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SCORPIONS, CENTRUROIDES SPECIES

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Classification   |    Detailed evidence-based information

Substances Included Synonyms

Therapeutic Toxic Class

    A) This management deals with stings from Centruroides scorpions. The most common stinging scorpions in the United States are members of the genera Vejovis, Hadrurus, Androctonus, and Centruroides. Only the Centruroides is a serious medical problem.
    B) There are at least 650 types of scorpions, divided into 6 families. In the United States, the dangerous family is the Buthidae, which contains the Centruroides species (Likes et al, 1984).

Specific Substances

    A) CONSTITUENTS OF THE GROUP
    1) Centruroides elegans
    2) Centruroides ertschi
    3) Centruroides exilicauda
    4) Centruroides infamatus infamatus
    5) Centruroides limpidus limpidus
    6) Centruroides l. tecomanus
    7) Centruroides noxius
    8) Centruroides pallidiceps
    9) Centruroides sculpturatus
    10) Centruroides suffusus suffusus
    11) Centruroides vittatus (Say)
    12) Bark scorpion
    13) Yellow scorpion
    14) Whip scorpion
    15) Lethal scorpion
    16) Centruroides species scorpions

Overview

Life Support

    A) This overview assumes that basic life support measures have been instituted.

Clinical Effects

    0.2.1) SUMMARY OF EXPOSURE
    A) USES: Scorpions of the Centruroides genera are found in the southern US, Mexico, Central America and the West Indies. In the US, symptomatic envenomation is caused most commonly by C sculpturatus and exilicauda species, primarily in southwestern States. Other common stinging scorpions in the US are members of the genera Vejovis, Hadrurus, and Androctonus, which may also produce a painful sting (similar to a bee or wasp sting), but are seldom serious.
    B) TOXICOLOGY: Most scorpion toxins affect the sodium channel of excitable cells by retarding inactivation (alpha toxins) or enhancing activation (beta toxins). A few of these toxins affect the potassium channel. As a result of effects on neuromuscular transmission and autonomic effects secondary to the release of acetylcholine at the vagal ganglia and on cardiac postganglionic nerves, affected individuals can develop signs and symptoms of cholinergic and sympathetic excess.
    C) EPIDEMIOLOGY: There are approximately 15,000 scorpion exposures per year in the US, mostly in the Southwest desert. The vast majority result only in pain. Fewer than 1000 require health care facility evaluation and treatment. A very small number, primarily in young children, result in significant neurologic toxicity. Deaths are very rare.
    D) WITH POISONING/EXPOSURE
    1) MILD TO MODERATE ENVENOMATION: In older children and adults, Centruroides stings generally cause only local pain, which may be severe at times and radiate up the affected limb.
    2) SEVERE ENVENOMATION: Systemic effects may develop after Centruroides envenomation, most commonly in children younger than 5 years. Sympathetic effects include increased heart rate and blood pressure, hyperglycemia, dilated pupils, piloerection, sweating, and hypertension. Parasympathetic effects include salivation, tearing, urination, defecation, bradycardia, hypertension, and gastric distension. Other effects include pain, paresthesias, hyperesthesia near the sting site, respiratory difficulties, increased secretions, stridor, irritability, blurred vision, difficulty swallowing, and slurred speech. The most dramatic signs of envenomation in young children are marked: hyperactivity, restlessness, opisthotonos accompanied by muscle twitching, fasciculations, roving eye movements, and nystagmus. In severe cases, rhabdomyolysis, dysrhythmias, and respiratory failure may develop, but these are rare. Effects are most severe in infants and toddlers. Life-threatening allergic reactions to Centruroides stings have also been reported rarely.
    0.2.5) CARDIOVASCULAR
    A) Tachycardia is common. Hypertension may also develop.
    0.2.6) RESPIRATORY
    A) Respiratory distress and insufficiency may develop with Centruroides species secondary to increased secretions, CNS depression, and neuromuscular effects.
    0.2.7) NEUROLOGIC
    A) Agitation, movement disorders, CNS depression, paresthesias, fasciculations, nystagmus and slurred speech are common with Centruroides stings.
    0.2.8) GASTROINTESTINAL
    A) Nausea, vomiting, and difficulty swallowing may occur. Excessive salivation is common.
    0.2.10) GENITOURINARY
    A) Urinary urgency has been reported but is not common.
    0.2.11) ACID-BASE
    A) Respiratory acidosis has been reported in young children.
    0.2.13) HEMATOLOGIC
    A) Coagulopathy is a rare complication.
    0.2.14) DERMATOLOGIC
    A) Diaphoresis and piloerection may develop.
    0.2.15) MUSCULOSKELETAL
    A) Local pain is common with most scorpion stings. Rhabdomyolysis is an unusual complication.
    0.2.16) ENDOCRINE
    A) Hyperglycemia is reported.
    0.2.19) IMMUNOLOGIC
    A) Anaphylaxis to Centruroides sting has been reported rarely.
    0.2.20) REPRODUCTIVE
    A) An uneventful pregnancy and delivery were seen following a finger sting and MYN antivenin infusion.

