Radiation dose to otologic structures during head and neck cancer radiation therapy

Eustachian Tube Functions in Concurrent Chemoradiotherapy for Head and Neck Cancer Patients

Ototoxicity is a dose-limiting adverse event for concurrent chemoradiotherapy (CCRT) with high-dose cisplatin for locally advanced head and neck squamous cell carcinoma (HNSCC). Both irradiation to the Eustachian tube (ET) and weight loss are risk factors for patulous ET. The aim of this prospective, observational study was to elucidate the incidences of patulous ET conditions before and after CCRT in HNSCC patients by means of ET function tests. This prospective, observational study was conducted in 27 HNSCC patients who received CCRT with high-dose cisplatin, and ET function tests (sonotubometry and tubo-tympano-aerodynamic graphy) were performed before and 3 months after CCRT. Factors potentially affecting the incidence of patulous ET conditions after CCRT were evaluated. Of the 54 ears from 27 patients investigated, patulous ET conditions were observed in 12 ears (22.2%) from 9 patients (33.3%) before CCRT and 15 ears (27.8%) from 11 patients (40.7%) at 3 months after CCRT. Only patulous ET conditions before CCRT in each ear were significantly associated with patulous ET conditions after CCRT (p = 0.010). This is the first report to describe the incidences of patulous ET conditions before and after CCRT in HNSCC patients. HNSCC patients are potentially at higher risk of patulous ET.

Is the risk of idiopathic sudden sensorineural hearing loss higher in nasopharyngeal carcinoma than in hypopharyngeal cancer? A population-based study

BACKGROUND

The aim of this study was to compare the risk of developing sudden sensorineural hearing loss (SSHL) in patients with hypopharyngeal cancer with that in patients with nasopharyngeal carcinoma (NPC).

METHODS

A population-based, retrospective cohort study was performed using the Taiwan National Health Research Database databank. Patients selected for this study were diagnosed with hypopharyngeal cancer or NPC and treated with radiotherapy in the period from 2001 to 2004. Routine follow-up was conducted for 8 years (2004-2012), and the incidence of SSHL was calculated at the final follow-up.

RESULTS

There was no significant difference in the risk of developing SSHL between the hypopharyngeal cancer group and its control group (p = 1.000). In hypopharyngeal cancer and NPC groups, the rates of SSHL were 0.12% and 1.00%, respectively (p < 0.001). The cumulative hazard of SSHL during the follow-up period was significantly higher in the NPC group than in the control group (p < 0.001).

CONCLUSION

Radiotherapy in patients with hypopharyngeal cancer did not increase the risk of developing SSHL, but postirradiation NPC was significantly associated with an increased incidence of SSHL.

Fighter Pilots With Nasopharyngeal Carcinoma Successfully Returning to Flight After Radiotherapy: A Case Series

For nasopharyngeal carcinoma (NPC), radiotherapy is the primary treatment. However, complications occur after radiation to the nasopharynx, which could potentially affect the flying safety. Four fighter pilots with NPC were reported. With early to locally advanced NPC, they received radiotherapy with or without concurrent chemotherapy. The prescribed radiation dose was 70 Gy to the primary tumor over the nasopharynx. Before treatment, all patients presented with various degrees of hearing loss on pure tone audiometry (main frequencies of 20-45 dB at 3-4.5 kHz for affected ears). After the full course of radiotherapy, tumor regression was noticed during months to years of follow-ups. The follow-up audiometry evaluation showed gradually recovered hearing function (average improvement of 5 dB at pretreatment frequencies) in all pilots. They then returned back to the flight line on annual waiver points. Here, we conclude that fighter pilots with NPC could successfully return to the flight line after radiotherapy. However, detailed physical examinations and confirmation of adaptation to flying condition are warranted.

Effects of radiation on the temporal bone in patients with head and neck cancer

Radiotherapy is a key component in the treatment of many head and neck cancers, and its potential to cause long-term adverse effects has become increasingly recognized. In this review, we describe the short-term and long-term sequelae of radiation-associated changes in and injury to the temporal bone and its related structures. The pathophysiology of radiation-induced injury and its clinical entities, including sensorineural hearing loss, chronic otitis media, osteoradionecrosis, and radiation-associated malignancies, are described. We also discuss radiation dose to the head and neck as it relates to these conditions. An improved understanding of radiation's effects on the temporal bone will enable physicians and researchers to continue efforts to reduce radiotherapy-related sequelae and guide clinicians in diagnosing and treating the various otologic conditions that can arise in patients with head and neck cancer who have received radiotherapy. © 2016 Wiley Periodicals, Inc. Head Neck 38: 1428-1435, 2016.

Audiological profile of patients treated for childhood cancer

Objective

To characterize the hearing loss after cancer treatment, according to the type of treatment, with identification of predictive factors.

