Biomedical subjects

Johannes Frasnelli

Publications and source records attributed to Johannes Frasnelli.

17 recordsLinked to original sources

PubMed2006

Interactions between olfaction and the trigeminal system: what can be learned from olfactory loss.

The olfactory and the trigeminal systems have a close relationship. Most odorants also stimulate the trigeminal nerve. Further, subjects with no sense of smell exhibit a decreased trigeminal sensitivity with unclear underlying mechanisms. Previous studies indicated that single stages of trigeminal processing may differently be affected by olfactory loss. A better knowledge of adaptive and compensatory changes in the trigeminal system of subjects with acquired anosmia (AA) will improve the understanding of interactive processes between the 2 sensory systems. Thus, we aimed to assess trigeminal function on different levels of processing in subjects with AA. Subjects with AA showed larger electrophysiological responses to irritants obtained from the mucosa than healthy controls. On central levels, however, they exhibited smaller event-related potentials and psychophysical measures to irritants. Over 9 months, they exhibited an increase in trigeminal sensitivity. Subjects with recovering olfactory function showed an even more increased peripheral responsiveness to irritants. These data suggest dynamic mechanisms of mixed sensory adaptation/compensation in the interaction between the olfactory and trigeminal systems, where trigeminal activation is increased on mucosal levels in subjects with AA and amplified on central levels in subjects with a functioning olfactory system.

Evoked Potentials↗

PubMed2006

Cross-modality of texture and aroma perception is independent of orthonasal or retronasal stimulation.

To assess the influence of orthonasal and retronasal stimulation on cross-modal interactions between texture and flavor perception of food, a series of experiments have been conducted. Healthy human subjects were exposed to strawberry aroma pulses delivered by a computer-controlled stimulator based on air dilution olfactometry. Just prior to exposure to the aroma, the human subjects consumed water, custard, or protein gels with different textures without any added aroma. The aroma was delivered as a sequence of aroma pulses, in either an orthonasal or a retronasal fashion. The retronasal presentation of aroma with concomitant presentation of texture is thought to more closely mimick the in vivo flavor release of semisolid food products as compared to orthonasal stimulation. The time between oral consumption of the food, including swallowing, and the exposure to the aroma varied between 0.5 and 6.5 s. The subjects rated the intensity of the strawberry aroma. It was observed that the intensity of aroma decreased with increasing firmness of the food that was consumed. Aroma pulses delivered 6.5 s after swallowing were perceived as being more intense as compared to aroma pulses delivered immediately after swallowing. In conjunction with late delivery, the effect cross-modal interactions apparently decreased. Significantly higher odor intensities were reported for the aroma stimuli supplied orthonasally in comparison to retronasal administration. The observed cross-modal effect of texture on aroma intensity was not significantly altered by the mode of aroma delivery, i.e., orthonasal or retronasal stimulus administration.

Humans↗

PubMed2006

The influence of stimulus duration on odor perception.

Although different parameters are known to alter the shape of olfactory event related potentials (ERP), ERP parameters are generally thought to be independent from stimulus duration. Evidence from recent studies investigating trigeminal ERP indicates that this may not be true. Aim of the present study was to investigate the relationship of stimulus duration and ERP. A total of 20 young healthy subjects participated. Subjects were investigated on 5 occasions on 5 different days. ERP were recorded to olfactory stimuli of two different concentrations and 3 different durations (100 ms, 200 ms, 300 ms). In two sessions olfactory ERP to PEA were recorded, in another two sessions H2S was applied. During the same sessions, intensity ratings were recorded. In the fifth session, subjects were asked to rate the duration of H2S stimuli and PEA stimuli. Whereas at weak stimulus concentrations no effect of stimulus duration could be observed, there was a clear effect of "duration" in ERP amplitudes following stimuli with higher concentrations: the longer the stimulus duration the larger the ERP amplitudes. No effect was found on ERP latencies. With regard to intensity ratings, strong stimuli and longer lasting stimuli lead to higher ratings. Similarly, ratings of stimulus duration were dependent from stimulus concentration and stimulus duration. Results of the present study showed that similar to trigeminal ERP, information about stimulus duration is encoded in olfactory ERP, mainly in amplitudes.

Adult↗

PubMed2006

Recovery of olfactory function following closed head injury or infections of the upper respiratory tract.