Laboratory Monitoring

    A) Laboratory evaluation may not be necessary. In severe envenomations, monitoring of blood pressure, respiratory rate, and oxygenation status should be performed and the ECG monitored. A 12-lead ECG, and basic laboratories, including a CK, may be needed in severe cases.

Treatment Overview

    0.4.7) BITES/STINGS
    A) SEVERITY OF ENVENOMATION
    1) Most envenomations are managed with symptomatic and supportive care, particularly pain control, which may require opioid-level relief and benzodiazepines for anxiety and hyperactivity. Atropine may be needed for excessive secretions. More severe envenomations, those producing significant effects or occurring in the very young, very old, or those with underlying comorbidities, may require antivenom therapy (available as Anascorp(R), a centruroides immune F(ab')2 equine-derived antivenom).
    2) Symptom severity can be graded as follows:
    1) GRADE I: Local pain, paresthesias, or both at the site of envenomation.
    2) GRADE II: Pain, paresthesias, or both, remote from the envenomation site in addition to local findings as in GRADE I.
    3) GRADE III: EITHER cranial nerve dysfunction OR somatic skeletal neuromuscular dysfunction.
    4) GRADE IV: BOTH cranial nerve AND somatic skeletal neuromuscular dysfunction.
    B) MANAGEMENT OF NO EFFECT TO MILD TOXICITY (GRADE I AND II)
    1) Mild to moderate envenomations may be managed by the use of benzodiazepines for agitation, and oral or parenteral opioids for pain. Monitoring of airway and oxygenation is required. In young children, mild or moderate symptoms may progress to severe symptoms over minutes to an hour.
    C) MANAGEMENT OF MODERATE TO SEVERE TOXICITY (GRADE III AND IV)
    1) Severe envenomations may require airway control with endotracheal intubation for primary symptoms, for anaphylaxis, or as a result of sedation from medications. Seizures should be managed initially with benzodiazepines. Phenobarbital or propofol may be considered for recurrent seizures. Pain may require oral or parenteral opioids. The FDA has approved an antivenom (Anascorp(R)) for scorpion envenomation (see ANTIVENOM).
    D) DECONTAMINATION
    1) Decontamination of envenomation is not possible.
    E) AIRWAY MANAGEMENT
    1) Airway management is unlikely to be an issue, but may be required in severe envenomations, at the extremes of age, as a result of sedation required for control of agitation, seizures or pain, or in rare patients with anaphylaxis.
    F) ANTIVENOM
    1) Centruroides (scorpion) Immune F(ab')2 (Anascorp(R)) is an equine-derived antivenom indicated for the treatment of patients with clinical signs of scorpion envenomation. Initiate treatment as soon as possible after envenomation.
    2) INITIAL DOSE: 3 vials: Reconstitute each vial with 5 mL of sterile normal saline. Combine the contents of all 3 reconstituted vials and further dilute to a total volume of 50 mL with sterile normal saline. Inspect solution; do NOT use if turbid. Infuse over 10 min. Monitor patient closely for up to 60 min after completion of the infusion for evidence of clinical improvement.
