Olfactory nerve is the first and shortest cranial nerve. It carries the sensation of smell to the brain. Any damage to this nerve causes loss of sense of smell i.e. Anosmia. The most common causes of damage to Olfactory Nerve are - Common cold and flu - Head injuries - Sinonasal diseases - Viral infections - Neurodegenerative diseases e.g. Alzheimer’s Disease and Parkinson’s Disease - Cancer e.g. Meningioma, Basal Skull Tumor, Glioma