OBJECTIVE: To investigate the outcome of olfactory function in patients with olfactory loss following infections of the upper respiratory tract (post-URTI) or head trauma. DESIGN: Retrospective patient-based study. SETTING: Smell and Taste Outpatient Clinic at a university hospital. PATIENTS: A total of 361 patients (228 women, 133 men) were included. MAIN OUTCOME MEASURES: Olfactory function was assessed using the "Sniffin' Sticks" test battery, which result in a threshold, discrimination, and identification score. The mean interval between first and last visit was 14 months. RESULTS: In comparing the overall threshold, discrimination, and identification scores between the last and first visit, olfactory function improved in 26% of the patients whereas it decreased in 6%. The cause of olfactory impairment had a significant effect on the recovery rate of olfactory function. Within the post-URTI group (n = 262), 32% of the patients improved, but in the posttraumatic group (n = 99) only 10% improved. In patients with post-URTI olfactory loss, a negative correlation was found between age and recovery of olfactory function. In general, the factor "sex" had no significant effect on recovery of smell function. CONCLUSIONS: To our knowledge, the series of patients presented herein is the largest in the literature to date in which standardized testing methods were used to assess the progression of impaired olfaction. It showed that the rate of improvement of olfactory function was significantly higher in patients with post-URTI dysosmia compared with patients with posttraumatic dysosmia. During an observation period of approximately 1 year, more than 30% of patients with post-URTI olfactory loss experienced improvement, whereas only 10% of patients with posttraumatic olfactory loss experienced improvement. Furthermore, age plays a significant role in the recovery of olfactory function.

Adolescent↗

PubMed2006

Loss of trigeminal sensitivity reduces olfactory function.

The trigeminal and olfactory nerves share overlapping innervation areas in the nasal cavity and seem to work in an interactive way. Loss of olfactory function leads to a decreased trigeminal sensitivity, as shown in anosmic subjects. To report the impact of disturbed trigeminal sensitivity on the olfactory function, we present a patient with unilateral loss of trigeminal function resulting from a meningeoma. Thresholds to a selective olfactory stimulus were elevated by a factor of 64 on the affected side. Recordings of event-related potentials in response to olfactory stimuli showed a significantly reduced response on the affected side. This report indicates that loss of trigeminal function may affect the sense of smell.

Female↗

PubMed2006

Increased olfactory sensitivity in euthymic patients with bipolar disorder with event-related episodes compared with patients with bipolar disorder without such episodes.

OBJECTIVE: Some patients with bipolar disorder experience mood episodes following emotional life events, whereas others do not. There is evidence that orbitofrontal hypoactivity may be related to this, because the orbitofrontal cortex is involved in the regulation of emotional and behavioural responses to external events. The close anatomical and functional connection between the orbitofrontal cortex and olfactory processing suggests that patients with bipolar disorder and heightened emotional reactivity may exhibit altered olfactory function compared with patients with bipolar disorder who do not exhibit this sensitivity. METHODS: In this pilot study, olfactory function was assessed in patients with bipolar disorder and a history of event-triggered episodes (n = 7) and in patients with bipolar disorder without such a history (n = 9) at the Department of Psychiatry and the Taste and Smell Clinic of the University of Dresden, Germany. Each patient's bipolar disorder was in remission at study entry, and they were on monotherapy with mood stabilizers. Assessment included olfactory event-related potentials (ERP) and psychophysical tests for odour threshold, odour identification and olfactory quality discrimination. RESULTS: Odour thresholds were lower in patients with bipolar disorder and event-triggered episodes compared with the other patient group. In addition, patients with event-triggered episodes exhibited shorter N1 peak latencies of the olfactory ERP. CONCLUSIONS: Our findings indicate disinhibition of orbitofrontal areas involved in the processing of emotional events in a subset of patients with bipolar illness.

Adult↗

PubMed2005

Mechanical obstruction of the olfactory cleft reveals differences between orthonasal and retronasal olfactory functions.

