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Clinical Flowchart

Autopharmacological effects

Experimental and clinical observations suggest that the major systemic effects of envenoming are caused by endogenous catecholamines and acetylcholine, which are released in response to scorpion venom. As these are transmitters in the sympathetic, parasympathetic and somatic nervous systems, the resulting clinical symptoms of envenoming are dealt within the section "Neurological effects".
However, scorpion venoms are also believed to lead to other indirect effects that are caused by the release of autopharmacologically active substances (such as kinins, prostaglandins and slow-reacting substances). The pathophysiological effects of these substances overlap to a great extent. This makes it difficult to be certain about aetiology. In particular with regard to pulmonary oedema, there has been discussion concerning the effects of mediators on vascular permeability, which might constitute a non-cardiac component of the pulmonary oedema. Peripheral blood pressure regulation is also responsive to a variety of different mediators that might be released.

Local effects

All scorpions
Minutes
 
Local pain is the dominant symptom, often severe; redness; oedema; numbness.

Haematological effects

Nebo hierochonticus1

Hemiscorpius lepturus2
1    Clotting disturbances
Localizing neurological signs, meningism, coma (intracranial bleeding!)
Systemic bleeding: retinal haemorrhages; cranial CT features of cerebellar and cerebral and cerebellar haemorrhages.
2 Microangiopathic haemolysis
Severe microangiopathic haemolysis causing early haemoglobinuria and leading to a HUS-like presentation with AKI that requiresrenal replacement therapy (Warrell 2023).

Neurological effects

Androctonus sp.
Buthus sp.
Centruroides sp.
Hottentotta thamulus
Leiurus sp.
Nebo hierochonticus
Parabuthus sp.
Tityus sp.

Hours
 

Transient cholinergic effects 
Vomiting, increased peristalsis, diarrhoea, abdominal pain; profuse sweating; pupil constriction. Priapism.
Bradycardia, arterial hypotension, shock. Hypersalivation; increased bronchial secretion, bronchospasm, respiratory failure.

Longer-lasting adrenergic effects 
Pupil dilatation.
Tachycardia, arrhythmias, arterial hypertension, myocardial failure, pulmonary oedema (cardiogenic + ?non-cardiogenic component), cardiac ischaemia, shock.
Hyperglycaemia (most likely due to hypercatecholaminaemia) 
Acute pancreatitis (also associated with hyperglycaemia)
Hypertensive encephalopathy. 

 Neuromuscular dysfunction
Cranial nerves: Ptosis, "wandering" eye movements, dysphagia (inhalation of vomitus!), dysarthria, pharyngeal reflex absent;
Skeletal musculature: Involuntary movements, restlessness, reduced grip and pinch strength; muscle spasms.
Descending flaccid paralysis (rarely progresses to involve respiratory muscles)
Cyanosis, shallow breathing, respiratory arrest (respiratory paralysis); respiratory arrest may be precipitated by obstruction of the upper airway, by the paralysed tongue or inhaled vomitus.
Loss of consciousness and generalized convulsions caused by hypoxaemia in patients who have respiratory paralysis.
 
Cardiovascular and pulmonary failure
 

Muscular effects

Not observed.

Cardiac effects

Experimental and clinical observations suggest that the major systemic effects of envenoming are caused by endogenous catecholamines and acetylcholine, which are released in response to scorpion venom. As these are transmitters in the sympathetic, parasympathetic and somatic nervous systems, the resulting clinical symptoms of envenoming are dealt with in the section "Neurological effects".

Renal effects

Not observed.