Tumor Response Assessment in Diffuse Intrinsic Pontine Glioma: Comparison of Semiautomated Volumetric, Semiautomated Linear, and Manual Linear Tumor Measurement Strategies

BACKGROUND AND PURPOSE

2D measurements of diffuse intrinsic pontine gliomas are limited by variability, and volumetric response criteria are poorly defined. Semiautomated 2D measurements may improve consistency; however, the impact on tumor response assessments is unknown. The purpose of this study was to compare manual 2D, semiautomated 2D, and volumetric measurement strategies for diffuse intrinsic pontine gliomas.

MATERIALS AND METHODS

This study evaluated patients with diffuse intrinsic pontine gliomas through a Phase I/II trial (NCT02607124). Clinical 2D cross-product values were derived from manual linear measurements (cross-product = long axis × short axis). By means of dedicated software (mint Lesion), tumor margins were traced and maximum cross-product and tumor volume were automatically derived. Correlation and bias between methods were assessed, and response assessment per measurement strategy was reported.

RESULTS

Ten patients (median age, 7.6 years) underwent 58 MR imaging examinations. Correlation and mean bias (95% limits) of percentage change in tumor size from prior examinations were the following: clinical and semiautomated cross-product, r = 0.36, -1.5% (-59.9%, 56.8%); clinical cross-product and volume, r = 0.61, -2.1% (-52.0%, 47.8%); and semiautomated cross-product and volume, r = 0.79, 0.6% (-39.3%, 38.1%). Stable disease, progressive disease, and partial response rates per measurement strategy were the following: clinical cross-product, 82%, 18%, 0%; semiautomated cross-product, 54%, 42%, 4%; and volume, 50%, 46%, 4%, respectively.

CONCLUSIONS

Manual 2D cross-product measurements may underestimate tumor size and disease progression compared with semiautomated 2D and volumetric measurements.

Nivolumab in patients with metastatic DNA mismatch repair-deficient or microsatellite instability-high colorectal cancer (CheckMate 142): an open-label, multicentre, phase 2 study

BACKGROUND

Metastatic DNA mismatch repair-deficient (dMMR)/microsatellite instability-high (MSI-H) colorectal cancer has a poor prognosis after treatment with conventional chemotherapy and exhibits high levels of tumour neoantigens, tumour-infiltrating lymphocytes, and checkpoint regulators. All of these features are associated with the response to PD-1 blockade in other tumour types. Therefore, we aimed to study nivolumab, a PD-1 immune checkpoint inhibitor, in patients with dMMR/MSI-H metastatic colorectal cancer.

METHODS

In this ongoing, multicentre, open-label, phase 2 trial, we enrolled adults (aged ≥18 years) with histologically confirmed recurrent or metastatic colorectal cancer locally assessed as dMMR/MSI-H from 31 sites (academic centres and hospitals) in eight countries (Australia, Belgium, Canada, France, Ireland, Italy, Spain, and the USA). Eligible patients had progressed on or after, or been intolerant of, at least one previous line of treatment, including a fluoropyrimidine and oxaliplatin or irinotecan. Patients were given 3 mg/kg nivolumab every 2 weeks until disease progression, death, unacceptable toxic effects, or withdrawal from study. The primary endpoint was investigator-assessed objective response as per Response Evaluation Criteria in Solid Tumors (version 1.1). All patients who received at least one dose of study drug were included in all analyses. This trial is registered with ClinicalTrials.gov, number NCT02060188.

FINDINGS

Of the 74 patients who were enrolled between March 12, 2014, and March 16, 2016, 40 (54%) had received three or more previous treatments. At a median follow-up of 12·0 months (IQR 8·6-18·0), 23 (31·1%, 95% CI 20·8-42·9) of 74 patients achieved an investigator-assessed objective response and 51 (69%, 57-79) patients had disease control for 12 weeks or longer. Median duration of response was not yet reached; all responders were alive, and eight had responses lasting 12 months or longer (Kaplan-Meier 12-month estimate 86%, 95% CI 62-95). The most common grade 3 or 4 drug-related adverse events were increased concentrations of lipase (six [8%]) and amylase (two [3%]). 23 (31%) patients died during the study; none of these deaths were deemed to be treatment related by the investigator.

