OBJECTIVES: To  report  a  case  of  congenital  oval  window  aplasia  (COWA)  in  a  Filipino  adult presenting   with      unilateral   maximal   conductive   hearing   loss   and   discuss   the   diagnostic considerations, pathophysiology and management.
METHODS:
Design: Case Report
Setting: Tertiary Public Referral Center
Patient: One
RESULTS: Audiometric evaluation showed a maximal unilateral left conductive hearing loss. High resolution temporal bone CT showed absence of the oval window on the left along with facial and stapes  abnormalities.    Exploratory  tympanotomy  showed  an  aberrant  facial  nerve,  monopodal and  abnormally  located  stapes  and  absent  oval  window. Postoperative  hearing  gain  achieved after a neo-oval window and Schuknecht piston wire prosthesis remained stable over two years.
CONCLUSION: A congenital minor ear anomaly classified as Cremers Class 4a in which a congenital oval  window  aplasia  was  associated  with  an  aberrant  facial  nerve  anomaly  and  a  monopodal stapes is reported. Recent literature supported the view that congenital oval window aplasia can in selected cases be amenable to various surgical approaches and a stable postoperative hearing gain is achievable in the long term.