Cavernous Sinus Syndrome and Traumatic Carotid-Cavernous Fistula Attributable to a Self-Inflicted BB Gunshot Injury

Introduction: Ball bearing or “BB” guns are a class of gas- or spring-powered projectile weapons whose power and muzzle velocity are often underestimated by casual users and children. Present technology has advanced such that modern BB guns produce high velocity but small caliber ballistic injuries which can penetrate the intracranial space and cause focal central neurologic deficits. The small size of the projectile simultaneously complicates diagnosis and treatment, particularly if the entry wound is not appreciated by the layperson, resulting in delayed care. We report a unique case of cavernous sinus syndrome precipitated by a self-inflicted facial BB gunshot injury in a child.

Methods: Case report.

Results: A 9-year-old boy was playing with a BB gun when he accidentally suffered a self-inflicted BB gunshot injury to the face. Family believed that a superficial injury only had been sustained, and medical evaluation was correspondingly delayed more than 5 days. During that time, the patient was unable to completely open his eye and complained of diplopia, eventually prompting ED presentation. At that time, he had progressed to malaise, nausea and vomiting, and a right complete CN III and IV nerve palsy, with intact vision, and functioning CN V and VI. Diagnostic angiography revealed a BB retained in the medial cavernous sinus, as well as a small carotid cavernous fistula. The BB was in contact with the cavernous segment of the ICA, inducing minimal arterial stenosis. The projectile was confirmed to be ferromagnetic, and so MRI was deferred. The patient was managed expectantly, and one-month follow-up angiography was arranged to rule out migration of the retained BB and reevaluate the status of the carotid-cavernous fistula. His serum lead level was followed periodically in consideration of medical management, although as this was a spherical BB and not a pellet, the lead content is believed to be low.

Conclusion: Modern BB guns can penetrate the cranium and injure skull base structures such as the cavernous sinus, potentially producing severe and highly focal neurological injuries, depending on the trajectory of the pellet. Traumatic vascular injuries causes by BB guns are managed similarly to other missile or penetrating trauma, although little is known about their specific natural history. Other specific management considerations are MRI safety and lead content, which vary significantly from other types of retained projectile injuries, due to differences in composition.

Fig. 1 AP and lateral digital subtraction angiography of the right internal carotid artery with 3D reconstruction demonstrates localization of the retained BB within the right cavernous sinus, intimately related with the intracavernous segment of the right internal carotid artery.