Prevalence of onodi cells in hospital raja permaisuri bainun, ipoh, malaysia.

Background: Onodi cell is a posterior ethmoid air cell that pneumatizes into the sphenoid sinus, It is an important entity for clinicians when performing endoscopic sinus surgery (EES) because it encroaches into the optic nerve and internal carotid artery. CT-scans are the road map for ESS to prevent damage to structures mentioned above. Its prevalence in Malaysia is unknown.

Methods: 102 CT-scans of paranasal sinuses dated from 2006- 2009 in Hospital Raja Permaisuri Bainun (HRPB), Ipoh, Malaysia were studied by Consultant Rhinologist (HS). The Onodi Cells were recorded as present on the left side, right side or bilaterally.

Results: A total of 59 males and 43 females with a mean age of 42 were studied. Twenty of the scans were noted to have Onodi cells. Of those with Onodi present, 5 were females and 15 were males; 9 of them had sinusitis and 11 had nasal polyposis. None of them were noted to have complications related to the Onodi cells. There were 6 with left side involvement, 7 with right side involvement and 7 with bilateral Onodi cells.

Conclusions: A prevalence of 19.6% was noted in the patients in HRPB, Ipoh, corresponding to other CT-scan studies ranging from 7-24%. The presence of Onodi cells should be routinely looked for by ESS surgeons to prevent damaging the optic nerve and internal carotid artery.