Methods

Two hundred patients who had cancer in childhood were prospectively evaluated. The mean age at diagnosis was 6 years, and at the audiometric assessment, 21 years. The treatment of the participants included chemotherapy without using platinum derivatives or head and neck radiotherapy in 51 patients; chemotherapy using cisplatin without radiotherapy in 64 patients; head and neck radiotherapy without cisplatin in 75 patients; and a combined treatment of head and neck radiotherapy and chemotherapy with cisplatin in ten patients. Patients underwent audiological assessment, including pure tone audiometry, speech audiometry, and immittancemetry.

Results

The treatment involving chemotherapy with cisplatin caused 41.9% and 47.3% hearing loss in the right and left ear, respectively, with a 11.7-fold higher risk of hearing loss in the right ear and 17.6-fold higher in the left ear versus patients not treated with cisplatin (p < 0.001 and p < 0.001, respectively). Children whose cancer diagnosis occurred after the age of 6 have shown an increased risk of hearing loss vs. children whose diagnosis occurred under 6 years of age (p = 0.02).

Conclusion

The auditory feature found after the cancer treatment was a symmetrical bilateral sensorineural hearing loss. Chemotherapy with cisplatin proved to be a risk factor, while head and neck radiotherapy was not critical for the occurrence of hearing loss.

Osteoradionecrosis of the temporal bone: a case series

OBJECTIVE

To study osteoradionecrosis (ORN) of the temporal bone.

STUDY DESIGN

Retrospective case review.

SETTING

Academic medical center.

PATIENTS

Patients were included who had previously undergone radiation to the head and neck and then developed exposed necrotic bone within the ear canal that persisted at least 3 months.

INTERVENTIONS

Patients were treated with a variety of modalities, including conservative therapy with antibiotic ear drops and in-office debridements, hyperbaric oxygen therapy, and surgery.

MAIN OUTCOME MEASURES

To describe the presentation and management of patients with temporal bone osteoradionecrosis.

RESULTS

Thirty-three patients with temporal bone osteoradionecrosis were included. The most common site of primary tumor was the parotid gland (n = 11), followed by the nasopharynx (n = 7). The time to development of ORN varied between 1 and 22 years, with mean of 7.9 years. The mean radiation dose was 62.6 Gy to the primary tumor, 53.1 Gy to the affected temporal bone, and 65.2 Gy to the affected tympanic bone. The most common symptoms of ORN were otorrhea (n = 15), hearing loss (n = 13), and otalgia (n = 12). Fifteen patients had bacterial superinfection, most commonly Staphylococcus aureus (n = 9). Conservative therapy was successful at managing symptoms but not in eradicating exposed bone in most patients. Surgery was used for recalcitrant pain, infection, cholesteatoma, cranial neuropathies, and intracranial complications.

CONCLUSION

Osteoradionecrosis is a rare complication of radiation to the temporal bone. Management should be aimed at relief of symptoms, eradication of superinfection, and treatment of other commonly present radiation effects like cholesteatoma and hearing loss.

Safety and otoprotection of metformin in radiation-induced sensorineural hearing loss in the guinea pig

OBJECTIVE

There is currently no treatment available to prevent radiation-induced sensorineural hearing loss. Metformin has antineoplastic effects and is able to regulate the mitochondrial production of reactive oxygen species after cellular stress, which is one of the mechanisms involved in apoptosis after radiation damage. The objective of this study was to determine the safety and radioprotective properties of metformin against radiation-induced cochlear damage both in vitro and in vivo.

STUDY DESIGN

In vitro and prospective animal study.

SETTING

Animal Care Facilities of the Montreal Children's Hospital Research Institute.

METHODS

Cultured auditory hair cells (HEI-OC1) were exposed to different concentrations of metformin to determine its safety. Cells were incubated with different metformin concentrations and subjected to radiation. Cell viability after experiments was determined with the 3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium (MTS) assay. Sixteen guinea pigs were divided in 2 groups: drinking tap water (n = 8) and drinking water containing metformin (n = 8). The animals were unilaterally irradiated for 20 days (total dose 70 Gy), and the ears were divided in 4 groups: control (n = 8), irradiated (n = 8), metformin (n = 8), and experimental (n = 8). Auditory brainstem responses were assessed before and 1, 6, and 16 weeks after completion of radiotherapy.

RESULTS

Metformin was not cytotoxic or radioprotective in cultured auditory hair cells. Experimental ears had less hearing loss than radiated ones; however, differences were not statistically significant (P > .05).

CONCLUSION

Metformin is not ototoxic or radioprotective in vitro or in vivo. Ears solely subjected to metformin had better hearing thresholds than the rest of the groups.