    3) ADDITIONAL DOSING: Infuse 1 vial at a time at 30 to 60 min intervals. Reconstitute the vial as described above. Infuse over 10 minutes. Monitor patient for up to 60 minutes for clinical improvement.
    4) HYPERSENSITIVITY REACTIONS: Severe hypersensitivity including anaphylaxis may develop. Intravenous therapy using epinephrine, corticosteroids, and diphenhydramine should be readily available during the infusion. Stop the infusion, if there is any evidence of anaphylaxis. Serum sickness may be occur as a delayed reaction.
    5) DISTRIBUTED BY: Accredo Health Group, Inc., Memphis, TN; (1-877-222-7336) or www.accredo.com.
    G) OTHER NON-INDICATED THERAPIES
    1) There is no role for cryotherapy, heat, tourniquets, incisions, or other local therapies.
    H) PATIENT DISPOSITION
    1) HOME MANAGEMENT: Healthy adults and children older than 5 years, who are experiencing only local symptoms, can be managed at home.
    2) OBSERVATION CRITERIA: Patients experiencing severe symptoms, those at the extremes of age, or with significant underlying medical illnesses should be referred for health care evaluation.
    3) ADMISSION CRITERIA: Hospitalize patients with severe symptoms not easily controlled with symptomatic and supportive care, or if antivenom has been given should be admitted. The level of care (eg, ICU) is determined by both symptomatology and underlying clinical status. Generally, admission is only required for young children, and rarely for more than 2 to 3 days.
    4) CONSULT CRITERIA: A clinician skilled in the management of scorpion envenomations should be involved in the care of severely envenomated patients. A regional poison center should also be consulted in such cases.
    I) PITFALLS
    1) Monitor airway carefully in patients with systemic manifestations who are treated with opioids, benzodiazepines, or other sedating drugs.
    J) PHARMACOKINETICS
    1) Symptom onset is rapid, generally within a few minutes of envenomation; duration of symptoms generally ranges from 10 to 30 hours.
    K) PREDISPOSING CONDITIONS
    1) Extremes of age (especially infants and toddlers) and underlying disease predispose individuals to more severe outcomes.
    L) DIFFERENTIAL DIAGNOSIS
    1) The history may not be apparent in preverbal children or in patients who collapse secondary to seizures or exacerbation of underlying medical conditions. Envenomation may appear to be an anaphylactic reaction, a primary seizure disorder, or an overdose of a sympathomimetic or cholinergic agent, depending on the predominant symptoms. The location of the scorpion sting should be sought. It will appear as a punctuate red mark surrounded by a small area of blanching and be very tender to touch. The typical clinical presentation in very young children in endemic areas (roving eye movements associated with severe agitation), along with negative toxicology tests, is usually sufficient to make the diagnosis.

Range Of Toxicity

    A) TOXIC DOSE: A single sting is sufficient to produce a severe envenomation or fatality. Very young children are more susceptible to the neurotoxic effects of Centruroides venom.