INTERPRETATION

Nivolumab provided durable responses and disease control in pre-treated patients with dMMR/MSI-H metastatic colorectal cancer, and could be a new treatment option for these patients.

FUNDING

Bristol-Myers Squibb.

Nivolumab in patients with DNA mismatch repair deficient/microsatellite instability high metastatic colorectal cancer: Update from CheckMate 142

519

Background: Approximately 4% of metastatic colorectal cancers (mCRCs) are associated with high microsatellite instability (MSI-H), indicating a deficient DNA mismatch repair (dMMR) system. dMMR/MSI-H CRC exhibits an increased tumor neoantigen load and immune cell infiltration and is hypothesized to be targetable by immune checkpoint inhibitors. CheckMate 142 (NCT02060188) evaluates the efficacy and safety of nivolumab (nivo) in patients (pts) with dMMR/MSI-H mCRC. Methods: Pts with dMMR/MSI-H mCRC who progressed on/were intolerant to ≥1 prior line of therapy received nivo 3 mg/kg (nivo 3) every 2 weeks (Q2W). The primary endpoint was objective response rate (ORR) per investigator (INV). The secondary endpoint was ORR per independent radiology review committee (IRRC); exploratory endpoints included safety, PFS, OS, and efficacy in biomarker-defined populations. Results: Among pts treated with nivo 3 Q2W (N = 74), 84% had received ≥2 prior lines of therapy. ORRs were 31% (INV) and 27% (IRRC); disease control rates were 69% (INV) and 62% (IRRC). The median time to response was ≈2.7 mo (INV/IRRC). PFS rates at 12 mo were 48.4% (INV) and 45.6% (IRRC). The duration of response and OS medians were not yet reached; OS rates were 83.4% (6 mo) and 73.8% (12 mo). Responses were observed in pts regardless of tumor programmed death-1 ligand 1 (PD-L1) expression level or BRAF or KRAS mutation status and were observed in pts with or without a history of Lynch syndrome (Table). Grade 3–4 treatment-related adverse events (TRAEs) occurred in 20% of pts. TRAEs leading to discontinuation included acute kidney injury, increased ALT, colitis, and stomatitis (1 each). No treatment-related deaths occurred in this arm. Conclusions: Nivo showed durable responses and disease control in heavily pretreated pts with dMMR/MSI-H mCRC. Treatment was well tolerated, with no new safety signals. Clinical trial information: NCT02060188. [Table: see text]

Normal Development and Measurements of the Occipital Condyle-C1 Interval in Children and Young Adults

BACKGROUND AND PURPOSE

Widening of the occipital condyle-C1 interval is the most specific and sensitive means of detecting atlanto-occipital dislocation. Recent studies attempting to define normal measurements of the condyle-C1 interval in children have varied substantially. This study was performed to test the null hypothesis that condyle-C1 interval morphology and joint measurements do not change as a function of age.

MATERIALS AND METHODS

Imaging review of subjects undergoing CT of the upper cervical spine for reasons unrelated to trauma or developmental abnormality was performed. Four equidistant measurements were obtained for each bilateral condyle-C1 interval on sagittal and coronal images. The cohort was divided into 7 age groups to calculate the mean, SD, and 95% CIs for the average condyle-C1 interval in both planes. The prevalence of a medial occipital condyle notch was calculated.

RESULTS

Two hundred forty-eight joints were measured in 124 subjects with an age range of 2 days to 22 years. The condyle-C1 interval varies substantially by age. Average coronal measurements are larger and more variable than sagittal measurements. The medial occipital condyle notch is most prevalent from 1 to 12 years and is uncommon in older adolescents and young adults.

CONCLUSIONS

The condyle-C1 interval increases during the first several years of life, is largest in the 2- to 4-year age range, and then decreases through late childhood and adolescence. A single threshold value to detect atlanto-occipital dissociation may not be sensitive and specific for all age groups. Application of this normative data to documented cases of atlanto-occipital injury is needed to determine clinical utility.

