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Journal of Neurological Surgery. Part... Jan 2024Surgical approaches to the anterior cranial fossa have great risk of damaging the olfactory tract and bulb. The goal of this study was to describe the outer arachnoid...
BACKGROUND
Surgical approaches to the anterior cranial fossa have great risk of damaging the olfactory tract and bulb. The goal of this study was to describe the outer arachnoid envelope around the olfactory bulb which plays significant role in the approach-related injury of the nerve.
MATERIAL AND METHODS
A total of 20 fresh human cadaveric heads were examined as a following: 5 cadaveric heads were used to describe a gross overview of the topographic anatomy of the outer arachnoid cover of the olfactory bulb. In 15 cadaveric heads endoscopic surgical approaches were performed to examine the in situ undisrupted anatomy of the outer arachnoid around the olfactory bulb. Four cadaveric heads were used for lateral subfrontal approach, 5 heads for medial subfrontal, 3 heads for median subfrontal approach and 3 heads for anterior interhemispheric approach.
RESULTS
The outer arachnoid membrane of the frontal lobe attaches the olfactory bulb strongly to the above lying olfactory sulcus. Only the most rostral portion of the olfactory bulb became slightly detached from the frontal lobe. The outer arachnoid forms a decent protrusion around the tip of the olfactory bulbs. The fila olfactoria have their own outer arachnoid cover as a continuation of the same layer of the olfactory bulb. The effect of brain retraction and manipulation forces on the olfactory bulb and the role of the here located arachnoid membranes were visually analysed and described in detail through the performed four different neurosurgical approaches.
CONCLUSION
The results of our observations provide important anatomical details for the preservation of smelling during neurosurgical procedures.
PubMed: 38242165
DOI: 10.1055/a-2249-7710 -
International Forum of Allergy &... Jun 2024Post-COVID parosmia may be due to dysautonomia and sympathetic hyperresponsiveness, which can be attenuated by stellate ganglion block (SGB). This study evaluates SGB as...
BACKGROUND
Post-COVID parosmia may be due to dysautonomia and sympathetic hyperresponsiveness, which can be attenuated by stellate ganglion block (SGB). This study evaluates SGB as a treatment for post-COVID olfactory dysfunction (OD).
METHODS
Retrospective case series with prospective data of patients with post-COVID OD undergoing unilateral (UL) or bilateral (BL) SGB. Patients completed Brief Smell Identification Tests (BSIT) (12 points maximum) and post-procedure surveys including parosmia severity scores on a scale of 1 (absent) to 10 (severe). Scores were compared from before treatment (pre-SGB) to after first (SGB1) or second (SGB2) treatments in overall, UL, and BL cohorts.
RESULTS
Forty-seven patients with post-COVID OD underwent SGB, including 23 UL and 24 BL. Twenty patients completed pre- and post-SGB BSITs (eight UL and 12 BL). Twenty-eight patients completed postprocedure surveys (11 UL and 17 BL). There were no differences in BSIT scores from pre-SGB to post-SGB1 or post-SGB2 for the overall (p = 0.098), UL (p = 0.168), or BL (p = 0.230) cohorts. Parosmia severity for the overall cohort improved from pre-SGB (8.82 ± 1.28) to post-SGB1 (6.79 ± 2.38) and post-SGB2 (5.41 ± 2.35), with significant differences from pre-SGB to post-SGB1 (p < 0.001) and pre-SGB to post-SGB2 (p < 0.001), but not post-SGB1 to post-SGB2 (p = 0.130). Number of parosmia triggers decreased for overall (p = 0.002), UL (p = 0.030) and BL (p = 0.024) cohorts. Quality of life (QOL) improved for all cohorts regarding food enjoyment, meal preparation, and socialization (p < 0.05).
CONCLUSION
SGB may improve subjective parosmia and QOL for patients with post-COVID OD, however it may not affect odor identification. Further placebo-controlled studies are warranted.
Topics: Humans; Stellate Ganglion; COVID-19; Male; Female; Middle Aged; Autonomic Nerve Block; Retrospective Studies; Olfaction Disorders; Aged; Adult; SARS-CoV-2; Treatment Outcome
PubMed: 38226898
DOI: 10.1002/alr.23314 -
The Journal of Experimental Biology Feb 2024The olfactory epithelium of fish is - of necessity - in intimate contact with the surrounding water. In euryhaline fish, movement from seawater to freshwater (and vice...
