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miércoles, 19 de septiembre de 2012

122.- DEATH FROM INSECT STINGS. PROF. GARFIA.A

122.-FATALITIES FROM INSECT STINGS IN SOUTH SPAIN. 
HISTOPATHOLOGICAL FINDINGS IN LEGAL MEDICINE CASES.
PROF. GARFIA.A

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AGUIJÓN DE ABEJA, DURANTE UNA PICADURA MORTAL, PENETRANDO EN LA PIEL. PROF.GARFIA.A
        Los  próximos casos se referirán a las muertes producidas por picaduras de insectos en el Sur de España.


Introduction


   Stinging insects of the order Hymenoptera include Apis species, ie. bees (European, African), vespids (wasps, yellow jackets, hornets), and ants. Although most deaths result from immunologic mechanisms, some are from direct toxicity. Severe anaphylactoid reactions occur occasionally when toxins directly stimulate mast cells. While the vast majority of stings cause only minor problems, Hymenoptera stings cause a significant number of deaths in numerous countries around the world. In Forensic Medicine stinging events involving honey bees and wasps are rare; most deaths or clinically important incidents involve very few stings (5-10) and anaphylactic shock. However, mass stinging events can prove life-threatening via the toxic action of the venom when injected in large amounts. For this reason, from a forensic point of view, it is preceptive differentiated between histopathological lesions due to acute fatal cases following one or several stings (fatal anaphylaxis) and those cases that occurred after mass envenomations (cytotoxic  venom death).

1.-Cytotoxic Venom Death in Nonallergic Persons.
     Massive bee envenomation can produce both immediate and delayed death due to toxic reaction.
   
1.1.-Immediate toxic reaction: histopathological findings.
    After numerous insect stings, the following findings can be found in the autopsy (Janssen, 1966).
      -Pulmonary and cerebral edema.
      -Hyperemia of the inner organs.
      -Petechial hemorrhages in the skin and serous coats.
      -Softening foci in the brain.
      -Toxic parenchymal lesions.
In isolated cases, cuneate skin necroses  have been found as far as the subcutis in the region of stings in addition to necroses of the spleen follicle, fatty degeneration of the liver, kidneys, and myocardium, and necrobiotic  softening foci in the cerebral cortex and striatum, with diffuse oligodendroglial and macroglial proliferation. Extensive hemorrhagic infarctions of the cerebral cortex, splenic arterial thrombosis, and splenic infarctions have also been observed as direct toxic effects of insect poison.
      However, from a clinical point of view, signs and symptons of immediate toxic reactions are:
Fatigue, nausea, vomiting, hemolysis, rhabdomyolysis (myoglobinemia and myoglobinuria), acute renal  failure (acute tubular necrosis), ARDS, disseminated intravascular coagulation and bleeding.

1.2.-Delayed Toxic Reaction: histopathological findings. 
       Some patients can be found asymtomatic after a massive bee envenomation, with normal initial laboratory results, but posteriorly demonstrates laboratory evidence of hemolysis, coagulopathy, thrombocytopenia, rhabdomyolysis, liver dysfunction, and disseminated intravascular coagulation (the first signs of a fatal multi-organ-system failure can be apparent until 18-20 hours after envenomation). 
The histopathological study   can shows:  
ARDS, hepatocellular necrosis, acute tubular necrosis, focal subendocardial necrosis and disseminated intravascular coagulation. 


2.-Anaphylaxis related deaths due to a single or a small number of insect stings.
      Of particular interest are fatalities  due to a single or a small number of insect stings. In Forensic Pathology deaths anaphylaxis related -where there is no  known  sensitization-  have always  been very difficult to demonstrate. Ocasionally, deaths due to single insect stings can  be very important in the context of legal accident insurance. For these reason they are object of study for many peoples who work in fields  related to the Legal Medicine and Justice Ministerium in Spain (Forensic Pathologist, Jurists and Legal Doctors).
Anaphylaxis is a severe, life-threatening allergic reaction. It must be diagnosed clinically and must treated immediately. Twenty percent or more of patients with anaphylaxis lack cutaneous manifestations, and patients with chronic asthma are at higher risk of undertreatment, misdiagnosis, and death.

Clinical manifestations
     The clinical manifestations of systemic anaphylaxis in man include:
1.-Respiratory distress caused by bronchospasm or angioneurotic edema involving the lariynx.
2.-Diffuse erythema, urticaria, and pruritus.
3.-Vomiting, abdominal cramps, and diarrhea that occasionally is bloody.
4.-Vascular collapse without preceding respiratory distress.


      The primary cause of mortality in anaphylaxis can be of two types:
1.-Acute Airway compromise ("respiratory shock").
2.-Cardiovascular collapse (circulatory shock).
   Of the deaths through  insect stings the median time interval between onset of symptons and cardiopulmonary arrest was less than 1st after the sting. 
   Fatal anaphylactic reactions are more common in asthmatic patient.

POSTMORTEM FINDINGS
     In fatal cases, the postmortem findings fall into two patterns:
1.-Acute Airway Compromise or "Respiratory Anaphylaxis."(Asphyxia Deaths).
Postmortem Findings.-
1.1.-Edema of the upper respiratory tract (including the hypophariynx, epiglottis, larynx, and even the trachea); acute pulmonary emphysema -revealed by gross and microscopic examination- resulting from obstruction in the upper and lower respiratory tract. 
      The postmortem examinations of patients who died of asphyxia with secondary vascular collapse reveal acute pulmonary emphysema, edematous laryngeal obstruction, or both.
                                   
This is the normal response to insect stings in    asmathic patients.

2.-Cardiovascular Collapse without Preceding Respiratory Distress. Circulatory Anaphylaxis (Circulatory Deaths/Anaphylactic Shock).
          No significant findings can be seen when the patient has died in a state of shock without antecedent of respiratory difficulty.
   The macroscopic and histological findings are uncharacteristic in the inner organs:
1.-Acute vascular congestion.
2.-Cyanosis.
3.-Cerebral edema.
4.-Subepicardial, subendocardial, and subpleural petechial hemorrhages.
5.-Microcirculatory changes shock-induced (sludging of erythrocytes, platelets aggregations, and multiple megacaryocytes in the pulmonary microcirculation).  

    
     
REFERENCES

1.-Nicoletta Trani, Luca Reggiani Bonetti, Giorgio Gualandri, Giuseppe Barbolini and Margherita Trani (2011). Forensic Investigation in Anaphylactic Deaths, Forensic Medicine - From Old Problems to New Challenges, Duarte Nuno Vieira (Ed.), ISBN: 978-953-307-262-3, InTech, Available from: http://www.intechopen.com/books/forensic-medicine-from-old-problems-to-new-challenges/forensic-investigation-in-anaphylactic-deaths.
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Forensic Investigation in Anaphylactic Deaths