Marco Alessandrini

Long-Term Postural Abnormalities in Benign Paroxysmal Positional Vertigo

Benign paroxysmal positional vertigo (BPPV) is a disorder in which patients suffer from acute rotatory vertigo due to the presence of free otoconial debris migrating into one or more semicircular canals during head movements and resulting in abnormal stimulation of the ampullary crest. A prolonged loss of equilibrium of unclear origin is also present. Static posturography is a useful tool for the study of postural control systems and their role in these abnormalities. The aim of the present study was to evaluate the frequency of body sway and long-term instability of BPPV patients by posturography frequency analysis. Twenty patients with canalithiasis of the posterior semicircular canal and 20 normal controls were subjected to static posturography. Informed consent was obtained from all subjects. Patients were tested 1 h after diagnosis, and 3 days and 12 weeks after the characteristic Epley repositioning maneuver. Patients with BPPV showed significantly increased body sway both on lateral (X) and anteroposterior (Y) planes compared to normal subjects. Corporal oscillation with a broad-frequency spectrum was observed in both closed and open eye tests. The repositioning maneuver decreased the X plane body sway, while the anteroposterior sway was unchanged. Twelve weeks after treatment, a normalization of the anteroposterior sway was observed. Results of this study suggest that the long-term postural disturbance associated with BPPV differs from the acute disequilibrium that subsides after canalith repositioning: the former is a sagittal plane/broad spectrum body sway, while the latter is primarily a frontal plane/low frequency sway. The Epley maneuver was shown to reduce frontal sway, a postural abnormality that might therefore be linked to posterior semicircular canal function. Conversely, the observed sagittal body sway was only partially relieved by the restoration of canal function, and therefore, may be more related to the chronic dizziness observed in these patients.

Vestibular compensation: analysis of postural re-arrangement as a control index for unilateral vestibular deficit.

&NA; Patients with an acute unilateral vestibular lesion show an impaired balance control.The initial presentation is vertigo followed by postural instability; but with time, the global balance functions can be completely restored by a process called vestibular compensation. The aim of our study was to evaluate short and long‐term variations of postural parameters in 20 patients affected by vestibular neuritis (VN), and to compare these patients to 20 normal individuals using computerized static posturography (CSP) along with patient feedback throughout the spectral frequency analysis. This analysis showed in patients with no residual dizziness a frequency shift of body sway from low to middle frequencies as a probable expression of the compensatory strategies used by the central nervous system. On the other hand, patients with persistence of postural instability did not show any frequency shift. Our results seem to provide an early index of a proper occurring compensation so that we can adjust therapeutic protocols according to each patients functional modifications.

Connexin 26 (GJB2) mutations, causing KID Syndrome, are associated with cell death due to calcium gating deregulation.

The autosomic dominant KID Syndrome (MIM 148210), due to mutations in GJB2 (connexin 26, Cx26), is an ectodermal dysplasia with erythematous scaly skin lesions, keratitis and severe bilateral sensorineural deafness. The Cx26 protein is a component of gap junction channels in epithelia, including the cochlea, which coordinates the exchange of molecules and ions. Here, we demonstrate that different Cx26 mutants (Cx26D50N and Cx26G11E) cause cell death in vitro by the alteration of intra-cellular calcium concentrations. These results help to explain the pathogenesis of both the hearing and skin phenotypes, since calcium is also a potent regulator of the epidermal differentiation process.

Septoturbinal surgery in contact point headache syndrome: long-term results.

ABSTRACT Facial pain syndrome secondary to sinonasal pathology is reported by the International Headache Society (IHS) classification (1988). It is underlined that a clear and proven nasal pathology with adequate painful stimuli must be present, i.e., acute sinusitis, vacuum sinus, or other unspecified pathologies. No clear role of septal abnormalities and turbinate hypertrophy has been attributed in the genesis of pain by the IHS classification. One of the most difficult problems in dealing with patients with sinonasal headaches is the definition of the primary cause of the pain. In our experience possible guidelines are history, endoscopic evaluation, diagnostic blocks, and computed tomography. The data reported here is from a long-term follow-up study of facial pain in a group of 34 patients with facial pain and nasal obstruction due to septoturbinal contact that did not respond to medical therapy. Patients, free from sinus disease or other causes of headache, were treated by septoplasty/rhinoseptoplasty, and middle turbinate electrocauterization. Pre- and post-operative patency was assessed by endoscopic evaluation and nasal resistance was assessed by anterior rhinomanometry. Patients were interviewed regarding pre- and post-operative intensity of pain (subjective pain was evaluated using the 0–10 Visual Analogue Scale (VAS) and frequency of the facial pain. The follow-up period ranged from 12 to 47 months (mean: 26.7±8.5 months). In 25% of the cases the pain relapsed post-operatively (from two days to one year); but in only three patients (8%) the relapses were persistent. Two out of three, however, reported a decreased VAS score after surgery. These results seem to indicate septoplasty and turbinate decongestion to be a fairly good surgical option in treating facial pain due to septoturbinal contact resistant to conservative nasal therapy.

