Downward cross-modal plasticity in single-sided deafness.

The auditory cortex has been shown to participate in visual processing in individuals with complete auditory deprivation. However, it remains unclear whether partial hearing deprivation like single-sided deafness (SSD) leads to similar cross-modal plasticity. To investigate this, we enrolled individuals with long-term SSD, into functional MRI scans under resting-state and a visuo-spatial working memory task. Contrary to previous findings in bilateral deafness, our study revealed decreased activation in the auditory cortex in both left (LSSD) and right (RSSD) single-sided deafness compared to normal hearing controls, with statistical significance in RSSD. The degree of involvement was correlated with residual hearing ability in RSSD. These observations suggest that SSD can lead to a downward cross-modal plasticity: the more hearing ability lost, the fewer brain resources in the auditory cortex can be applied to visual tasks. In addition, the fronto-parietal cortex was observed to be less activated during the visual task in RSSD while the resting-state fMRI revealed increased functional connectivity between the fronto-parietal cortex and the auditory cortex, suggesting fronto-parietal resources may be recruited less by vision but more by hearing. The LSSD showed a similar alteration trend with RSSD, but without statistical significance. Together these findings may indicate that when hearing is partially deprived in SSD, there may be redistribution for brain resources between hearing and vision, and vision tends to allocate less resources. Our findings in this pilot study of unilateral auditory-deprived individuals enrich the understanding of cross-modal plasticity in the brain.

Reliability and validity of the Chinese version of the questionnaire of olfactory disorders (QOD) when used with patients having olfactory dysfunction.

To cross-culturally adapt the Questionnaire of olfactory disorders (QOD) into a Chinese version, and then evaluate its reliability and validity for testing patients with olfactory dysfunction. A Chinese version of the QOD was evaluated for test-retest reliability, split-half reliability, and internal consistency. The validity analysis included components of content validity and criterion-related validity, as well as comparisons between The Medical Outcomes Study's36-Item ShortForm Health Survey(SF-36)questionnaire and the WHO Quality of Life-BREF (WHOQOL-BREF)questionnaire. A total of 125 patients with olfactory dysfunction were tested, and 104 patients completed three different surveys (QOD, SF-36, and WHOQOL-BREF). The test-retest reliabilities of the QOD-Parosmia statements (QOD-P), QOD-Quality of life (QOD-QoL), and QOD-Visual simulation (QOD-VAS)sections were 0.802 (P < 0.001), 0.797 (P < 0.001), and 0.468 (P < 0.001), respectively, and the Cronbach's α coefficients of internal consistency were 0.473, 0.814, and 0.882, respectively. The split-half reliability was 0.70. No correlation was found between the QOD-P section and the SF-36; however, there were statistically significant correlations between the QOD-QoL andQOD-VAS sections and the SF-36. The same results were observed for correlations between the QOD and WHOQOL-BREF. The Chinese version of the QOD was proven to be a generally reliable and valid questionnaire for use in evaluating mainland Chinese patients suspected of having olfactory dysfunction. However, the QOD-P section requires further modifications to properly evaluate patients with a Chinese cultural background and type of cognition.

A study of cochlear and auditory pathways in patients with tension-type headache.

BACKGROUND: The purpose of this study was to systematically evaluate the function of cochlear and auditory pathways in patients suffering from tension-type headache (TTH) using various audiological methods. METHODS: Twenty-three TTH patients (46 ears) and 26 healthy controls (52 ears) were included, and routine diagnostic audiometry, extended high-frequency audiometry, acoustic reflex (ASR), transient evoked otoacoustic emissions (TEOAEs), distortion product otoacoustic emissions (DPOAEs) and suppression TEOAEs were tested. RESULTS: The TTH group showed higher thresholds (P < 0.05) for both pure tone and extended high-frequency audiometry at all frequencies except for 9, 14 and 16 kHz. All ASR thresholds were significantly higher (P < 0.05) in the TTH group compared with the controls, except for the ipsilateral reflex at 1 kHz, but the threshold differences between the ASR and the corresponding pure tone audiometry did not differ (P > 0.05). For the DPOAEs, the detected rates were lower (P < 0.05) in the TTH group compared with the controls at 4 and 6 kHz, and the amplitudes and signal to noise ratio (S/N) were not significantly different between groups. No differences in the TEOAEs (P > 0.05) were observed for the detected rates, amplitudes, S/Ns or contralateral suppression, except for the S/Ns of the 0.5-1 kHz TEOAE responses, which were significantly higher (P < 0.05) in the TTH group. CONCLUSIONS: The results of our study indicate that subclinical changes in cochlear function are associated with TTH.

