Ricardo José de Almeida Leme

Distant microglial and astroglial activation secondary to experimental spinal cord lesion

Este trabalho analisou se a resposta glial apos a lesao da medula espinhal e restrita a formacao da cicatriz no local do trauma ou pode tambem estar relacionada a efeitos troficos paracrinos em toda a medula espinhal. Hemitranseccao da medula espinhal de ratos adultos foi realizada em nivel toracico baixo. Apos 7 dias e 3 meses as medulas espinhais dos animais foram removidas e submetidas a imuno-histoquimica para a visualizacao da proteina fibrilar glial acida GFAP (marcador do astrocito), do OX42 (marcador da microglia), e do fator de crescimento basico derivado do fibroblasto (bFGF), produzido pelo astrocito. Para a quantificacao das alteracoes dos perfis imunoreativos utilizou-se analise de imagem computadorizada. No local da lesao observou-se aumento no numero de astrocitos GFAP positivos bem como de celulas fagociticas OX42 positivas, caracterizando uma formacao cicatricial densa que aumentou aos 3 meses da lesao. A analise morfometrica da area e microdensitometrica da intensidade das imunoreatividades do OX42 e da GFAP mostrou microglia e astrocitos reativos nas substâncias cinzenta e branca em toda a medula espinal 7 dias e 3 meses apos cirurgia. Marcacao imunofluorescente com 2 cromogenos demonstrou o aumento da expressao do bFGF nos astrocitos reativos. Estes resultados mostram que a ativacao glial no local da lesao da medula espinhal e necessaria ao processo de cicatrizacao e reparo do tecido nervoso. Embora a gliose constitua uma barreira a regeneracao axonal, a ativacao glial em niveis distantes da lesao pode contribuir para o trofismo e plasticidade neuronal favorecendo a manutencao neuronal e o crescimento de fibras nervosas.This paper analysed whether glial responses following a spinal cord lesion is restricted to a scar formation close to the wound or they might be also related to widespread paracrine trophic events in the entire cord. Spinal cord hemitransection was performed in adult rats at the thoracic level. Seven days and three months later the spinal cords were removed and submitted to immunohistochemistry of glial fibrillary acidic protein (GFAP) and OX42, markers for astrocytes and microglia, as well as of basic fibroblast growth factor (bFGF), an astroglial neurotrophic factor. Computer assisted image analysis was employed in the quantification of the immunoreactivity changes. At the lesion site an increased number of GFAP positive astrocytes and OX42 positive phagocytic cells characterized a dense scar formation by seven days, which was further augmented after three months. Morphometric analysis of the area and microdensitometric analysis of the intensity of the GFAP and OX42 immunoreactivities showed reactive astrocytes and microglia in the entire spinal cord white and gray matters 7 days and 3 months after surgery. Double immunofluorescence demonstrated increased bFGF immunostaining in reactive astrocytes. The results indicated that glial reaction close to an injury site of the spinal cord is related to wounding and repair events. Although gliosis constitutes a barrier to axonal regeneration, glial activation far from the lesion may contribute to neuronal trophism and plasticity in the lesioned spinal cord favoring neuronal maintenance and fiber outgrowth.

Glial cell line-derived neurotrophic factor added to a sciatic nerve fragment grafted in a spinal cord gap ameliorates motor impairments in rats and increases local axonal growth

PURPOSE The aversive nature of regenerative milieu is the main problem related to the failure of neuronal restoration in the injured spinal cord which however might be addressed with an adequate repair intervention. We evaluated whether glial cell line-derived neurotrophic factor (GDNF) may increase the ability of sciatic nerve graft, placed in a gap promoted by complete transections of the spinal cord, to enhance motor recovery and local fiber growth. METHODS Rats received a 4 mm-long gap at low thoracic level and were repaired with a fragment of the sciatic nerve. GDNF was added (NERVE+/-GDNF) or not to the grafts (NERVE--GDNF). Motor behavior score (BBB) and sensorimotor tests-linked to the combined behavior score (CBS), which indicate the degree of the motor improvement and the percentage of functional deficit, respectively, and also the spontaneous motor behavior in an open field by means of an infrared motion sensor activity monitor were analyzed. At the end of the third month post surgery, the tissue composed by the graft and the adjacent regions of the spinal cord was removed and submitted to the immunohistochemistry of the neurofilament-200 (NF-200), growth associated protein-43 (GAP-43), microtubule associated protein-2 (MAP-2), 5-hidroxytryptamine (serotonin, 5-HT) and calcitonin gene related peptide (CGRP). The immunoreactive fibers were quantified at the epicenter of the graft by means of stereological procedures. RESULTS Higher BBB and lower CBS levels (p < 0.001) were found in NERVE+/-GDNF rats. GDNF added to the graft increased the levels of individual sensorimotor tests mainly at the third month. Analysis of the spontaneous motor behavior showed decreases in the time and number of small movement events by the third month without changes in time and number of large movement events in the NERVE

