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Biomedical subjects

L S Parnes

Publications and source records attributed to L S Parnes.

At least 37 records · Page 2Linked to original sources
PubMed1995

Acoustic neuroma management: a six-year review.

The purpose of this investigation is to review the outcome of 83 consecutive acoustic neuroma patients, managed solely or in part by the Department of Otolaryngology at University Hospital, London, Ontario, over a 6-year period (1987 to 1993). The majority of patients underwent operative intervention, utilizing the middle cranial fossa, suboccipital, or most commonly, the translabyrinthine approach depending on the tumour size and level of residual hearing. Demographic, preoperative, intraoperative, and postoperative data are analyzed including complications of surgery. As well, we report on our experience with the use of fibrin glue in the dural closure following translabyrinthine resections and the resultant impact on the postoperative CSF leak rate. Overall, our results and complications are comparable to other large acoustic neuroma series in the literature. In addition, we feel that further study is merited in the use of fibrin glue in dural repair and its relationship to postoperative cerebrospinal fluid fistula.

Adolescent↗
PubMed1995

Intratympanic gentamicin therapy for Menière's disease: preliminary comparison of two regimens.

Selective chemical ablation of the vestibular endorgan using intratympanic gentamicin is an effective and safe treatment for incapacitating vertigo in patients with unilateral Menière's disease. A major risk of the treatment is sensorineural hearing loss. In this retrospective study, two different regimens of intratympanic gentamicin therapy are compared. In one group, multiple daily doses were administered in hospital over 4 consecutive days. The other group received single treatments at weekly intervals on an outpatient basis, following pretreatment audiometric and clinical assessment. We adopted the weekly protocol to theoretically reduce the incidence of treatment-related hearing loss by a more controlled titration of dosing. Preliminary results indicate that the weekly interval treatment offers equivalent efficacy with considerably less risk to hearing.

Audiometry, Pure-Tone↗
PubMed1994

A cure for benign positional vertigo.

Benign positional vertigo is a common clinical entity encountered in any dizzy clinic. It is easily diagnosed on the basis of historical information and a positive Dix-Hallpike position test. The available evidence suggests that this condition is due to involvement of the posterior semicircular canal. The pathophysiology of this condition can be explained theoretically on the basis of free-floating particles within the endolymph of the posterior semicircular canal that move under the influence of gravity with certain provocative positional changes. Based on this theoretical model, a variety of particle-repositioning manoeuvres have been developed that attempt to relocate the loose particles from the posterior semicircular canal to the utricular sac. If the particles are kept in the utricular sac for a period of 48 h by maintaining the patient in an upright position, the clinical symptoms are relieved in a high proportion of patients. If the manoeuvre is unsuccessful on a first attempt, or if the benign positional vertigo recurs at a later date, the condition can usually be relieved by a second manoeuvre. Bilateral benign positional vertigo can be treated by performing a manoeuvre on one side followed by a manoeuvre on the other side at a later date. On occasion, posterior canal benign positional vertigo is converted to horizontal canal benign positional vertigo, but this subsides readily within the 48-h post-manoeuvre period.

Humans↗
PubMed1993

Aerodynamic assessment of the speech of adults undergoing multichannel cochlear implantation.

This investigation was designed to evaluate the aerodynamic characteristics of the speech of adult multichannel cochlear implant (Nucleus, 21-channel) recipients. Five adults with an acquired profound sensorineural hearing loss were tested before implantation, immediately following implantation, and 3, 6, 9, and 12 months after implantation. A commercially available computerized pressure-flow instrumentation system was employed to assess the respiratory, laryngeal, velopharyngeal, and oral articulatory subsystems of speech of the implantees. The results of the investigation indicated 1) a slight increase in airflow rate values for sustained vowel /a/phonation after implantation, 2) a slight increase in duration of sustained vowel phonation from the preimplant period to the last postimplant period, 3) an increase in laryngeal airway resistance after implantation that resulted from a larger increase in estimated transglottal pressure than in transglottal airflow, 4) maintenance of normal velopharyngeal closure in oral-nasal contrastive contexts, and 5) slight increases in oral orifice area for fricative syllable utterances following implantation. Individual strategies for coordinated control of the speech mechanism appear to be potent variables to consider when assessing speech production.

Adult↗
PubMed1993

Particle repositioning maneuver for benign paroxysmal positional vertigo.