[Analysis of clinical characteristics of partial olfactory dysfunction].

OBJECTIVE: To apply different types and concentrations of T&T olfactometer odorants to exam smell function and explore the clinical characteristics of partial olfactory dysfunction. METHODS: From March 2007 to May 2008, a total of 24 patients with olfactory dysfunction were examined by medical and psychiatric history enquiry, physical examination, smell testing and medical imaging. Olfactory function of each nostril was assessed separately by T&T olfactometer. The test contained five kinds of odorants at different concentrations. Recognition threshold (RT) scores for all five odorants and for each individual odorant were measured in all patients. RESULTS: Among them, total RT scores were normal while single odorant testing yielded only significant higher RT scores for one or two odorants. For patients who suffered partial olfactory dysfunction, 51.4% are for pleasant odors, while the rest are for unpleasant odors. CONCLUSION: Normal total RT scores and abnormal single RT scores of T&T olfactometer are present in partial olfactory dysfunction. As a special clinical manifestation of olfactory disorder, it may be easily ignored in smell testing.

Effect of subject state on auditory brainstem response threshold using Kalman-weighted averaging.

OBJECTIVES: This study aims to explore the impact of a subject's testing state on auditory brainstem response (ABR) thresholds using a novel ABR system (Vivosonic Integrity™), which incorporates Kalman-weighted averaging and bluetooth electrical isolation to address the limitation of conventional ABR limitation to obtain a stable result under non-sedated conditions, especially for infants and children. METHOD: Twenty-four adults (18-34 years old, 48 ears) with normal hearing were enrolled for ABR testing under three different states (lying quietly in the supine position or sleeping-lying; watching silent videos quietly in a seated position-sitting; and writing in a seated position-writing), which simulate the behaviors of young children most often encountered during non-sedated Kalman-weighted ABR testing in clinical practice. The click ABR (cABR) and tone-burst ABR (tbABR) thresholds (0.5, 1, 2, and 4 kHz) of each subject and the time taken to reach the monaural threshold for each kind of stimulus were recorded. RESULTS: (1) The cABR and tbABR thresholds were observed to increase in the following order: lying < sitting < writing. Significant threshold differences were found between any two states, except for between the sitting and lying states for the cABR and between sitting and writing for the 0.5 kHz tbABR. (2) The time required for cABR testing in the writing state was significantly longer than that in the lying and sitting states. The time required for 1 and 4 kHz tbABR testing in the lying state was significantly shorter than that in the sitting or writing state. For 2 KHz tbABR, only testing time under writing was significantly longer than that under lying. There were no significant differences in the time used for 0.5 kHz tbABR testing among different states. CONCLUSIONS: Different testing states have significant impacts on the thresholds of ABRs using Kalman-weighted averaging. A subject's state during ABR testing warrants consideration, and normal levels and correction values to estimate the hearing threshold from the ABR threshold should be determined for different testing states.

[Clinical and magnetic resonance imaging characteristics of isolated congenital anosmia].