The olfactory epithelium of fish is - of necessity - in intimate contact with the surrounding water. In euryhaline fish, movement from seawater to freshwater (and vice versa) exposes the epithelium to massive changes in salinity and ionic concentrations. How does the olfactory system function in the face of such changes? The current study compared olfactory sensitivity in seawater- (35‰) and brackish water-adapted seabass (5‰) using extracellular multi-unit recording from the olfactory nerve. Seawater-adapted bass had higher olfactory sensitivity to amino acid odorants when delivered in seawater than in freshwater. Conversely, brackish water-adapted bass had largely similar sensitivities to the same odorants when delivered in seawater or freshwater, although sensitivity was still slightly higher in seawater. The olfactory system of seawater-adapted bass was sensitive to decreases in external [Ca2+], whereas brackish water-adapted bass responded to increases in [Ca2+]; both seawater- and brackish water-adapted bass responded to increases in external [Na+] but the sensitivity was markedly higher in brackish water-adapted bass. In seawater-adapted bass, olfactory sensitivity to l-alanine depended on external Ca2+ ions, but not Na+; brackish water-adapted bass did respond to l-alanine in the absence of Ca2+, albeit with lower sensitivity, whereas sensitivity was unaffected by removal of Na+ ions. A possible adaptation of the olfactory epithelium was the higher number of mucous cells in brackish water-adapted bass. The olfactory system of seabass is able to adapt to low salinities, but this is not immediate; further studies are needed to identify the processes involved.
Topics: Animals; Bass; Salinity; Calcium; Seawater; Water; Sodium; Alanine; Gills
PubMed: 38197261
DOI: 10.1242/jeb.246448 -
ENeuro Feb 2024Activity-dependent neuronal plasticity is crucial for animals to adapt to dynamic sensory environments. Traditionally, it has been investigated using deprivation...
Activity-dependent neuronal plasticity is crucial for animals to adapt to dynamic sensory environments. Traditionally, it has been investigated using deprivation approaches in animal models primarily in sensory cortices. Nevertheless, emerging evidence emphasizes its significance in sensory organs and in subcortical regions where cranial nerves relay information to the brain. Additionally, critical questions started to arise. Do different sensory modalities share common cellular mechanisms for deprivation-induced plasticity at these central entry points? Does the deprivation duration correlate with specific plasticity mechanisms? This study systematically reviews and meta-analyzes research papers that investigated visual, auditory, or olfactory deprivation in rodents of both sexes. It examines the consequences of sensory deprivation in homologous regions at the first central synapse following cranial nerve transmission (vision - lateral geniculate nucleus and superior colliculus; audition - ventral and dorsal cochlear nucleus; olfaction - olfactory bulb). The systematic search yielded 91 papers (39 vision, 22 audition, 30 olfaction), revealing substantial heterogeneity in publication trends, experimental methods, measures of plasticity, and reporting across the sensory modalities. Despite these differences, commonalities emerged when correlating plasticity mechanisms with the duration of sensory deprivation. Short-term deprivation (up to 1 d) reduced activity and increased disinhibition, medium-term deprivation (1 d to a week) involved glial changes and synaptic remodeling, and long-term deprivation (over a week) primarily led to structural alterations. These findings underscore the importance of standardizing methodologies and reporting practices. Additionally, they highlight the value of cross-modal synthesis for understanding how the nervous system, including peripheral, precortical, and cortical areas, respond to and compensate for sensory inputs loss.
Topics: Male; Animals; Female; Rodentia; Hearing; Synaptic Transmission; Synapses; Vision, Ocular; Neuronal Plasticity; Sensory Deprivation
PubMed: 38195533
DOI: 10.1523/ENEURO.0435-23.2023 -
Neurochemical Research Apr 2024Dysfunctional sensory systems, including altered olfactory function, have recently been reported in patients with autism spectrum disorder (ASD). Disturbances in...