Surgical management of Guyon's canal syndrome, an ulnar nerve entrapment at the wrist: report of two cases

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Experimental Models of Partial Lesion of Rat Spinal Cord to Investigate Neurodegeneration, Glial Activation, and Behavior Impairments

GDNF rats. Immunoreactive fibers were encountered inside the grafts and higher amounts of NF-200, GAP-43 and MAP-2 fibers were found in the epicenter of the graft when GDNF was added. A small amount of descending 5-HT fibers was seen reentering in the adjacent caudal levels of the spinal cords which were grafted in the presence of GDNF, event that has not occurred without the neurotrophic factor. GDNF in the graft also led to a large amount of MAP-2 perikarya and fibers in the caudal levels of the cord gray matter, as determined by the microdensitometric image analysis. CONCLUSIONS GDNF added to the nerve graft favored the motor recovery, local neuronal fiber growth and neuroplasticity in the adjacent spinal cord.

Contuse lesion of the rat spinal cord of moderate intensity leads to a higher time-dependent secondary neurodegeneration than severe one. An open-window for experimental neuroprotective interventions.

Guyons canal syndrome, an ulnar nerve entrapment at the wrist, is a well-recognized entity. The most common causes that involve the ulnar nerve at the wrist are compression from a ganglion, occupational traumatic neuritis, a musculotendinous arch and disease of the ulnar artery. We describe two cases of Guyons canal syndrome and discuss the anatomy, aetiology, clinical features, anatomical classification, diagnostic criteria and treatment. It is emphasized that the knowledge of both the surgical technique and anatomy is very important for a satisfactory surgical result.

Causes and treatment of intracranial haemorrhage complicating shunting for paediatric hydrocephalus

The article demonstrates two experimental models of spinal cord partial injury in rats: a contuse model promoted by the NYU impactor system and a partial hemitransection model achieved by a stereotaxic-posi-tioned adjustable wire knife. By means of a defined impact weight (10 g) and a digital optical potentiometer linked to a computer, the impactor transferred and registered a moderate or a severe contusion to the rat spinal cord at a low thoracic level after dropping the weight from distances of 25 mm and 50 mm, respectively, to the dorsal surface of the exposed dura spinal cord. Impact curve was calculated and the parameters of the trauma, like impact velocity, cord compression distance and cord compression rates were obtained in order to demonstrate trauma severity. To promote partial hemitransection, rats were positioned in a spinal cord unit of a stereotaxic apparatus and lesion was made with the adjustable wire knife spatially oriented. By means of a computerized infrared motion sensor-home cage activity monitor and a noncomputerized evaluation of motor behavior using the inclined plane and the motor score of Tarlov tests, behavior was analyzed in an acute period postlesion. Rats were sacrificed and spinal cords were processed for routine staining to show neurons and for GFAP and OX42 immunohistochemistry to demonstrate glial cells. The tissue labelings were quantified using computer assisted stereology by means of an optical disector and microden-sitometric image analysis by means of quantification of gray values of discriminated profiles. While partial hemitransection model favored a more accurate control of the lesion location, the contuse model allowed us to perform different degrees of lesion severity. A close correlation between behavioral impairment and severity of trauma was seen in the rats submitted to spinal cord contusion. The stereologic lesion index showed a correlation between severity of trauma and tissue damage by 7 days and demonstrated a time-dependent secondary degeneration after moderate but not after severe spinal cord contusion from 7 to 30 days after injury. Long-lasting activations of astrocytes and microglia seen by persisted increases in the specific mean gray values of immu-noreactivities were also found in all levels of the white and gray matters of the partial hemitransected spinal cord until 3 months postinjury which can he related to wound/repair events and paracrine trophic support to spinal cord remaining neurons. The results showed that controlled partial lesions may provide an important toll to study trophism and plasticity in the spinal cord.