Benign paroxysmal positional vertigo is a common, most often self-limited, vestibular end organ disorder that in some cases may be quite disabling. Recent evidence suggests that some, if not most, cases result from free-floating posterior semicircular canal endolymph particles. We postulate that the particle repositioning maneuver displaces these particles from the posterior canal through the common crus into the utricle, where they no longer induce pathologic responses. Our report focuses on 38 consecutive patients treated with this simple bedside technique during a 10-month period. On follow-up, 26 patients (68.4%) were free of disease, 4 (10.5%) were significantly improved, 4(10.5%) remained unchanged, and 4(10.5%) were lost to follow-up. Of the 4 patients who remained unchanged, 2 underwent successful posterior semicircular canal occlusions. The direction of the nystagmus during the second stage of the maneuver appears important in predicting the efficacy, with reversal of nystagmus denoting a poor response. These findings provide additional insight into the pathophysiology of this disorder.

Adult↗
PubMed1993

Irritative spontaneous nystagmus following intratympanic gentamicin for Menière's disease.

Intratympanic aminoglycosides were first used to treat unilateral intractable Meniere's disease over 30 years ago. Gentamicin, the current drug of choice, provides excellent vertigo control with a low incidence of hearing loss. Its salutory effect results from direct damage to both the sensory neuroepithelium and the dark cells of the labyrinth. This latter effect may reverse the degree of endolymphatic hydrops. Twelve patients with unilateral Meniere's disease were treated and prospectively studied. Although further follow-up is necessary, 10 patients have complete vertigo control, while 2 remain significantly improved. Three patients developed a spontaneous "irritative" nystagmus during the early post-treatment period. This new unique finding may represent a recovery phenomenon resulting from a temporary reversible ototoxic effect in the treatment ear. Despite our patients having a somewhat higher incidence of hearing loss compared to the reported rate, the results of this treatment are encouraging.

Adult↗
PubMed1993

Cochlear implants and otitis media: considerations in two cleft palate patients.

Cochlear implantation is a safe and effective means of rehabilitating profound sensory deafness. The implications of coincident chronic middle ear disease upon the operative procedure and auditory results have received little attention in the literature. We describe two patients, each with congenital cleft lip and palate and secondary chronic otitis media with effusion, who received multichannel cochlear implants following bacterial meningitis. One patient (a three-year-old girl) was implanted in the standard fashion while the other (a 38-year-old-man) underwent middle ear and mastoid obliteration. Our findings suggest that chronic otitis media should not be a deterrent to cochlear implantation.

Adult↗
PubMed1993

Medial meatal fibrosis: the University of Western Ontario experience.

Medial meatal fibrosis is an uncommon but surgically treatable cause of conductive hearing loss. A review of 10 years experience with this entity at The University of Western Ontario revealed a total of 15 cases involving nine patients. Each of them was treated by one of four otologists. This disease may arise from either recurring or chronic infection or from chronic dermatitis, and it frequently presents with bilateral involvement. It may occur at virtually any age, and to our knowledge, this series includes the first cases of this disease to be described in children. The medical and surgical management of this condition is described in detail and the results are summarized.

Child, Preschool↗
PubMed1992

Chronic perilymph fistula in the guinea pig with implications in the human.

To improve understanding of the pathophysiology of perilymph fistulas, a predictable animal model of a chronic fistula was developed. Our findings suggest that guinea pig fistulas do not remain patent for prolonged periods. By extrapolating these findings to humans, we postulate that the symptoms and signs of perilymph fistula are possibly due not to one prolonged constant fistula, but rather a series of "blowouts" from an inherent congenital or posttraumatic weak spot in either the round or oval window. We feel that a diagnosis of perilymph fistula must be considered in any patient presenting with a Meniere's-like symptom set concomitant with a congenital inner ear deformity or a history of inner ear trauma.

Acoustic Stimulation↗
PubMed1992

Free-floating endolymph particles: a new operative finding during posterior semicircular canal occlusion.

Most clinicians accept cupulolithiasis as the pathophysiological mechanism underlying benign paroxysmal positional vertigo (BPPV.) According to this theory, a cupular deposit induces a gravitational effect on the posterior canal crista. Posterior semicircular canal occlusion is a new operative procedure for treating incapacitating BPPV. It is postulated that canal occlusion abolishes endolymph movement within the canal, effectively fixing the cupula and rendering it unresponsive to both angular and linear acceleration (gravity). During two recent canal occlusions, abundant "free-floating particles" were identified within the posterior canal endolymph. When changing the position of the canal in the earth vertical plane, these free-floating particles would move under the influence of gravity. The hydrodynamic drag of the particles would induce endolymph movement with cupular displacement leading to the typical response. This finding supports an alternate explanation to cupulolithiasis as the pathophysiological mechanism underlying BPPV.