Following up on recent observations in patients with nasal polyposis (NP), the present study aimed to investigate whether a mechanical obstruction of the anterior olfactory cleft (OC) would produce differential effects on orthonasal and retronasal olfactory functions. To this end, we studied 33 healthy subjects in a randomized trial. Sponges with high content of saline were either placed in the OC or on the respiratory epithelium, such that this was blinded to both subject and observer. The results indicated that orthonasal (P = 0.04) but not retronasal (P = 0.15) olfactory identification ability was lower when the OC was blocked. This confirms the idea that differences between orthonasal and retronasal olfactory functions, as observed in NP patients, are, at least to some degree, due to mechanical obstruction of the anterior portion of the OC. The present data also suggest that mechanical obstruction is a means to induce reversible hyposmia void of side effects which can be performed in a blinded fashion. This might become a valuable model of hyposmia for future investigations.

Adult↗

PubMed2005

Intranasal concentrations of orally administered flavors.

The odorants emanating from the oral cavity during eating and drinking reach the olfactory mucosa via the pharynx (retronasal olfaction). It is unclear which variables influence the perception of intraorally applied substances. The aim of the present study was to determine the temporal profiles of volatile odor concentrations at different locations in the nasal cavity during consumption of liquid and solid custard samples using proton transfer reaction mass spectrometry. Intranasal odor concentrations were measured at least twice in nine subjects (six female, three male) at four nasal positions during the consumption of liquid and solid custards. The low-viscosity custard was swallowed earlier than the more solid one. The compounds were found to reach the nose in different concentrations. Largest maximal amplitudes were measured in the nasopharynx, whereas lowest concentrations were found in the region of the olfactory cleft. In addition, different odorants reached the different regions in the nasal cavity in varying concentrations, indicated by a significant interaction between factors "position" and "compound". Furthermore, the compounds were found to reach the positions within the nasal cavity with different latencies. These results indicate that different volatile flavor compounds exhibit different temporal and spatial profiles in terms of their intranasal distribution.

Administration, Oral↗

PubMed2005

Sex differentiated responses to intranasal trigeminal stimuli.

The aim of the study was to address sex-related hemispheric differences in trigeminal event-related potentials while controlling for the subjects' olfactory sensitivity. Event-related potentials to lateralized stimulation using the trigeminal stimulant CO(2) were recorded in 28 healthy young subjects (16 women). There was no sex-related difference in olfactory sensitivity. Results indicated a sex-differentiated response to trigeminally induced pain. Women were found to have generally higher amplitudes and shorter latencies of the late positive component than men. Moreover, men and women exhibited different hemispheric activations in that women expressed shorter latencies over the left hemisphere than men. The pronounced sex-related difference of the late positive component suggests a cognitive/emotional impact on the processing of intranasal pain as indicated by others.

Adult↗

PubMed2005

Differences between orthonasal and retronasal olfactory functions in patients with loss of the sense of smell.

OBJECTIVE: To investigate differences between orthonasal and retronasal olfaction in patients with loss of the sense of smell without taste complaints. DESIGN: Electrophysiological and psychophysical testing of orthonasal and retronasal olfactory functions. SETTING: Outpatient clinics. PATIENTS: A series of 18 patients who had olfactory loss due to various reasons but no "taste" complaints. MAIN OUTCOME MEASURES: Orthonasal and retronasal olfactory functions assessed by olfactory event-related potentials and psychophysical smell tests. RESULTS: Psychophysical testing revealed retronasal olfaction to be normal or slightly altered, whereas orthonasal olfaction was either absent or severely compromised. Findings from nasal endoscopic examinations and computed tomographic scans were within the reference range in all subjects. In response to orthonasal stimulation there were neither detectable olfactory event-related potentials nor any with small amplitudes, whereas olfactory event-related potentials in response to retronasal stimulation were clearly present in some patients. CONCLUSION: These clinical observations, together with the psychophysical and electrophysiological findings, suggest that orthonasal and retronasal olfaction might be processed differently.

Adult↗

PubMed2004

Responsiveness of human nasal mucosa to trigeminal stimuli depends on the site of stimulation.