OBJECTIVE: To report a series of patients with isolated congenital anosmia and summarize their clinical and magnetic resonance imaging (MRI) characteristics. METHODS: Twenty patients with isolated congenital anosmia were reviewed retrospectively. A thorough medical and chemosensory history, physical examination, nasal endoscopy, T&T olfactory testing, olfactory event-related potentials, sinonasal computed tomography scan and magnetic resonance image of olfactory pathway were performed in all patients. RESULTS: Neither ENT physical examination nor nasal endoscopy was remarkable. Subjective olfactory testing indicated all of them were of anosmia. No olfactory event-related potentials to maximal stimulus were obtained. Computed tomography scan was normal. MRI revealed the absence of olfactory bulbs and tracts in all cases. And hypoplasia or aplasia of olfactory sulcus was found in all cases. All the patients had normal sex hormone level. CONCLUSION: The diagnosis of isolated congenital anosmia is established on chief complaints, physical examination, olfactory testing and olfactory imaging. MRI of olfactory pathway is indispensable.

[Olfactory functional magnetic resonance imaging with modified OEP-98C olfactometer and event-related design].

OBJECTIVE: To explore the feasibility of functional magnetic resonance imaging (fMRI) in analysis of olfaction function with modified OEP-98C olfactometer and event-related design. METHODS: Six young right-handed men underwent olfactory fMRI with event-related design. OEP-98C olfactometer was modified to accommodate MR environment. There were 2 types of tasks in the experiment. In one task, only isoamyl acetate was used as odorant. In the other task, to avoid possible decreased olfactory attention, vanillin was given before each presentation of isoamyl acetate. RESULTS: In both tasks, uniform activation in piriform cortex and secondary olfactory cortexes was determined. The activation of piriform cortex was not significantly different between the two tasks (P > 0.01). CONCLUSIONS: With isoamyl acetate as odorant, modified OEP-98C olfactometer, and event-related design, olfaction fMRI can depict cortex activation at primary and secondary olfactory cortex. Applying other odorant with similar quality to avoid olfactory attention decrease can not promote depiction of activation in primary olfactory cortex.

A Study of Wideband Energy Reflectance in Patients with Otosclerosis: Data from a Chinese Population.

OBJECTIVES: The purpose of this study was to explore the effectiveness of wideband acoustic immittance (WAI) in the diagnosis of otosclerosis by comparing the differences in the energy reflectance (ER) of WAI between patients with otosclerosis and age- and gender-matched normal hearing controls in the Chinese population. METHODS: Twenty surgically confirmed otosclerotic ears were included in the otosclerotic group. The ER of WAI at ambient and peak pressures, resonance frequency, and 226-Hz tympanogram were collected prior to surgery using a Titan hearing test platform (Interacoustics A/S, Middelfart, Denmark). All diagnoses of otosclerosis in the tested ear were confirmed by surgery after the measurements. Thirteen normal adults (26 ears) who were age- and gender-matched with the otosclerotic patients were included as the control group. RESULTS: At peak pressure, the ERs of otosclerotic patients were higher than those of the control group for frequencies less than 4,000Hz and were lower for frequencies greater than 4,000Hz. In addition, within the analyzed frequencies, the differences observed at 2,520Hz was statistically significant (p<0.05/16=0.003, Bonferroni corrected). At ambient pressure, the differences observed at 1,260 and 6,350Hz were statistically significant (p<0.05/16=0.003, Bonferroni corrected). Although the differences between the otosclerotic and control groups exhibited similar trends to those in studies implemented in Caucasian populations, the norms in the present study in the control group were different from those in the Caucasian populations, suggesting racial differences in WAI test results. Regarding the middle ear resonance frequency, no significant difference was observed between the two groups (P>0.05). CONCLUSION: WAI can provide valuable information for the diagnosis of otosclerosis in the Chinese population. Norms and diagnostic criteria corresponding to the patient's racial group are necessary to improve the efficiency of WAI in the diagnosis of otosclerosis.

[Olfactory event-related functional magnetic resonance imaging in young adults with normal sense of smell and anosmia patients].