Application of Normative Occipital Condyle-C1 Interval Measurements to Detect Atlanto-Occipital Injury in Children

BACKGROUND AND PURPOSE

Prior studies have found that widening or asymmetry of the occipital condyle-C1 interval on CT is a sensitive and specific marker for atlanto-occipital dislocation. Previously reported abnormal occipital condyle-C1 interval values are not age-specific, possibly leading to false-positive findings in younger children, in whom this joint space is normally larger than that in adults. This study assesses the utility of applying age-specific normative occipital condyle-C1 interval ranges to documented cases of atlanto-occipital injury compared with previously reported abnormal cutoff values.

MATERIALS AND METHODS

Retrospective review of CT and MR imaging of 14 subjects with atlanto-occipital injury was performed, and occipital condyle-C1 interval measurements were made for each subject. Sensitivities and specificities of proposed occipital condyle-C1 interval cutoffs of 2 and 3 SDs above the mean and previously published occipital condyle-C1 interval cutoffs for atlanto-occipital injury were then calculated on the basis of occipital condyle-C1 interval measurements for each subject.

RESULTS

An occipital condyle-C1 interval 2 SDs above the age-specific mean has a sensitivity of 50% and specificity of 89%-100%, depending on the age group. An occipital condyle-C1 interval 3 SDs above the age-specific mean has a sensitivity of 50% and a specificity of 95%-100%. A 4.0-mm occipital condyle-C1 interval has a sensitivity of 36% and a specificity of 100% in all age groups. A 2.5-mm occipital condyle-C1 interval has a sensitivity of 93% and a specificity of 18%-100%.

CONCLUSIONS

Occipital condyle-C1 interval widening cutoffs used to establish atlanto-occipital injury lack both sensitivity and specificity in children and young teenagers. MR imaging is necessary to establish a diagnosis of atlanto-occipital injury in children and young teenagers when the appropriate mechanism of injury is present.

Increased Prevalence of Developmental Venous Anomalies in Children with Intracranial Neoplasms

BACKGROUND AND PURPOSE

Developmental venous anomalies are considered variants of venous development that, in and of themselves, are of little clinical import. A possible association between intrinsic brain tumors and developmental venous anomalies has been suggested, but a rigorous investigation has not been performed. The aim of this study was to assess any association between developmental venous anomalies and intrinsic brain neoplasms.

MATERIALS AND METHODS

A radiology report text search of terms used to describe developmental venous anomalies was performed on a study population of 580 patients with primary intracranial neoplasms and on a control population of 580 patients without neoplasms from the same time period. All positive results were reviewed to confirm that the report was describing a developmental venous anomaly, and the imaging examination was reviewed to confirm the diagnosis.

RESULTS

Fifty-nine of the 580 subjects with brain tumors (10.17%) had a developmental venous anomaly identified by report and confirmed on review of the imaging. Thirty-one of the 580 controls (5.34%) had a developmental venous anomaly identified by report and confirmed on review of the imaging (P = .003). No statistically significant difference was noted in the prevalence of developmental venous anomalies among tumor types. No developmental venous anomaly drained the vascular territory of the tumor, and there was no correlation between the location of the developmental venous anomaly and the location of the neoplasm.

CONCLUSIONS

The prevalence of developmental venous anomalies in this pediatric population with intracranial primary neoplasms is significantly greater than in those without neoplasms, suggesting an association that may be related to shared causative factors or susceptibilities to the development of these 2 separate entities.

Brain parenchymal signal abnormalities associated with developmental venous anomalies in children and young adults

BACKGROUND AND PURPOSE

Abnormal signal in the drainage territory of developmental venous anomalies has been well described in adults but has been incompletely investigated in children. This study was performed to evaluate the prevalence of brain parenchymal abnormalities subjacent to developmental venous anomalies in children and young adults, correlating with subject age and developmental venous anomaly morphology and location.