There is evidence that functionally different areas can be distinguished within the nasal mucosa with regard to stimulation site and stimulus properties. The aim of the present study was the comparison of electrophysiological and psychophysical measures obtained in response to mechanical and chemosomatosensory stimulation of two different regions of the nasal mucosa. A total of 40 volunteers participated in this study (age range 21-36 years). Chemosomatosensory event-related potentials (ERPs) were recorded using gaseous CO2 as stimulant, while somatosensory ERPs were recorded in response to intranasal mechanical stimuli (air puffs). Stimuli were released to the anterior portion and to the posterior portion of the nasal cavity. A significant interaction between stimulus properties and site of stimulation could be detected after analysis of ERP parameters and intensity ratings. Thus, the chemosensory stimulus was perceived as stronger in the anterior portion of the nasal cavity whereas this was not the case for mechanosensory stimuli. In addition, mechanosensory stimuli were found to evoke ERPs with shorter latencies. These results underline the idea that the respiratory mucosa should not be seen as a homogeneous tissue. It exhibits varying sensitivities to trigeminal stimulation depending on stimulus quality and site of stimulation. Hence, perception of chemosensory stimuli seems to be most accurate in the anterior portion of the nasal cavity, while sensitivity to mechanical stimuli appears to be highest in the posterior portion. In addition, these differences within the respiratory mucosa may contribute to differences in the perception of orthonasal and retronasal odorous stimulation.

Adult↗

PubMed2004

Olfactory dysfunction and daily life.

The objective of the present study was to investigate the hypothesis that subjects with parosmia suffer more in their daily life than patients who experience only quantitative olfactory loss. Two hundred five outpatients of the Smell and Taste Clinic and 25 healthy controls were included. The newly developed Questionnaire of Olfactory Disorders (QOD) was administered in combination with other psychometric tests (Beck Depression Inventory, "Befindlichkeitsskala" and the Short Form-36 Health Survey) along with an olfactory test ("Sniffin' Sticks"). Results of the QOD were found to be an appropriate and valid measure of the impact of olfactory dysfunction on daily life. Patients with parosmia and quantitative olfactory dysfunction show higher rates of daily life complaints when compared to patients suffering from quantitative olfactory impairment only (QOD-PS: P=0.005). In addition, hyposmic and anosmic patients indicated significantly more complaints compared to patients with normosmia. Further, female patients seemed to suffer more from olfactory dysfunction than male patients. In conclusion, the assessment of the degree of qualitative olfactory dysfunction may be possible by the use of instruments based on questionnaires regarding daily life problems.

Adult↗

PubMed2004

Detection of presymptomatic Parkinson's disease: combining smell tests, transcranial sonography, and SPECT.

Olfactory loss is among the early signs of Parkinson's disease (PD). We investigated whether "idiopathic" olfactory dysfunction might relate to signs of nigral degeneration. Olfactory tests were combined with transcranial sonography of the substantia nigra and single photon emission computed tomography (SPECT) imaging. Thirty patients diagnosed with idiopathic olfactory loss participated. Eleven of these patients exhibited an increased echogenicity of the SN in the transcranial sonography. In 10 of these 11 patients, SPECT scans with (123)I-FP-CIT were performed. Median uptake ratios in the basal ganglia were pathological in 5 patients, 2 patients exhibited borderline findings, and 3 patients had normal results. Considering patients with idiopathic olfactory dysfunction, noninvasive transcranial sonography seems to be helpful in identifying patients potentially at risk to develop PD. Longitudinal follow-up studies are necessary to estimate the ratio of patients with dopaminergic cell loss in the basal ganglia who will develop PD in the future.

Adult↗

PubMed2003

Age-related decline of intranasal trigeminal sensitivity: is it a peripheral event?

Compared to younger subjects, older people have a reduced sensitivity of the intranasal trigeminal system which responds to irritation of the nasal cavity. It is unclear whether the cause of this difference relates to age-dependent changes in the periphery of the system. The aim of the present study was the comparison of intranasal trigeminal thresholds assessed through electrophysiological measurements in eight young (four women, four men; mean age 25 years) and eight older subjects (four women, four men; mean age 62 years). The negative mucosa potential (NMP), a peripheral correlate of trigeminal activation, was recorded from the nasal mucosa in response to stimulation with varying concentrations of the mixed olfactory/trigeminal stimulants menthol and linalool. Thresholds were estimated as the strongest concentration which did not elicit a NMP response. Older subjects were found to have higher thresholds for menthol when compared to younger subjects. Furthermore, an explorative analysis indicated that the increase of response amplitudes to increasing stimulus concentrations was shallower in older subjects. These findings indicate that age related loss of intranasal trigeminal sensitivity seems to take place, at least to some degree, in the periphery of the intranasal trigeminal system.

Acyclic Monoterpenes↗

PubMed2003

Effects of olfactory function, age, and gender on trigeminally mediated sensations: a study based on the lateralization of chemosensory stimuli.

