Scorpion sting and blindness: A case report

ABSTRACT

Scorpion stings are one of the most common envenomations seen in the world. Rarely scorpion stings are known to cause a stroke. We report a case of a 60-year-old male, who presented with an unknown bite over the right middle finger which the patient revealed to be a scorpion sting, followed by altered sensorium and blindness. Brain imaging revealed an occipital infarct. This case report was written because scorpion sting causing an ischemic stroke is rare and ischemic stroke in the occipital region secondary to scorpion causing blindness has not been reported before.

Introduction

Scorpion sting is one of the common envenomation in tropical countries like India. Most of the patients present to the hospital with non-fatal manifestations such as local pain and discoloration. Fatal manifestations are usually due to cardiac problems such as arrhythmias and hypotension. Rarely, a patient can present with cerebrovascular accidents. Here, we report a very rare presentation of a patient presenting with painless loss of vision and altered sensorium secondary to an occipital infarct.

Case Presentation

A 60-year-old male, a farmer from southern India came with a history of unknown bites and altered sensorium. The patient had a history of an unknown bite on his right ring finger at around 6.30 pm on agricultural land. He started having progressively increasing pain and swelling over the bite site 2 days after the bite. One day later, the patient had a sudden painless loss of vision, followed by an altered sensorium in the form of irrelevant speech and disorientation. The patient was conscious, not oriented to time, place, and person with stable hemodynamics. The nervous system examination revealed Glascow Coma Scale (GCS) of E4V4M5-13/15. Bilateral pupils and fundus examination were normal. He was moving all four limbs at admission and was walking. The bilateral plantar was normal. Local examination revealed swelling and severe tenderness over the right ring finger with blackish discoloration of the distal part of the right ring finger [Figure 1a]. Non Contrast Computed Tomography (NCCT) brain revealed a hypodense lesion in the bilateral basal ganglia, and bilateral occipital lobe (left more than right) consistent with ischemic stroke [Figure 1b and c]. The patient was started on aspirin and atorvastatin. The patient’s sensorium gradually improved over the next 3 days. History was retaken which revealed that he was stung by a scorpion when he was removing the weeds from the field. Re-examination revealed normal mental functions, cranial nerves, and motor and sensory functions. Visual acuity was only the perception of light in both eyes. On examining the cerebellar signs, he had swaying toward both sides (left more than right), with Scanning speech and absent B/L dysdiadochokinesia.

Figure 1.

(a) Dry gangrene of the distal part of the right ring finger. (b) Plain CT brain showing multiple hypodensities in bilateral cerebellar lobes suggestive of ischemic stroke. (c) Plain CT brain showing bilateral occipital hypodensities, left more than right, suggestive of posterior circulation ischemic stroke. (d) MRI of the brain—FLAIR sequence which shows hyperintensity in the posterior cerebellum—PICA territory. (e) MRI of the brain—flair sequence showing hyperintensities in bilateral thalami and occipital region. (f) MR angiogram of the circle of Willis showing narrowing of P1 and P2 segments of posterior cerebral artery on the left side

Complete Blood Count (CBC) with peripheral smear and Pro thrombin Time and International Normalised Ratio (PT-INR) were done to rule out venom-induced consumptive coagulopathy and were normal. To rule out myocarditis, ECG, transthoracic ECHO, and cardiac enzymes (Cardiac troponins/creatinine kinase) were done and were normal. MRI brain with MRA showed multiple infarcts, the largest in the cerebellum and occipital areas with a filling defect in the left vertebral artery [Figure 1d, 1e and 1f]. Causes of stroke, like diabetes and dyslipidemia, were ruled out by normal HbA1c and fasting lipids. The patient’s vision never improved and was discharged on antiplatelet and anti-lipids drugs.

Discussion

Scorpion stings are one of the common public health problems in tropical and subtropical countries and almost 1.2 million people are stung by a scorpion every year, out of which 0.27% die.[1] Less than 10% of patients presenting to the hospital with scorpion stings had fatal manifestations, and stroke is very rare.[2] In a case series done in southern India, cerebrovascular involvement was noted in 8% of patients out of which 4% had hemorrhagic stroke and 4% had thrombotic stroke.[3] The following were the proposed causes for stroke in a patient with scorpion sting: Venom-induced coagulopathy, also known as defibrination syndrome, can cause both hemorrhagic and ischemic stroke, myocarditis causing arrhythmias giving rise to embolic stroke or causing hypotension and watershed areas infarcts, autonomic storm causing hypertension and ICH, and secondary to vasculotoxic effect of the venom.[4] Our patient did not have any evidence of defibrination syndrome, myocarditis, or autonomic storm. Our patient’s most probable cause of the stroke was vasculitis caused by scorpion venom. There are case reports of scorpion stings causing a stroke.[5] We could not find any case in the literature where a scorpion sting has caused blindness secondary to an occipital infarct.[5] Atypical presentation, such as occipital infarct causing blindness in a patient with scorpion sting is probably due to the vasculotoxic effect of the venom, prompted us to write this case report.

The key message from this case report is[5] that scorpion stings though very common rarely can present as stroke or hemorrhagic stroke more than ischemic stroke. Patients with stroke may have varied clinical presentations like weakness of limbs, cranial nerve palsies, altered mental status and very rarely as painless loss of vision like our patient. There are multiple hypotheses for the development of stroke including venom-induced consumptive coagulopathy, myocarditis, arrhythmias throwing up embolus, autonomic storm causing hypertension, and vasculitis due to the direct effect of the venom on the vessels. The primary care physician should suspect scorpion sting as a rare cause of stroke in patients with no or little risk factors for atherosclerosis or cardio-embolic stroke.

Consent

The patient’s family has granted permission to write this report.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.