Sensorineural Hearing Loss after Treatment for Head and Neck Cancer: A Review of the Literature

BACKGROUND

Definitive cisplatin-based chemoradiation is increasingly delivered as the treatment of choice for patients with head and neck cancer. Sensorineural hearing loss is a significant long-term side effect of cisplatin-based chemoradiation and is associated with potential major quality of life issues for patients. The purpose of this article was to review the mechanism behind sensorineural hearing loss in patients treated with cisplatin-based chemoradiation, including incidence, the contributions of radiotherapy and cisplatin to sensorineural hearing loss, and the impact of the toxicity on patient quality of life.

METHODS

Database searches were conducted through PubMed (National Centre for Biotechnology Information) and OvidSP Medline via the Queensland University of Technology Library website. General article searches were conducted through the online search engine Google Scholar. Articles were excluded if the full text was unavailable, they were not in English, or if they were published before 1990. Key words included hearing loss, ototoxicity, cancer, quality of life, cisplatin, and radiotherapy.

RESULTS/DISCUSSION

The total number of journal articles accessed was 290. Because of exclusion criteria, 129 articles were deemed appropriate for review. Findings indicated that sensorineural hearing loss is a significant, long-term complication for patients treated with cisplatin-based chemoradiation. Current literature recognizes the ototoxic effects of cisplatin and cranial irradiation as separate entities; however, the impact of combined modality therapy on sensorineural hearing loss is seldom reported. Multiple risk factors for hearing loss are described; however, there are contradictory opinions on incidence and severity and the exact radiation dose threshold responsible for inducing hearing loss in patients receiving combined modality therapy. Sensorineural hearing loss creates a subset of complexities for patients with head and neck cancer and these patients face significant quality of life impairment.

CONCLUSIONS

The literature review identified that sensorineural hearing loss is a major quality of life issue for patients treated with cisplatin-based chemoradiation for head and neck cancer. Further investigation evaluating the contribution of cisplatin-based chemoradiation to sensorineural hearing loss and the subsequent effect on patient quality of life is warranted.

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.

Speech recognition and frequency of hearing loss in patients treated for cancer in childhood

BACKGROUND

The aim of this study was to characterize the audiological profile accompanying oncological treatment in patients who had cancer in childhood and had been free of oncological treatment for at least 8 years. Our main interest lay in identifying the affected frequencies that interfered with speech intelligibility (SI) in those who had acquired hearing loss after treatment.

PROCEDURE

Two hundred patients who had cancer in childhood were evaluated. Diagnosis was made at the mean age of 6 years old, and hearing evaluation was performed at a mean age of 21 years. Fifty-one of these patients received chemotherapy without cisplatin, carboplatin or head and neck radiotherapy; 64 received cisplatin without head and neck radiotherapy; 75 received head and neck radiotherapy without cisplatin; and 10 received both head and neck radiotherapy and cisplatin chemotherapy. All patients underwent pure tone audiometry and speech audiometry.

RESULTS

Patients who had hearing loss primarily had bilateral symmetric sensorineural hearing loss. Although the average SI for ears with hearing loss in the frequency range from 4 to 8 kHz was normal, the Kruskall-Wallis test showed a significant difference between ears without hearing loss and those with hearing loss between 4 and 8 kHz. The average SI score in ears with hearing loss between 1 and 8 kHz was significantly different from all other ears.

CONCLUSIONS

Hearing loss involving frequencies at and above 4 kHz determines a decline in SI.

Prospective study on the dose distribution to the acoustic structures during postoperative 3D conformal radiotherapy for parotid tumors: dosimetric and audiometric aspects

BACKGROUND AND PURPOSE

To analyze dose distribution in the hearing organ and to evaluate the dose effect on the hearing thresholds in patients treated with post-parotidectomy 3-dimensional conformal radiotherapy (3D-CRT).

METHODS AND MATERIALS

A total of 17 patients received post-parotidectomy 3D-CRT (median dose: 63 Gy). The audiometric evaluation comprised pure tone audiometry and tympanometry performed before radiotherapy (RT) and 3, 6, and 24 months after RT. The ear structures were delineated on planning computer tomography scans. Mean and maximum doses were calculated and dose-volume histograms were plotted.

RESULTS

Before RT, the median baseline audiometric thresholds were normal. At 3 months post-RT, 3 patients were diagnosed as having middle ear underpressure and/or effusion that resolved completely by 6 months. During 2-year follow-up, none of the ears showed perceptive hearing loss at speech frequencies. The mean doses at ipsilateral external auditory canal, mastoids cells, tympanic case, Eustachian tube, semicircular canals, and cochlea were 44.8 Gy, 39.0 Gy, 30.9 Gy, 33.0 Gy, 19.6 Gy, and 19.2 Gy, respectively. The doses to the contralateral ear were negligible, except for the Eustachian tube (up to 28.2 Gy).

