Lorne S. Parnes

Corticosteroid Pharmacokinetics in the Inner Ear Fluids: An Animal Study Followed by Clinical Application

Objective: Autoimmune disease (e.g., Cogan syndrome) and other inflammatory inner ear diseases may ravage the labyrinth if not treated aggressively with antiinflammatory medication. Corticosteroids are the mainstay of treatment, yet, partly because of the existence of the blood—labyrinthine barrier, the ideal drug, dose, and route of administration are currently unknown. Study Design: In the present study, we established cochlear fluid pharmacokinetic profiles of hydro‐cortisone, methylprednisolone, and dexamethasone in the guinea pig following oral, intravenous, and topical (intratympanic) administration. High‐performance liquid chromatography was used to determine the drug concentrations, and comparisons were made with simultaneous pharmacokinetic profiles from blood and cerebrospinal fluid. Results: Our findings demonstrated a much higher penetration of all three drugs into the cochlear fluids following topical application as compared with systemic administration, with methylprednisolone showing the best profile. Discussion: The results suggested that intratympanic administration of corticosteroids might be more efficacious while avoiding high blood levels and therefore the deleterious side effects of systemic use. Clinical Application: Thirty‐seven patients with various inner ear disorders causing sensorineural hearing loss were subsequently treated using intratympanic corticosteroids, 20 with dexamethasone, and 17 with methlyprednisolone. Patients with immune‐mediated hearing losses showed the best results, with notable improvement also seen in several cases of a “sudden deafness.” No benefit was seen in patients with cochlear hydrops or those with sudden deterioration of a preexisting hearing loss. Three patients developed a transient otitis media related to the treatments, easily controlled with antibiotics. There were no cases of treatment‐induced hearing loss and no permanent tympanic membrane perforations. Conclusions: Overall, injection of intratympanic corticosteroids for the treatment of hearing loss in inner ear disorders appears to be both safe and highly effective for certain disorders. The concept of this technique is supported by animal experimental data. The findings from the present study warrant further clinical application and experimental investigation.

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.

Posterior semicircular canal occlusion for intractable benign paroxysmal positional vertigo.

Benign paroxysmal positional vertigo (BPPV) is most often a self-limited disorder arising from the posterior semicircular canal of the undermost ear in the Hallpike position. Some individuals with this disorder have severe and protracted symptoms requiring more than expectant therapy. We describe two patients with intractable BPPV and profound sensorineural hearing loss in the affected ear treated by transmastoid posterior semicircular canal occlusion. Postoperatively, both were relieved of their BPPV and demonstrated preserved lateral semicircular canal function as measured by electronystagmography. We feel this new procedure provides a simpler and possibly safer alternative to singular neurectomy and should be given future consideration in the treatment of intractable BPPV in a normal-hearing ear.

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.

Particulate Matter in the Posterior Semicircular Canal

The pathoetiology of benign paroxysmal positional vertigo (BPPV) is controversial. Particulate matter within the posterior semicircular canal has been identified intraoperatively in patients with BPPV but has also been reported in non‐BPPV patients at the time of translabyrinthine surgery (Parnes LS, McClure JA. Free‐floating endolymphatic particles: a new operative finding during posterior semicircular canal occlusion. Laryngoscope 1992;102:988‐92; Schuknecht HF, Ruby RRF. Cupulolithiasis. Adv Otorhinolaryngol 1973;20:434‐43; Kveton JF, Kashgarian M. Particulate matter within the membranous labyrinth: pathologic or normal? Am J Otol 1994;15:173‐6). The nature of the particulate matter remains unknown.

Intratympanic corticosteroids for sudden idiopathic sensorineural hearing loss.

Objective: To determine whether instillation of intratympanic steroids is effective in the treatment of sudden idiopathic sensorineural hearing loss. Methods: A retrospective chart review of all patients who underwent intratympanic steroid treatment (methylprednisolone and/or dexamethasone) between 1996 and 2002 at a tertiary care university otology clinic. Thirty-three patients were identified, of which 26 met inclusion criteria for having an idiopathic hearing loss. Pretreatment and posttreatment pure-tone audiograms and speech discrimination scores were compared. Results: Overall, there was a 27.2 ± 5.7dB improvement in the pure-tone thresholds and a 25.4 ± 6.2% improvement in speech discrimination scores. Those treated within 10 days of onset had a statistically significant better outcome than those treated after 10 days. No adverse reactions or complications were reported. Conclusion: Instillation of intratympanic steroids represents a safe and potentially effective treatment of sudden idiopathic sensorineural hearing loss.

Middle cranial fossa acoustic neuroma excision: results and complications.

The middle cranial fossa surgical approach has been used for the removal of acoustic neuromas in 43 patients at the University of Iowa since 1974. Hearing was maintained in 50% of patients with tumors 1.5 cm or less outside the porus acusticus. Postoperative hearing, facial nerve function, and complications were similar to reports using the suboccipital or retrosigmoid approach to preserve hearing for this size tumor. The character of the tumor appears to dictate the postoperative outcome rather than the surgical approach.

Human Experience with Canal Plugging

Abstract: Canal occlusion/plugging is a very effective technique with a low risk to hearing. The series of posterior semicircular canal occlusions described in this review now becomes the largest in the literature to date. It continues to support this procedure as the treatment of choice for intractable benign paroxysmal positional vertigo (BPPV). All 44 operated ears were relieved of BPPV, with one patient having an atypical late recurrence. Of the 40 ears with normal preoperative hearing, one had a delayed (3‐month) sudden and permanent profound loss, while one other had a mild (20 dB) loss. Six patients had protracted courses of imbalance and motion sensitivity.

Transmastoid semicircular canal occlusion: A safe and highly effective treatment for benign paroxysmal positional vertigo and superior canal dehiscence

Transmastoid occlusion of the superior semicircular canal in superior semicircular canal dehiscence (SSCD) syndrome and the posterior semicircular canal in intractable benign paroxysmal positional vertigo (BPPV) will produce resolution of preoperative symptoms.

Intratympanic Steroids for Inner Ear Disorders: A Review

Background/Aim: The use of intratympanic steroids (ITS) has proliferated over the past 10–15 years to include treatments for inner ear disorders, like Ménière’s Disease (MD) and sudden sensorineural hearing loss (SSNHL). The aim of this study was to review the clinical trials of ITS for inner ear disorders. Methods: PubMed and Ovid Medline databases were searched from 1966 to present for clinical trials on ITS in the treatment of MD and SSNHL. Studies were evaluated based on comparability and internal and external validity. Results: Thirty-eight studies were identified in total, 13 studies on MD and 25 studies on SSNHL. Most studies lacked placebo controls. Only 3 studies were double-blinded randomized prospective trials. Overall, there were heterogeneous steroid doses, treatment protocols, previous treatments, and definitions of disease and improvement. Conclusion: There are no good studies on ITS that meet the criteria of comparability, internal validity, and external validity. It is difficult to compare studies due to the heterogeneous nature of the data. More rigorously designed studies are required to determine the efficacy of this treatment, the optimal steroid to use, and the best treatment regimen.