versión ISSN 0104-7930
J. Venom. Anim. Toxins v.8 n.1 Botucatu 2002
LOCAL EDEMA AND HEMORRHAGE CAUSED BY Crotalus durissus terrificus ENVENOMING EVALUATED BY MAGNETIC RESONANCE IMAGING (MRI)
1 Faculdade do Norte Paulista, Bebedouro, São Paulo State, Brazil; 2 Magnetic Resonance Unit, University Hospital, Botucatu School of Medicine, UNESP; 3 Department of Tropical Diseases and Imaging Diagnosis, Botucatu School of Medicine - UNESP, São Paulo State, Brazil; 4 Center for the Study of Venoms and Venomous Animals-CEVAP-UNESP, State of São Paulo, Brazil.
ABSTRACT: The objective of this study was to detect the presence of local edema and hemorrhage caused by Crotalus durissus terrificus envenoming using magnetic resonance imaging (MRI). Six patients bitten by Crotalus durissus terrificus snakes were treated at the Emergency Unit and Tropical Diseases Unit of Botucatu School of Medicine, UNESP, São Paulo State, Brazil. After receiving specific serotherapy, the patients were submitted to MR of the bite site. Post contrast T1 and T2 spin-echo MRI were obtained revealing the following lesions: edema associated with hemorrhage in subcutaneous and muscular tissue (n=3), edema in subcutaneous tissue (n=2), and perimuscular hemorrhage (n=1). In this study, MR demonstrated a local effect of Crotalus durissus terrificus envenoming in inducing edema and hemorrhage, mainly in muscular tissues and perimuscular areas. These results indicate that Crotalus durissus terrificus venom cause a local muscular tissue damage in human envenoming represented by edema and hemorrhage.
KEY WORDS: Crotalus durissus terrificus, muscular damage, edema, hemorrhage, magnetic resonance.
In Brazil, human envenoming caused by rattlesnakes (Crotalus durissus terrificus) are of major importance because they may cause severe clinical problems or lead to death (1,6). These have been clinically characterized as showing low proteolytic activity, causing slight edema at the bite site (2-4,13). Crotalus durissus terrificus venom shows higher toxicity than other viperid venoms, especially in relation to systemic neurotoxic, nephrotoxic, and myotoxic activities (2). There are only a few reports in literature about its effects on local tissue (7,8,16), especially clinical studies (7,8,16). Magnetic resonance imaging (MRI) provides a precise diagnosis tool to investigate damaged tissue (7). This is a non-invasive procedure, producing images with anatomical detail showing lesions based on morphology and the difference between signals for normal and damaged tissues (5,14). The objective of this study was to evaluate affected limbs in patients bitten by Crotalus durissus terrificus after specific serotherapy, especially looking for the presence of local edema and hemorrhage.
PATIENTS AND METHODS
We studied six patients (four males and two females) aged between nine and 63 years. All patients were treated at the Emergency Unit and the Tropical Diseases Unit of the University Hospital, Botucatu School of Medicine, UNESP, where they received specific treatment and clinical follow up. After serotherapy, all patients were submitted to MR of the affected limb. Table 1 describes the patients upon hospital admission.
Table 1. Patients (P) bitten by Crotalus durissus terrificus in relation to age (A), sex (S), time elapsed (hours) between the envenoming and medical treatment (TT), clinical picture (CP), use of tourniquet (T), bite site (BS), local manifestations (LM), systemic manifestations (SM), number of vials (NV) administered intravenously and resonance magnetic evaluation (hours).
|Mo = Moderate; SE = Severe
RLL = right lower limb; LLL = left lower limb
(+) present; (-) absent; F = female; M = male
LM = erythema
SM = palpebral ptosis, myalgia, blurred vision, increased creatinine phosphokinase (CPK), urea, and creatinine
* = myoglobinuria
patients 1,2,4, = muscle lesion in resonance magnetic evaluation (edema and hemorrhage)
patients 3 and 6= subcutaneous cellular tissue lesion in resonance magnetic evaluation (edema)
patient 5= lesion perimuscular hemorrhage in resonance magnetic evaluation
MRI evaluations were performed using an imager that incorporates a superconductive magnet operating at 0.5 Tesla. Images were obtained using post-contrast T1 and T2 spin-echo sequences in the adaxial/axial and coronal planes. Lesions were identified using 0.2ml/kg intravenous paramagnetic contrast. Lesion identification was by signal comparison of normal and damaged tissue. This paper has been approved by the Research Ethics Committee of Botucatu School of Medicine, UNESP.