OBJECTIVE: To explore the brain activation mapping following odor presentation with event -related functional magnetic resonance imaging. METHODS: Ten healthy young volunteers with normal sense of smell and 5 anosmia patients, all right-handed, underwent routine otorhinolaryngological examination and T&T subjective smelling test. Odorant isoamyl acetate was delivered by olfactometer synchronously with inspiration birhinally for 10 times with the interstimulus interval of 60 seconds. Functional magnetic resonance imaging (fMRI) based on the blood-oxygen-level dependent effect was carried out on a 3.0 T scanner, using gradient-recalled echo and echo-planar imaging technique, and the image data were analyzed with SPM2 software. RESULTS: Functional activations were found in the volunteers with normal sense of smell, but not in the patients with anosmia. The activation regions were present in the orbitofrontal gyrus, anterior cingulate gyrus, piriform cortex, insular gyrus, amygdala, thalamus, basal nuclei, temporal gyrus, and frontal gyrus. There were more active regions in the right hemisphere than in the left hemisphere, and there were 314 and 57 active voxels in the right and left hemispheres respectively. CONCLUSION: Olfactory event-related fMRI is an objective measurement of olfaction, and has potential clinical application value.

Effects of Phase-Locking Deficits on Speech Recognition in Older Adults With Presbycusis.

Objective: People with presbycusis (PC) often report difficulties in speech recognition, especially under noisy listening conditions. Investigating the PC-related changes in central representations of envelope signals and temporal fine structure (TFS) signals of speech sounds is critical for understanding the mechanism underlying the PC-related deficit in speech recognition. Frequency-following responses (FFRs) to speech stimulation can be used to examine the subcortical encoding of both envelope and TFS speech signals. This study compared FFRs to speech signals between listeners with PC and those with clinically normal hearing (NH) under either quiet or noise-masking conditions. Methods: FFRs to a 170-ms speech syllable /da/ were recorded under either a quiet or noise-masking (with a signal-to-noise ratio (SNR) of 8 dB) condition in 14 older adults with PC and 13 age-matched adults with NH. The envelope (FFRENV) and TFS (FFRTFS) components of FFRs were analyzed separately by adding and subtracting the alternative polarity responses, respectively. Speech recognition in noise was evaluated in each participant. Results: In the quiet condition, compared with the NH group, the PC group exhibited smaller F0 and H3 amplitudes and decreased stimulus-response (S-R) correlation for FFRENV but not for FFRTFS. Both the H2 and H3 amplitudes and the S-R correlation of FFRENV significantly decreased in the noise condition compared with the quiet condition in the NH group but not in the PC group. Moreover, the degree of hearing loss was correlated with noise-induced changes in FFRTFS morphology. Furthermore, the speech-in-noise (SIN) threshold was negatively correlated with the noise-induced change in H2 (for FFRENV) and the S-R correlation for FFRENV in the quiet condition. Conclusion: Audibility affects the subcortical encoding of both envelope and TFS in PC patients. The impaired ability to adjust the balance between the envelope and TFS in the noise condition may be part of the mechanism underlying PC-related deficits in speech recognition in noise. FFRs can predict SIN perception performance.

Intranasal application of glucocorticoid alleviates olfactory dysfunction in mice with allergic rhinitis.

The aim of the present study was to investigate the effect of glucocorticoid intervention on olfactory dysfunction in mice with allergic rhinitis (AR). An AR animal model was established by intraperitoneal injection and intranasal application of ovalbumin to mice. The olfactory function of the mice was evaluated using a buried food test, and morphological changes in the nasal mucosa were determined using hematoxylin and eosin staining. The expression of olfactory marker protein (OMP) in the olfactory mucosa was tested by immunohistochemistry, and was observed on days 7 and 14 after the application of glucocorticoid. The incidence rate of olfactory dysfunction in AR mice was 75.34%, and the olfactory epithelium became thinner in mice with AR compared to the control group. In addition, the expression of OMP in the olfactory epithelium was downregulated in mice with AR compared with the control group. Expression of OMP in the olfactory epithelium was upregulated in the budesonide group A and betamethasone group A compared with the medicine-free group, whereas the expression of OMP in the olfactory epithelium of budesonide group A or betamethasone group A was not significantly different from the control group. Moreover, the expression of OMP in the budesonide group B was similar to budesonide group A, and expression of OMP in betamethasone group B was similar to betamethasone group A. The expression of OMP in olfactory mucosa is downregulated in AR mice with olfactory dysfunction. Following the application of glucocorticoid, the expression of OMP in the olfactory mucosa in mice is upregulated. Moreover, intranasal local glucocorticoid has a low incidence of systemic adverse reactions, and is recommended for the treatment of olfactory dysfunction in AR.