MATERIALS AND METHODS

Two hundred eighty-five patients with developmental venous anomalies identified on brain MR imaging with contrast, performed from November 2008 through November 2012, composed the study group. Data were collected for the following explanatory variables: subject demographics, developmental venous anomaly location, morphology, and associated parenchymal abnormalities. Associations between these variables and the presence of parenchymal signal abnormalities (response variable) were then determined.

RESULTS

Of the 285 subjects identified, 172 met inclusion criteria, and among these subjects, 193 developmental venous anomalies were identified. Twenty-six (13.5%) of the 193 developmental venous anomalies had associated signal-intensity abnormalities in their drainage territory. After excluding developmental venous anomalies with coexisting cavernous malformations, we obtained an adjusted prevalence of 21/181 (11.6%) for associated signal-intensity abnormalities in developmental venous anomalies. Signal-intensity abnormalities were independently associated with younger subject age, cavernous malformations, parenchymal atrophy, and deep venous drainage of developmental venous anomalies.

CONCLUSIONS

Signal-intensity abnormalities detectable by standard clinical MR images were identified in 11.6% of consecutively identified developmental venous anomalies. Signal abnormalities are more common in developmental venous anomalies with deep venous drainage, associated cavernous malformation and parenchymal atrophy, and younger subject age. The pathophysiology of these signal-intensity abnormalities remains unclear but may represent effects of delayed myelination and/or alterations in venous flow within the developmental venous anomaly drainage territory.

Prevalence of subdural collections in children with macrocrania

BACKGROUND AND PURPOSE

The relationship between enlarged subarachnoid spaces and subdural collections is poorly understood and creates challenges for clinicians investigating the etiology of subdural collections. The purpose of this study was to determine the prevalence of subdural collections on cross sectional imaging in children with macrocephaly correlating with subarachnoid space enlargement.

MATERIALS AND METHODS

The radiology information system of a large pediatric medical center was reviewed for "macrocrania" and "macrocephaly" on reports of cranial MRI/CT examinations in children <24 months of age, over a 24-month period. Head circumference was obtained from the clinical record. Studies were reviewed blindly for subdural collection presence and subarachnoid space size. Children with prior cranial surgery, parenchymal abnormalities, hydrocephalus, or conditions predisposing to parenchymal volume loss were excluded. Chart review was performed on those with subdural collections.

RESULTS

Imaging from 177 children with enlarged head circumference was reviewed. Nine were excluded, for a final cohort of 168 subjects (108 with enlarged subarachnoid space). Subdural collections were identified in 6 (3.6%), all with enlarged subarachnoid space (6/108, 5.6%). In 4, subdural collections were small, homogeneous, and nonhemorrhagic. In 2, the collections were complex (septations or hemorrhage). Two children were reported as victims of child abuse (both with complex collections). No definitive etiology was established in the other cases.

CONCLUSIONS

The prevalence of subdural collections in imaged children with macrocrania was 3.6%, all occurring in children with enlarged subarachnoid space. Our results suggest that enlarged subarachnoid space can be associated with some subdural collections in this cohort. Despite this, we believe that unexpected subdural collections in children should receive close clinical evaluation for underlying causes, including abusive head trauma.

Fetal and postnatal brain MRI in premature infants with twin-twin transfusion syndrome

OBJECTIVE

To describe the findings on fetal and postnatal magnetic resonance imaging (MRI) in premature infants with twin-twin transfusion syndrome (TTTS) and to determine whether currently used staging systems and other fetal and postnatal factors correlate with brain injury in this population.

STUDY DESIGN

We performed a prospective study of 22 premature infants with TTTS whose mothers had fetal MRIs. Postnatal brain MRI was performed at term equivalent age (38 to 44 weeks) and medical records were reviewed. Brain injury was scored on fetal and postnatal MRIs using an injury scale incorporating hemorrhagic and nonhemorrhagic injury.