The present investigation aimed to compare trigeminal nasal function of anosmic and hyposmic patients to healthy controls. Further, we aimed to study effects of age and gender on trigeminally mediated sensations following intranasal chemosensory stimulation. Participants were 35 patients with olfactory dysfunction (n=13: functional anosmia; n=22: hyposmia; age 28-69 years, mean age 56 years). Their results were compared with 17 normosmic subjects (28-82 years, mean 52 years). To analyze effects of age and gender in healthy subjects, an additional 24 healthy subjects were included (19-27 years; mean 24 years). Olfactory function was assessed using the 'Sniffin' Sticks' test kit (butanol odor threshold, odor discrimination, odor identification). The subjects' ability to lateralize odors was investigated for benzaldehyde and eucalyptol. Patients with olfactory dysfunction had lower scores in the lateralization task than controls (P<0.001) indicating decreased trigeminal sensitivity. Among anosmic patients scores were not different in relation to different causes of olfactory dysfunction (P>0.29). There was a weak, but significant, correlation between localization of eucalyptol and duration of olfactory dysfunction (P=0.017). When investigating normosmic subjects only, no gender-related difference was apparent for lateralization scores. However, older subjects had lower scores than younger ones (P<0.01). Results of partial correlational analyses controlling for age suggested a relation between the trigeminal and the olfactory systems. In conclusion, results of the present study indicate that patients with olfactory dysfunction have lower trigeminal sensitivity compared with normosmic controls. This seems to be independent of the cause of olfactory loss. The deficit appears to improve with duration of the olfactory dysfunction, possibly indicating adaptive mechanisms. Further, the data suggest an age-related decrease of intranasal trigeminal sensitivity in healthy subjects. Analyses additionally indicate a correlation between olfactory and trigeminal sensitivity.

Adult↗

PubMed2003

Event-related potentials to intranasal trigeminal stimuli change in relation to stimulus concentration and stimulus duration.

Few data are available on the relation of EEG-derived trigeminal event-related potentials (ERPs) to stimulus duration or stimulus concentration. Thus, the aim of this study was to analyze the relation between ERP components and both stimulus duration and stimulus concentration. Twenty healthy young subjects participated. Trigeminal ERPs were recorded after stimulation with CO(2). Five concentrations (45 to 65% volume per volume CO(2)) and five stimulus durations (100 to 300 msec) were used. Trigeminal ERPs were quantified in terms of amplitudes and latencies of its major peaks N(410) (termed N1) and P(622) (termed P3). The relation between stimulus duration, concentration, and amplitudes or latencies of trigeminal ERP components could be described as a model of power, following the formula p = b + k.I g1.D(g2). A linear relationship was found between stimulus concentration, amplitude N1, and amplitude P3, and between stimulus duration and amplitude P3 respectively. Furthermore, a linear relationship was seen between intensity ratings, and stimulus duration and concentration. These data confirm that the different ERP components encode different stimulus characteristics. Specifically, later components of the trigeminal ERP encode not only stimulus concentration but, other than earlier ERP components, also encode stimulus duration. Thus, they reflect the integration of stimuli over relatively long periods of time.

Adolescent↗

PubMedDate not supplied

Severe chemotherapy-induced parosmia.

BACKGROUND: Smell and taste disorders are among the side effects of chemo- and radiotherapy. Although direct radionecrosis of the salivary glands and the taste buds might explain the chemosensory problems after radiotherapy, the olfactory and gustatory complaints seen after chemotherapy remain unexplained. The patients reporting olfactory symptoms rarely complain about qualitative olfactory disorders such as parosmia or phantosmia. Quantitative olfactory loss such as anosmia and hyposmia seem to be more frequent. METHODS: We present the case of a 63-year-old woman with chemotherapy-induced parosmia leading to severe nutrition and appetite problems resulting in a life-threatening weight loss. RESULTS: With the aid of a simple nose clip the parosmia could be abolished and oral food intake became possible again. Parosmia resolved gradually over an observation period of 9 months, in parallel to an increase of olfactory sensitivity. The patient progressively gained appetite and weight. CONCLUSION: Parosmia can occur as a severe and potentially life-threatening complication of chemotherapy. This rare presentation of parosmia illustrates the importance of olfactory testing with an adequate recognition of the underlying problem and a consecutive treatment.

Antineoplastic Combined Chemotherapy Protocols↗