Loss of Sense of Smell

CLINICAL DIAGNOSTIC MANUAL

Loss of the sense of smell, also known as anosmia, is a condition that can significantly impact quality of life, affecting not only the ability to detect odours but also the sense of taste. Anosmia can be temporary or permanent, with a variety of causes including infections, allergies, head trauma, and neurological disorders. Evaluation of anosmia involves a detailed medical history, physical examination, and specific tests to identify the underlying cause.

Condition	Clinical Symptoms and Signs	Suspected Diagnosis	Confirmatory Diagnosis
Common cold (coryza)	Nasal congestion, runny nose, mild fever, headache, temporary anosmia	History of acute respiratory infection	Medical history, physical examination
Nasal allergy	Nasal congestion, sneezing, nasal itching, clear nasal discharge, temporary anosmia	History of allergen exposure, recurrent symptoms	Allergy testing, medical history
Skull fracture	History of head trauma, headache, periorbital bruising, cerebrospinal fluid rhinorrhoea, anosmia	History of trauma, associated neurological symptoms	CT or MRI showing skull fracture
Frontal lobe tumour	Headache, personality changes, visual disturbances, anosmia, focal neurological symptoms	Progressive neurological dysfunction symptoms	MRI or CT showing mass in the frontal lobe
Kallmann syndrome	Congenital anosmia, delayed puberty, GnRH deficiency, infertility	History of delayed pubertal development, symptoms of hypogonadism	Blood tests showing low GnRH levels, brain MRI