RESULT

The median (range) gestational age (GA) was 31 weeks (26 to 35) and birth weight (BW) was 1296 g (762 to 2330). In all, 5/22 patients (23%) had brain injury seen on fetal MRI and 15/22 patients (68%) had brain injury seen on postnatal MRI. Quintero stage was the only predictor variable that was significantly correlated with the total brain injury score (P=0.05).

CONCLUSION

Postnatal brain injury in premature infants with TTTS is correlated with Quintero stage. GA and BW are not predictive of brain injury in this cohort of infants.

Diprosopus tetraophthalmus: CT as a complement to autopsy

Diprosopus is the rarest form of conjoined twinning. This anomaly is characterised by craniofacial duplication to varying degrees and is associated with anomalies of the central nervous, cardiac, respiratory and musculoskeletal systems. We present an infant characterised as diprosopus tetraophthalmus who underwent post-mortem CT, which served as a highly useful complement to autopsy.

Trainee misinterpretations on pediatric neuroimaging studies: classification, imaging analysis, and outcome assessment

BACKGROUND AND PURPOSE

The scope of trainee misinterpretations on pediatric neuroimaging studies has been incompletely assessed. Our aim was to evaluate the frequency of trainee misinterpretations on neuroimaging exams in children, describe a useful classification system, and assess related patient management or outcome changes.

MATERIALS AND METHODS

Pediatric neuroimaging examinations with trainee-dictated reports performed without initial attending radiologist assessment were evaluated for discrepant trainee interpretations by using a search of the RIS. The frequency of discrepant trainee interpretations was calculated and classified on the basis of the type of examination on which the error occurred, the specific type and severity of the discrepancy, and the effect on patient management and outcome. Differences relating to examination type and level of training were also assessed.

RESULTS

There were 143 discrepancies on 3496 trainee-read examinations for a discrepancy rate of 4.1%. Most occurred on CT examinations (131; 92%). Most discrepancies (75) were minor but were related to the clinical presentation. Six were major and potentially life-threatening. Thirty-seven were overcalls. Most had no effect on clinical management (97, 68%) or resulted simply in clinical reassessment or imaging follow-up (43, 30%). There was no permanent morbidity or mortality related to the misinterpretations. The most common misinterpretations were related to fractures (28) and ICH (23). CT examinations of the face, orbits, and neck had the highest discrepancy rate (9.4%). Third- and fourth-year residents had a larger discrepancy rate than fellows.

CONCLUSIONS

Trainee misinterpretations occur in 4.1% of pediatric neuroimaging examinations with only a small number being life-threatening (0.17%). Detailed analysis of the types of misinterpretations can be used to inform proactive trainee education.

Multimodality imaging in the surgical treatment of children with nonlesional epilepsy

OBJECTIVES

To evaluate the diagnostic value of individual noninvasive presurgical modalities and to study their role in surgical management of nonlesional pediatric epilepsy patients.

METHODS

We retrospectively studied 14 children (3-18 years) with nonlesional intractable focal epilepsy. Clinical characteristics, surgical outcome, localizing features on 3 presurgical diagnostic tests (subtraction peri-ictal SPECT coregistered to MRI [SISCOM], statistical parametric mapping [SPM] analysis of [18F] FDG-PET, magnetoencephalography [MEG]), and intracranial EEG (iEEG) were reviewed. The localization of each individual test was determined for lobar location by visual inspection. Concordance of localization between each test and iEEG was scored as follows: 2=lobar concordance; 1=hemispheric concordance; 0=discordance or nonlocalization. Total concordance score in each patient was measured by the summation of concordance scores for all 3 tests.

RESULTS

Seven (50%) of 14 patients were seizure-free for at least 12 months after surgery. One (7%) had only rare seizures and 6 (43%) had persistent seizures. MEG (79%, 11/14) and SISCOM (79%, 11/14) showed greater lobar concordance with iEEG than SPM-PET (13%, 3/14) (p<0.05). SPM-PET provided hemispheric lateralization (71%, 10/14) more often than lobar localization. Total concordance score tended to be greater for seizure-free patients (4.7) than for non-seizure-free patients (3.9).