CONCLUSION

Post-parotidectomy 3D-CRT is associated with relatively low doses to the ear and the surrounding structures. Post-RT audiometry did not show any permanent (neither conductive nor perceptive) hearing impairment. Only in 3 patients were there signs of transient unilateral dysfunction of the Eustachian tube observed during the first few months after RT. Longer follow-up and larger patient series are warranted to confirm these preliminary findings.

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.

[Tolerance of normal tissues to radiation therapy: ear]

The main objective of this work was to describe, based on a literature survey, the radiation-induced toxicity of the ear and to try to establish the limiting dose. The limiting toxicity was the sensorineural hearing loss. A dose-effect relationship has been described by several authors. Thirty to 40% of patients who are irradiated for head and neck cancer are concerned, but the intensity of the hearing loss tends to depend on the exact localisation of the primary tumour: nasopharyngeal irradiations, paranasal sinusal and parotid irradiation are at greater risk of complication. High frequencies are more vulnerable than the lower ones. Age of patients, as well as baseline hearing abilities, deeply influence the issue. As far as possible, the dose to the inner ear--the cochlea more precisely--should be kept under 40 Gy. In case of association with other causes of toxicity (such as age, low baseline value, association to cisplatin), this dose should be as low as possible. Should carcinologic constraints lead to toxic doses, then patients should be properly informed.

Comparison of Intensity-Modulated Radiotherapy Using Helical Tomotherapy and Segmental Multileaf Collimator-based Techniques for Nasopharyngeal Carcinoma: Dosimetric Analysis Incorporating Quality Assurance Guidelines from RTOG 0225

Intensity-modulated radiotherapy (IMRT) treatment plans generated by segmental multileaf collimator (SMLC) and helical tomotherapy (HT) techniques for patients with nasopharyngeal carcinoma were compared using standardized criteria proposed by Radiation Therapy Oncology Group (RTOG) protocol 0225. The goal was to deliver a prescribed dose of 70 Gy to at least 95% of the planning target volume (PTV) encompassing gross tumor, and 59.4 Gy and 50.4 Gy, respectively, to areas at high and low risk for microscopic disease, over 33 treatments while respecting constraints to organs at risk (OAR). HT-IMRT significantly reduced dose to the contralateral parotid gland and improved dose homogeneity to the PTVs. Mean doses to the inner and middle ears were also reduced by 18% and 24%, respectively, on the ipsilateral side, and 24%, and 35%, respectively, on the contralateral side using HT-IMRT compared to SMLC-IMRT. Additionally, HT-IMRT reduced mean doses to brainstem (p = 0.02), larynx (p = 0.03), and oral cavity (p = 0.03). These findings suggest that HT-IMRT may be of improve the therapeutic ratio in the radiotherapeutic treatment of nasopharyngeal carcinoma.

Analysis of the cytoprotective effect of amifostine on the irradiated inner ear of guinea pigs: an experimental study

Radiation can cause damage to the inner ear, from a simple hearing loss all the way to profound deafness. Amifostine is a cytoprotective substance extensively used during radio-chemotherapy for malignant tumors.

Aim

the objective of the present investigation was to establish the antioxidant and radioprotective effects of amifostine on the organ of Corti of albino guinea pigs irradiated in the head and neck region.

Materials and Methods

An experimental study conducted on four groups of guinea pigs were used; One group received only amifostine, one group was submitted to a single dose of 350 cGy and the other two were similarly irradiated but received amifostine doses of 100 or 200 mg/kg. All animals were slaughtered 30 days after the experiment, their bullae were removed and the damaged outer hair cells were counted.

Result

The extent of injury was lower in the outer hair cells of the two groups treated with amifostine compared to the group that was only irradiated. There was no difference between the group treated with 100 and 200 mg/kg of amifostine. The group that received only amifostine had no cochlear damage.

Conclusion

Amifostine is an effective cytoprotective substance in the Organ of Corti of irradiated guinea pigs.

Prospective study of sensorineural hearing loss following radiotherapy for nasopharyngeal carcinoma

Objectives:

To investigate the severity and incidence of sensorineural hearing loss in patients with nasopharyngeal carcinoma treated with radiotherapy.

Methods:

Forty-two patients with nasopharyngeal carcinoma were treated with conventional radiotherapy. Audiological testing was performed to compare patients' hearing before and at varying stages after radiotherapy.

Results:

At one month post-radiation, a significant hearing threshold increase was seen only for high frequencies. At 12, 24 and 60 months post-radiation, significant threshold increases were observed at speech frequencies (4.0 and 8.0 kHz), compared with pre-radiation data. The mean values of wave I, III and V latencies and of the I–V interpeak latency intervals were not significantly altered at one month post-radiation, but were significantly prolonged at 12, 24 and 60 months post-radiation, compared with pre-radiation data.

Conclusion:

In patients with nasopharyngeal carcinoma treated with radiotherapy, the severity and incidence of radiation-induced sensorineural hearing loss increased with time, especially at high frequencies. This hearing impairment may be due to changes in the cochlea and/or the retrocochlear auditory pathway.

