Vestibulotoxicity: strategies for clinical diagnosis and rehabilitation.

OBJECTIVE: The purpose of this article is to discuss the most commonly prescribed vestibulotoxic medications and their impact on the vestibular system, to describe the clinical features of vestibular ototoxicity including symptoms reported by patients, and to describe assessment tools that may be used in a monitoring programme, including the functional impact of vestibular loss. Recently published data from a cohort of patients exposed to systemic aminoglycosides (AGS) are summarised, which highlight the importance of monitoring. The role and importance of vestibular rehabilitation in treating affected individuals is discussed. DESIGN: This is a descriptive article. STUDY SAMPLE: Recently published data from 71 patients with cystic fibrosis with AGS exposure are summarised. RESULTS: Recently published data from a cohort of patients exposed to systemic AGS reveal a high prevalence of vestibular system involvement. CONCLUSIONS: Evidence suggests that including assessment of vestibular function in a programme to monitor for ototoxic damage is essential. While suggestions about possible components of a monitoring programme are made, the need for further study in order to determine an ideal protocol for assessing vestibular system function during and following exposure to toxic agents is stressed.

[The application of supravascular laser irradiation of blood for the treatment of cochleovestibular disorders].

A total of 165 patients presenting with neurosensory impairement of hearing and Meniere's disease were treated by supravascular (extracorporeal) laser irradiation of blood. The study undertaken to evaluate the efficacy of this treatment confirmed its beneficial effect in patients with acute hearing disorders. It was equally effective as regards elimination of labyrinthine hydropsis in patients presenting with Meniere's disease. The method proved less efficacious for the management of long-standing hearing impairement and chronic loss of hearing, but it can be used to prevent the development of these conditions.

Effects of ErbB2 signaling on the response of vestibular schwannoma cells to gamma-irradiation.

OBJECTIVE: For vestibular schwannomas (VSs) that require treatment, options are limited to microsurgery or irradiation (IR). Development of alternative therapies that augment or replace microsurgery or IR would benefit patients not suitable for current therapies. This study explored the ability of ErbB2 inhibitors to modulate the effects of IR on VS cells. STUDY DESIGN: Prospective study using primary cultures derived from human VSs. METHODS: Primary cultures of VS cells were derived from acutely resected tumors. Cultures received single escalating doses (15-40 Gy) of gamma-irradiation from a Cs gamma-irradiation source. Cell proliferation was determined by BrdU uptake and apoptosis by terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL). Trastuzumab (Herceptin) and PD158780 were independently used to inhibit ErbB2 signaling while neuregulin-1beta (NRG-1) was used to activate ErbB2. RESULTS: IR induces VS cell cycle arrest and apoptosis in doses greater than 20 Gy, demonstrating that VS cells are relatively radioresistant. This radioresistance likely arises from their low proliferative capacity as a sublethal dose of IR (10 Gy) strongly induces deoxyribonucleic acid (DNA) damage evidenced by histone H2AX phosphorylation. Inhibition of ErbB2, which decreases VS cell proliferation, protects VS cells from radiation-induced apoptosis, while NRG-1, an ErbB2 ligand and VS cell mitogen, increases radiation-induced VS cell apoptosis. CONCLUSIONS: Compared with many neoplastic conditions, VS cells are relatively radioresistant. The radio-protective effect of ErbB2 inhibitors implies that the sensitivity of VS cells to IR depends on their proliferative capacity. These results hold important implications for current and future treatment strategies.

Surgical treatment of endolymphatic sac tumor with adjunctive stereotactic radiation therapy--case report.

A 44-year-old man presented with an endolymphatic sac tumor (ELST) associated with von Hippel-Lindau disease, which required four surgical procedures within 10 years. The earlier two surgeries resulted in only partial removal of the tumor because of vigorous intraoperative bleeding. Stereotactic radiation therapy was performed twice. The intraoperative bleeding was easy to control in the third operation, and ultimately the tumor was totally extirpated in the fourth operation. Histological examination of the tumor specimen harvested in the final surgery showed that the tumor cells had clearly decreased in number, and the interstitial tissue had become fibrous with organization of the tumor vessels, compared with the tumor specimen from the first surgery. Preoperative radiotherapy may be effective to reduce the devastating intraoperative bleeding of ELST.

Small-field fractionated radiotherapy with or without stereotactic boost for vestibular schwannoma.

PURPOSE: To assess the efficacy and toxicity of small-field fractionated radiotherapy with or without stereotactic boost (SB) for vestibular schwannomas. METHODS AND MATERIALS: Thirty-nine patients with vestibular schwannoma were treated with irradiation between March 1991 and February 1996. Extra-meatal tumor diameters were under 30 mm. Thirty-three patients received small-field fractionated radiotherapy followed by SB. Basic dose schedule was 44 Gy in 22 fractions over 5 1/2 weeks plus 4 Gy in one session. Six patients received small-field fractionated radiotherapy only (40-44 Gy in 20-22 fractions over 5-5 1/2 weeks or 36 Gy in 20 fractions over 5 weeks).dash;p > RESULTS: Follow-up ranged from 6 to 69 months (median, 24 months). Tumors decreased in size in 13 cases (33%), were unchanged in 25 (64%), and increased in one (3%). The actuarial 2-year tumor control rate was 97%. Fifteen patients had useful hearing (Gardner-Robertson class 1-2) and 25 patients had testable hearing (class 1-4) before irradiation. The 2-year actuarial rates of useful hearing preservation (free of deterioration from class 1-2 to class 3-5) were 78%. The 2-year actuarial rates of any testable hearing preservation (free of deterioration from class 1-4 to class 5) were 96%. No permanent facial and trigeminal neuropathy developed after irradiation. The 2-year actuarial incidences of facial and trigeminal neuropathies were 8% and 16%, respectively. CONCLUSIONS: Small-field fractionated radiotherapy with or without SB provides excellent short-term local control and a relatively low incidence of complications for vestibular schwannoma, although further follow-up is necessary to evaluate the long-term results.