Sunday, 5 August 2012

Intracranial extension of Shotgun pellet through orbit

Neuroradiology Cases
A 30 year male came for follow up imaging with history of accidental shot gun injury to left eye while working in field. There is a small entrance wound scar in the lower left orbital fold. Neurological examination including visual acuity and eye movements are normal.
MRI not done as it is contraindicated in this case.
CT study of brain shows a pellet stuck at left petrous apex, the region corresponds to junction of left cavernous sinus and superior petrosal sinus. Streak artifact due to its high density. 
In the present case the left eye appears to be an entry point, going intra cranially through superior orbital fissure appears to have gained entry in left cavernous sinus stuck at the tip of left petrous apex due to resistance in the trajectory of the pellet.


Missile injuries and intracranial extension through bony calvarium or orbit are common but embolisation of the bullet or pellet is rare event. Most of the reports are related to arterial embolisation in that anterior cerebral circulation are relatively common. Posterior cerebral circulation embolisation are rarely mentioned in the literature.
The embolism after penetrating the vessel let it be artery or vein depends on the size of the missile and its velocity. Small size and low velocity are requirements for embolization to occur. Because of the small size and low velocity with the wider area covered at a time by the large number of these pellets, the shotgun wounds are most commonly associated with arterial or venous penetration and embolism. The site of entrance of the missile in cases of embolization to the intracranial circulation is usually the chest or the neck, where it can either enter the heart, aortic arch or the neck vessels.
The treatment of intra cranial extension and embolism of pellet is controversial. Conservative treatment is suggested for such asymptomatic patient. Metallic pellets are not amenable to endovascular removal because of the risk of intimal injury.

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