Clinical Effects

Summary Of Exposure

    A) USES: Scorpions of the Centruroides genera are found in the southern US, Mexico, Central America and the West Indies. In the US, symptomatic envenomation is caused most commonly by C sculpturatus and exilicauda species, primarily in southwestern States. Other common stinging scorpions in the US are members of the genera Vejovis, Hadrurus, and Androctonus, which may also produce a painful sting (similar to a bee or wasp sting), but are seldom serious.
    B) TOXICOLOGY: Most scorpion toxins affect the sodium channel of excitable cells by retarding inactivation (alpha toxins) or enhancing activation (beta toxins). A few of these toxins affect the potassium channel. As a result of effects on neuromuscular transmission and autonomic effects secondary to the release of acetylcholine at the vagal ganglia and on cardiac postganglionic nerves, affected individuals can develop signs and symptoms of cholinergic and sympathetic excess.
    C) EPIDEMIOLOGY: There are approximately 15,000 scorpion exposures per year in the US, mostly in the Southwest desert. The vast majority result only in pain. Fewer than 1000 require health care facility evaluation and treatment. A very small number, primarily in young children, result in significant neurologic toxicity. Deaths are very rare.
    D) WITH POISONING/EXPOSURE
    1) MILD TO MODERATE ENVENOMATION: In older children and adults, Centruroides stings generally cause only local pain, which may be severe at times and radiate up the affected limb.
    2) SEVERE ENVENOMATION: Systemic effects may develop after Centruroides envenomation, most commonly in children younger than 5 years. Sympathetic effects include increased heart rate and blood pressure, hyperglycemia, dilated pupils, piloerection, sweating, and hypertension. Parasympathetic effects include salivation, tearing, urination, defecation, bradycardia, hypertension, and gastric distension. Other effects include pain, paresthesias, hyperesthesia near the sting site, respiratory difficulties, increased secretions, stridor, irritability, blurred vision, difficulty swallowing, and slurred speech. The most dramatic signs of envenomation in young children are marked: hyperactivity, restlessness, opisthotonos accompanied by muscle twitching, fasciculations, roving eye movements, and nystagmus. In severe cases, rhabdomyolysis, dysrhythmias, and respiratory failure may develop, but these are rare. Effects are most severe in infants and toddlers. Life-threatening allergic reactions to Centruroides stings have also been reported rarely.

Vital Signs

    3.3.3) TEMPERATURE
    A) HYPOTHERMIA may develop after stings (Stahnke, 1965).
    B) HYPERTHERMIA: Elevated temperature, ranging from 37.6 degrees C to 41.1 degrees C has been reported in pediatric patients (Rachesky et al, 1984).
    1) INCIDENCE: 50% of patients stung by Centruroides margaritatus developed hyperthermia in 1 study (Marinkelle & Stahnke, 1965).

Heent

    3.4.3) EYES
    A) MYDRIASIS has been reported after stings by these species (Rachesky et al, 1984).
    B) Roving eye movements and nystagmus have been reported (Elston & Stockwell, 2002; Rimsza et al, 1980).
    1) INCIDENCE: In a series of 149 patients with C sculpturatus sting, 58% developed nystagmus (Gateau et al, 1994). Nystagmus was most common in children aged 10 years or younger .
    C) BLURRED VISION and even temporary blindness was seen after stings by members of the Centruroides species (Elston & Stockwell, 2002; Rachesky et al, 1984).
    1) INCIDENCE: In a series of 149 patients with C sculpturatus sting, 33% developed blurred vision (Gateau et al, 1994). Blurred vision was most common in adults.

Cardiovascular

    3.5.1) SUMMARY
    A) Tachycardia is common. Hypertension may also develop.
    3.5.2) CLINICAL EFFECTS
    A) HYPERTENSIVE EPISODE
    1) CASE REPORT: A 22-year-old stung on the finger was admitted with a blood pressure of 160/90 mmHg.
    2) CASE REPORT: A 27-year-old stung on the left little finger had a blood pressure of 160/70 mmHg (Russell & Madon, 1984).
    3) CASE REPORT: A 14-year-old was stung on the neck and ankle; her blood pressure on admission was 130/80 mmHg (Trestrail, 1981).
    4) The venom of Centruroides sculpturatus has been shown to elevate plasma renin levels (LaGrange, 1977).
    B) TACHYARRHYTHMIA
    1) CASE REPORT: An 8-month-old stung by C exilicauda had a heart beat that intermittently exceeded 200 beats per minute (bpm) about 2 hours poststing. A 17-month-old discussed in the same report had a heart rate of 170 bpm on admission (Rachesky et al, 1984).
    2) INCIDENCE: In a series of 15 children with Centruroides envenomation, 14 developed tachycardia (Bond, 1992).
    C) ELECTROCARDIOGRAM ABNORMAL
    1) WITH POISONING/EXPOSURE
    a) In a prospective study of 113 children (aged 5 to 14 years) with Centruroides scorpion envenomation, 45 children (39.8%) had abnormal ECGs. The frequency of different ECG abnormalities was sinus tachycardia 13.3%; atrial tachycardia 48.8%; supraventricular tachycardia 4.5%; hyperacute T waves 6.6%; inverted T waves 2.2%; incomplete right bundle branch block 22.2%; right bundle branch block 8.8%; increased ventricular automatism 2.2%. There was no correlation between the frequency of ECG abnormalities and the severity of presenting symptoms. Children aged 8 to 9 years developed ECG abnormalities more frequently as compared with other age groups (Diaz et al, 2005).
    D) HEART FAILURE
    1) WITH POISONING/EXPOSURE
    a) C exilicauda stings may cause cardiac failure (Elston & Stockwell, 2002).