Dysfunctional sensory systems, including altered olfactory function, have recently been reported in patients with autism spectrum disorder (ASD). Disturbances in olfactory processing can potentially result from gamma-aminobutyric acid (GABA)ergic synaptic abnormalities. The specific molecular mechanism by which GABAergic transmission affects the olfactory system in ASD remains unclear. Therefore, the present study aimed to evaluate selected components of the GABAergic system in olfactory brain regions and primary olfactory neurons isolated from Shank3-deficient () mice, which are known for their autism-like behavioral phenotype. Shank3 deficiency led to a significant reduction in GEPHYRIN/GABAR colocalization in the piriform cortex and in primary neurons isolated from the olfactory bulb, while no change of cell morphology was observed. Gene expression analysis revealed a significant reduction in the mRNA levels of GABA transporter 1 in the olfactory bulb and Collybistin in the frontal cortex of the Shank3 mice compared to WT mice. A similar trend of reduction was observed in the expression of Somatostatin in the frontal cortex of Shank3 mice. The analysis of the expression of other GABAergic neurotransmission markers did not yield statistically significant results. Overall, it appears that Shank3 deficiency leads to changes in GABAergic synapses in the brain regions that are important for olfactory information processing, which may represent basis for understanding functional impairments in autism.
Topics: Humans; Mice; Animals; Autism Spectrum Disorder; Nerve Tissue Proteins; Neurons; Synapses; gamma-Aminobutyric Acid; Olfactory Cortex; Microfilament Proteins
PubMed: 38183586
DOI: 10.1007/s11064-023-04097-2 -
Zhurnal Nevrologii I Psikhiatrii Imeni... 2023A systematic review of literature on the issue of involvement in the sense of smell, as well as the interaction between the trigeminal and olfactory nerves, was carried...
A systematic review of literature on the issue of involvement in the sense of smell, as well as the interaction between the trigeminal and olfactory nerves, was carried out. The article discusses the features of the chemical perception systems, as well as the treatment of olfactory disorders using transcranial electrical stimulation of the trigeminal nerve.
Topics: Humans; Smell; Olfaction Disorders; Transcranial Direct Current Stimulation; Trigeminal Nerve
PubMed: 38147376
DOI: 10.17116/jnevro20231231217 -
Frontiers in Cellular Neuroscience 2023Vomeronasal sensory neurons (VSNs) recognize pheromonal and kairomonal semiochemicals in the lumen of the vomeronasal organ. VSNs send their axons along the vomeronasal...
Vomeronasal sensory neurons (VSNs) recognize pheromonal and kairomonal semiochemicals in the lumen of the vomeronasal organ. VSNs send their axons along the vomeronasal nerve (VN) into multiple glomeruli of the accessory olfactory bulb (AOB) and form glutamatergic synapses with apical dendrites of mitral cells, the projection neurons of the AOB. Juxtaglomerular interneurons release the inhibitory neurotransmitter γ-aminobutyric acid (GABA). Besides ionotropic GABA receptors, the metabotropic GABA receptor has been shown to modulate synaptic transmission in the main olfactory system. Here we show that GABA receptors are expressed in the AOB and are primarily located at VN terminals. Electrical stimulation of the VN provokes calcium elevations in VSN nerve terminals, and activation of GABA receptors by the agonist baclofen abolishes calcium influx in AOB slice preparations. Patch clamp recordings reveal that synaptic transmission from the VN to mitral cells can be completely suppressed by activation of GABA receptors. A potent GABA receptor antagonist, CGP 52432, reversed the baclofen-induced effects. These results indicate that modulation of VSNs via activation of GABA receptors affects calcium influx and glutamate release at presynaptic terminals and likely balances synaptic transmission at the first synapse of the accessory olfactory system.
PubMed: 38130867
DOI: 10.3389/fncel.2023.1302955 -
European Archives of... May 2024Olfactory dysfunction (OD) can be a long-term consequence of various viral infections, including COVID-19. Dysfunction includes hyposmia/anosmia and parosmia (odor...
PURPOSE
Olfactory dysfunction (OD) can be a long-term consequence of various viral infections, including COVID-19. Dysfunction includes hyposmia/anosmia and parosmia (odor distortions). Interactions of the virus with the olfactory nerve have been extensively researched, but little is known about the interactions of the intranasal trigeminal nerve system in modulating this sensory loss.
METHODS
We investigated intranasal trigeminal function across COVID-19 OD patients with and without parosmia compared to normosmic controls, to determine whether (1) post-viral hyposmia and/or (2) post-viral hyposmia with parosmia is associated with altered trigeminal function. OD patients (n = 27) were tested for olfactory function using the extended Sniffin' Sticks olfactory test and for trigeminal function through three methods-odor lateralization, subjective ratings of nasal patency, and ammonium vapor pain intensity ratings. This group was subsequently compared to controls, normosmic subjects (n = 15).
