Anosmia
Cards (8)
- Definition:
- Inability to perceive smell
- Can be partial or complete
- Can be temporary or permanent
- Types:
- Conductive - issue preventing the odour molecules getting to the olfactory nerve projections
- Sensorineural - odour molecules can get to the olfactory nerve projections, but the nerve cannot interpret them properly
- Sensorineural causes:
- Viral/post viral - damage to nerve projections and sensory receptors
- Congenital e.g. Kallmann syndrome (olfactory nerve cells don't migrate)
- Medications that damage nerves e.g. ACE inhibitors, diuretics, CCB, statins, tobacco and drugs (cocaine)
- Compression/damage from SOL or trauma
- Neurological e.g. temporal lobe epilepsy, MS, stroke
- The peripheral olfactory system has the ability to regenerate so sensorineural anosmia is not always permanent e.g. following covid
- Conductive causes:
- Diseases that cause congestion and inflammation of mucosa - chronic rhinosinusitis, allergic rhinitis
- Physical blockage - polyp, septal deviation, intranasal tumour, granulomatous disease
- Trauma to the mucosa
- Diversion of air and odour molecules away from the receptors e.g. following total laryngectomy where trachea completely separated from nose, mouth and oesophagus
- Management:
- Most patients with olfactory dysfunction can be managed in primary care
- Treatment targeted at the cause e.g. rhinosinusitis
- If anosmia lasts over 2 weeks - intranasal steroids or short course oral steroids can help
- Red flags:
- Unilateral nasal symptoms
- Bleeding
- Crusting/scabbing within the nasal cavity
- Orbital symptoms (swelling, visual symptoms, ophthalmoplegia)
- Severe frontal headaches
- New onset of neurological/meningitis symptoms
- Cacosmia - perceived malodorous smell - can be benign but also due to seizures and tumours
- Indications for ENT referral:
- Red flags - review/imaging for tumour, MS, SOL, seizures
- Symptoms for over 6 weeks (give 3 months if symptoms due to covid)
- Atypical presentation
- Not responding to initial treatment