Incidence of Myonecrosis in Haemotoxic, Neurotoxic Snakebites and Its correlation with Acute Renal Failure

Venkatesh, I (2008) Incidence of Myonecrosis in Haemotoxic, Neurotoxic Snakebites and Its correlation with Acute Renal Failure. Masters thesis, Madurai Medical College, Madurai.

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Abstract

INTRODUCTION: Snake bite is a preventable public health hazard in tropical and subtropical countries. India has always been a land of exotic snakes, which has a warm climate and dense vegetations. The causes of renal failure in snake bite are hypotension, bleeding, DIC, direct nephrotoxicity of the snake venom and myoglobinuria. Rhabdomyolysis is a common cause of renal failure in sea snakes. Even though there is a high incidence of myonecrosis in haemotoxic snake bites, there are no extensive studies done on myonecrosis in haemotoxic and neurotoxic snake bites and its correlation with renal failure. Better understanding of the problem is essential for the prevention and therapeutic measures to reduce if not eradicate the morbidity and mortality from snake bite. AIM OF THE STUDY: 1) To study the incidence of myonecrosis in haemotoxic and neurotoxic snake bites. 2) To correlate CPK-MM levels with acute renal failure. MATERIALS AND METHODS: Patients admitted in the medical wards of Govt. Rajaji Hospital, Madurai formed the materials of this study. Totally, 100 patients have been studied. History, clinical findings and investigations were written in printed proforma. INCLUSION CRITERIA : 1) All patients with definite history of snake bite. 2) Patients above 12 years of age. EXCLUSION CRITERIA : 1) Chronic kidney disease, 2) Hypotension, 3) Sepsis, 4) Acute coronary syndromes, 5) Patients who had intramuscular injection one week before the snake bite. CPK-MM levels are detected using kinetic methods and myoglobinuria is detected using spectroscopy. DISCUSSION: The age distribution of snake bite in our study shows the age group between 20-49 years constitute 75% of the snake bite cases. This is related to the outdoor activities of this age group. Older people are least involved because of sedentary habits. In our study, cellulitis was present in 84% of patients. 91.1% of patients with viper bite developed cellulitis, 50% of patients with cobra bite developed cellulitis and there was no cellulitis in krait bite. The reason for this prevalence of cellulitis in viper bite is because the enzyme metalloproteinase and the proteolytic enzymes are more abundant in Crotalidae and Viperidae snakes. These enzymes cause more tissue destruction and damage. Proteolytic enzymes produce local changes in vascular permeability leading to oedema, blistering, bruising and necrosis. Proteolytic enzymes are present in lesser amounts in Elapidae and hence, they cause minimal cellulitis. In a study conducted by Philips et al, 73% of patients had cellulitis. In our study, the incidence of cellulitis is 84%. Creatine kinase-MM levels correlates directly with the presence of cellulitis. CPKMM elevation is seen only in patients with cellulitis and CPK-MM is not elevated in patients without cellulitis. The incidence of myonecrosis in our study is 81%. A significant proportion of patients had only minimal elevation of CPK-MM ( 35% of patients have CPK-MM levels less than 500 IU/L ). 29% of patients have CPK-MM levels between 500-999 IU/L. 6% of patients have CPK-MM levels between 1000-1499 IU/L. 3% have CPK-MM levels between 1500-1999 IU/L and 8% have CPK-MM levels greater than 2000 IU/L. The level of CPK-MM elevation is very much low when compared to the CPK-MM elevation seen in sea snake bites. The incidence of myonecrosis is higher in our study because of the more prevalence of viper in this part of our country. 79% of snake bites in our study were due to viper. High levels of CPK-MM elevation is seen more in patients less than 40 years of age. This may be due to the degree of envenomation and there is no study done correlating the age distribution of myonecrosis. The degree of myonecrosis is equal in males and females and there is no significant statistical difference among the sex wise distribution of myonecrosis. CPK-MM elevation is more with viper bite when compared to cobra and krait bites. This is because of the greater amount of tissue damage caused by proteolytic enzymes in viper bite. Cobra causes minimal cellulitis and hence mild elevation of CPK-MM. There are no local effects in krait bite and therefore CPK-MM is not elevated. A significant level of CPK-MM elevation is seen in unknown snake bites. This can be explained, that most of the unknown bites may be due to viper. Out of 100 patients, 8 patients developed renal failure. In a study conducted by Philips et al, 9% of his patients developed renal failure. In our study, all renal failure patients had myoglobinuria. In a study conducted by Philips et al, 60.86% of his had myoglobinuria. This can be explained that a different species of viper snake may be involved in his study. Neurotoxicity was the commonest sign in his study and 82% had external ophthalmoplegia and 77% had ptosis. But, neurotoxicity was not reported in viper bites in our study. This explains that a different species of viper snake may be involved in his study. Myoglobinuria correlates directly with the level of CPK-MM elevation. The patients who developed renal failure have greater elevation of CPK-MM. Seven patients have levels greater than 2000 IU/L and one patient has a value of 1874 IU/L. This shows that there is a definite correlation between the level of CPK-MM elevation and renal failure. The mechanism by which rhabdomyolysis causes renal failure are hypovolemia, renal ischemia, direct nephrotoxicity of myoglobin, tubular obstruction from heme pigment casts/ uric acid crystals and DIC. Although the presence of myoglobinemia or myoglobinuria is indicative of skeletal muscle injury, it may not be the most sensitive method to detect rhabdomyolysis. As myoglobin has a relatively rapid renal clearance( 1-6 hours ), a patient with rhabdomyolysis may have a normal plasma level by the time he or she is hospitalized. In contrast, creatine kinase, appears to be a more sensitive plasma marker for rhabdomyolysis because of its slower clearance( serum half-life 1.5 days). Thus, at initial clinical evaluation, patients with rhabdomyolysis will have increased serum creatine kinase levels, whereas urine myoglobin levels may or may not be detected. This study indicates the importance of myonecrosis in haemotoxic/ neurotoxic snake bite as a cause of snake failure. There are no extensive studies done correlating the myonecrosis in haemotoxic/ neurotoxic snake bite and renal failure. Limitations of this study are 1) direct nephrotoxicity of the snake venom could not be excluded. 2) DIC as a cause of renal failure could not be excluded as DIC is commonly seen in rhabdomyolysis. CONCLUSION: 1. The incidence of myonecrosis in haemotoxic/ neurotoxic snake bite in our study is 81%. There is high incidence of myonecrosis in our study. 2. Viper and cobra bites are definitely associated with myonecrosis. Krait bite is not associated with myonecrosis. The degree of myonecrosis is highest in viper. 3. There is definite correlation between the severity of myonecrosis and ARF in snake bite.

Item Type: Thesis (Masters)
Uncontrolled Keywords: Myonecrosis ; Haemotoxic ; Neurotoxic Snakebites ; Acute Renal Failure.
Subjects: MEDICAL > General Medicine
Depositing User: Subramani R
Date Deposited: 15 Mar 2018 07:42
Last Modified: 15 Mar 2018 07:55
URI: http://repository-tnmgrmu.ac.in/id/eprint/6254

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