Ototoxicity after combined platinum and fractionated radiation in a novel guinea pig model

PURPOSE

Cis-platinum and radiation in combination are current organ preservation treatment strategies for head and neck cancer. Their individual ototoxicity has been investigated, with recent demonstration of ototoxicity in clinical studies. Currently, no ototoxicity studies have been performed in animals receiving similar schedules of radiation or cis-platinum to those patients with head and neck cancer.

MATERIALS AND METHODS

In the present study, an animal model was developed to investigate the effects of combined modality therapy on hearing. Albino guinea pigs were given equivalent protocol dosages of cis-platinum (3 parenteral courses), fractionated radiation (25 fractions over 5 weeks), or both. Click and tone burst auditory brainstem response (ABR) measurements were performed before and 6 weeks after the completion of treatment.

RESULTS

Animals receiving radiation or cis-platinum and radiation experienced permanent significant ABR shifts at all frequencies, with 33% of the animals experiencing complete unilateral sensorineural hearing loss at 2 or more frequencies in the ear receiving the full radiation dose (7075 cGy over 25 fractions) (P < .05, paired t test analysis). The animals receiving 3 doses of cis-platinum had no significant ABR threshold shifts at 6 weeks. These data suggest that cis-platinum and radiation cause greater ototoxicity than cis-platinum alone. These findings correlate closely with sensorineural hearing loss in combined modality patients at our institution and in recent studies.

CONCLUSIONS

We conclude that the current animal results parallel those seen clinically and serve as a model for ototoxicity from combined modality therapies in future protocols.

Bacterial Biofilms May Explain Chronicity in Osteoradionecrosis of the Temporal Bone

OBJECTIVE

To identify biofilm formation within a case of temporal bone osteoradionecrosis.

PATIENT

Single-case patient presenting with temporal bone osteoradionecrosis.

INTERVENTION(S)

Antibiotic therapy and then surgical debridement of the temporal bone.

MAIN OUTCOME MEASURE(S)

Histologic identification of biofilm formation within the affected temporal bone specimen.

RESULTS

Positive identification of biofilm formation in multiple sections of the temporal bone specimen removed from a patient affected by osteoradionecrosis.

CONCLUSION

This is the first evidence that temporal bone osteoradionecrosis involves biofilm formation. Such a pathogenic mechanism may explain the recalcitrance of this disease process and offer new strategies in formulating therapeutic interventions.

Chronic ear surgery in irradiated temporal bones

OBJECTIVE

To analyze outcomes of chronic ear surgery in patients with irradiated temporal bones.

STUDY DESIGN

Retrospective case review.

METHODS

Fifteen patients who received radiation involving the temporal bone underwent 21 surgical procedures from 1977 to 1997. Intraoperative findings, long-term complications, and hearing outcomes were analyzed.

RESULTS

Over 50% of cases involved abnormal intraoperative findings including facial nerve dehiscence, labyrinthine fistulas, or dural exposure. Audiologic data revealed that these patients suffered from conductive, mixed, and sensorineural hearing loss. Long-term complications included tympanic membrane perforation and recurrent cholesteatoma. All patients had dry, non-draining ears at the end of the study.

CONCLUSIONS

Irradiated temporal bones present difficult intraoperative anatomy and often require multiple procedures to cure otologic disease. Although radiation significantly reduces vascularity and hampers healing, vascularized reconstruction flaps are not necessary for good outcomes.

Sudden Deafness Due to Intralabyrinthine Haemorrhage: A Possible Rare Late Complication of Head and Neck Irradiation

Introduction: Radiation injury resulting in sudden, late onset sensorineural hearing loss is a recognised complication in patients who have received head and neck irradiation. We describe the magnetic resonance imaging (MRI) of the internal acoustic canal (IAC) of 3 such patients and postulate a cause for these findings. Clinical Picture: A total of 63 patients were referred for MRI IAC for sudden-onset sensorineural hearing loss. Of these patients, only 5 patients had abnormal MRI finding in the affected ear and the remaining patients had normal studies. Two patients had acoustic neuromas. Three patients demonstrated high T1-weighted signal in the labyrinths of the affected ears and had past histories of head and neck irradiation. The MRI findings and medical records of these 3 patients were reviewed and described in this case series. Outcome: High labyrinthine signal on unenhanced T1-weighted images in the symptomatic ear of these patients was observed, suggesting the possibility of haemorrhage. In the patient who had a history of brain tumour, susceptibility artifacts were also seen in the right hemipons on the gradient-echo images, indicating the presence of paramagnetic substances from previous therapy. Conclusion: We postulate that labyrinthine haemorrhage is a rare, late complication of head and neck irradiation, resulting in sudden sensorineural hearing loss. Key words: Irradiation, Magnetic resonance, Temporal bone

Sensorineural hearing loss in combined modality treatment of nasopharyngeal carcinoma

BACKGROUND

Combined modality therapy has become the standard of care for nasopharyngeal carcinoma, yet the combined ototoxic effects of radiation and cisplatin are poorly understood. The incidence and severity of sensorineural hearing loss (SNHL) with combined modality therapy was evaluated and the dose-response relation between radiation and hearing loss was investigated.