An effective compromise between cost and referral rate: A sequential hearing screening protocol using TEOAEs and AABRs for healthy newborns.

OBJECTIVE: This study evaluated the efficacy of a sequential hearing screening protocol using transient evoked otoacoustic emission (TEOAE) and automated auditory brainstem response (AABR) tests in healthy newborns. DESIGN: A TEOAE screening was performed during the first 48-72 h of life. If the infants failed, an AABR test was performed at the same time, and they were referred for a TEOAE rescreening at six weeks old. The results of screening Protocol 1 (only TEOAE) were compared with those of screening Protocol 2 (sequential TEOAE + AABR screenings for the first screening and TEOAE for the rescreening). STUDY SAMPLE: A total of 1062 healthy newborns were enrolled in this research. RESULTS: For Protocol 1, the first screening and rescreening referral rates were 11.1% and 2.2%, respectively. In contrast, for Protocol 2, the referral rates were significant lower at 3.8% and 0.9%, respectively. Using the two protocols, six infants were diagnosed with hearing loss (0.57%). CONCLUSIONS: Adding simultaneous AABR tests for infants who fail TEOAE testing at the first screening stage can significantly reduce referral rates without increasing misdiagnosis rates. Although this sequential screening process involves slightly more time and has a higher cost than TEOAE alone, its greater accuracy compensates for this difference.

Neural cograft stimulates the survival and differentiation of embryonic stem cells in the adult mammalian auditory system.

Mouse embryonic stem (ES) cells were transplanted into the cochlea of adult guinea pigs in order to explore their survival, differentiation, and possible integration with the host tissue. With the purpose of investigating the possible effect of manipulating the local embryonic microenvironment, ES cells were transplanted into the cochlea with or without an embryonic neuronal cograft consisting of dorsal root ganglion (DRG) tissue. To detect the survival and differentiation of ES cells, cells expressing green fluorescent protein (GFP) were used in combination with immunohistochemical detection of a neuronal marker, neural class III beta-tubulin (TUJ1 antibody). At 4 weeks following transplantation implanted ES cells were found close both to the sensory epithelium, and the spiral ganglion neurons (SGNs) with their peripheral dendritic processes projecting to the organ of Corti. There was a significant difference in the number of surviving TUJ1 (+) ES cells between the DRG cograft group and the non-cograft group (P < 0.01, ANOVA). Neurite-like projections were also identified between TUJ1-positive ES cells and the peripheral dendritic processes from SGNs. The results suggest that an embryonic neuronal microenvironment may be one of the key factors in the survival and differentiation of ES cells in the adult auditory system.

[Surgical management of metastatic disease in the conjunctive area between neck and thorax].

