1,721,050 research outputs found
Responses of Purkinje-cells of the cerebellar anterior vermis to stimulation of vestibular and somatosensory receptors.
No full textIn decerebrate cats, sinusoidal rotation of the forepaw around the wrist modifies the activity of the ipsilateral forelimb extensor triceps brachii (TB) and leads to plastic changes of adaptive nature in the gain of vestibulospinal (VS) reflexes (VSRs). Both effects are depressed by functional inactivation of the cerebellar anterior vermis, which also decreases the gain of VSRs. In order to better understand the mechanisms of these phenomena, the simple spike activity of Purkinje (P-) cells was recorded from the vermal cortex of the cerebellar anterior lobe during individual and/or combined stimulation of somatosensory wrist, neck and vestibular receptors. About one third of the recorded units were affected by sinusoidal rotation of the ipsilateral forepaw around the wrist axis (0.16 Hz, ±10°). Most of these neurons (∼60%) increased their activity during ventral flexion of the wrist and decreased it during the oppositely directed movement, with an average phase lag of −141° with respect to the position of maximal dorsiflexion. The remaining cells (∼40%) were excited during dorsiflexion of the wrist, with an average phase lead of 59° with respect to the extreme dorsal flexion. Both populations showed comparable response gains, with an average value of 0.42±0.52, S.D., imp/s/deg. About half of the recorded units were also tested during sinusoidal roll tilt of the animal around the longitudinal axis (0.16 Hz, ±10°), leading to stimulation of labyrinthine receptors. When both stimuli were applied simultaneously, the responses to combined stimulation usually corresponded to the sum of individual responses. While the phase distribution of somatosensory responses was clearly bimodal, vestibular responses showed phase angle values uniformly scattered between ±180° and 0°, so that, during combined stimulation, each neuron could be maximally activated by coupling the two stimuli with a particular phase relation. Finally, a proportion of the recorded neurons was also tested during sinusoidal rotation of the body around its longitudinal axis, with the head fixed in space, leading to stimulation of neck receptors. The proportion of neurons affected by individual stimulation of vestibular or neck receptors (81% and 72%, respectively) was larger than that of wrist-driven neurons. Convergence of signals from vestibular, somatosensory wrist and neck receptors was found in 18% of the neurons analyzed. In conclusion, the results of this study show that somatosensory signals from the forelimb: i) modulate the activity of a sizeable proportion of neurons located within the cerebellar anterior vermis and ii) interact widely with labyrinthine and neck signals at this level. Moreover, iii) this corticocerebellar region is largely dominated by vestibular and neck signals that may be utilized to build up a neuronal representation of the position of body in space. These findings suggest that: 1) the modulation of TB activity induced by rotation of the ipsilateral wrist may at least partially depend upon the simultaneous changes in P-cell activity and 2) the interaction of vestibular and somatosensory wrist signals at P-cell level may represent the substrate of the plastic changes that affect the VSR when animal tilt and wrist rotation are driven together. A preliminary report of these data has been presented [Bruschini L, Manzoni D, Pompeiano O (2000) Responses of cerebellar Purkinje cells to forepaw rotation in decerebrate cat. Pflügers Arch 440:R31]
Coupling sensory inputs to the appropriate motor responses: new aspects of cerebellar function.