METHODS

Patients with newly diagnosed AJCC Stage II-IVB nasopharynx carcinoma treated from 1994-2003 were identified. The records of 44 ears in 22 patients who received a preirradiation pure tone audiogram and followup audiograms 12+ months postirradiation were included in the analysis. All patients were treated with conformal radiotherapy to 70 Gy and received platinum-based chemotherapy similar to the Intergroup 0099 trial. Composite cochlear dose distributions were calculated. Ototoxicity was measured using intrasubject audiogram comparisons and SNHL was defined as per the American Speech and Hearing Association guidelines, with standard range of speech between 2000-4000 Hz. SNHL was analyzed using Fisher exact test and linear and logistic regression models.

RESULTS

PATIENT CHARACTERISTICS

median age, 45; 27% Asian; 68% male; 64% WHO III. Median audiologic followup was 29 months (range, 12-76 mos). Mean cochlear dose (Dmean) ranged from 28.4-70.0 Gy (median, 48.5 Gy). SNHL was detected in 25 of the 44 ears (57%) studied. There was an increased risk of SNHL for ears receiving Dmean > 48 Gy compared with those receiving < or = 48 Gy at all frequencies within the range of speech (P = 0.04). Using univariate logistic regression analysis, Dmean to the cochlea, cycles of cisplatin, and time postradiotherapy were independently significant factors in determining the incidence of SNHL (P = 0.02, P = 0.03, and P = 0.04, respectively). In univariate and multivariate linear regression analysis, Dmean was statistically significant at all frequencies in affecting degree of SNHL, whereas the significance of cisplatin and time was variable.

CONCLUSIONS

There was a significant increase in risk of SNHL among patients receiving > 48 Gy, suggesting a threshold in cochlear radiation dose-response in the setting of combined modality therapy. This dose should serve as a Dmean constraint maximum for intensity-modulated radiotherapy treatment of nasopharynx carcinoma.

Decreased hearing after combined modality therapy for head and neck cancer

PURPOSE

Combined platinum-based chemoradiation therapy is frequently being used as therapy for head and neck cancer at multiple sites. These therapies are individually ototoxic, but little has been reported on their combined toxicity.

MATERIALS AND METHODS

A retrospective investigation of 37 patients known to have undergone therapy with both agents, in combination, for head and neck malignancy was performed. Sixty percent of the patients had complaints of hearing loss subjectively. Reliable pretreatment and posttreatment audiograms were obtained on 15 of these patients. Audiograms were analyzed for sensorineural changes at 0.5, 1, 2, 4, and 8 kHz.

RESULTS

By paired t test analysis, there were significant changes in the patients with pretreatment and posttreatment audiograms at all frequencies. More than 50% of the patients had a change of 10 dB or greater in their pure-tone average. More than 85% of the patients experienced changes in their hearing at 4 and 8 kHz.

CONCLUSIONS

We conclude that patients undergoing combined modality therapy for head and neck cancer experience hearing loss. We recommend that hearing assessment, including pretreatment and posttreatment audiometry, be performed in all patients undergoing combined platinum-based chemotherapy and radiation for the treatment of head and neck cancer.

Effect of radiotherapy on retro-cochlear auditory pathways

OBJECTIVES

The cochlea may be damaged by modern conventional radiotherapy (RT) for head and neck cancers when the ear is included in the radiation field. It is unclear however, if the retro-cochlear auditory pathways are affected as well, which has clinical significance in cochlear implantation. This study aims to investigate the integrity of the retro-cochlear auditory pathways in patients who had received RT for nasopharyngeal carcinoma.

STUDY DESIGN

Prospective study.

METHODS

Patients who were newly diagnosed with nasopharyngeal carcinoma and treated by RT alone were studied. Evoked response audiometry and PTAs were carried out prior to and after RT (at 3, 18, and 48 months postRT). In addition, evoked response audiometry was also performed during the 3rd, 5th, and 7th week of RT. Waves 1 to 5, 1 to 3, and 3 to 5 latencies were measured. The values recorded during and postRT were compared with those recorded before RT. In addition, a subset of ears that demonstrated postRT sensorineural hearing loss were identified so that their respective wave 1 to 5 interwave latencies could be similarly compared. Wilcoxon signed ranks test was used in the statistical analysis. To confirm that the cochlea and internal auditory meatus receive significant doses of radiation, the RT treatment plans of nine other nasopharyngeal carcinoma patients treated by the same RT technique were analyzed to derive dose-volume histograms of these structures.

