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Biomedical subjects

G Freyss

Publications and source records attributed to G Freyss.

At least 19 recordsLinked to original sources
PubMed2002

Intratympanic gentamicin injections for Meniere disease: vestibular hair cell impairment and regeneration.

The authors treated 22 patients with intratympanic gentamicin. Vestibular function was measured using caloric and head impulse tests and vestibular evoked myogenic potentials induced by high amplitude sounds and short duration galvanic currents. Roughly one-third of the patients, after initially losing their caloric responses and displaying refixation saccades to head impulse tests, recovered within 2 years of the lesion. Vertigo did not recur in patients in whom the galvanic response was abolished.

Adult↗
PubMed1999

Saccular dysfunction in Meniere's disease.

OBJECTIVE: The aim of this study was to assess any dysfunction of the sacculus in patients with unilateral Meniere's disease by monitoring the vestibular evoked myogenic potentials (VEMPs) evoked by high level clicks on the Stemomastoid muscles (SCMs). STUDY DESIGN: The study was a retrospective analysis. SETTING: The study was performed in the E.N.T. department of the Lariboisière Hospital. PATIENTS: Fifty-nine patients aged 18 to 74 years with well-established unilateral Meniere's disease were included in the study. INTERVENTIONS: Loud monaural clicks were delivered unilaterally, and the VEMPs were recorded with skin electrodes on the ipsilateral SCM. All the patients were also subjected to a pure tone audiometric test and bithermal caloric testing. The postural performances of 39 patients were analyzed using the Equitest. MAIN OUTCOME MEASURE: VEMP results were the main outcome measure. RESULTS: The saccular response was absent on the affected side in 54% of the patients with Meniere's disease. This absence was correlated with the degree of low frequency hearing loss but not with canal paresis. Finally, nonfalling patients with saccular dysfunction had a significantly poorer postural performance than those without such dysfunction in the condition 5. CONCLUSION: Patients with Meniere's disease could have a saccular dysfunction (54% in this series). This saccular impairment correlated with low frequency hearing loss but not with canal paresis. Patients without VEMPs had poorer postural performances in condition 5 than those with normal VEMPs. Therefore, VEMP testing is useful for detecting patients at risk: in patients with saccular lesion, the dynamic postural performances should be assessed on a movable platform to detect visually dependent patients and to orient vestibular rehabilitation.

Adolescent↗
PubMed1999

[Rehabilitation of the paralyzed face by hypoglossal-facial nerve anastomosis. An analysis of 7 cases].

After facial nerve injury, in cerebello-pontine tumors surgery, hypoglossal-facial anastomosis is the most common procedure, to rehabilite a paralysed face, if direct facio-facial graft is not possible. This procedure must be done, in a second time, during the next year and followed with a specific reeducation. In seven patients operated between 1985 and 1996, we performed clinical evaluation and electrophysiological examination. The best evaluation is the clinical evaluation using the G. Freyss's facial testing. Best results are seen in early, specific and continued reeducation. All our patients have a good recovery of facial nerve function, but clinical examination and electrophysiological results are not correled with an objective video performance. The management of such patients needs efficient oto-neurosurgical team and specific trained physiotherapists.

Adult↗
PubMed1995

3-D eye movement measurements on four Comex's divers using video CCD cameras, during high pressure diving.

Previous studies have shown the vulnerability of the vestibular system regarding barotraumatism (1) and deep diving may induce immediate neurological changes (2). These extreme conditions (high pressure, limited examination time, restricted space, hydrogen-oxygen mixture, communication difficulties etc.) require adapted technology and associated fast experimental procedure. We were able to solve these problems by developing a new system of 3-D ocular movements on line analysis by means of a video camera. This analyser uses image processing and forms recognition software which allows non-invasive video frequency calculation of eye movements including torsional component. As this system is immediately ready for use, we were able to realize the subsequent examinations in a maximum time of 8 min for each diver: oculomotor tests including saccadic, slow and optokinetic traditional automatic measurements; vestibular tests regarding spontaneous and positional nystagmus, and reactional nystagmus to the pendular test. For pendular induced nystagmus we used appropriate head positions to stimulate separately the lateral and the posterior semicircular canal, and we measured the gain by operating successively in visible light and complete darkness. Recordings were done during a simulated onshore dive to an ambient pressure corresponding to a depth of 350 m. The above examinations were completed on the first and last days by caloric tests with the same video system analyser. The results of the investigations demonstrated perfect tolerance of the oculomotor and vestibular systems of these 4 divers thus fulfilling the preventive conditions defined by Comex Co. We were able to overcome the limitations due to low cost PC computer operation and cameras (necessity of adaptation to pressure, focus difficulties and direct light exposure eye reflexions). We still have on line accurate measurements even on the torsional component of the eye movement. Due to this technological efficiency we also present some mathematical aspects of the software.

Adult↗
PubMed1995

Videonystagmoscopy: its use in the clinical vestibular laboratory.

