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Congenital anosmia is well described in conjunction with various sexual and other developmental abnormalities and has been reported to run in families. Congenital anosmia occurring as an isolated defect in a single family member is extremely rare, and tends to present late. We describe a case of a five year old girl with congenital anosmia and we outline the investigations which should be undertaken in such cases.
BACKGROUND: Both environmental and occupational pollutants can affect the functional integrity of the olfactory epithelium or even destroy olfactory tissue. However, occupational hyposmia and anosmia have not been included into the list of occupational diseases. Therefore, compensation of occupationally induced smell disorders is difficult. OBJECTIVE: To evaluate patients with toxic hyposmia for the pollutants involved and to discuss consequences for occupational and environmental medicine. METHODS: A total of 19 patients were evaluated in our departments between 1993 and 1997 for olfactory disorders related to environmental or occupational pollutants. The charts of these patients were retrospectically analyzed and the causative pollutants compared with the literature. RESULTS: A chronical exposure to mixtures of metal dusts and steam, volatile organic substances, and anorganic gases were the most common pollutants involved in occupational dysosmia. Only one case of acute development of an anosmia due to exposure to CO and combustion gases was documented. CONCLUSIONS: Olfactory disorders are underestimated in occupational and environmental medicine. Relevance of olfactotoxic substances for occupational medicine can be postulated in metal and chemical workers, in welding and disinfection. The list of occupational diseases should be completed by olfactory hyposmia and anosmia.
Magnetic Resonance Imaging (MRI) was performed on 9 patients who lacked a sense of smell since birth. Seven of them, including two patients with Kallmann syndrome, exhibited abnormality of the olfactory bulb, olfactory tract, olfactory sulcus, or rectus gyrus, with some variation among patients in type and degree of abnormality. The other two patients exhibited normal olfactory pathway morphology, and for them the possibility of acquired sensorineural anosmia could not be ruled out. MRI is useful for determining whether patients with congenital anosmia have olfactory pathway anomalies. Many patients with congenital anosmia and hypoplasty or aplasty of the olfactory pathway nevertheless had no gonadal or endocrinological disorders.
Coma, hemiparesis, unilateral optic neuropathy, and anosmia manifested in a patient with leukemia after he received only three courses of intravenous high-dose cytosine arabinoside (ARA-C). The patient's mental status returned to normal after several days, and his hemiparesis resolved. However, the visual loss persisted, and near complete visual loss in the other eye ensued over the following month. Severe bilateral optic atrophy appeared as the visual loss progressed. Anosmia became evident after resolution of the coma and did not improve. The patient had previously had a thoracic myelopathy 2 weeks after receiving low-dose i.v. ARA-C. The neurotoxicity of high-dose i.v. ARA-C may arise at much lower cumulative doses than has been reported. In addition to cerebellar dysfunction and somnolence, high-dose i.v. ARA-C may produce optic neuropathy, anosmia, and hemiparesis.
The effect of induced peripheral anosmia on gonadal development and maturation was investigated in sexually immature male rabbits. Furthermore, the effect of agents promoting gonadal maturation (LHRH, hMG or methyl testosterone) on testicular development was examined in anosmic rabbits. Peripheral anosmia was induced by spraying the olfactory mucosa with 5% ZnSO4 solution; its effects were evaluated after a 45-day period, corresponding to the duration of spermatogenesis. Evaluation was based on measurement of body-weight, testicular size, testicular biopsy score count (TBSC) and a standard LHRH test (0 and 30 min) involving measurement of the blood levels of FSH, LH and testosterone before and at the end of the test. Markedly lower final and incremental values were noted in anosmic, compared to intact, animals for body-weight (P less than 0.001), TBSC (P less than 0.001), FSH (P less than 0.01) and LH (P less than 0.05). On the other hand, treatment of the anosmic rabbits with 0.9% saline, resulted in lower FSH, TBSC and testicular size increments than in rabbits treated with LHRH, hMG or testosterone, while testosterone levels and body-weight increments were similar in all groups. These findings indicate that induced peripheral anosmia is probably responsible for the inadequate gonadal maturation in prepubertal anosmic male rabbits. This relationship was confirmed by the observed stimulatory effect of administration of agents activating pituitary gonadotrophin secretion or gonadal function in anosmic animals.
Detection thresholds for a representative from each of seven odorant classes (putrid, pepperminty, ethereal, camphoraceous, pungent, musky, floral) were determined by double-blind smell testing of seven normal males, six normal females, 6 patients with uncomplicated congenital anosmia and 13 patients with the syndrome of congenital anosmia and hypogonadotropic hypogonadism (the Kallmann syndrome, olfactogenital dysplasia). The median detection thresholds did not differ significantly between hypogonadal and eugonadal anosmics for any of the odorants, suggesting that the endocrine deficit does not result from inadequate rhinencephalic input to brain centers controlling gonadotropin release. Phenylethylmethylethylcarbinol (PEMEC), a stable chemical of the floral class, was detecred at very low concentrations (10(-6) to 10(-8) M in water) by all normals tested. Since no patient with congenital anosmia was able to distinguish even undiluted PEMEC from water, we suggest that this compound is the material of choice for convenient, rapid and objective testing of the sense of smell (cranial nerve I).
