Vestibular apparatus disorders after external radiation therapy for head and neck cancers

Unilateral cochlea sparing in locoregionally advanced head and neck cancer: a planning study

BACKGROUND

Cochlea sparing can reduce late ototoxicity in head and neck cancer patients treated with cisplatin-based radiochemotherapy. In this situation, a mean cochlear dose (MCD) constraint of 10 Gy has been suggested by others based on the dose-effect relationship of clinical data. We aimed to investigate whether this is feasible for primary and postoperative radiochemotherapy in locoregionally advanced tumors without compromising target coverage.

PATIENTS AND METHODS

Ten patients treated with definitive and ten patients treated with adjuvant intensity-modulated radiotherapy (IMRT) and concurrent chemotherapy were investigated. The cochleae and a planning risk volume (PRV) with a 3 mm margin were newly delineated, whereas target volumes and other organs at risk were not changed. The initial plan was recalculated with a constraint of 10 Gy (MCD) on the low-risk side. The quality of the resulting plan was evaluated using the difference in the equivalent uniform dose (EUD).

RESULTS

A unilateral MCD of below 10 Gy could be achieved in every patient. The mean MCD was 6.8 Gy in the adjuvant cohort and 7.6 Gy in the definitive cohort, while the non-spared side showed a mean MCD of 18.7 and 30.3 Gy, respectively. The mean PRV doses were 7.8 and 8.4 Gy for the spared side and 18.5 and 29.8 Gy for the non-spared side, respectively. The mean EUD values of the initial and recalculated plans were identical. Target volume was not compromised.

CONCLUSION

Unilateral cochlea sparing with an MCD of less than 10 Gy is feasible without compromising the target volume or dose coverage in locoregionally advanced head and neck cancer patients treated with IMRT. A prospective evaluation of the clinical benefit of this approach as well as further investigation of the dose-response relationship for future treatment modification appears promising.

Radiation dose constraints for organs at risk in neuro-oncology; the European Particle Therapy Network consensus

PURPOSE

For unbiased comparison of different radiation modalities and techniques, consensus on delineation of radiation sensitive organs at risk (OARs) and on their dose constraints is warranted. Following the publication of a digital, online atlas for OAR delineation in neuro-oncology by the same group, we assessed the brain OAR-dose constraints in a follow-up study.

METHODS

We performed a comprehensive search to identify the current papers on OAR dose constraints for normofractionated photon and particle therapy in PubMed, Ovid Medline, Cochrane Library, Embase and Web of Science. Moreover, the included articles' reference lists were cross-checked for potential studies that met the inclusion criteria. Consensus was reached among 20 radiation oncology experts in the field of neuro-oncology.

RESULTS

For the OARs published in the neuro-oncology literature, we summarized the available literature and recommended dose constraints associated with certain levels of normal tissue complication probability (NTCP) according to the recent ICRU recommendations. For those OARs with lacking or insufficient NTCP data, a proposal for effective and efficient data collection is given.

CONCLUSION

The use of the European Particle Therapy Network-consensus OAR dose constraints summarized in this article is recommended for the model-based approach comparing photon and proton beam irradiation as well as for prospective clinical trials including novel radiation techniques and/or modalities.

Geographic Variation in Use of Vestibular Testing among Medicare Beneficiaries

Objective

There is a lack of consensus regarding the indications for vestibular testing in the evaluation of dizziness and balance disorders. Geographic variation in health services utilization is associated with lack of consensus. To understand the variation in current practice, we investigated the patterns of use of vestibular testing and diagnosis codes for dizziness and balance disorders among individuals ≥65 years of age across different regions of the United States.

Study Design

Cross-sectional study.

Setting

Medicare administrative claims data.

Subjects and Methods

Using the Summarized Denominator file, a sample of the US population linked to the Surveillance, Epidemiology, and End Results (SEER)–Medicare files (years 2000-2010), we identified persons who were ≥65 years of age. We used multivariable analyses to determine the factors associated with vestibular testing and diagnoses.

Results

Of the 231,984 eligible Medicare beneficiaries, 27% were diagnosed with dizziness and balance disorders. Patterns of use of vestibular tests (eye movement recording for spontaneous nystagmus, caloric testing, and rotary chair testing) varied significantly by geographic region. Rotary chair test utilization varied most. We found significant geographic variation in vestibular testing and diagnoses after controlling for age, sex, race, Medicaid participation, and rurality.

Conclusions

There may be opportunities to improve the consistency and efficiency of care for dizziness and balance disorders. It will be important to define appropriate levels of vestibular diagnostic testing and which tests add sufficient value to justify the costs. Further work is needed to better characterize the causes and consequences of variation in vestibular test utilization.