CONCLUSIONS

Our data suggest that MEG and SISCOM are better tools for lobar localization than SPM analysis of FDG-PET in children with nonlesional epilepsy. A multimodality approach may improve surgical outcome as well as selection of surgical candidates in patients without MRI abnormalities.

Changing patterns of tracheotomy use in anterior skull base surgery with free tissue reconstruction

OBJECTIVE

To evaluate how changing patterns of tracheotomy use with free tissue reconstruction of the anterior skull base affect postoperative complications.

DESIGN

Retrospective comparison of clinical cohort to historic control group.

SETTING

Tertiary care medical center.

PATIENTS

We reviewed 201 patients with a diagnosis of malignant or locally aggressive benign neoplasms of the nasal cavity and paranasal sinuses between January 1993 and December 2006. Of these, we studied 33 consecutive patients that underwent ablative anterior skull base surgery reconstructed with free tissue transfers. We divided the study group into two cohorts: Group 1, patients treated from 1993-2000, and Group 2, patients treated from 2000-2006.

MAIN OUTCOME MEASURES

Tracheotomy use and postoperative complications.

RESULTS

There were 16 patients in Group 1 and 17 patients in Group 2. There were 11 patients who received a tracheotomy in Group 1, and only 5 in Group 2 (P = .038). Five patients in either group experienced complications (P = 1.000). There was one case of meningitis in Group 1 and no cases in Group 2 (P = .485). There were two cases of pneumocephalus in Group 2 and none in Group 1 (P = .485) and no cases of tension pneumocephalus. Six patients in each group had recurrent disease (P = 1.000). There was no statistically significant difference in survival (P = .675).

CONCLUSIONS

The decreased use of tracheotomy in patients undergoing free tissue transfer reconstruction of anterior skull base defects did not lead to an increase in complications. Routine use of tracheotomy in these patients is unnecessary and should be reserved for selected cases. Laryngoscope, 2009.

The acetazolamide challenge: techniques and applications in the evaluation of chronic cerebral ischemia

The acetazolamide (ACZ) challenge test is a useful clinical tool and a reliable predictor of critically reduced perfusion. In patients with chronic steno-occlusive disease, the ability to maintain normal cerebral blood flow by reducing vascular resistance secondary to autoregulatory vasodilation is compromised. Identification of the presence and degree of autoregulatory vasodilation (reflecting the cerebrovascular reserve) is a significant prognostic factor in patients with chronic cerebrovascular disease. The pharmacologic challenge of a vasodilatory stimulus such as ACZ can also be used to optimize the treatment strategies for these patients. The pathophysiology, methods, and clinical applications of the ACZ challenge test are discussed in this article.

De novo cerebral arteriovenous malformation: case report and literature review

We describe a rare case of a de novo cerebral arteriovenous malformation (AVM) in a 9-year-old girl. MR imaging at 6 years of age demonstrated band heterotopia. Follow-up MR imaging 3 years later demonstrated a new 3.5-cm AVM in the left parietol-occipital region, confirmed by conventional angiography. This report, along with limited previous reports, suggests that AVMs can be acquired lesions and that AVM development is a dynamic process extending into the postnatal period.

Large arachnoid granulations involving the dorsal superior sagittal sinus: findings on MR imaging and MR venography

BACKGROUND AND PURPOSE

Large arachnoid granulations (AG) within the dorsal superior sagittal sinus (SSS) have been incompletely characterized and can be confused with pathology. This report reviews the characteristics of these anatomic structures to establish common imaging features that allow differentiation from pathology.

MATERIALS AND METHODS

Twelve cases of large AG in the dorsal SSS are presented, identified by MR imaging. Signal intensity characteristics, size, location, venographic appearance, and association with adjacent venous and osseous structures were documented.

