Mechanical and pathophysiological aspects of acute spinal cord trauma

ω-Conotoxina MVIIC e células-tronco mesenquimais promovem recuperação motora em ratos Wistar após trauma medular agudo

RESUMO O objetivo deste estudo foi avaliar o efeito da ω-conotoxina MVIIC e das células-tronco mesenquimais (CTM) de forma isolada e sua associação nos ratos submetidos ao trauma medular agudo (TMA). Trinta Rattus novergicus, linhagem Wistar, três meses de idade, foram distribuídos igualmente em cinco grupos experimentais: controle negativo (CN), controle positivo (CP), ω-conotoxina MVIIC (MVIIC), células-tronco mesenquimais da medula óssea (CTM-MO) e associação (MVIIC + CTM-MO). O grupo CN foi submetido à laminectomia sem trauma medular, e os grupos CP, MVIIC, CTM-MO e MVIIC + CTM-MO foram submetidos ao trauma medular contusivo. O grupo CP recebeu, uma hora após o TMA, 10μL de PBS estéril, e os grupos MVIIC e MVIIC + CTM-MO receberam 10μL de PBS contendo 20pmol da ω-conotoxina MVIIC, todos por via intratecal. Os grupos CTM-MO e MVIIC + CTM-MO receberam, 24 horas após, 1x106 de CTM via intravenosa. Avaliou-se a recuperação da função locomotora até o sétimo dia pós-trauma. Os animais tratados com MVIIC + CTM-MO obtiveram recuperação motora após o trauma medular agudo (P<0,05). Conclui-se que essa associação apresentou efeito neuroprotetor com melhora na função locomotora em ratos Wistar.

Efeito da prednisona em lesão medular aguda experimental em ratos

Foram utilizados 25 ratos (Rattus novergicus) submetidos a trauma experimental da medula espinhal, empregando-se aparelho estereotáxico com um peso de 50,5g comprimindo a duramáter durante cinco minutos. Após o trauma, os animais foram divididos em cinco grupos de cinco. O grupo A (controle) recebeu placebo oito horas após o trauma; os grupos B, C, D e E receberam prednisona oito, 24, 48 e 120 horas após o trauma, respectivamente. A prednisona foi administrada na dose inicial de 2mg/kg, durante cinco dias, com diminuição progressiva até o 26º dia. Os animais foram avaliados conforme a capacidade motora, posicionamento proprioceptivo, reflexo de localização, plano inclinado e sensibilidade dolorosa. Após 33 dias da cirurgia, foram sacrificados para avaliação histológica das medulas espinhais. Observaram-se degeneração das raízes nervosas, necrose medular, inflamação local e reação glial, sem diferenças entre os grupos. Não houve correlação entre os testes neurológicos. A utilização da prednisona na lesão medular aguda não teve efeito diferenciado com o tempo e não foi prejudicial na recuperação neurológica, mesmo quando utilizada tardiamente.

Association of spinal cord compression seen on magnetic resonance imaging with clinical outcome in 67 dogs with thoracolumbar intervertebral disc extrusion

OBJECTIVES

To determine whether there is an association between the degree of transverse spinal cord compression detected by magnetic resonance imaging following thoracolumbar Hansen type 1 intervertebral disc disease in dogs and their presenting and postsurgical neurological status.

METHODS

Medical records of 67 dogs with surgically confirmed Hansen type 1 intervertebral disc disease (2000 to 2004) were reviewed to obtain the rate of onset of disease, duration of clinical signs and presurgical and postsurgical neurological grade. Percentage of spinal cord compression was determined on transverse T2-weighted magnetic resonance images. Linear regression was used to examine the association between spinal cord compression and each of the above variables. Chi-squared tests were used to examine associations among postsurgical outcome and presurgical variables.

RESULTS

Eighty-five per cent (57 of 67) of dogs were chondrodystrophoid. Mean spinal cord compression was 53 per cent (sd=219.7, range 14.3 to 84.9 per cent). There was no association between the degree of spinal cord compression and the neurological grade at presentation, rate of onset of disease, duration of clinical signs or postsurgical outcome, with no difference between chondrodystrophoid and non-chondrodystrophoid dogs.

CLINICAL SIGNIFICANCE

The degree of spinal cord compression documented with magnetic resonance imaging in dogs with thoracolumbar Hansen type 1 intervertebral disc disease was not associated with the severity of neurological signs and was not a prognostic indicator in this study.