Respiratory

    3.6.1) SUMMARY
    A) Respiratory distress and insufficiency may develop with Centruroides species secondary to increased secretions, CNS depression, and neuromuscular effects.
    3.6.2) CLINICAL EFFECTS
    A) APNEA
    1) The venom of these species may cause neuromuscular block and respiratory failure (Russell & Madon, 1984).
    2) CASE REPORT: An 8-month-old and a 17-month-old stung by C exilicauda both developed coughing. The younger child became cyanotic with stridor despite a respiratory rate of 48/minute. The older child had a rate of 42/minute (Rachesky et al, 1984).
    3) INCIDENCE: Four of 24 children (16%) stung by Centruroides sculpturatus had inspiratory stridor, and 2 had expiratory wheezing (Rimsza et al, 1980).
    4) Cough, wheezing, inspiratory stridor, cyanosis, and respiratory failure were seen in patients have been reported (Berg & Tarantino, 1991).
    5) INCIDENCE: In a series of 15 children with Centruroides envenomation, 13 (87%) had excessive secretions, difficulty handling secretions or hypersalivation (Bond, 1992). Five developed hypercarbia, hypoxia, or both, and 1 required intubation for respiratory failure.
    B) RESPIRATORY TRACT PARALYSIS
    1) WITH POISONING/EXPOSURE
    a) C exilicauda stings may cause respiratory paralysis (Elston & Stockwell, 2002).