OBJECTIVE: To study the surgical management of metastatic disease in the conjunctive area between the neck and thorax and its efficacy. METHODS: Fourteen cases with metastatic node disease in the area between neck and thorax were collected and analysed. Eleven tumors were from the thyroid cancer, and the other three were from the hypopharyngeal cancer, esophagual cancer and malignant pheochromocytoma, respectively. The clavicle was displaced or resected, and the upper half of the manubrium might also be resected when necessary. The recurrent laryngeal nerve and phrenic nerve were exposed and protected. The metastatic disease was completely removed with the internal jugular and/or the brachiocephalic vein resected or spared, depending on the disease condition. RESULTS: In 10 cases with metastases from the thyroid, no local recurrence was found within the follow-up period from 2 to 5 years. In contrast, no patient with metastatic disease from hypopharyngeal or esophageal cancer survived more than 11 months. No serious complications were found in this group. CONCLUSIONS: The surgical treatment of node metastases in the conjunctive area between neck and thorax from the well-developed thyroid cancer has promising effect and is comparatively safe.

[Application of unilateral olfactory testing and clinical analysis of unilateral hyposmia].

OBJECTIVE: To investigate whether patients presenting with self-reported olfactory disorders demonstrates significant side difference in odour recognition by measuring separately for each nostril. METHODS: One hundred and four patients with chief complaint of hyposmia were evaluated by medical history, physical examination, T&T olfactory testing and medical imaging. Smell was tested using T&T olfactometry in each nostril separately. RESULTS: Based on the history and results from the clinical examination, unilateral sinonasal diseases and abnormal nasal structure were excluded. In almost one eighth of all presenting patients (13.46%), a side difference was detected. Especially, six of the patients were identified with lateralized hyposmia. CONCLUSIONS: Olfactory testing could be performed in each nostril separately. The above findings suggested that testing each nostril separately was necessary so as not to miss unilateral hyposmia as a special clinical manifestation of olfactory disorder.

Study of cochlear hydrops analysis masking procedure in patients with Meniere's disease and otologically normal adults.

BACKGROUND: The cochlear hydrops analysis masking procedure (CHAMP) is a new diagnostic technique for Meniere's disease (MD). But its value has not been well proven. This study aimed to evaluate the diagnostic value of CHAMP for MD. METHODS: CHAMP test was taken in three populations using the Auditory Evoked Potential system delivered by Bio-logic Systems Corporation: (1) otologically normal subjects; (2) patients clinically diagnosed with definite MD; (3) patients clinically diagnosed with probable and possible MD. RESULTS: According to the comparison between the normal and definite MD group, if the abnormal criterion of CHAMP was defined as latency delay less than 0.3 ms, then the corresponding sensitivity was only 52%. However, if the abnormal criterion was defined as latency delay between 0.6 and 3.8 ms, then a sensitivity of 93% and a specificity of 100% can be achieved. The complex amplitude ratio showed a significant overlap between normal and definite MD group. If the abnormal criterion was defined as a complex amplitude ratio less than 0.95, the corresponding specificity was only 50%. However, if the abnormal criterion was defined as less than 0.80, the corresponding sensitivity was 60%, and the specificity was 97%. If the abnormal criterion of CHAMP was defined as latency delay less than 0.6 ms or the complex amplitude ratio less than 0.80, CHAMP result can be obtained in all subjects with good sensitivity and specificity. CONCLUSIONS: CHAMP can differentiate patients with Meniere's disease from otologically normal subjects with high sensitivity and specificity. The recommended criterion of abnormal CHAMP was a latency delay less than 0.6 ms or a complex amplitude ratio less than 0.80.

[Comparison of tone burst evoked auditory brainstem responses with different filter settings for referral infants after hearing screening].