RESULTS

Twenty-seven patients (20 males and 7 females) with a mean age of 51.2 (range 36-75) years participated in the study. There was no statistically significant difference in waves 1 to 5, 1 to 3, and 3 to 5 interwave latencies recorded during RT and postRT as compared with those recorded before RT (P > .05). Pre- and postRT wave 1 to 5 latencies of the 16 ears that had postRT hearing deterioration were also not statistically significant (P = .366). The mean radiation doses delivered to the cochlea and internal auditory meatus ranged from 24.1 to 62.2 Gy and 14.4 to 43.4 Gy, respectively.

CONCLUSION

This study suggests in patients who have had RT for nasopharyngeal carcinoma, the retro-cochlear auditory pathways are functionally intact even in the longer term.

Effects of Piracetam Supplementation on Cochlear Damage Occuring in Guinea Pigs Exposed to Irradiation

In this study we aimed to determine the role of piracetam (PIR) in preventing radiation induced cochlear damage after total-cranium irradiation (radiotherapy; RT). Male albino guinea pigs used in the study were randomly divided into three groups. Group 1 (Control group) (n=11) received neither PIR nor irradiation, but received saline solution intraperitoneally (i.p.) and received sham irradiation. Group 2 (RT group) (n=32) was exposed to total cranium irradiation of 33 Gy in 5 fractions of 6.6 Gy/d for five successive days, with a calculated (alpha/beta=3.5) biological effective dose of fractionated irradiation equal to 60 Gy conventional fractionation, then received saline solution for five successive days i.p. Group 3 (PIR+RT group) (n=33) received total cranium irradiation, plus 350 mg/kg per day PIR for five successive days i.p. After the last dose of RT, the guinea pigs were all sacrificed at the 4th, 24th and 96th hours, respectively. Their cochleas were enucleated for histopathologic examination. It was observed that total cranium irradiation (RT group) promoted degeneration in stria vascularis (SV), spiral ganglion cells (SG), outer hair cells (OHC) and inner hair cell (IHC) of cochleas at these times (p<0.05). While in the PIR+RT group, there was no statistically significant difference on radiation-induced cochlear degeneration in SV and OHC at 4th (p>0.05) and IHC at 4th, 24th hours (p>0.05), there was a significant difference on radiation-induced cochlear degeneration in SV and OHC at 24th and 96th hours (p<0.05), IHC at 96th hour (p<0.05) and SG at 4th, 24th and 96th hours (p<0.05). There was no any cochlear degeneration in the control group. Piracetam might reduce radiation-induced cochlear damage in the guinea pig. These results are pioneer to studies that will be performed with PIR for radiation toxicity protection.

The relationship between the protective effect of amifostine and decreased intercellular adhesion molecule 1 expression

PURPOSE

The objective of our study was to characterize the relationship between the protective effect of amifostine and decreased intercellular adhesion molecule 1 (ICAM-1) expression in early-phase, radiation-induced otitis media and to illustrate the possible mechanism of early-phase radiation-induced otitis media.

MATERIALS AND METHODS

A comparison study of middle ear tissue was performed by the expression of ICAM-1 and the electron microscope from total 38 guinea pigs. Group A, consisting of 2 pigs, was used as control, and these pigs were not irradiated. Groups B, C, D, and E, consisting of 9 pigs each, were irradiated. Sterile saline was administered intraperitoneally to the pigs in groups B and D before irradiation, and amifostine was administered intraperitoneally as an aqueous solution 30 minutes before irradiation to the pigs in groups C and E. The pigs in groups B and C were killed on the second day after irradiation, and the pigs in groups D and E were killed 30 days after irradiation.

RESULTS

Intercellular adhesion molecule 1 was strongly expressed in the middle ear mucosa of the irradiated pigs after a 45-Gy dose of radiation was administered. Enhanced ICAM-1 expression was accompanied by pathomorphologic changes in the middle ear tissue. Scanning electron microscopy demonstrated the changes. Intercellular adhesion molecule 1 expression in the mucosa of the groups killed on the second day was stronger than that in the mucosa of the groups killed 30 days after irradiation. Amifostine protected the middle ear from radiation injury, and we found that the expression of ICAM-1 in the middle ear mucosa was down-regulated. However, slight expression of ICAM-1 remained 30 days after irradiation.

CONCLUSIONS

Irradiation increased the expression of ICAM-1 in the middle ear mucosa. Amifostine protected the middle ear from early irradiation injury. There was a relationship between oxygen free radicals derived from irradiation and up-regulation of ICAM-1 expression. Continuous ICAM-1 expression might be related to stenosis of the eustachian tube.

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.

Ultrastructural and electrophysiologic changes of rat cochlea after irradiation

OBJECTIVE/HYPOTHESIS

To determine the acute and subacute cochlear effects of sublethal total body irradiation.