Neurologic

    3.7.1) SUMMARY
    A) Agitation, movement disorders, CNS depression, paresthesias, fasciculations, nystagmus and slurred speech are common with Centruroides stings.
    3.7.2) CLINICAL EFFECTS
    A) PSYCHOMOTOR AGITATION
    1) Restlessness, agitation, and hyperactivity are common after Centruroides sting (Russell & Madon, 1984; Wilson, 1987).
    2) INCIDENCE: Restlessness and agitation developed in 59% of 149 patients in 1 series (Gateau et al, 1994). Restlessness was more common in children younger than 10 years (Gateau et al, 1994).
    3) CASE REPORT: Two children stung by C exilicauda exhibited agitation, restlessness, and irritability (Rachesky et al, 1984).
    B) CENTRAL NERVOUS SYSTEM DEFICIT
    1) CASE REPORT: Coma was reported in 1 child stung by an unidentified (thought to be Centruroides exilicauda) scorpion. This patient had concurrent respiratory failure (Berg & Tarantino, 1991).
    C) PARESTHESIA
    1) INCIDENCE: Paresthesias are common after Centruroides sting, developing in 39% of 149 patients in 1 series (Elston & Stockwell, 2002; Gateau et al, 1994).
    2) CASE REPORT: A 22-year-old who was stung on the finger complained of hyperesthesias of the right hand and right forearm (Russell & Madon, 1984).
    3) CASE REPORT: A 27-year-old stung on the finger 90 minutes prior to being seen reported hypersensitivity to touch on the hand and arm, and tingling of her tongue. Her arm eventually "became numb" (Russell & Madon, 1984).
    4) CASE REPORT: A 14-year-old stung on the neck and ankle complained of hyperesthesia near the sting site of the ankle, and a strange tingling sensation in her throat when swallowing. The scorpion was identified as C sculpturatus (Trestrail, 1981).
    5) The hyperesthesia or paresthesias are generally of 4 hour or less duration (Likes et al, 1984).
    D) SPASMODIC MOVEMENT
    1) INCIDENCE: Fasciculations are common after Centruroides sting, developing in 34% of 149 patients in 1 series (Elston & Stockwell, 2002; Gateau et al, 1994). Fasciculations were more common in children younger than 10 years.
    2) CASE REPORT: A 22-year-old stung on the first finger of the right hand first developed cramping of his right arm, then muscle fasciculations of his right forearm, the right side of the neck, and both sides of the face (Russell & Madon, 1984).
    E) DYSKINESIA
    1) Opisthotonus and choreiform movements have been reported following C exilicauda envenomation (Wax, 2002).
    2) CASE REPORT: An eight-month-old child exhibited spastic movements, and unusual "stretching and tensing" after a sting by C exilicauda (Rachesky et al, 1984).
    3) CASE REPORT: A 17-month-old stung by the same species showed opisthotonic posturing (Rachesky et al, 1984).
    F) DISTURBANCE IN SPEECH
    1) INCIDENCE: Slurred speech is common after Centruroides sting, developing in 17% of 149 patients in 1 series (Gateau et al, 1994).
    G) NYSTAGMUS
    1) Roving eye movements and nystagmus have been reported (Elston & Stockwell, 2002; Rimsza et al, 1980).
    2) INCIDENCE: In a series of 149 patients with C sculpturatus sting, 58% developed nystagmus (Gateau et al, 1994). Nystagmus was most common in children younger than 10 years.

Gastrointestinal

    3.8.1) SUMMARY
    A) Nausea, vomiting, and difficulty swallowing may occur. Excessive salivation is common.
    3.8.2) CLINICAL EFFECTS
    A) VOMITING
    1) Vomiting may be seen with these stings (Curry et al, 1984; Berg & Tarantino, 1991; Gateau et al, 1994) but is not common.
    B) DYSPHAGIA
    1) INCIDENCE: Difficulty swallowing is common after Centruroides sting, developing in 33% of 149 patients in 1 series (Elston & Stockwell, 2002; Gateau et al, 1994).
    2) CASE REPORT: Difficulty in swallowing and a tingling sensation in the tongue were reported in a 27-year-old stung on the finger (Russell & Madon, 1984). Dysphagia occurred in a child stung by this species (Rimsza et al, 1980).
    C) EXCESSIVE SALIVATION
    1) Excessive salivation has been reported in several patients after stings by C exilicauda scorpions (Elston & Stockwell, 2002; Rachesky et al, 1984; Berg & Tarantino, 1991).
    2) INCIDENCE: Excessive salivation is common after Centruroides sting, developing in 35% of 149 patients in 1 series (Gateau et al, 1994). Hypersalivation is more common in children younger than 10 years (Gateau et al, 1994).

Genitourinary

    3.10.1) SUMMARY
    A) Urinary urgency has been reported but is not common.
    3.10.2) CLINICAL EFFECTS
    A) URGENT DESIRE TO URINATE
    1) CASE REPORT: Urinary urgency was noted in a 22-year-old stung on the finger (Russell & Madon, 1984).

Acid-Base

    3.11.1) SUMMARY
    A) Respiratory acidosis has been reported in young children.
    3.11.2) CLINICAL EFFECTS
    A) RESPIRATORY ACIDOSIS
    1) INCIDENCE: In a series of 15 children with Centruroides envenomation, 5 had arterial blood gas determinations; all had a respiratory acidosis (Bond, 1992).

Hematologic

    3.13.1) SUMMARY
    A) Coagulopathy is a rare complication.
    3.13.2) CLINICAL EFFECTS
    A) BLOOD COAGULATION PATHWAY FINDING
    1) CASE REPORT: Gross bleeding through the nasogastric tube and coagulopathy developed after a Centruroides sting (Berg & Tarantino, 1991).

