A 39-YEAR-OLD man with a history of chronic psychosis and alcohol abuse had a new right hemiparesis and confusion after reportedly hitting his head against a table. He was writing a letter just prior to the event, and reportedly screamed aloud, "This will never happen again." On examination, the patient had a right hemiparesis with hyperreflexia, the Babinski sign, right-sided neglect, and disorientation.
A noncontrast computed tomographic scan of the head showed a metal density and a linear air density in the medial left parietal lobe, extending anteriorly down to the hypothalmic region and traversing the left cerebral peduncle, with hemorrhage and edema in the left thalamus. The tract of air was parallel, unlike the irregular and closed tracts associated with gunshots. On the scout images, we noted a parallel density that appeared to contain air, and also a column of another density, all of which had the appearance of a ballpoint pen, with metal density at the tip (Figure 1). Reconstructions of the computed tomographic images angled to the plane of the pen were made to further highlight the mucosal thickening in the sphenoid sinus and to demonstrate continuity of the foreign body, thus confirming the entry site (Figure 2, and Figure 3).
Kreitzman D, Knorr J. Cerebral Foreign Body. Arch Neurol. 2003;60(11):1640. doi:10.1001/archneur.60.11.1640