RESULTS

A defect in the dura of the SSS was seen in all of the cases communicating with the subjacent subarachnoid space. The average size of the AG was 8.1 x 9.4 x 10.0 mm (range, 4-19 mm). Ten produced calvarial remodeling, and 11 were in the direct vicinity of the lambda. On T2-weighted images, all were hyperintense to the brain. On T1-weighted images, 8 were hypointense and 4 were hypointense with mixed areas of isointense signal intensity. All of the AGs were associated with cortical venous structures entering the sinus. On MR venography, AGs appeared as focal protrusions into the sinus, displacing, distorting, and narrowing the sinus lumen. Seven patients had headache without other visible cause on MR imaging, and 4 were initially interpreted as thrombosis or tumor.

CONCLUSION

Large AGs can occur in the dorsal SSS. They are well-defined projections of the subarachnoid space into the sinus, can cause luminal narrowing and calvarial remodeling, and have typical signal intensity characteristics, position, and morphology differentiating them from other pathology. Association with patient symptoms is uncertain.

Brain parenchymal signal abnormalities associated with developmental venous anomalies: detailed MR imaging assessment

BACKGROUND AND PURPOSE

The occurrence of brain parenchymal signal-intensity changes within the drainage territory of developmental venous anomalies (DVAs) in the absence of cavernous malformations (CMs) has been incompletely assessed. This study was performed to evaluate the prevalence of brain parenchymal signal-intensity abnormalities subjacent to DVA, correlating with DVA morphology and location.

MATERIALS AND METHODS

One hundred sixty-four patients with brain MR imaging with contrast studies performed from July 2005 through June 2006 formed the study group. The examinations were reviewed and data were collected regarding the following: location, depth, size of draining vein, associated increased signal intensity on fluid-attenuated inversion recovery and T2-weighted images, associated CMs, and associated signal intensity on gradient recalled-echo sequences.

RESULTS

Of the 175 DVAs identified, 28 had associated signal-intensity abnormalities in the drainage territory. Seven of 28 DVAs with signal-intensity abnormalities were excluded because of significant adjacent white matter signal-intensity changes related to other pathology overlapping the drainage territory. Of the remaining DVAs imaged in this study, 21/168 (12.5%) had subjacent signal-intensity abnormalities. An adjusted prevalence rate of 9/115 (7.8%) was obtained by excluding patients with white matter disease more than minimal in degree. Periventricular location and older age were associated with DVA signal-intensity abnormality.

CONCLUSION

Signal-intensity abnormalities detectable by standard clinical MR images were identified in association with 12.5% of consecutively identified DVAs. Excluding patients with significant underlying white matter disease, we adjusted the prevalence to 7.8%. The etiology of the signal-intensity changes is unclear but may be related to edema, gliosis, or leukoaraiosis secondary to altered hemodynamics in the drainage area.

Eye position information on CT increases the identification of acute ischemic hypoattenuation

BACKGROUND AND PURPOSE

It is possible that identification of eye deviation may sensitize a scan reader to early brain hypodensity associated with an arterial occlusive process. Our aim was to investigate the value of observing eye deviation on blinded CT identification of early hypoattenuation following ischemic infarct.

MATERIALS AND METHODS

Two staff and 2 fellow neuroradiologists reviewed 75 brain CT scans obtained within 3 hours of acute ischemia from subjects in the Interventional Management of Stroke Study. Films were reviewed 3 months apart, the first time with tape over the eyes on the images, the second with the eyes visible. Readers were asked if early hypoattenuation in the middle cerebral artery (MCA) distribution or if a hyperattenuated MCA was present. kappa statistics were calculated to determine agreement among the 4 readers and between each of the 2 readings by the same reader, not only for the original interpretation of the blinded study neuroradiologist but also for the Alberta Stroke Program Early CT Score (ASPECTS) for each subject assigned by an unblinded expert panel. A generalized estimating equations modeling approach was used to look at the overall effect of including eye information for agreement between interpretations.

RESULTS

Eye information availability was associated with improved agreement for detection of early ischemic hypoattenuation not only among the 4 readers but also between the 4 readers and both the blinded study neuroradiologist (P = .02) and the unblinded expert ASPECTS panel. When comparing first and second readings for hypoattenuation, we also noted increased mean values for sensitivity (46.8% first, 56.5% second), specificity (78.2%, 80.2%), positive predictive value (72.0%, 80.7%), negative predictive value (55.5%, 61.0%), and percentage agreement (61.0%, 67.5%).