Dermatologic

    3.14.1) SUMMARY
    A) Diaphoresis and piloerection may develop.
    3.14.2) CLINICAL EFFECTS
    A) SKIN IRRITATION
    1) WITH POISONING/EXPOSURE
    a) C exilicauda stings may cause pain and systemic symptoms, but rarely cause swelling, erythema, or local purpura. The absence of local tissue reaction may help distinguish C exilicauda stings from those of other scorpions (Elston & Stockwell, 2002).
    B) EXCESSIVE SWEATING
    1) Increased sweating has also been reported after stings by these species (Elston & Stockwell, 2002; Rachesky et al, 1984).
    C) PILOERECTION
    1) Piloerection has been reported as a symptom after stings by this species (Rachesky et al, 1984).

Musculoskeletal

    3.15.1) SUMMARY
    A) Local pain is common with most scorpion stings. Rhabdomyolysis is an unusual complication.
    3.15.2) CLINICAL EFFECTS
    A) PAIN
    1) INCIDENCE: Local pain is common after Centruroides sting, developing in 19% of 149 patients in 1 series (Gateau et al, 1994).
    B) RHABDOMYOLYSIS
    1) Rhabdomyolysis with CPK elevations over 5000 units/L have been reported (Berg & Tarantino, 1991; Bond, 1992).

Endocrine

    3.16.1) SUMMARY
    A) Hyperglycemia is reported.
    3.16.2) CLINICAL EFFECTS
    A) HYPERGLYCEMIA
    1) Hyperglycemia was been reported as a finding in patients stung by these species (Rachesky et al, 1984).

Immunologic

    3.19.1) SUMMARY
    A) Anaphylaxis to Centruroides sting has been reported rarely.
    3.19.2) CLINICAL EFFECTS
    A) ANAPHYLAXIS
    1) Two cases of anaphylaxis to Centruroides scorpion sting have been described, one of which was fatal (Boyer et al, 2001; Welch & Thomas, 1998).
    B) IMMUNE SYSTEM FINDING
    1) WITH POISONING/EXPOSURE
    a) CASE REPORT: IgE antibodies were detected in a 65-year-old female's serum 7 months after an acute anaphylactic reaction from Centruroides sculpturatus envenomation(Chase et al, 2002).
    b) C exilicauda stings may cause immediate hypersensitivity reactions (Elston & Stockwell, 2002).

Reproductive

    3.20.1) SUMMARY
    A) An uneventful pregnancy and delivery were seen following a finger sting and MYN antivenin infusion.
    3.20.3) EFFECTS IN PREGNANCY
    A) LACK OF EFFECT
    1) CASE REPORT: A 27-year-old pregnant woman was stung on the finger (point in pregnancy unknown). She received 1 vial of MYN antivenin by slow infusion in 250 mL of saline. She was discharged 48 hours after exposure. Her pregnancy and delivery were uneventful (Russell & Madon, 1984).

Laboratory Monitoring

Monitoring Parameters Levels

    4.1.1) SUMMARY
    A) Laboratory evaluation may not be necessary. In severe envenomations, monitoring of blood pressure, respiratory rate, and oxygenation status should be performed and the ECG monitored. A 12-lead ECG, and basic laboratories, including a CK, may be needed in severe cases.
    4.1.2) SERUM/BLOOD
    A) BLOOD/SERUM CHEMISTRY
    1) Laboratory evaluation may not be necessary. Monitor CK in severe envenomations (patients with prolonged coma or increased motor activity).

Radiographic Studies

    A) CHEST RADIOGRAPH
    1) Obtain a chest x-ray in patients with significant respiratory distress or evidence of pulmonary edema.

Methods

    A) CHROMATOGRAPHY
    1) May be used to separate and quantify the various components of some of the scorpion venoms (Martin et al, 1987). This is of scientific interest, but is not done in clinical settings.

