In 4 per cent of the cases the pain was referred to the upper teeth, on the same side as the affected maxillary sinus. This is presumably an involvement of the posterior superior alveolar nerve. In another 4 per cent there was involvement of the infraorbital nerve, with numbness over the skin of the cheek on the same side.
Two separate branches of the maxillary division of trigeminal nerve can thus be affected as they traverse the maxillary sinus16,17: the infraorbital nerve as it runs along the wall of the maxillary sinus and the posterior superior alveolar nerve as it runs along the lateral or inferior wall of the maxillary sinus. The former produces a numbness or paraesthesia over the cheek and the latter a numbness over the upper teeth, gums and mucosa on the same side. In some cases pain and hypersensitivity are observed. Problems with neurapraxia are more common with ascent than descent, a finding suggesting that impaired circulation is more frequent than congestion or haemorrhage of the nerve as a basis of the presentation.
There is a possibility of involvement of any division of the trigeminal nerve, including its maxillary division, with involvement of the sphenoidal sinus18.