RESULTS
Our findings revealed that post-COVID OD patients without parosmia experienced decreased sensitivity in ammonium vapor pain intensity ratings and odor lateralization scores-but similar nasal patency ratings-compared to normosmic controls. There were no significant differences in trigeminal function between OD patients with and without parosmia.
CONCLUSIONS
Based on our results, we conclude that the trigeminal nerve dysfunction may partially explain post-viral OD, but does not seem to be a major factor in the generation of parosmia pathophysiology.
Topics: Humans; Anosmia; COVID-19; Smell; Olfaction Disorders; Ammonium Compounds
PubMed: 38127097
DOI: 10.1007/s00405-023-08391-1 -
Insect Science Apr 2024The olfactory system of adult lepidopterans is among the best described neuronal circuits. However, comparatively little is known about the organization of the olfactory...
The olfactory system of adult lepidopterans is among the best described neuronal circuits. However, comparatively little is known about the organization of the olfactory system in the larval stage of these insects. Here, we explore the expression of olfactory receptors and the organization of olfactory sensory neurons in caterpillars of Pieris brassicae, a significant pest species in Europe and a well-studied species for its chemical ecology. To describe the larval olfactory system in this species, we first analyzed the head transcriptome of third-instar larvae (L3) and identified 16 odorant receptors (ORs) including the OR coreceptor (Orco), 13 ionotropic receptors (IRs), and 8 gustatory receptors (GRs). We then quantified the expression of these 16 ORs in different life stages, using qPCR, and found that the majority of ORs had significantly higher expression in the L4 stage than in the L3 and L5 stages, indicating that the larval olfactory system is not static throughout caterpillar development. Using an Orco-specific antibody, we identified all olfactory receptor neurons (ORNs) expressing the Orco protein in L3, L4, and L5 caterpillars and found a total of 34 Orco-positive ORNs, distributed among three sensilla on the antenna. The number of Orco-positive ORNs did not differ among the three larval instars. Finally, we used retrograde axon tracing of the antennal nerve and identified a mean of 15 glomeruli in the larval antennal center (LAC), suggesting that the caterpillar olfactory system follows a similar design as the adult olfactory system, although with a lower numerical redundancy. Taken together, our results provide a detailed analysis of the larval olfactory neurons in P. brassicae, highlighting both the differences as well as the commonalities with the adult olfactory system. These findings contribute to a better understanding of the development of the olfactory system in insects and its life-stage-specific adaptations.
Topics: Animals; Olfactory Receptor Neurons; Insecta; Larva; Lepidoptera; Sensilla; Receptors, Odorant; Insect Proteins
PubMed: 38105530
DOI: 10.1111/1744-7917.13304 -
Brain Research Feb 2024Trigeminal neuralgia (TN) is a common form of facial pain, which primarily manifests as severe pain similar to facial acupuncture and electric shock. Olfactory...
Trigeminal neuralgia (TN) is a common form of facial pain, which primarily manifests as severe pain similar to facial acupuncture and electric shock. Olfactory ensheathing cells (OECs) are glial cells with high bioactivity; these cells are essential for the periodic regeneration of the olfactory nerve and have been utilized for the repair of nerve injuries. A member of the P2X receptor family, P2X7R, is an ion channel type receptor that has been confirmed to participate in various pain response processes. In this study, we transplanted OECs into trigeminal nerve-model rats with distal infraorbital nerve ligation to observe the therapeutic effect of transplanted OECs in rats. Additionally, we utilized the P2X7R-specific inhibitor brilliant blue G (BBG) to study the therapeutic mechanisms of cell transplantation. The facial mechanical pain threshold of these rats significantly increased following cell transplantation. The immunohistochemistry, immunoblotting, and RT-qPCR results demonstrated that the levels of P2X7R, (NOD)-like receptor protein-3 (NLRP3), nuclear factor-κB (NF-κB), interleukin (IL)-1β, and IL-18 in the trigeminal ganglion of rats treated with OEC transplantation or BBG treatment were significantly lower than those in the injured group without treatment. Overall, our results demonstrate that OEC transplantation can alleviate TN in rats, and it can reduce the expression of P2X7R related inflammatory factors in TN rats, reducing neuroinflammatory response in TG.
Topics: Rats; Animals; Trigeminal Neuralgia; Rats, Sprague-Dawley; Facial Pain; Pain Threshold; Cell Transplantation; Olfactory Bulb
PubMed: 38104922
DOI: 10.1016/j.brainres.2023.148732