STUDY DESIGN

The study was designed prospectively as a Sprague-Dawley (SD) rat model with otoacoustic emission measurement.

METHODS AND MATERIALS

Ten rats and 20 ears were included in the study. Distortion product otoacoustic emission (DPOAE) measurements were performed under ketamine anesthesia before and 1 to 8 weeks after sublethal dose total body irradiation. Eight and six rats survived at the first and eighth week measurements, respectively. The frequency bandwidth was set to 1,067 Hz (referenced to f1) - 9,512 Hz (referenced to f2) (2f1 - f2 = 832 - 6,076 Hz) and eight points were sampled per octave, but low-frequency (<2,549 Hz [referenced to 2f1 - f2]) results were not included in the analysis. Averages were obtained at each frequency, and statistical analysis was performed to compare the pre-and postradiation values. Then, three of the rats were killed for transient electron microscopy (TEM) of the temporal bones.

RESULTS

The posttreatment DPOAEs at almost all frequencies showed a trend toward decline at both the first and eighth weeks, but significant reduction was only detected at 3,600 and 3,961 Hz (referenced to 2f1 - f2) in the first week. TEM of the cochlea revealed ultrastructural changes in the outer hair cells (OHCs) and stria vascularis of the basal turn. The cochlear ganglion nuclei and cochlear nerve axons were unaffected.

CONCLUSION

Radiation can affect the cochlea in the acute phase at the mid to high frequencies; further prediction for long-term effects requires longer follow-ups.

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.

Sensori-neural hearing loss after radiotherapy for nasopharyngeal carcinoma: individualized risk estimation

BACKGROUND AND PURPOSE

Sensori-neural hearing loss (SNHL) is a common complication to radiation therapy in the upper head and neck region. In this study, we estimated the dose response relationship for SNHL with adjustment for pre-therapeutic risk factors.

PATIENTS AND METHODS

The pre- and post-therapeutic hearing levels were recorded in a previously published study of 20 patients receiving radiotherapy for nasopharyngeal carcinoma. In the present study, the dose to the inner ear of these patients was estimated with a computed tomography (CT) based treatment planning system. CT data from a 'proxy patient' were used for patients with no available CT scan. SNHL was analyzed as a function of radiation dose and potential risk factors were tested.

RESULTS

The incidence of SNHL increased significantly with increasing dose to the cochlea. Increasing patient's age, and decreasing pre-therapeutic hearing level were statistically significantly associated with an increased risk of SNHL. A nomogram is presented for estimating individualized dose constraints of potential use in treatment planning.

CONCLUSIONS

The inner ear is a critical structure in patients with nasopharyngeal carcinoma and the dose to the inner ear should be carefully considered when planning radiation treatment in this region.

Sensorineural hearing loss induced by radiation as a late effect: five cases followed by audiogram

OBJECTIVE

We studied the progression of the late radiation-induced sensorineural hearing loss (SNHL) to discuss the pathological mechanism responsible for the progression with referring to past reports.

METHODS

Five cases were selected among the SNHL cases diagnosed at the Department of Otolaryngology. Hokkaido University. All the cases were followed up with audiograms.

RESULTS

All of the five cases showed gradual progression of SNHL, which developed mostly 1 2 years after irradiation for brain tumors. Two of them showed rapid progression from time to time with sudden onset in their clinical courses. All the patients were resistant to any medication such as steroid, vitamin B12 or cerebral circulation activators.

CONCLUSION

Two patterns of progressions of radiation-induced hearing loss were observed. Both of them were considered to be explainable by ischemic changes of the vessels as reported earlier. Since there is no effective treatment for radiation-induced SNHL, it is most important to enlighten clinicians in general on this disease.

Recommendations for cancer prevention trials using potentially ototoxic test agents

PURPOSE

Preventive oncology applies pharmacologic agents to reverse, retard, or halt progression of neoplastic cells to invasive malignancy, a process that may require administration of agents over long periods of time. Although ototoxicity may be a tolerable side effect of anticancer or antimicrobial therapy, even modest ototoxicity may not be acceptable in agents developed for preventive oncology that are routinely administered to subjects who neither are, nor necessarily will become, clinically ill.

MATERIALS AND METHODS

Age-related shifts in hearing may occur over the course of longterm or open-ended therapy; consequently, age-adjusted norms enable researchers to better distinguish hearing loss caused by drugs from that caused by aging. Norms for hearing sensitivity are derived from the Baltimore Longitudinal Study of Aging and are the basis for the proposed audiologic monitoring recommendations.

RESULTS

Audiologic monitoring recommendations are presented that standardize patient selection, adverse event reporting, posttreatment follow-up, and audiologic testing for potentially ototoxic investigational agents.

CONCLUSION

These recommendations are applicable to trials of investigational agents as well as various classes of drugs used in routine clinical care.