Research article summary (published 29 Sep 2009):

Predictors of hearing preservation after stereotactic radiosurgery for acoustic neuroma.

Full Abstract

OBJECT: Many patients with acoustic neuromas (ANs) have hearing function at diagnosis and desire to maintain it. To date, radiosurgical techniques have been focused on conformal irradiation of the tumor mass, with less attention to inner ear structures for which there was scant radiobiological information. The authors of this study evaluated tumor control and hearing preservation as they relate to tumor volume, imaging characteristics, and nerve and cochlear radiation dose following stereotactic radiosurgery (SRS) using the Gamma Knife. METHODS: Seventy-seven patients with ANs had serviceable hearing (Gardner-Robertson [GR] Class I or II) and underwent SRS between 2004 and 2007. This interval reflected more recent measurements of inner ear dosimetry during the authors' 21-year experience. The median patient age was 52 years (range 22-82 years). No patient had undergone any prior treatment for the ANs. The median tumor volume was 0.75 cm(3) (range 0.07-7.7 cm(3)), and the median radiation dose to the tumor margin was 12.5 Gy (range 12-13 Gy). At diagnosis, a greater distance from the lateral tumor to the end of the internal auditory canal correlated with better hearing function. RESULTS: At a median of 20 months after SRS, no patient required any other additional treatment. Serviceable hearing was preserved in 71% of all patients and in 89% (46 patients) of those with GR Class I hearing. Significant prognostic factors for maintaining the same GR class included (all pre-SRS) GR Class I hearing, a speech discrimination score (SDS) >or= 80%, a pure tone average (PTA) < 20 dB, and a patient age < 60 years. Significant prognostic factors for serviceable hearing preservation were (all pre-SRS) GR Class I hearing, an SDS >or= 80%, a PTA < 20 dB, a patient age < 60 years, an intracanalicular tumor location, and a tumor volume < 0.75 cm(3). Patients who received a radiation dose of < 4.2 Gy to the central cochlea had significantly better hearing preservation of the same GR class. Twelve of 12 patients < 60 years of age who had received a cochlear dose < 4.2 Gy retained serviceable hearing at 2 years post-SRS. CONCLUSIONS: As currently practiced, SRS with the Gamma Knife preserves serviceable hearing in the majority of patients. Tumor volume and anatomy relate to the hearing level before radiosurgery and influence technique. A low radiosurgical dose to the cochlea enhances hearing preservation.

Author information

Author/s: Kano, Hideyuki (H); Kondziolka, Douglas (D); Khan, Aftab (A); Flickinger, John C (JC); Lunsford, L Dade (LD);

Affiliation: Department of Neurological Surgery, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania 15213, USA.

Journal and publication information

Publication Type: Journal Article; Research Support, Non-U.S. Gov't

Journal: Journal of neurosurgery (J Neurosurg), published in United States. (Language: eng)

Reference: 2009-Oct; vol 111 (issue 4) : pp 863-73

Dates: Created 2009/10/02; Completed 2009/10/23;

PMID: 19284227, status: MEDLINE (last retrieval date: 10/23/2009, IMS Date: )

Sourced from the National Library of Medicine. Abstract text and other information may be subject to copyright.

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MeSH headings (categories)

This article was linked to the MESH Headings shown below.

Adult Age Factors Aged Aged, 80 and over Cochlea - physiology Female Follow-Up Studies Hearing Loss - prevention & control Humans Kaplan-Meiers Estimate

Kaplan-Meiers Estimate Magnetic Resonance Imaging Male Middle Aged Neuroma, Acoustic - pathology; physiopathology; surgery Predictive Value of Tests Radiation Dosage Radiosurgery - methods Retrospective Studies Treatment Outcome

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