Vestibular function of a population including labyrinthine-defective patients and a control group of age-matched normal healthy volunteers was evaluated using videonystagmoscopy. This device is made of one or two CCD infra-red cameras mounted on diving glasses and allows observation of ocular movements on a video monitor and/or recording on a videotape. Eye movements are observed after rotations in a Bárány chair and during passive head tilts. With this simple and non-invasive test, a screening of vestibular function at bedside or during ENT clinical investigations can be performed. A further study with videonystagmography to quantify these results being prepared.

Humans↗
PubMed1994

[Research of Lyme's disease in facial paralysis. A French multicenter study].

OBJECTIVES: Apparent a frigore facial palsy could possibly mask manifestations of unrecognized Lyme's disease. Since commonly used corticosteroid treatment could be deleterious if Borrelia burgdorferi infection was indeed the cause, we conducted a prospective study to search for possible infections in cases of recently diagnosed a frigore facial palsy. METHODS: For 3 years, 1990-1992, 49 French centres diagnosed a facial palsy in 346 patients (310 adults, 36 children under 15 years of age; mean age 38; range 16 months to 83 years). The patients were divided into three groups: a) facial palsy alone, b) zoster origin recognized due to outer ear eruption and c) cases with meningoradiculitis or joint signs or cases with facial diplegia. A questionnaire was used to evaluate exposure to risk of tick bits. A control group was established with 246 serum samples from subjects matched with the patients for age, geographical origin and exposure to risk of tick bits. Laboratory tests (indirect immunofluorescence and Western blot) were performed to search for anti-Borrelia burgdorferi antibodies in serum samples, and cerebral spinal fluid when possible, collected at presentation, on day 30 and on day 90. RESULTS: Sixty percent of the patients were urban dwellers, 15% lived in rural and 25% in semi-rural areas. There were 294 patients with facial palsy alone and their serum results were compared with those of the matched controls. There was no significant difference in the positivity for Borrelia burgdorferi antibodies between these two groups. CONCLUSION: These findings indicate that, unless there are clinical signs suggestive of borreliosis, it would not be necessary to test for Lyme's disease in patients with apparent a frigore facial palsy.

Adolescent↗
PubMed1994

[Instrumental study of vertigo: when and how?].

Any case of vertigo and equilibrium disorder for which an origin is not rapidly determined requires exploration for diagnosis. This exploration comprises two parts: first, that of peripheral components, including a standard audiometric examination, completed by study of the evoked auditory potentials. This is followed by vestibular examination comprising at least caloric tests of both ears, usually associated with rotation tests; second, exploration of the central pathways, by electro-oculography, study of pursuit and saccadic movements. The techniques of posturography, especially dynamic posturography by the equi-test, allow determination of the role of the vestibular apparatus in equilibrium and to define the respective roles of the labyrinth, vision and sensitivity in equilibrium. The technique is rapidly developing and will no doubt include the study of coordination of head and eye movements, study of stabilisation of vision and the head, and in particular study of otolithic function.

Audiometry↗
PubMed1992

[Surgical landmarks of the temporo-frontal branch of the facial nerve].

The temporal branches of the facial nerve, and in particular the rami for the frontalis muscle, have been the subject of many studies with the main objective of avoiding injury. The usual reference points, sometimes difficult to localise, anatomical variations in their branching and anastomoses are the main points of our investigation. This anatomical dissection study of 30 cadavres, with easy reference points available both superficially and in the depths allow a simple, non complicated localisation of the frontal branch and its anastomosis in a precise way on the mandibular condyle, the zygomatic arch and the temporal region. The distances described a, b, c, are useful in common surgical practice: temporo-mandibular joint surgery, facial lifting, temporal and temporo-parietal fascia flaps, and contralateral neurotomy for frontal symmetrization among others.

Dissection↗
PubMed1992

[Vestibular studies: current status, prospects].

Equilibrium is based on gaze stabilization. Clinical examinations currently test, individually the three components involved in equilibrium: vestibular, visual and proprioception. New investigations are being developed to test equilibrium dynamic conditions. After briefly reviewing vestibular physiology, under the authors discuss the various tests of vestibular function and equilibrium.

Eye Movements↗
PubMed1991

[Diagnostic strategy of acoustic neuroma. Evaluation of efficacy of auditory evoked potentials. Apropos of a series of 50 neuroma cases].

The authors carry out a retrospective study of the diagnostic procedures used in a series of 50 acoustic neuromas. AEP were performed for thirty-four neuromas at some stage of their history. The findings were perfectly normal for eight of them, which represents a sensitivity level of 76%. Various elements likely to account for this are put forward, then the role of AEP and MRI in the diagnostic strategy for neuroma is discussed in the light of this study. Finally, the authors emphasize the necessity to regularly evaluate the diagnostic methods in order to guarantee their quality and reliability.

Evoked Potentials, Auditory↗
PubMed1991

[Evaluation of the prognosis of facial paralysis after surgery of acoustic neurinoma by an early Hilger's test].

