Intractable sneezing: case report and literature review.

Intractable sneezing is rare; the 12th case is reported here. Various causative factors have been identified in the literature; these include psychologic problems, cervical lymphadenitis, epilepsy, and allergy. The sneeze reflex consists of two phases, nasal and respiratory, which are mediated by cranial nerves V and VII and by brain-stem respiratory centers. Hypotheses that have been proposed to explain the multiple causation of sneezing are the concept of the trigeminal system as a central neuronal pool, optic-trigeminal summation, and parasympathetic generalization.