Traumatic Acute Giant Epidural Hematoma in a Hydrocephalic Shunted Child

Secondary neurodegeneration takes place in the surrounding tissue of spinal cord trauma and modifies substantially the prognosis, considering the small diameter of its transversal axis. We analyzed neuronal and glial responses in rat spinal cord after different degree of contusion promoted by the NYU Impactor. Rats were submitted to vertebrae laminectomy and received moderate or severe contusions. Control animals were sham operated. After 7 and 30 days post surgery, stereological analysis of Nissl staining cellular profiles showed a time progression of the lesion volume after moderate injury, but not after severe injury. The number of neurons was not altered cranial to injury. However, same degree of diminution was seen in the caudal cord 30 days after both severe and moderate injuries. Microdensitometric image analysis demonstrated a microglial reaction in the white matter 30 days after a moderate contusion and showed a widespread astroglial reaction in the white and gray matters 7 days after both severities. Astroglial activation lasted close to lesion and in areas related to Wallerian degeneration. Data showed a more protracted secondary degeneration in rat spinal cord after mild contusion, which offered an opportunity for neuroprotective approaches. Temporal and regional glial responses corroborated to diverse glial cell function in lesioned spinal cord.

Comparison between two surgical techniques for prenatal correction of meningomyelocele in sheep

Abstract Intracranial haematomas are a well-known complication of shunting procedures for hydrocephalic patients. Most are subdural haematomas, and epidural haematomas are much less common in this setting. Their aetiology is thought to be due to an overdrainage of cerebrospinal fluid and a rapid lowering of intracranial pressure, leading to the development of these haematomas. Since the advent of modern neuroimaging techniques, prompt diagnosis of postshunting intracranial haematoma has been possible even in asymptomatic patients. The choice between surgical and nonsurgical management of postshunting intracranial haematoma is a difficult and controversial issue, especially in asymptomatic patients. Several therapeutic options have been proposed for the treatment of postshunting intracranial haematoma. Evacuation of the haematoma by conventional neurosurgical methods with the implantation of a higher pressure valve system is the most common option adopted. Intraventricular haemorrhage is occasionally reported, chiefly in children with hydrocephalus associated with vein of Galen malformation.

Primary spinal meningioma in a 10-year-old boy

Extradural hematoma (EDH) is considered to be a rare complication of head trauma in children, and represents a serious and urgent pathology from which complete recovery can be expected if specialized treatment is instituted in time. In this article, the authors report the potential danger to a hydrocephalic shunted child who was apparently asymptomatic at the time of hospital admission with a mild head injury and developed an EDH of venous origin. This child had a rapid (time interval from injury to decerebrate posture of about 2 h), atypical (remained asymptomatic most of the time until abruptly deterioration) and fatal course, stressing the importance of early diagnosis and rapid therapy in order to avoid the death of the patient. The authors discuss the role of the ventriculoperitoneal shunting system in the lack of clinical symptoms associated with the presence of a giant EDH and a rapid and fatal course, and stress the importance of computed tomographic (CT) scanning in these patients, even if they are asymptomatic. If a skull fracture is suspected, a CT scan must be performed without delay.

Neuroendoscopic Assessment of Choroid Plexus Coagulation to Release Ventricular Catheter: Note on the Seldinger Technique

OBJETIVO: Comparar a tecnica neurocirurgica classica a uma nova tecnica simplificada, para correcao de mielomeningocele, em fetos de ovelhas. METODOS: Em 9 fetos, foi criado um defeito semelhante a mielomeningocele (laminectomia e excisao de dura-mater) no 90o dia de gestacao. O tipo de correcao foi randomizado. No Grupo 1, o defeito foi corrigido usando a tecnica neurocirurgica classica, com a sutura de tres camadas (dura-mater, musculo e pele), realizada por um neurocirurgiao. No Grupo 2, um especialista em Medicina Fetal utilizou a tecnica simplificada, colocando um fragmento de celulose biossintetica sobre a medula e suturando apenas da pele sobre a celulose. Proximo ao termo da gestacao (132 dias), os fetos foram sacrificados para analise anatomopatologica. RESULTADOS: Ocorreram dois casos de aborto e uma morte materna, restando seis casos para avaliacao - tres em cada grupo. No Grupo 1, todos os casos mostraram aderencia da medula a cicatriz (meningoadesao) e perda da arquitetura medular, com destruicao do funiculo posterior e perda da visualizacao da substância cinzenta. No Grupo 2, observou-se, em todos os casos, a formacao de uma neodura-mater, separando o tecido nervoso do musculo adjacente, sendo que o funiculo posterior e a substância cinzenta estavam preservados. CONCLUSAO: A tecnica simplificada foi superior a neurocirurgica, com maior preservacao da medula e evitando as aderencias do tecido nervoso. Os presentes achados sugerem que a tecnica utilizada atualmente na correcao de mielomeningocele em fetos humanos deva ser reavaliada.