1. Department of Otorhinolaryngology – Head and Neck Surgery, Faculty of Medicine El‐Demerdash Hospital, Ain Shams University Cairo Egypt
2. Department of Otolaryngology – Head and Neck Surgery The Ohio State University Columbus Ohio USA
3. Department of Otorhinolaryngology – Head and Neck Surgery, Faculty of Medicine Assiut University Assiut Egypt
4. Department of Neurological Surgery The Ohio State University Columbus Ohio USA