Scorpion stings: focus on cerebrovascular complications of envenoming


  • Conflict of interest: Nothing to disclose.

Correspondence: Oscar H. Del Brutto, Air Center 3542, PO Box 522970, Miami, FL 33152-2970, USA.


Dear editor,

Scorpion stings kills thousands of people every year [1]. Clinical picture of envenoming is dominated by local pain, weakness, arterial hypertension, cardiac arrhythmias, myocarditis, or pulmonary oedema. These manifestations occur as the result of massive release of catecholamines into the bloodstream or due to direct toxicity of the venom [2].

Cerebrovascular complications occur in up to 8% of severely envenomed scorpion sting victims, particularly after the sting of Mesobuthus thalamus (Indian red scorpion). Intracranial haemorrhages occur in the setting of acute increases in blood pressure related to sympathetic overstimulation, and cerebral infarctions are related to cerebral hypoperfusion, consumption coagulopathy, vasculitis, intracranial vessels spasm, or cardiogenic brain embolism [3, 4]. A PubMed search revealed 23 well-documented cases of stroke following scorpion stings (mean age 25 years; 71% men). Fifteen patients (65%) had ischaemic and eight had haemorrhagic strokes.

Infarctions were located in the middle cerebral artery territory (six patients), watershed areas between major cerebral arteries (three patients), the cerebellum (two patients), multiple arterial territories (two patients), and the posterior cerebral artery territory and the pons (one patient each). Pathogenetic mechanisms responsible for the infarction were suspected in 13 patients, six of whom had cerebral hypoperfusion (related to systemic hypotension), four had disseminated intravascular coagulation, two had vasculitis, and one had spasm of intracranial arteries.

Haemorrhagic strokes were located in the basal ganglia in four cases, the subcortical white matter in two, and the ventricular system in one. The remaining patient had multiple intracranial haemorrhages. In seven cases, the cause of the haemorrhage was an increase in arterial blood pressure occurring as part of the ‘autonomic storm’ observed in scorpion sting victims.

Prompt management of these patients reduces stroke morbidity and mortality. Prazosin reverses the overstimulation of peripheral α1-adrenergic receptors and reduces the risk of cardiac and pulmonary complications. While the use of antivenom has been questioned due to allergic reactions, combination therapy with antivenom plus prazosin was more effective than prazosin alone for enhancing recovery in a recent trial [5].