Benign paroxysmal positional vertigo in irradiated nasopharyngeal carcinoma survivors

Purpose. It has been assumed that postirradiated nasopharyngeal carcinoma (NPC) patients are prone to benign paroxysmal positional vertigo (BPPV). The purpose of this study was to better understand this clinical entity. Materials and Methods. From September 2003 to June 2011, we conducted a retrospective study of 11 irradiated NPC patients with BPPV in our institute. During the same period, 11 irradiated NPC patients without BPPV were randomly selected and enrolled as the control group. All medical records of these patients were evaluated. Results. The risk of BPPV rises significantly when the patient undergoes radiotherapy (RT) twice and the threshold radiation dose is >120 Gy (P = 0.027). The occurrence of postirradiated BPPV was significantly related to incidences of otitis media and sensorineural hearing loss (SNHL) (P = 0.011 and 0.009, resp.). All the patients responded well to repositioning maneuvers. Conclusion. A second course of RT, postirradiated otitis media, or SNHL is associated with the potential risk of radiation-induced BPPV. Repositioning maneuvers were safe and effective for relief of this disease.

Comparison of otologic complications between intensity-modulated and two-dimensional radiotherapies in nasopharyngeal carcinoma patients

OBJECTIVE

To investigate the otologic complications in patients with nasopharyngeal carcinoma (NPC) who were treated by intensity-modulated radiotherapy (IMRT) and compared with those who were treated by two-dimensional radiotherapy (2DRT).

STUDY DESIGN

A historical cohort study was performed comprising NPC patients who underwent IMRT or 2DRT at Chung Shan Medical University Hospital.

SETTING

Chung Shan Medical University Hospital.

SUBJECTS AND METHODS

Twenty-six NPC patients treated by IMRT (group A) and 18 NPC patients treated by 2DRT (group B) were enrolled. All patients underwent otoscopy, audiometry, and a vestibular-evoked myogenic potential (VEMP) test at a mean interval of three years after irradiation.

RESULTS

Although groups A and B did not significantly differ in the occurrence rate of otitis media with effusion (OME), group B had a significantly greater occurrence rate of chronic otitis media than group A ( P < 0.05, χ2 test). The incidences of high-frequency sensorineural hearing loss were 46 percent in group A and 67 percent in group B, with no significant difference between the two. In terms of VEMPs, group A had a significantly lower abnormal rate (31%) than group B (61%; P < 0.05, χ2 test). In addition, a significant relationship existed between T stages and OME in NPC patients treated by IMRT ( P < 0.01, Fisher-Freeman-Halton test) but not by 2DRT.

CONCLUSION

The incidence of chronic otitis media and abnormal VEMPs in NPC patients treated by IMRT were significantly lower when compared with those treated by 2DRT, demonstrating the superiority of IMRT in decreasing unwanted otologic complications. However, occurrence of OME, which was related with advanced T stage, cannot be reduced by IMRT.

Medical issues in cancer survivors--a review

Cancer survivorship is an emerging area of scientific and clinical interest. Several decades ago, most people diagnosed with cancer did not live long beyond their initial diagnosis. Today the number of cancer survivors exceeds ten million, and this group may experience unique healthcare issues related to their cancer treatment. Chemotherapy, surgery, and radiation therapy each have their own late and long-term complications. It is imperative for clinicians who are caring for cancer survivors to be aware of long-term complications of therapy and to treat these appropriately. When cancer therapy has successfully added years of life, it is equally as important that medical care assures the best quality of life during those years.

Otological Toxicity After Postoperative Radiotherapy for Parotid Tumours

Radiotherapy is commonly used in the management of malignant parotid gland tumours that have adverse pathological risk factors after surgery. Radiation to the parotid bed is associated with predictable complications. In particular, the close proximity of the auditory apparatus, which receives a significant radiation dose, results in significant toxicity in a proportion of patients. Here we review auditory toxicity after radiation to the parotid bed.

Radiation-induced oscillopsia in nasopharyngeal carcinoma patients

PURPOSE

To apply a battery of audiovestibular function tests and magnetic resonance imaging (MRI) to investigate the causes of oscillopsia in nasopharyngeal carcinoma (NPC) patients after irradiation (RT).

METHODS AND MATERIALS

Of 300 NPC patients, 12 (4%) developed oscillopsia after RT. The mean accumulated radiation dose to the nasopharynx was 112 +/- 30 Gy. Each patient underwent a battery of audiovestibular function tests, including audiometry and the dynamic illegible E, caloric, and rotational tests.