Early and Phasic Cortical Metabolic Changes in Vestibular Neuritis Onset

Functional brain activation studies described the presence of separate cortical areas responsible for central processing of peripheral vestibular information and reported their activation and interactions with other sensory modalities and the changes of this network associated to strategic peripheral or central vestibular lesions. It is already known that cortical changes induced by acute unilateral vestibular failure (UVF) are various and undergo variations over time, revealing different cortical involved areas at the onset and recovery from symptoms. The present study aimed at reporting the earliest change in cortical metabolic activity during a paradigmatic form of UVF such as vestibular neuritis (VN), that is, a purely peripheral lesion of the vestibular system, that offers the opportunity to study the cortical response to altered vestibular processing. This research reports [18F]fluorodeoxyglucose positron emission tomography brain scan data concerning the early cortical metabolic activity associated to symptoms onset in a group of eight patients suffering from VN. VN patients’ cortical metabolic activity during the first two days from symptoms onset was compared to that recorded one month later and to a control healthy group. Beside the known cortical response in the sensorimotor network associated to vestibular deafferentation, we show for the first time the involvement of Entorhinal (BAs 28, 34) and Temporal (BA 38) cortices in early phases of symptomatology onset. We interpret these findings as the cortical counterparts of the attempt to reorient oneself in space counteracting the vertigo symptom (Bas 28, 34) and of the emotional response to the new pathologic condition (BA 38) respectively. These interpretations were further supported by changes in patients’ subjective ratings in balance, anxiety, and depersonalization/derealization scores when tested at illness onset and one month later. The present findings contribute in expanding knowledge about early, fast-changing, and complex cortical responses to pathological vestibular unbalanced processing.

The AESOP robot system for video-assisted rigid endoscopic laryngosurgery

Surgeons may occasionally encounter difficulty in visualizing the whole larynx with a direct laryngoscope. In such cases, rigid endoscopic laryngosurgery using a direct laryngoscope is an optimal solution. Multidirectional examination of the larynx using rigid endoscopes during direct laryngoscopy, leads to better control and management of the ventricle, inferior surface of the vocal fold and subglottis, and the anterior commissure. Currently, 0°, 30°, 70° and 120° angled rigid telescopes are used worldwide. Our experience in telescopic endolaryngeal surgery provided us the opportunity to work with AESOP 3000 (automated endoscope system for optimal positioning), coupling a robotic arm to a rigid endolaryngeal telescope. The use of this device allows the surgeon to control the field of view and operate with both hands. A total of 20 patients presenting a laryngeal lesion were randomly selected and included in this study undergoing a robot-assisted procedure. Three of 20 patients presented a difficult laryngeal exposure with direct laryngoscopy due to a rigid, short neck (1 male, 1 female) and prominent teeth (1 male). We used Karl Storz Hopkins II long rigid endoscopes having 0°, 30° and 70° direction of view, a Storz Xenon 300 cold light, a Storz Tricam SL camera, the Kleinsasser direct laryngoscope. The instruments we used are all commercially available for microlaryngeal surgery and included upward curved instruments in case of difficult laryngeal exposure. The operative equipment was the same for all procedures. We evaluated the acquisition of skills in controlling the AESOP 3000, the feasibility of a single surgeon performing procedures with this machine, and any advantages that it might offer to endolaryngeal surgery. The use of robotic devices improves the precision of surgical procedures, offering surgeons a more comfortable working position, particularly for longer procedures, and without an assistant to hold the camera.

Posturography frequency analysis of sound-evoked body sway in normal subjects.