Surgery for acoustic neuroma is highly risky for the facial nerve. This is why we have tried to assess immediate postoperative facial impairment by performing Hilger's test within the first few hours. Further evolution of the facial function showed the predictive value of Hilger's test as regards facial recovery. Indeed, a difference greater than 2 mA as compared with the opposite side indicates a lack of facial recovery at the 3rd postoperative month. In addition, facial muscle testing performed within the first postoperative 72 hours makes the prognosis of facial function recovery possible. Lack of facial recovery at the 3rd postoperative month was observed for neuromas with a diameter exceeding 2 cm. Preoperative assessment of the risk of facial sequellae is fundamental and essentially depends on the size of the tumor and on the surgical approach. Intraoperative facial monitoring allows better ensuring the preservation of the VIIth cranial nerve and consequently improves postoperative function.

Electric Stimulation↗
PubMed1991

[Bone augmentation in implant surgery].

The authors experience on twelve patients in the field of bone grafting prior to implant surgery is presented. The technique employed depends largely on the anatomical location of bone insufficiency, such as: 1) Where there is not enough bone beneath sinus locations, grafting with cancellous iliac bone blended with coral particles is suggested. 2) Where the jaw is not sufficiently thick, such as in the incisor-cuspid regions, the authors employ cancellous and/or cortical bone grafts. 3) Horizontal osteotomy and interposition of cortical-cancellous bone graft is proposed where there is a lack of bone height in the incisor-cuspid regions. The results of the various techniques are analysed from a clinical, radiographic and histologic perspective. Twelve patients have been treated with 2 years follow-up.

Adult↗
PubMed1990

[Vestibular compensation. Review of the literature and clinical applications].

Vestibular compensation is an excellent model for the study of plasticity of the adult central nervous system. Therefore it has been the subject of several studies in humans and animals, which will be briefly summed up by the authors. Lesions of the labyrinth or vestibular neurectomy are immediately followed of postural and oculomotor disorders, as well as by dynamic deficits of the various vestibular reflexes (vestibulo-ocular and vestibulonucal reflexes). While the former problems always recede in all species, the restoration of the dynamic properties of vestibular reflexes largely depends upon the species considered, in particular for the vestibulo-ocular reflex. However, this function seems to recover the gain and phase it had prior to the lesion in both humans and monkeys. What is the neuronal substrate of these various deficits? Electrophysiological studies have demonstrated at the acute stage a symmetrical activity between the two vestibular nuclei: on the side of the lesion, the nucleus becomes inactive, while the resting discharge of the contralateral vestibular neurons is increased. Following compensation, symmetric activity is restored between both nuclei due to the regeneration of a new basic discharge in the deafferented neurons. The matter of vestibular compensation can therefore be formulated as follows: which mechanisms enable a central neuron inactivated du to the suppression of most of its excitatory afferences to recover a normal spontaneous activity? Several hypotheses, either pre- or postsynaptic, are currently put forward. Presynaptic hypotheses consider the role of the various afferences of the vestibular nuclei, ie. visual, proprioceptive, commissural, cerebellar and other afferences. In fact, the vestibular nuclei are not merely relays between the labyrinthine receptors and the nuclei of the oculomotor nerves, but actually form real sensorimotor integration centers. Besides the afferences from the vestibular nerve, they receive several other sorts of information, including visual and spinal proprioceptive inputs. An increase in the activity of these afferences, a sprouting of their axon collaterals, may favor the return to a normal basic discharge of the central vestibular neurons. The postsynaptic hypotheses involve either a change in the intrinsic membrane properties of the central vestibular neurons following the lesion, or an increase in the number of receptors located on their surface. More specifically, denervation supersensitivity of the glutamatergic receptors has been put forward as the possible origin of vestibular compensation.

Afferent Pathways↗
PubMed1989

[Benign paroxysmal positional vertigo and provocative maneuvers].

Main features of the benign paroxysmal positional vertigo (B.P.P.V.) are: latency before the onset of vertigo, nystagmus of the rotatory type beating toward the lower ear, nystagmus tires out, nystagmus gets inverted when the head is brought back to orthostatism, nystagmus is reproducible as many times as the position is taken. B.P.P.V. is due to a deposit of heavy material on the cupula of the posterior semi circular canal. In this unusual condition, the cupula moves under the effect of gravity acceleration. The goal of the treatment is to free the cupula. The manoeuvre consists after determination of the position that elicits the vertigo to move the whole head and body together of the patient to a 180 degree opposite position in which the addition to the endolymph flow forces and weight forces of the material will unstick it from the cupula. The positive result of the manoeuvre is instantly proved by the arising of a rotatory nystagmus beating again toward the sick ear. In other words it is not the inversion of the primary nystagmus but a nystagmus beating the same direction. This is explained by the dynamic of the cupula: in the prime position the density modified cupula moves toward the canal. At the end of the manoeuvre when the velocity of the head is zero, the cupula has to support different forces. First the addition of the endolymph flow forces and the inertia of the heavy material makes the cupula move toward the ampulla. Secondly when the superficial tension forces are too high the heavy material unstick from the cupula and it goes back to its normal position. En this very moment the cupula moves toward the canal. The results are of more than 90% positive in one ore two sessions 4,2% of recurrence. The manoeuvre is unsuccessful in spontaneous nystagmus revealed by a position, in torsional nystagmus as in fistulas or in central position nystagmus.

Humans↗