RESULTS

Excluding 3 patients with neck fibrosis who could not perform the head turning movement, the remaining 9 patients displayed 100% abnormal dynamic illegible E test results and 100% abnormal refixation saccades. All 12 patients presented with bilateral hearing loss, caloric reductions, and reduced gains of the vestibular ocular reflex (VOR) on the rotational test, indicating bilateral VOR loss. After excluding tumor relapse and radiation necrosis of the brain by MRI, the oscillopsia in these 12 irradiated NPC patients was attributed to bilateral VOR loss.

CONCLUSION

Radiation-induced oscillopsia in our NPC patients was attributed to bilateral VOR loss, possibly as a result of higher radiation doses. Hence, the therapeutic benefits of a second course of RT are associated with the potential risk of oscillopsia after RT.

Postirradiation vertigo in nasopharyngeal carcinoma survivors

OBJECTIVE

Vertigo rarely manifested as an initial symptom of nasopharyngeal carcinoma or an early symptom after irradiation; however, increasing numbers of long-term nasopharyngeal carcinoma survivors experienced it. The purpose of this study was to investigate the causes of vertigo in irradiated nasopharyngeal carcinoma survivors.

SETTING

University hospital.

PATIENTS

From January 1992 to December 2001, a total of 113 nasopharyngeal carcinoma patients (67 men and 46 women) with postirradiation vertigo consecutively visited our vertigo clinic. The mean interval from completion of irradiation to the occurrence of vertigo was 10 years. Each patient underwent otoscopic examination and a battery of audiovestibular function tests. Then, correlation between the vertigo and the radiation effect was explored.

RESULTS

Postirradiation vertigo was mainly attributable to peripheral labyrinthine disorder (69%), followed by central vestibular lesions (31%). The vertiginous and associated symptoms including severity, nausea/vomiting, oscillopsia, or imbalance in cases of peripheral labyrinthine disorder were milder than those in central vestibular lesion. Meanwhile, the former had less life impact and better response to therapy compared with the latter. The mean radiation dosage in both groups was 73 +/- 6 Gy and 74 +/- 5 Gy, respectively, without a significant difference. Of these 113 patients, 85 patients (75%) had radiation otitis media in one or both ears, and 28 patients disclosed bilateral intact eardrums. The prevalence of radiation otitis media in patients with postirradiated vertigo was 53% versus 73% for those with radiation dosage less than or more than 71 Gy, respectively, exhibiting a significant difference. However, the prevalence of radiation otitis media is unrelated to radiation interval. In comparison with absent caloric responses in radiation otitis media ears, 32% versus 57% in those of less than or more than 71 Gy, respectively, indicates a significant difference.

CONCLUSIONS

Vertigo is a late complication in irradiated nasopharyngeal carcinoma survivors, which is mainly caused by the sequela of radiation otitis media. Because the latter is correlated with the radiation dosage, 70 Gy is recommended as the maximum dosage for nasopharyngeal carcinoma. Eradicating radiation otitis media in nasopharyngeal carcinoma survivors may subsequently prevent the postirradiation vertigo.

Hearing in workers exposed to low-dose radiation for a long period

The aim of the present study was to evaluate changes in hearing thresholds with standard and high frequency audiometry in workers exposed to low-dose ionizing radiation for a long period. A total of 57 (49 male and 8 female) technical staff working in radiology-related jobs who were exposed to occupational radiation were included in the study. The control group consisted of 32 (27 male and 5 female) volunteer subjects with normal hearing. The symptoms like tinnitus, vertigo, weakness and lack of appetite were evaluated. A standard ascending/descending method was applied to the subjects of the study and the control groups in order to determine their hearing thresholds at eleven different frequencies between 250 and 16,000 Hz. In the study group, the working duration of subjects ranged from 4 to 23 years, and the percentage of tinnitus, weakness, vertigo and lack of appetite were 47%, 28%, 24% and 17%, respectively. It was observed that pure tone hearing thresholds were markedly increased for 4,000, 6,000, 8,000, 14,000 and 16,000 Hz frequencies in the study group compared to the control group (p<0.01). Levels of static compliance and middle ear pressures of the study group were similar to the control group. Tinnitus, vertigo and hearing loss in high frequencies were observed in the subjects exposed to the radiation for a long period. Subjects under high risk should be evaluated periodically. We suggest that the use of standard and high frequency audiometry together could be beneficial in the evaluation of these subjects.