Sound-evoked activation of the vestibular system has been suggested for a long time, and myogenic potentials have been recorded at the level of different muscular groups while a high intensity sound was applied. The aim of this study was to analyse sound-evoked postural responses in normal subjects and to correlate them with the activation of the vestibular system. Body sway was measured by posturography and elaborated through spectral frequency analysis in 40 healthy volunteers in the basal condition and after applying a sound stimulus monoaurally. Spectral frequency analysis results showed a significant increase, in presence of stimulus, of body sway at low and middle frequencies only on the lateral plane and in the closed-eyes condition. As it seems that these frequency ranges are mainly under vestibular control, our results suggest that sound activates specifically the vestibular system, and posturography during sound stimulation represents an alternative approach to assess vestibular function.

Experimental and clinical aspects of the efferent auditory system

The discovery of active mechanisms in the cochlea and the efferent auditory pathways from the brain to the cochlea demonstrated the existence of a modulation of the auditory input in the central nervous system (CNS). Otoacoustic emissions (OAEs) are weak signals that can be recorded in the ear canal and are considered a byproduct of an active process from the outer hair cells (OHCs) to the basilar membrane. The efferent auditory system plays an inhibitory role on the activity of OHCs; its stimulation reduces auditory nerve response, basilar membrane motility and OAEs amplitude. Indirect stimulation by contralateral sound is also inhibitory; a reduction of OAEs amplitude can be recorded and such an effect disappears after olivocochlear bundle section. The efferent system seems to play a role in detection of signals in noise, protection in noise-induced cochlear damage, development of hearing and processing of complex auditory signals. With respect to clinical application, OAEs suppression after contralateral auditory stimulation seems to be the only objective and non-invasive method for evaluation of the functional integrity of the medial efferent system, and, therefore, for evaluation of the structures lying along its course, at least up to the level of inferior colliculi.

Involvement of Subcortical Brain Structures During Olfactory Stimulation in Multiple Chemical Sensitivity.

Multiple chemical sensitivity (MCS) patients usually react to odour compounds and the majority of neuroimaging studies assessed, especially at the cortical level, many olfactory-related correlates. The purpose of the present study was to depict sub-cortical metabolic changes during a neutral (NC) and pure (OC) olfactory stimulation by using a recently validated 18F-2-fluoro-2-deoxy-d-glucose (FDG)-positron emission tomography/computer tomography procedure in 26 MCS and 11 healthy (HC) resting subjects undergoing a battery of clinical tests. Twelve subcortical volumes of interest were identified by the automated anatomical labeling library and normalized to thalamus FDG uptake. In both groups, when comparing OC to NC, the within-subjects ANOVA demonstrated a relative decreased metabolism in bilateral putamen and hippocampus and a relative increased metabolism in bilateral amygdala, olfactory cortex (OLF), caudate and pallidum. The between-groups ANOVA demonstrated in MCS a significant higher metabolism in bilateral OLF during NC. As in HC subjects negative correlations were found in OC between FDG uptake in bilateral amygdala and hippocampus and odor pleasantness scale, the latter positively correlated with MCS subjects’ bilateral putamen FDG uptake in OC. Besides FDG uptake resemblances in both groups were found, for the first time a relative higher metabolism increase in OLF in MCS subjects at rest with respect to HC was found. When merging this aspect to the different subcortical FDG uptake correlations patterns in the two groups, the present study demonstrated to describe a peculiar metabolic index of behavioral and neurological aspects of MCS complaints.

Impaired mental rotation in benign paroxysmal positional vertigo and acute vestibular neuritis

Vestibular processing is fundamental to our sense of orientation in space which is a core aspect of the representation of the self. Vestibular information is processed in a large subcortical–cortical neural network. Tasks requiring mental rotations of human bodies in space are known to activate neural regions within this network suggesting that vestibular processing is involved in the control of mental rotation. We studied whether mental rotation is impaired in patients suffering from two different forms of unilateral vestibular disorders (vestibular neuritis – VN – and Benign Paroxysmal positional Vertigo – BPPV) with respect to healthy matched controls (C). We used two mental rotation tasks in which participants were required to: (i) mentally rotate their own body in space (egocentric rotation) thus using vestibular processing to a large extent and (ii) mentally rotate human figures (allocentric rotation) thus using own body representations to a smaller degree. Reaction times and accuracy of responses showed that VN and BPPV patients were impaired in both tasks with respect to C. Significantly, the pattern of results was similar in the three groups suggesting that patients were actually performing the mental rotation without using a different strategy from the control individuals. These results show that dysfunctional vestibular inflow impairs mental rotation of both own body and human figures suggesting that unilateral acute disorders of the peripheral vestibular input massively affect the cerebral processes underlying mental rotations.