Prognostic value of magnetic resonance imaging in dogs with paraplegia caused by thoracolumbar intervertebral disk extrusion: 77 cases (2000-2003)

OBJECTIVE

To determine whether magnetic resonance imaging findings in dogs with paraplegia caused by thoracolumbar intervertebral disk extrusion were predictive of clinical outcome.

DESIGN

Retrospective case series.

ANIMALS

77 dogs.

PROCEDURE

Medical records and magnetic resonance images were reviewed; clinical outcome was classified as successful (regained ability to walk with no more than mild neurologic deficits) or unsuccessful (severe neurologic deficits persisted). The prognostic value of magnetic resonance imaging was compared with prognostic value of deep pain perception, duration of clinical signs, and rate of onset of clinical signs.

RESULT

33 (43%) dogs had areas of hyperintensity of the spinal cord greater than or equal to the length of the L2 vertebral body on T2-weighted magnetic resonance images. All 44 dogs without areas of hyperintensity on T2-weighted images had a successful outcome, but only 18 of the 33 (55%) dogs with an area of hyperintensity did. Only 5 of 16 dogs with an area of hyperintensity that had also lost deep pain perception had a successful outcome. The odds ratio for an unsuccessful outcome for a dog with an area of hyperintensity (29.87) was higher than the odds ratio for a dog that had lost deep pain perception (5.24). Duration and rate of onset of clinical signs were not associated with clinical outcome.

CONCLUSIONS AND CLINICAL RELEVANCE

Findings suggest that results of magnetic resonance imaging can be used to predict clinical outcome in dogs with paraplegia caused by intervertebral disk extrusion.

Thoracolumbar disc disease in 71 paraplegic dogs: influence of rate of onset and duration of clinical signs on treatment results

Seventy-one paraplegic dogs with confirmed intervertebral thoracolumbar disc disease and intact deep pain sensation were treated by hemilaminectomy and fenestration of at least two adjacent discs. The success rate of treatment in the overall population was 86 per cent (61/71 cases), with a mean length of time to regaining the ability to walk of 10.8 days and a mean follow-up time of 29 months. The rate of onset of clinical signs significantly influenced the clinical outcome (P=0.01) but not the length of recovery time (P=0.45). Conversely, the duration of clinical signs did not seem to significantly affect the outcome (P=0.27), but did affect the length of recovery time (P=0.001). Animals which had shown clinical signs for more than six days took significantly longer to regain the ability to walk (ie, an additional 6.9 days, P=0.04 and 4.5 days, P=0.01), when compared with those which had shown clinical signs for less than two days, or more than two but less than six days, respectively.

Spinal fracture or luxation

Spinal trauma is a common cause of spinal cord dysfunction in dogs and cats. When the spine is injured by exogenous injury, the impact often results in vertebral fracture or luxation. As each injury is unique, treatment guidelines have to be individualized to the animal. This article reviews the clinical management including surgical and nonsurgical treatments for animals with vertebral fracture/luxation.

Spinal cord swelling as a myelographic indicator of prognosis: a retrospective study in dogs with intervertebral disc disease and loss of deep pain perception

The association of myelographic spinal cord swelling with neurological outcome was examined in 46 dogs with intervertebral disc disease and absence of deep pain perception (DPP). Spinal cord swelling was measured by calculating a ratio of the length of the loss of the myelographic dye column to the length of the second lumbar vertebra (L2). A positive neurological outcome was defined as return of voluntary motor function. A cut-off value for swelling:L2 of 5.0 was established by the creation of a receiver operator characteristic curve. Using a swelling:L2 ratio of 5.0 as a cutoff for indication of neurological recovery yielded a sensitivity of 74% and a specificity of 61%. Overall neurological recovery rate was 43%. Dogs with spinal cord swelling:L2 ratios less than 5.0 had a recovery rate of 61%, whereas dogs with a ratio greater than or equal to 5.0 had a recovery rate of 26%. Evaluation of these data by chi square analysis confirmed that a ratio less than 5.0 was associated with a positive outcome, and a ratio greater than or equal to 5.0 was associated with a negative outcome, (P < .05). Although other factors, such as duration of neurological signs, affect neurological outcome in dogs with no DPP, evaluation of myelographic spinal cord swelling can assist in establishing a prognosis.

Spinal fracture/luxation

Clinical management of the spinal fracture/luxation patient requires prompt and accurate diagnosis of the extent of injury coupled with intensive medical or surgical intervention. Convalescent patient care is often physically challenging and labor intensive.