No full textAbstract
It is known that proprioceptive signals modify the spatial organization of the postural reflexes, thus leading to body stability. The neurophysiological basis of this phenomenon are at present unknown. The present report documents that, in decerebrate cat, body-to-head rotation in the horizontal plane modified the preferred response direction to labyrinthine stimulation of the forelimb extensor triceps brachii. Such direction resulted always perpendicular to the longitudinal body axis of the animal, whatever its relative position with respect to the head could be. The rotation of the preferred response direction of the triceps was greatly reduced by functional inactivation of the ipsilateral cerebellar vermis. On the other hand, following body-to-head displacement, the preferred response directions of the corresponding P-cells tended, on the average, to rotate in the same direction and by the same angle as the body. We propose that the neck input finely tunes parallel vestibular channels, endowed with different spatial and temporal properties, impinging upon P-cells, thus modifying their responses to animal tilt and, as a consequence, the spatial properties of VS reflexes. It is possible that, by a similar mechanism, the cerebellum may contribute to the changes in reference frame occurring in sensorimotor transformations of reflex and voluntary nature
Experience in Transoral Robotic Surgery in Pediatric Subjects: A Systematic Literature Review
Full text linkPediatric transoral robotic surgery (TORS) has improved from 2007 to 2020, widening
its indications and feasibility. This article aims to systematically analyze the procedures
performed from the first use until the current year, observing their evolution over time. A
systematic literature review was performed using PubMed, Scopus, Web of Science, and
Cochrane databases between March 1, 2000, and April 1, 2020. We selected studies
that were written only in English and were performed in live human subjects. About
16 studies were found with a total of 73 subjects treated, among them 41 were men
and 32 were women with an average age of 6.8 ± 4.99 years. There have been four
(5.47%) conversions. Both functional and benign-malignant diseases have been treated
in the series. Eleven (15.06%) pre-operative tracheostomy and zero post-operative
tracheostomy were performed. The bleeding data was only reported in 9 studies and was
<50 ml. Only one (1.36%) intra-operative complication and 10 (12.32%) postoperative
complications were reported. We consider the TORS procedures in pediatric subjects
safe, feasible and with good surgical outcomes up to the laryngeal region
Implantable hearing aids in otosclerosis: indications, surgical applications, and cost-effectiveness
No full textSince the 1980s, implantable hearing devices have revolutionised otologic surgery, providing new options for patients with otosclerosis. This article discusses two primary types of devices that are beneficial to patients with otosclerosis: bone anchored hearing devices (BAHDs) and active middle ear implants (AMEIs). BAHDs include percutaneous, passive, and active transcutaneous devices, offering an alternative for patients where stapes surgery or conventional hearing aids are not feasible. Although BAHDs improve audiological outcomes, they are generally considered a third-line treatment due to their limited cost-effectiveness ratio in otosclerosis. AMEIs, such as the Vibrant Soundbridge, are another option, offering superior speech recognition without the occlusion effects of traditional hearing aids. While implantable hearing devices show promising results, they are typically reserved for patients at high surgical risk or who do not benefit from conventional hearing aids. Further cost-benefit analysis is needed, as implantable devices are less economically favourable compared to stapes surgery
Exploring the genetic landscape of otosclerosis: current understanding and future perspectives
No full textOtosclerosis is characterised by abnormal bone remodelling in the otic capsule, leading to progressive hearing loss. Unlike many genetic disorders, the causative genes for otosclerosis remain largely unidentified despite extensive research using linkage analysis and genome-wide association studies (GWAS). Inheritance patterns in otosclerosis suggest a multifactorial model involving genetic predisposition and environmental triggers, a model applied to other common diseases, such as age-related hearing loss, coronary artery disease, and Alzheimer’s disease. Linkage analysis has identified nine loci associated with monogenic forms of otosclerosis, yet the specific causative genes and variants remain elusive. Promising insights have emerged from GWAS, with strong associations identified for novel candidate regions, including the RELN gene. Recent studies using next generation sequencing have identified several candidate genes such as SERPINF1, ACAN, and MEPE. SERPINF1, encoding pigment epithelium-derived growth factor, is linked to regulation of angiogenesis in bone remodelling. ACAN, associated with the OTSC1 locus, encodes aggrecan a crucial component of the extracellular matrix in cartilage, showing a range of variants with varied effect sizes and frequencies. MEPE, involved in bone homeostasis, has been significantly associated with otosclerosis in large family-based and case-control cohorts. While considerable progress has been made in identifying potential genetic contributors, the precise genetic architecture of otosclerosis remains to be fully elucidated. An integrated approach combining genetic data and clinical information, such as audiometric testing and temporal bone imaging, is essential for a comprehensive understanding of otosclerosis
Neck input modifies the reference frame for coding labyrinthine signals in the cerebellar vermis: a cellular analysis.
