The combination of pain, ipsilateral oculosympathetic defect (ptosis and miosis), and ipsilateral trigeminal dysfunction constitutes Raeder's syndrome. We describe a patient with an acute presentation of Raeder's syndrome due to spontaneous internal carotid artery dissection. True trigeminal dysfunction due to carotid dissection is rare, and the potential mechanisms for its involvement are reviewed in this paper. Finally, we remind clinicians to consider dissection in the differential diagnosis of Raeder's syndrome because of its potential for ischemic cerebral neurologic sequelae and suggest early cranial and neck imaging in the evaluation of such patients.