestésicos locales dentro de las fundas que formaban el trabeculado aracnoideo podría justificar una dilución inadecuada de estas soluciones y el origen de síndromes neurotóxicos transitorios o permanentes. La alta permeabilidad de la piamadre podría deberse, en parte, a la existencia de perforaciones naturales, las cuales facilitarían un pasaje rápido de las sustancias introducidas en el líquido cefalorraquídeo hacia las raíces nerviosas y la médula espinal. En este caso, la membrana basal ubicada por debajo de las fibras colágenas del compartimiento subpial sería la única estructura limitante previa al tejido glio-neuronal de la médula.

Few details are to be found in anesthesiology texts concerning the trabecular arachnoid membrane and the human spinal pia mater in spite of being structures that are intimately related to local anesthetics administered in subarachnoid anesthesia. We were driven to investigate the ultrastructure of these meninges by complications such as the cauda equina syndrome and the transitory radicular irritation syndrome following subarachnoid blocks, added to the high permeability associated to the pia mater. Method. The samples analyzed were taken from recently deceased cadavers and were examined under transmission and scanning electron microscopy. Results. The arachnoid trabeculation surrounded the nerve roots, the spinal cord and the vessels within the subarachnoid space, limiting areas. The pia mater was formed by a cellular plane and by a sub-pial compartment. There were natural perforations in the cellular plane, particularly in the medullar cone region and the nerve roots. Conclusions. Accidental injection of local anesthetics into the sheaths formed by arachnoid trabeculation could be the cause of inadequate dilution of these solutions and the source of transitory or permanent neurotoxic syndromes. The high permeability of the pia mater could be partly due to the existence of natural perforations, which enable the quick passage of the substances introduced in the cerebrospinal fluid into the nerve roots and spinal cord. ln this case, the basal membrane located underneath the collagen fibers of the subpial compartment would be the only limiting structure before the glioneural tissue of the spinal cord.

Os textos de anestesiologia fornecem poucos detalhes sobre a aracnóide trabecular e a pia-máter espinhal humana, apesar delas serem estruturas intimamente relacionadas com os anestésicos locais administrados em uma anestesia subaracnóidea. Complicações tais como a síndrome de cauda eqüina e a síndrome de irritação radicular transitória posterior a bloqueios subaracnóideosas quais se soma a alta permeabilidade, que tem sido associada à pia-máter -levou-nos a pesquisar a ultraestrutura dessas meninges. Método. As amostras estudadas foram coletadas de cadáveres recentes e examinadas por microscopia eletrónica de transmissão e de varredura. Resultados. A trabeculação aracnóidea rodea va as raízes nervosas, a medula e os vasos no interior do espaço subaracnóide, limitando zonas. A pia-máter estava formada por um plano celular e um espaço subpial. No plano celular existiam perfurações naturais, especialmente na regiáo do cone medular e nas raízes nervosas. Conclusóes. A injeção acidental de anestésicos locais no interior das coberturas que formavam a trabeculação aracnoidea poderia justificar uma diluição inadequada das soluções e a origem de síndromes neurotóxicas transitórias ou permanentes. A causa da alta permeabilidade da pia-máter seria, em parte, a existencia de perfurações naturais que facilitariam a rápida passagem das substancias introduzidas no líquido cefalorraquiano para as raizes nervosas e a medula espinhal. Neste caso, a membrana basal localizada abaixo das fibras colágenas do espaço subpial seria a única estrutura limitante anterior ao tecido glio-neuronal da medula.

Treatment of refractory partial status epilepticus with multiple subpial transection: case report.

Status epilepticus (SE) represents a medical emergency that annually affects 60,000--150,000 individuals in the United States. Selective neuronal loss in vulnerable areas has been pathologically demonstrated following convulsive SE primarily affecting the limbic system, thalamus and cerebellum. Morbidity in those cases that follow refractory SE (RSE) is poorly documented. There have been anecdotal reports of surgical treatment for this condition, especially secondary to brain lesions. We report a 6-year-old patient who was in RSE for 60 days, without a brain lesion documented by MRI. The patient underwent multiple subpial transection (MST) of the sensorimotor cortex, which by ictal EEG and ictal SPECT proved to be the epileptogenic zone. We conclude that MST should be considered as an alternative treatment for refractory partial SE.

Leptomeningeal and skin fibroblasts: two different cell types?

Leptomeningeal and skin fetal (E16-17) fibroblasts were subcultured in vitro either in DMEM/F12 basal medium (with or without 10% FCS) or in astroglial conditioned medium (ACM). Both populations were characteristically composed of flat, undifferentiated, fibronectin(+), GFAP(-)cells where cultured in fetal serum supplemented basal media. When exposed to ACM leptomeningeal cells developed a population of thin, elongated, fibronectin(+) cells with radial type long processes while skin fibroblasts did not show significant changes in their characteristic morphotype. Exposure to db cAMP in basal medium resulted within 3 hr in their transformation to an astrocytic-like morphotype characterized by a condensed soma and multiple, short processes. Twenty-four hours later skin fibroblasts had returned to their flat appearance while leptomeningeal ones showed elongated, radial-like forms. Results indicate the possible existence of different receptors (to ACM factors) and/or cytoskeletal properties, and suggest that ACM-reactive fibroblasts of leptomeningeal origin represent a different cell type from those of skin origin. The hypothetical role of leptomeningeal cells during brain development is considered.

[Effect of hypertonic solutions by intravenous route into cerebral perivascular spaces in the dog]. / Efeitos de soluçao hipertônica por via endovenosa nos espaços perivasculares cerebrais do cão.

The authors studied the behavior of vessels penetrating the nervous parenchyma in the basal paraolfactory space after an intravenous injection of the hypertonic sodium chloride solution (20/1000), plus a 1% India ink solution injected via subarachnoidal space. The experiments were performed in 10 dogs of different races keeping 6 as controls. The experiment followed Mallory's method and consisted in cutting series of 20 microns sections, going from the surface down to 10mm deep, 10 plates (in each case) of the vessels and the pio-glial membrane were drawn up with the aid of a "camera lucida". The statistical analysis showed a significant enhance in the perivascular space due to the hipertonic solution which seems to results from an osmotic phenomenon through the pio-glial membrane. In this way, the pio-glial membrane can be considered as an active structure in the neuronal-glial-meningeal complex.