RESULTS AND DISCUSSION
MRI showed the following lesions: edema associated with hemorrhage (n=3), edema only (n=2), and hemorrhage only (n=1). Figure 1 shows extensive areas of edema associated with hemorrhage in muscular tissue. Figure 2 shows only edema in subcutaneous tissue, and Figure 3 shows only hemorrhage in the perimuscular area. Hemorrhage could be seen as discrete or diffuse perimuscular bands in muscular tissue, edema by a discrete hyper-intense cluster in the subcutaneous cellular tissue. In Brazil, pathogenesis of tissue damage in crotalid envenoming has been specifically studied in relation to systemic alterations. There are few reports in literature about the effect of venom on local skeletal muscles. Patients bitten by Crotalus durissus terrificus, the snake responsible for most envenomings in this country especially in southeastern Brazil, sometimes show discreet local manifestations (mild edema and erythema) after envenoming (1,6,10). Some authors reported (7,8,10) that local muscular lesions are common in Viperidae envenomings. Some studies have shown that skeletal muscle function can be affected in different ways by total venom toxins and isolated venom toxins (11). Both the crude venom and the main toxin (crotoxin) from Crotalus durissus terrificus venom are capable of producing increased muscular enzymes and also systemic myotoxicity of variable intensity, as shown by histological studies (7,9). However, experimental studies have also shown the presence of significant muscular lesions as well as those seen in other muscles in both baths of isolated muscle preparations and muscles injected with venom or toxin (15). Experiments using snake venom hemorrhagic fractions have shown that they are capable of causing edema, hemorrhage, and myonecrosis secondary to hemorrhage (12). In this study, MRI demonstrated a major local effect of Crotalus durissus terrificus envenoming in inducing edema and hemorrhage, mainly in muscular tissues and perimuscular areas. These results allow us to suggest that patients bitten by Crotalus durissus terrificus may present local muscle lesion represented by edema and hemorrhage.
Images obtained by post-contrast T1 and T2 sequence spin-echo. |
N = normal limb; L = limb with lesion and R = reference image
|Figure 1. Characteristics of edema and hemorrhage by Crotalus durissus terrificus envenoming in muscular tissue shown in MRI. Arrows (A,B) indicate edema and hemorrhage in extensive band of high signal in the basal muscular tissue right calf (patient 1). Arrows (C,D) indicate edema and hemorrhage in the inner lateral portion of the muscular tissue of the right foot (patient 4).|
|N = normal limb; L = limb with lesion and R = reference image|
|Figure 2. Subcutaneous cellular tissue edema (patient 3) shown in MRI obtained by post-contrast T1 and T2 sequence spin-echo. Note the band of high signal in the subcutaneous cellular tissue (arrows).|
MRI obtained by post- contrast T1 and T2 spin-echo sequence.
|Figure 3. Perimuscular hemorrhage (patient 5) shown by MRI of the left ankle. Note the high signal in the upper peripheral muscular tissue (arrows).|
The author wish to thank CAPES (Fundação Coordenação de Aperfeiçoamento de Pessoal de Nível Superior) and the staff of the Tropical Diseases Unit, Botucatu School of Medicine, UNESP.
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Received July 2, 2001
Accepted August 24, 2001
M. G. Fonseca - Rua: Bartolomeu Bueno Filho, no. 405, 15060-230, São José do Rio Preto, São Paulo, Brasil.