Treatment

Life Support

    A) Support respiratory and cardiovascular function.

Patient Disposition

    6.3.6) DISPOSITION/BITE-STING EXPOSURE
    6.3.6.1) ADMISSION CRITERIA/BITE-STING
    A) Hospitalize patients with severe symptoms not easily controlled with symptomatic and supportive care, or if antivenom has been given should be admitted. The level of care (eg, ICU) is determined by both symptomatology and underlying clinical status. Generally, admission is only required for young children, and rarely for more than 2 to 3 days.
    6.3.6.2) HOME CRITERIA/BITE-STING
    A) Healthy adults and children older than 5 years who are experiencing only local symptoms can be managed at home.
    6.3.6.3) CONSULT CRITERIA/BITE-STING
    A) A clinician skilled in the management of scorpion envenomations should be involved in the care of severely envenomated patients. A regional poison center should also be consulted in such cases.
    6.3.6.5) OBSERVATION CRITERIA/BITE-STING
    A) Patients experiencing severe symptoms, those at the extremes of age, or with significant underlying medical illnesses should be referred for health care evaluation.

Monitoring

    A) Laboratory evaluation may not be necessary. In severe envenomations, monitoring of blood pressure, respiratory rate, and oxygenation status should be performed and the ECG monitored. A 12-lead ECG, and basic laboratories, including a CK, may be needed in severe cases.

Range Of Toxicity

Summary

    A) TOXIC DOSE: A single sting is sufficient to produce a severe envenomation or fatality. Very young children are more susceptible to the neurotoxic effects of Centruroides venom.

Minimum Lethal Exposure

    A) SPECIFIC SUBSTANCE
    1) CENTRUROIDES SPECIES: A single sting may be fatal for a child or debilitated or hypertensive adult but is rare in the United States. Although scorpion stings that produced fatalities were not uncommon years ago, good supportive care has made this a rare outcome (Rachesky et al, 1984; Likes et al, 1984).
    2) In Mexico, Centruroides scorpion stings may cause approximately 300 deaths per year (Dehesa-Davila & Possani, 1994).
    B) ANIMAL DATA
    1) MOUSE: The minimum lethal dose of venom from C exilicauda in mice is 1.12 mg/kg (Stahnke, 1963; Stahnke, 1965).

Pharmacology Toxicology

Toxicologic Mechanism

    A) SCORPION VENOM
    1) GENERAL: Their venom consists of 10 or more basic, neurotoxic proteins and at least 6 nonproteins (Meves et al, 1984). Most scorpion toxins affect the sodium channel of excitable cells by retarding inactivation (alpha toxins) or enhancing activation (beta toxins). A few of these toxins affect the potassium channel (Watt et al, 1990).
    2) CENTRUROIDES scorpion venom, the so-called "lethal scorpion," as most scorpion venoms, is poor in enzymes but has at least 5 neurotoxins (Rachesky et al, 1984), all having similar numbers of amino acids, lysine, and tyrosine residues, and 4 disulfide bridges. It has a particular effect on the peripheral nervous system, causing a block in neuromuscular transmission. The clinical effect seen is hypertension. Toxins I alpha, II alpha, III alpha, and III beta act primarily on the activation process of sodium channels. After nerve membranes are depolarized, these toxins reduce the flow of the sodium channel. After membrane repolarization, these toxins (with the exception of I alpha) induce a new inward current, resulting in spontaneous firing and repetitive firing of action potentials even after a single impulse (Rachesky et al, 1984; Wang & Strichartz, 1983). Another group of toxins, which includes IV alpha, affects the sodium channel by slowing and preventing complete inactivation, which results in a prolonged action potential via stabilization of sodium channels in their ion-conducting state (Rachesky et al, 1984; Carbone et al, 1984; Meves et al, 1984). The bradycardia caused by these venoms is thought to be due to the release of acetylcholine by the action on vagal ganglia and postganglionic nerve endings found in the heart (Freire-Maia et al, 1974).

References

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