A 65-year-old man developed subacute horizontal diplopia due to left abducens nerve (AN) palsy and excessive left eye tearing. Brain MRI revealed a hyperintense T2 lesion with an elongated course within the left carotid canal, presenting homogenous contrast enhancement (figure 1). The imaging findings were characteristic for an internal carotid artery sympathetic plexus (ICSP) schwannoma compressing the left AN. Subsequent irritation of the deep petrosal nerve originating directly from ICSP and continuing as the Vidian nerve may have led to the lacrimal gland edema and excessive left eye tearing (figure 2). Thorough case presentation and a figure demonstrating the relevant anatomy are available from Dryad at doi.org/10.5061/dryad.pzgmsbck6.