Damage to the olfactory nerve during frontotemporal approach to the basal cisternal region has not previously been investigated in a quantified manner. In this retrospective study of 25 patients operated on for ruptured intracranial aneurysms via the frontotemporal route, 22 patients suffered postoperatively from anosmia ipsilateral to the side of surgery. This complication most often goes unrecognized by the patient as well as the physician, and attention should be drawn to it because of its widespread occurrence. This investigation demonstrates a high incidence of anosmia (24 (88.9%) of 27 surgical sides) occurring ipsilateral to the frontotemporal approach in aneurysm surgery. Recovery after traumatic anosmia has been recorded up to 5 years after injury. Nevertheless, the authors believe that the damage is permanent when lasting 35 months or longer.
Insensitivity to single odors, called specific anosmia, has been repeatedly reported in the literature. The main question of the present study was whether olfactory sensitivity is inducable in subjects with specific anosmia. For this reason the olfactory sensitivity of women with specific anosmia to the volatile steroid androstenone was investigated by threshold measurements at two times, before and after repeated odor exposure. Androstenone is a compound that contributes to human body odor and is found at a higher concentration in male axillary sweat than in female sweat. The results show that in more than 80% of the odor exposed anosmics olfactory perception of androstenone could be induced.
Chemosensory dysfunction is relatively common. This article describes a series of 306 patients who presented with anosmia. We divided olfactory disorders into those associated with interruption of the transport of stimulus and those associated with damage to either peripheral or central nervous system structures. Nasal and paranasal sinus disease (transport interruption) was found to be causative in 67% of patients presenting with anosmia. These patients are generally 45 years old, the loss of olfaction is progressive and associated with additional nasal symptoms. Upper respiratory infection was found to be causative in 18% of patients. They are generally older, with a mean age of 58 years and are predominantly female (78%). The loss of smell is sudden and anosmia is often accompanied by troublesome parosmias (50%). CT-scan is necessary for the evaluation of a smell dysfunction.
OBJECTIVE: To investigate the olfactory origin of the event-related potential (OEP) by evaluating OEP and standardized psychophysical measures in patients with congenital anosmia. METHODS: Olfactory function was evaluated by OEP and standardized psychophysical measures including smell identification test and odor detection threshold tests for 3 chemosensory stimulants: phenylethyl alcohol (PEA), isoamyl acetate (IAA), and chloracetyl phenone (CAP) in 9 subjects with isolated congenital anosmia and 9 age- and gender-matched normosmic controls. RESULTS: There was a significant difference in the smell identification test score (P < 0.001) and odor detection thresholds for PEA and IAA (P < 0.001) between the anosmic and normosmic subjects. Detection thresholds for CAP, a trigeminal stimulant, did not differ between the 2 groups. In the control subjects, OEP to IAA was characterized by 4 reproducible components (P1, N1, P2 and N2). In the subjects with congenital anosmia, no reproducible evoked potential components were identified in response to IAA. No reproducible evoked potential components were seen in response to the air control stimulus in either the anosmic or normosmic groups. CONCLUSION: These data suggest that OEP provide a specific and objective measure of olfactory function.
Imaging studies are often obtained during the evaluation of the patient with an olfactory deficit. The purpose of this article is to describe an investigation that was conducted to assess the effectiveness of imaging studies in determining the etiology of olfactory loss in the patient with an isolated complaint of anosmia and no relevant findings on physical examination, including nasal endoscopy. The author conducted a retrospective review of the records of 20 women and eight men, aged 22 to 71 years (mean: 45), whose duration of anosmia had ranged from 1 month to 2 years (median: 3 mo). Twenty of these patients had undergone contrast-enhanced magnetic resonance imaging of the paranasal sinuses and brain, and the other eight had undergone enhanced computed tomography. The author found that these imaging studies did not add to the information obtained by the clinical history and endoscopic nasal examination and were thus not useful in determining the cause of anosmia. Based on these findings, the author does not recommend that imaging studies be included as part of the evaluation of these patients.
In order to support the contention that the feeding pattern seen after olfactory bulb removal is due to a sensory loss, the feeding pattern of rats was studied after a peripheral chemical lesion of the olfactory mucosa. A conditioned smell aversion procedure was used to assess the occurence and duration of anosmia after the topical application of zinc sulfate to the olfactory mucosa. It was found that the sensory deficit induced by the peripheral lesion lasted from four to six days. The occurrence of the disrupted feeding pattern in the peripherally lesioned rats coincided in time with the short period of anosmia. Thus, the disruption of the feeding pattern after bulbectomy and after lesions of the central olfactory pathways is clearly the result of anosmia and not of the loss of other non-sensory functions of the olfactory bulbs.
