ABSTRACT
<p><b>OBJECTIVE</b>To report on a series of patients with congenital anosmia, and to discuss its classification and clinical characteristics.</p><p><b>METHODS</b>Eight patients with congenital anosmia were reviewed retrospectively. Four of eight cases were congenital anosmia with other abnormalities, including three cases with Kallmann's syndrome, one with hypoplasia of nasal cavity and nasal sinus. Four cases were isolated congenital anosmia. A thorough medical and chemosensory history, physical examination, nasal endoscopy, T&T olfactory testing, olfactory event-related potentials and sinonasal computed tomography scan were performed in all patients. Magnetic resonance image of olfactory pathway was available in seven cases, and olfactory biopsies were done in two cases.</p><p><b>RESULTS</b>All patients reported had never been able to smell anything. ENT physical examination and nasal endoscopy were normal, except one case with hypoplasia of nasal cavity. Subjective olfactory test indicated all of them were anosmia. No olfactory event-related potentials to maximum stimulus were obtained. Magnetic resonance imaging revealed the absence of olfactory bulbs and tracts in six cases, hypoplasia of bilateral olfactory bulbs and tracts in one case. Computed tomography scan indicated normal except hypoplasia of nasal cavity and sinus in one case. Three cases with Kallmann syndrome showed poor development of both primary and secondary sexual characteristics and had decreased serum luteinizing hormone, follicle-stimulating hormone, testosterone and estradiol.</p><p><b>CONCLUSIONS</b>Diagnosis of congenital anosmia is established on chief complain, physical examination, nasal endoscopy, olfactory testing and olfactory imaging. Magnetic resonance imaging of olfactory pathway is indispensable.</p>