Radiotherapy-induced ear toxicity

Despite their particular functional consequences, radiotherapy-induced ear injuries remain under-evaluated and under-reported. These reactions may have acute or late character, may affect all structures of the hearing organ, and result in conductive, sensorineural or mixed hearing loss. Up to 40% of patients have acute middle ear side effects during radical irradiation including acoustic structures and about one-third of patients develop late sensorineural hearing loss (SNHL). Total radiotherapy dose and tumour site seem to be among the most important factors associated with the risk of hearing impairment. Thus, reduction in radiation dose to the auditory structures should be attempted whenever possible. New radiotherapy techniques (3-dimensional conformal irradiation, intensity modulated radiotherapy, proton therapy) allow better dose distribution with lower dose to the non-target organs. Treatment of acute and late external otitis is mainly conservative and includes the anti-inflammatory agents (applied topically and systematically). Post-radiation chronic otitis media and the eustachian tube pathology may be managed with tympanic membrane incision with insertion of a tympanostomy tube (grommet), although the benefit of such approach is controversial and some authors advocate a more conservative approach. In these patients the functional deficit can be alleviated by application of bone conduction hearing aids such as, e.g., the bone anchored hearing aid (BAHA). There is no standard therapy for post-irradiation sudden or progressive SNHL yet corticosteroid therapy, rheologic medications, hyperbaric oxygen or carbogen therapy are usually employed (as for idiopathic SNHL), although controversial data on the efficacy of these treatment modalities have been published. In selected cases with bilateral profound hearing loss or total deafness, cochlear implants may prove effective. Further improvements in radiotherapy techniques and progress in otologic diagnostics and therapy may allow better prevention and management of radiation-related acoustic injury.

Effect of irradiation on vestibular evoked myogenic potentials in nasopharyngeal carcinoma survivors

BACKGROUND

This study aims to investigate the effect of irradiation on vestibular evoked myogenic potentials (VEMPs) in nasopharyngeal carcinoma (NPC) survivors, because radiotherapy to NPC covers a column from the basal skull to the clavicle level.

METHODS

Twenty-two irradiated NPC survivors and five fresh NPC patients were subjected to VEMP testing, which is evoked by short-tone burst (95 dBHL, 500 Hz) stimulation. Interactions among VEMPs and radiation effects, such as radiation dosage, postirradiation interval, radiation-induced otitis media, sensorineural hearing loss, or canal paresis, were then explored.

RESULTS

The mean latencies of p13 and n23 in irradiated ears were significantly delayed compared with either pr-irradiated ears or normal control ears. Delayed VEMPs represented 50% in ears with a mean radiation dosage of 71 Gy, whereas it represented 100% in those with a mean radiation dosage of 123 Gy. Ears with radiation otitis media revealed higher occurrence (65%) of delayed VEMPs than those without radiation otitis media (29%, p <.05), possibly because of radiation sequela affecting the brainstem and neck. However, delayed VEMPs were unrelated to sensorineural hearing loss or canal paresis caused by irradiation.

CONCLUSIONS

Delayed VEMPs in NPC survivors are possibly due to radiation-induced otitis media, a brainstem lesion, or neck fibrosis. Hence, VEMP testing may expand the test battery for clinicians to explore balance problems in NPC survivors after irradiation.

Late radiation effects on hearing, vestibular function, and taste in brain tumor patients

PURPOSE

To investigate late radiation effects on hearing, vestibular function, and taste after conventional radiotherapy in brain tumor patients.

METHODS AND MATERIALS

Hearing, vestibular function, and taste were assessed in 33 brain tumor patients irradiated unilaterally to the tumor-bearing hemisphere and the temporal bone. Median observation time after completion of radiotherapy was 13 years; the fraction dose was 1.8 Gy, and mean radiation dose was 53.1 Gy.

RESULTS

Deep ulceration in the external ear canal and osteoradionecrosis on the irradiated side was seen in three patients. Reduced hearing was found for air and bone conduction of the irradiated side compared to the opposite side (0.25-2 kHz: 6.1 dB, 4 kHz: 10.3 dB, 6 kHz: 15.6 dB, and 8 kHz: 16.5 dB). For bone conduction, the corresponding figures were 0.25-2 kHz: 5.5 dB and 4 kHz: 8.2 dB. Three patients had a canal paresis of the irradiated side, and three patients had affection of the chorda tympani.

CONCLUSION

Irradiation of the temporal bone with doses usually given in the treatment of patients with brain tumors may cause osteoradionecrosis, sensorineural hearing loss, dysfunction of the vestibular inner ear, and loss of taste. Head-and-neck examination should be included in the follow-up of long-term survivors.