OBJECTIVE: Auditory brainstem responses (ABR) evoked by tone burst is an important method of hearing assessment in referral infants after hearing screening. The present study was to compare the thresholds of tone burst ABR with filter settings of 30 - 1500 Hz and 30 - 3000 Hz at each frequency, figure out the characteristics of ABR thresholds with the two filter settings and the effect of the waveform judgement, so as to select a more optimal frequency specific ABR test parameter. METHODS: Thresholds with filter settings of 30 - 1500 Hz and 30 - 3000 Hz in children aged 2 - 33 months were recorded by click, tone burst ABR. A total of 18 patients (8 male/10 female), 22 ears were included. RESULTS: The thresholds of tone burst ABR with filter settings of 30 - 3000 Hz were higher than that with filter settings of 30 - 1500 Hz. Significant difference was detected for that at 0.5 kHz and 2.0 kHz (t values were 2.238 and 2.217, P < 0.05), no significant difference between the two filter settings was detected at the rest frequencies tone evoked ABR thresholds. The waveform of ABR with filter settings of 30 - 1500 Hz was smoother than that with filter settings of 30 - 3000 Hz at the same stimulus intensity. Response curve of the latter appeared jagged small interfering wave. CONCLUSIONS: The filter setting of 30 - 1500 Hz may be a more optimal parameter of frequency specific ABR to improve the accuracy of frequency specificity ABR for infants' hearing assessment.

[Study of characteristic of the cochlear hydrops analysis masking procedure in normal adults].

OBJECTIVE: To study the characteristic of the cochlear hydrops analysis masking procedure (CHAMP) in normal adults, and to evaluate the diagnostic values of its parameters for membranous labyrinth hydrops. METHODS: Twenty otologically normal adults were recruited (male:female = 10:10), and their auditory brainstem responses (ABR) were obtained to six stimulus conditions using Bio-logic auditory evoked potential system: clicks presented alone (unmasked condition) and clicks presented with ipsilateral pink noise high-pass filtered at 8, 4, 2, 1, and 0.5 kHz respectively. RESULTS: The wave V latency of ABR to the high-pass masking pink noise clicks were longer than ABR to clicks alone. The latency delays of wave V for clicks presented with ipsilateral pink noise high-pass filtered at 8, 4, 2, 1, and 0.5 kHz compared to clicks alone were (0.30 ± 0.18), (0.97 ± 0.43), (1.65 ± 0.64), (3.21 ± 0.56), (4.66 ± 0.37) ms respectively. The complex amplitude ratio between ABR to click + 0.5 kHz high-pass noise and click alone was 0.95 ± 0.11. CONCLUSIONS: CHAMP is a promising diagnostic method for membranous labyrinth hydrops, and the latency delay of wave V might be used as the normal criterion. The specificity of the complex amplitude ratio need further evaluation in clinical work.

Diagnosis and clinical characteristics of congenital anosmia: case series report.

OBJECTIVE: congenital anosmia is extremely rare and tends to present late. We report on a series of patients with congenital anosmia to analyze its clinical characteristics and present illustrative cases. DESIGN: retrospective chart review. SETTINGS: tertiary care centre. METHODS: thirty-five patients with congenital anosmia were reviewed. A thorough medical history taking, physical examination, and nasal endoscopy were performed in all patients. T&T olfactory testing (n = 33), olfactory event-related potentials (OERPs) (n = 33), and sinonasal computed tomography (CT) (n = 35) were carried out. Magnetic resonance images (MRIs) of the olfactory pathway (n = 34) were available. Serum sex hormones were tested (n = 33). MAIN OUTCOME MEASURES: physical examination, olfactory testing, MRI of the olfactory pathway, and serum sex hormones. RESULTS: twenty cases were isolated congenital anosmia (ICA). Fifteen cases were congenital anosmia with other anomalies, including 12 cases with Kallmann syndrome (KS), two with CHARGE syndrome, and one with hypoplasia of the nasal cavity and nasal sinus. T&T olfactory testing indicated anosmia (n = 33). No OERP was obtained (n = 33). CT scans indicated three abnormal patients, including two with unilateral choanal atresia and one with hypoplasia of the nasal cavity and sinus. MRI demonstrated aplasia or hypoplasia of the olfactory bulbs, tracts, and olfactory sulci (n = 34). Serum sex hormones were low in 12 patients with KS. CONCLUSIONS: early diagnosis of congenital anosmia on the basis of olfactory symptoms is difficult. MRI of the olfactory pathway plays an important role in anatomic location. ICA is the most common congenital anosmia. KS is the primary presentation of congenital anosmia with other anomalies.