An influence of peripheral anosmia on sex-related differences in training and maintaining the conditioned avoidance (CA) behaviour in a shuttlle box was studied. Intact males have been shown to manifest conditioned behaviour earlier than intact females, whereas the degree of CA maintenance did not depend on an animal's sex. Prolonged anosmia facilitated training of conditional avoidance in both males and females, but it reversed the ratio of the amount of intersignal responses at anosmatic males to females versus the intact ones. Observed effects of anosmia are supposed to be realized due to the appropriate changes in the functional activity of the nuclei of the amygdaloid complex.
This study sought to verify two earlier reports that up to 93% of patients with closed head injury (CHI) and anosmia are vocationally dysfunctional due to executive impairments associated with orbitofrontal damage. Participants were 11 men and 4 women identified from a pool of 60 potential subjects referred for evaluation of trauma-related chemosensory dysfunction at the University of Pennsylvania Smell and Taste Center from 1988 to 1994. These 15 subjects met four criteria: (i) willingness to complete a brief semi-structured interview concerning their pre- and post-CHI work history; (ii) age <60 years; (iii) evidence of mild to moderate CHI; and (iv) scores on the University of Pennsylvania Smell Identification Test indicative of anosmia or severe microsmia and non-malingering. In contrast to the earlier reports, only 7% of the subjects were vocationally dysfunctional. This study calls into question previous reports suggesting that anosmia is a reliable predictor of post-CHI vocational outcome.
Two methods for producing peripheral anosmia in the dog were described. One method involved infusion of 3.5% zinc sulfate into the nasal cavity. An anosmia lasting at least 6 weeks, and, in most cases, for several months, was produced. A second technique, producing short periods of reversible anosmia, was the insertion of a tracheostomy tube with inflatable cuff. Inflation of the cuff prevented the dogs from inhaling air over the olfactory mucosa. Deflation of the cuff restored functional olfaction. The advantages and disadvantages of each technique were discussed.
Previous studies from our laboratory indicate that somatosensory inputs to the snout and ventral trunk, but not visual or auditory stimuli, play critical roles in the elicitation and maintenance of maternal aggression by lactating Norway rats toward a strange male intruder. There are conflicting reports on the influence of olfaction on maternal aggression. We explored the possible roles of central or peripheral anosmia on maternal aggression in Long-Evans rats during early lactation. In Experiment 1, responsiveness to both volatile and non-volatile odors was eliminated by bilateral olfactory bulbectomy (BOB), carried out during mid-gestation. BOB resulted in a reduced likelihood and intensity of maternal aggression on days 1 and 5 of lactation (L1 and L5), but also severe deficiencies in maternal behavior and litter growth and survival. In Experiment 2, anosmia to volatile odors was induced by spraying zinc sulfate intranasally on gestation day 21 and L1. This treatment had little or no effect on maternal aggression on L1 or L2 or on maternal behavior, especially if there was a 1-day recovery between the second treatment and testing. In Experiment 3, responsiveness to non-volatile odors was eliminated by vomeronasal-organ removal (VNX) carried out prior to mating. VNX did not disturb maternal behavior on L2-L8 or maternal aggression on L1 or L5. These results and others suggest that the expression of maternal aggression is affected by volatile odors, mediated possibly by accessory chemosensory systems such as the septal organ, or by neural changes that follow olfactory deafferentation, or both.
We report a large Italian pedigree in which five out of six males are affected by a syndrome, following an X-linked inheritance pattern, characterized by ichthyosis, hypogonadotropic hypogonadism, and anosmia. The concurrence of features of X-linked ichthyosis (XLI) with those of Kallmann syndrome, another disease often inherited as an X-linked trait, prompted us to perform biochemical, cytogenetic, and molecular studies in relation to the short arm of the X chromosome (Xp). Steroid sulphatase (STS) activity was found to be completely deficient in all affected members of the family. Prometaphase chromosome analyses of two obligate heterozygous women and one affected male showed normal karyotypes. Xg blood group antigen analysis and molecular studies employing cloned DNA sequences from the distal segment of the Xp (probes RC8, 782, dic56, and M1A), did not provide evidence for deletions or rearrangements of the X chromosome. The linkage analysis showed no crossovers between the disease, Xg, and DXS143, the locus defined by probe dic56, thus suggesting the possibility of a linkage between these two markers of the distal segment of Xp and the X-linked ichthyosis, hypogonadism, and anosmia syndrome.
As an approach to a general theory of olfaction, different specific anosmia phenotypes characterized by different profiles of odorant sensitivities have been proposed for humans. In the present experiments, male inbred mice were tested for relative odorant sensitivity using a conditioned aversion technique and odors classified as primary or complex for humans. C57BL/6J and C57BL/10J mice appeared to be less sensitive to the primary odorant isovaleric acid than were males of seven other inbred strains (A/J, AKR/J, BALB/cJ,C3HeB/FeJ, DBA/2J, SJL/J, and SWR/J). In comparisons of C57BL/6J and AKR/J strains, the relative insensitivity of C57 to isovaleric acid did not generalize to the musklike primary odor of pentadecalactone or to the complex odor of amyl acetate. The C57BL/6J genotype may provide an animal model of a specific anosmia as characterized among humans.