No full textAbstract
The activity of 68 neurons, mainly Purkinje cells, was recorded from the cerebellar anterior vermis of decerebrate cats during wobble of the whole animal (at 0.156Hz, 5°), a mixture of tilt and rotation, leading to stimulation of labyrinth receptors. Most of the neurons (65/68) were affected by both clockwise and counterclockwise rotations. Twenty-four units showing responses of comparable amplitude to these stimuli (narrowly tuned cells) were represented by a single vector (S(max)), whose preferred direction corresponded to the direction of stimulation giving rise to the maximal response. The remaining 41 units, however, showed different amplitude responses to these rotations (broadly tuned cells) and were characterized by two spatially and temporally orthogonal vectors (S(max) and S(min)), suggesting that labyrinthine signals with different spatial and temporal properties converged on these cells. All these units were tested while the body was aligned with the head (control position), as well as after static displacement of the body under a fixed head by 15°and/or 30°around a vertical axis passing through C1-C2, thus leading to stimulation of neck receptors. The orientation component of the response vector of the Purkinje cells to vestibular stimulation changed following body-to-head displacement. Moreover, the amplitude of vector rotation corresponded, on the average, to that of body rotation. Changes in temporal phase, gain and tuning ratio of the responses were also observed.We propose that information from neck receptors regulates the convergence of labyrinthine signals with different spatial and temporal properties on corticocerebellar units. Due to their strict relationship with the motor system, these units may give rise to appropriate responses in the limb musculature, by modifying the spatial organization of the vestibulospinal reflexes according to the requirements of body stability. The cerebellar vermis may thus represent an important structure, where frames of reference can be altered to account for changes in position of trunk, head and neck
Is the Da Vinci Xi system a real improvement for oncologic transoral robotic surgery? A systematic review of the literature
No full textIn this paper, we reviewed the current literature about TORS procedures performed with Xi system and we discussed the pros and cons of this robotic system comparing it to the previous Si model. A systematic literature review was conducted using the PubMed, Scopus, Web of Science and Cochrane databases for adequate published studies about TORS procedure performed with da Vinci Si and Xi models. Five papers on the TORS-Xi procedures met our inclusion and exclusion criteria. These papers showed results based on 74 subjects (mean age 60.51 ± 4.55 years old). The most common TORS procedure was performed to address the oropharynx (65 procedures). One case (1.35%) of a tongue base tumor was converted into a transmandibular approach. One subject (1.35%) had a positive margin, while two subjects (2.7%) had close/uncertain margins at final histology. Nine papers on the TORS-Si procedures met our inclusion and exclusion criteria. These papers showed results based on 128 subjects (mean age 59.79 ± 5.93 years old). The most common TORS procedure was performed to address the oropharynx (90 procedures). Three procedures (2.34%) were aborted due to inadequate exposure of the tumor. None of the subject had positive margins, while three subjects (2.34%) had close/uncertain margins at final histology. Despite its improved vision, easier docking and narrower robotic arms, the da Vinci Xi system has structural peculiarities that limit its applications for certain TORS procedures
Giant neck neoplasm. Case report
No full textGiant latero-cervical neoplasias usually originate in the parotid gland, as slow-growing adenomas, in subjects who take little care of their personal health. Giant adenomas of submandibular gland are very rare. These neoplasias involve prevalently male sex (male/female ratio: 2/1) and usually occur between 20 and 40 years of age. Signs of malignant transformation may be observed in the adenomatous epithelial component in a percentage ranging from 1% to 10% of cases. The case is reported of a giant malignant latero-cervical neoplasia originating from a pleomorph adenoma of the submandibular gland. The diagnostic work-up and treatment protocol are described
Enlarged vestibular aqueduct and Mondini Malformation: audiological, clinical, radiologic and genetic features
Full text linkPurpose: When referring to enlarged vestibular aqueduct (EVA) we should differentiate between nonsyndromic enlarged vestibular aqueduct (NSEVA) and Pendred Syndrome (PDS), a disease continuum associated with pathogenic sequence variants of Pendrin’s Gene (SLC26A4) in about half of the cases. The study was aimed to analyse the clinical and audiological features of a monocentric cohort of Caucasian patients with NSEVA/PDS, their genetic assessment and morphological inner ear features. Methods: We retrospectively reviewed the audiologic, genetic and anamnestic data of 66 patients with NSEVA/PDS followed by our audiology service. Results: SLC26A4 mutations was significantly correlated with the presence of PDS rather than NSEVA (p < 0.019), with the expression of inner ear malformations (p < 0.001) and with different severity of hearing loss (p = 0.001). Furthermore, patients with PDS showed significantly worse pure tone audiometry (PTA) than patients with NSEVA (p = 0.001). Anatomically normal ears presented significantly better PTA than ears associated with Mondini Malformation or isolated EVA (p < 0.001), but no statistically significative differences have been observed in PTA between patients with Mondini Malformation and isolated EVA. Conclusion: NSEVA/PDS must be investigated in all the congenital hearing loss, but also in progressive, late onset, stepwise forms. Even mixed or fluctuating hearing loss may constitute a sign of a NSEVA/PDS pathology. Our findings can confirm the important role of SLC26A4 mutations in determining the phenotype of isolated EVA/PDS, both for the type/degree of the malformation, the hearing impairment and the association with thyroid dysfunction
- …
