Surgical Treatment of Peripheral Vertigo and Vertiginous Diseases

Predictors of central vestibular compensation after surgery for vestibular schwannomas

Surgical removal of vestibular schwannoma causes acute vestibular symptoms, including postoperative vertigo which is the most negative factor affecting quality of life in patients after vestibular schwannoma surgery. The main aim of this study is to determine whether the results from routine electronystagmography with pathological visually-provoked responses can predict poor postoperative compensation. We also investigate whether postoperative central compensation is related to objective parameters such age, tumour size, length of surgery and persistent nystagmus. According to the results from preoperative electronystagmography, patients were divided into three groups: peripheral, central and combined vestibular syndrome. Signs of central compensation were evaluated by the presence of postoperative nystagmus, vertigo, deviation of subjective visual vertical and head impulse test. There were no statistically significant differences between groups in observed signs of compensation. These results suggest that pathological central oculomotor parameters are not a negative predictive factor for central vestibular compensation.

Sensitivity of the cochlear nerve to acoustic and electrical stimulation months after a vestibular labyrinthectomy in guinea pigs

Single-sided deafness patients are now being considered candidates to receive a cochlear implant. With this, many people who have undergone a unilateral vestibular labyrinthectomy for the treatment of chronic vertigo are now being considered for cochlear implantation. There is still some concern regarding the potential efficacy of cochlear implants in these patients, where factors such as cochlear fibrosis or nerve degeneration following unilateral vestibular labyrinthectomy may preclude their use. Here, we have performed a unilateral vestibular labyrinthectomy in normally hearing guinea pigs, and allowed them to recover for either 6 weeks, or 10 months, before assessing morphological and functional changes related to cochlear implantation. Light sheet fluorescence microscopy was used to assess gross morphology throughout the entire ear. Whole nerve responses to acoustic, vibrational, or electrical stimuli were used as functional measures. Mild cellular infiltration was observed at 6 weeks, and to a lesser extent at 10 months after labyrinthectomy. Following labyrinthectomy, cochlear sensitivity to high-frequency acoustic tone-bursts was reduced by 16 ± 4 dB, vestibular sensitivity was almost entirely abolished, and electrical sensitivity was only mildly reduced. These results support recent clinical findings that patients who have received a vestibular labyrinthectomy may still benefit from a cochlear implant.

Expression and clinical significance of Ki-67, oestrogen and progesterone receptors in acoustic neuroma

Objective:

The objective was to assess the presence of Ki-67, and oestrogen and progesterone hormone receptors as well as their clinical correlates in acoustic neuroma.

Methods:

Medical records of 59 patients who were operated on for acoustic neuroma between 1995 and 2003 were evaluated retrospectively. Formaldehyde-fixed paraffin-embedded archival acoustic neuroma specimens of the patients were used for immunohistochemical assessments of oestrogen and progesterone hormone receptors, and Ki-67 proliferative marker.

Results:

Tumour sizes were small (<19 mm), medium (20–39 mm) and large (>40 mm) in 21, 35 and 3 patients, respectively. On immunohistochemistry, all samples were (+) for progesterone receptor and (–) for oestrogen receptor staining. Ki-67 staining was encountered in 34 of 59 (57.6 per cent) patients, and Ki-67 values ranged from 0 per cent to 10.9 per cent (mean 1.36 per cent). There was no correlation between Ki-67, gender, tumour size and symptoms of the patients (p > 0.05).

Conclusion:

Oestrogen is not an important hormone in acoustic neuroma due to the absence of oestrogen receptor expression in the tissue samples. Since the progesterone receptor is expressed in all acoustic neuroma samples, further studies are necessary to find out about the inhibitory effect of antiprogesterone treatment on acoustic neuroma growth, which may be important particularly in elderly people or high-risk patients. Although Ki-67 is expressed in the majority of acoustic neuromas, it is not an important marker in clinical practice due to a lack of any correlation with the clinical parameters.

Surgical exposure in retrosigmoid approach: do we need cerebellar retractors?

BACKGROUND

The aim of this study was to present our technique of posterior fossa surgery and to evaluate whether cerebellar retractors are needed.

METHODS

Since March 1989, more than 500 surgeries were performed through retrosigmoid approach, and our surgical technique was described. The data were evaluated whether or not cerebellar retractors were used in the operations.

RESULTS

The surgeries were vestibular neurectomy, acoustic neuroma removal, and neurovascular decompression in 351, 135, and 14 patients, respectively. Cerebellar retractors have not been used in vestibular neurectomies and in most acoustic neuroma surgeries. The cerebellar retractors have been used in all of the neurovascular decompression surgeries where better exposure of the root entry zones of the cranial nerves is needed, and intracranial endoscopy is applied for further exposure and decompression of the vascular loop.

CONCLUSION

There is no need for cerebellar retractors when adequate conditions such as patient positioning, adequate anesthesia techniques, and surgical manipulations are applied in posterior fossa approach except for neurovascular decompression and some of the acoustic neuroma surgeries.

Combined retrosigmoid retrolabyrinthine vestibular nerve section: results of our experience over 10 years

OBJECTIVE

We aimed to evaluate the results of our experience in vestibular nerve sectioning (VN), which was performed using combined retrosigmoid-retrolabyrinthine approach.

STUDY DESIGN

Medical records of 280 patients who were consecutively operated on for incapacitating peripheral vertigo were retrospectively evaluated, and 210 patients who completed 2 years follow-up and had adequate follow-up data were found to be suitable for inclusion in the study.

METHODS

Hearing results, vertigo control rates, and complications of the retrosigmoid-retrolabyrinthine VN were evaluated.

RESULTS

The patients were suffering from vertigo for a mean period of 32.2 months. Bilateral Meniere's disease occurred in 5.7% of the patients in the follow-up period. A complete or substantial vertigo control could be achieved in 94.4% of the patients (191 [90.1%] in Class A and 9 [4.3%] in Class B). Preoperative speech reception threshold, pure-tone average, and speech discrimination score of the patients were 56.5 dB, 47.4 dB, and 73.6%, respectively. Postoperative corresponding values were 62.2 dB, 43.4 dB, and 68.5%, respectively (p > 0.05). The complication rate was low (2.5%). Most common complication was abdominal hematoma, which was seen in 4.5%.

CONCLUSION

VN performed using retrosigmoid-retrolabyrinthine approach has low complication and high vertigo control and hearing preservation rates. It can be applied as an initial surgery or reserved as the last step when the other surgical treatments have failed to control vertigo.