Aged↗
PubMed1992

Real-life performance considerations of four pediatric multi-channel cochlear implant recipients.

Most pediatric cochlear implant programs support a team approach for post-implant services. However, individuals directly involved in the care of these children often have differing opinions on the child's performance. We describe our experience with four children, aged 3 to 10 at the time of implantation, who have used the Nucleus 22-channel cochlear implant device for at least nine months. A questionnaire, focusing on the individual's observations of the child's speech and hearing performance in their particular setting (i.e., clinic, home, school), was completed by the child's parent(s), therapist and classroom teacher. Overall, performance in structured settings (i.e., testing and therapy sessions) was not in agreement with performance in unstructured settings (i.e., classroom and home environments). The results suggest that different individuals interacting with the same child in different environments often have differing perceptions of the child's performance. Based on the information obtained on the four cases, we discuss factors to consider in assessing the real-life performance of pediatric cochlear implant recipients.

Child↗
PubMed1992

Tuberculous mastoiditis.

The prevalence of Mycobacterium tuberculosis is increasing due in part to the rising incidence of immunocompromised hosts. Although Mycobacterium tuberculosis is a well-documented pathogen in otitis media and mastoiditis, its extremely low incidence often precludes consideration when treating these infections. This is especially true when concomitant pulmonary symptoms are absent. We describe two patients who initially presented after prolonged unsuccessful medical and surgical therapy for chronic mastoiditis. In both, the diagnosis of Mycobacterium tuberculosis mastoiditis was made after the onset of complete facial paralysis. On subsequent investigations, one had an asymptomatic pulmonary focus while the other was felt to have primary mastoid disease. Both patients had normal immunological profiles. This report underscores the importance of considering a tuberculous infection in all cases of otitis media and mastoiditis which do not initially respond to conventional antibacterial therapy. This holds true in both immunocompromised and immunocompetent hosts. Early diagnosis with prompt institution of antituberculous therapy is essential to avoid facial nerve paralysis and other grave complications.

Adult↗
PubMed1991

Effectiveness of an intensive speech perception training program for adult cochlear implant recipients.

A staggered multiple baseline single-subject experimental design was used to assess the effectiveness of a postimplant intensive aural rehabilitation program. Four adults with an acquired profound hearing loss were provided with a Nucleus 22-channel cochlear implant. The subjects completed a speech perception test protocol once before their cochlear implant operation and at 3-month intervals for a period of 12 months postimplantation. Each subject participated in a 12-week postimplant intensive aural rehabilitation program. A comparison of the prerehabilitation and postrehabilitation results failed to reveal any systematic improvements in performance on the speech perception tests that could be attributed unequivocally to the aural rehabilitation program.

Adult↗
PubMed1991

Posterior semicircular canal occlusion in the normal hearing ear.

This report outlines our experience with posterior semicircular canal occlusion, a new operative procedure for intractable benign paroxysmal positional vertigo (BPPV). We postulate that the resulting solid canal "plug" prevents endolymph movement within the posterior canal, which effectively fixes the cupula. This selectively abolishes the receptivity of the posterior canal to both angular acceleration and gravity without influencing the other inner ear receptors. We previously reported the success of this procedure in two patients with BPPV and a co-existing profound sensorineural hearing loss in the affected ear. Since that report, a slightly modified technique has been used to occlude six more posterior canals--five in normal hearing ears. While our follow-up times range from only 3 to 18 months, all eight patients continue to be relieved of their BPPV. Temporary mixed hearing losses occurred in three of the five ears with normal preoperative hearing. Hearing in all five patients ultimately returned to the preoperative state. We believe this procedure is a simpler and safer alternative to singular neurectomy for the treatment of intractable benign paroxysmal positional vertigo.

Aged↗
PubMed1991

Magnetic resonance imaging of facial nerve neuromas.

Facial nerve neuromas are uncommon tumors often confused with other tumors of the temporal bone and cerebellopontine angle. Radiologically, it may be impossible to differentiate an intracanalicular facial nerve neuroma from an acoustic neuroma. We present three case reports of facial nerve neuromas arising within the internal auditory canal to show the important magnetic resonance imaging features of these tumors. One tumor extended into the cerebellopontine angle, middle cranial fossa, and middle ear. Another filled the internal auditory canal and extended through the cerebellopontine angle to the brain stem. The third occurred in a patient who had neurofibromatosis as well as numerous other intracranial tumors. We feel that gadolinium-enhanced magnetic resonance imaging provides the most useful information in the preoperative assessment of this disorder.

Adolescent↗