CONCLUSION

Observation of CT eye deviation significantly improves reader identification of acute ischemic hypoattenuation.

Overnight preliminary head CT interpretations provided by residents: locations of misidentified intracranial hemorrhage

BACKGROUND AND PURPOSE

Our aim was to determine the patterns of error of radiology residents in the detection of intracranial hemorrhage on head CT examinations while on call. Follow-up studies were reviewed to determine if there was any adverse effect on patient outcome as a result of these preliminary interpretations.

MATERIALS AND METHODS

Radiology residents prospectively interpreted 22,590 head CT examinations while on call from January 1, 2002, to July 31, 2006. The following morning, the studies were interpreted by staff neuroradiologists, and discrepancies from the preliminary report were documented. Patients' charts were reviewed for clinical outcomes and any imaging follow-up.

RESULTS

There were a total of 1037 discrepancies identified, of which 141 were due to intracranial hemorrhage. The most common types of intracranial hemorrhage that were missed were subdural and subarachnoid hemorrhage occurring in 39% and 33% of the cases, respectively. The most common location for missed subdural hemorrhage was either parafalcine or frontal. The most common location of missed subarachnoid hemorrhage was in the interpeduncular cistern. There was 1 case of nontraumatic subarachnoid hemorrhage that was not described in the preliminary report. Fourteen patients were brought back to the emergency department for short-term follow-up imaging after being discharged. We did not observe any adverse clinical outcomes that resulted from a discrepant reading.

CONCLUSION

Discrepancies due to intracranial hemorrhage are usually the result of subdural or subarachnoid hemorrhage. A more complete understanding of the locations of the missed hemorrhage can hopefully help decrease the discrepancy rate to help improve patient care.

The Effect of a Hydrogen Peroxide Wound Care Regimen on Tensile Strength of Suture

OBJECTIVE

To compare the tensile strength of nylon, polypropylene, and fast-absorbing gut sutures treated with either 3% hydrogen peroxide or water for a period of 5 days to emulate a wound care regimen.

METHODS

An In-Spec 2200 bench-top tester was used to find the maximum load that a particular suture could sustain prior to breaking.

RESULTS

Analysis of the data showed a statistically significant decrease in tensile strength of fast-absorbing gut sutures treated with hydrogen peroxide compared with fast-absorbing gut suture control samples and fast-absorbing gut sutures treated with only water.

CONCLUSION

Though no in vivo studies were performed, a logical extension of these results would be that premature degradation of fast-absorbing gut sutures secondary to use of hydrogen peroxide might lead to widened and/or hypertrophic scars.

Cerebral venous thrombus signal intensity and susceptibility effects on gradient recalled-echo MR imaging

BACKGROUND AND PURPOSE

Cerebral venous thrombus (CVT) signal intensity is variable on MR imaging, and the appearance of CVT on gradient recalled-echo (GRE) sequences has been incompletely assessed. This study was performed to evaluate the GRE imaging appearance of CVT in different stages of thrombus evolution and its relationship to signal intensity on other MR pulse sequences.

MATERIALS AND METHODS

The clinical and MR imaging findings in 18 patients with CVT and GRE imaging were reviewed. Sixty-nine thrombosed venous segments were evaluated, and the signal intensity of thrombus relative to gray matter was determined. The degree of thrombus susceptibility effect (SE) was assessed and related to time of imaging after onset of symptoms (clinical thrombus age) and appearance on other pulse sequences. Segments were classified as SE+ (demonstrating susceptibility effect) or SE- (no susceptibility effect).

RESULTS

Thirty-six venous segments exhibited visible SE. SE+ segments had a clinical thrombus age that was less than that in SE- segments (8.1 versus 24.6 days, P=.003). Sixty-three percent (23/36) of SE+ segments exhibited hypointensity on T2-weighted images (T2WI) versus 12% (4/33) of SE- segments (P<.001). Twenty-nine of 32 (90.6%) segments with clinical thrombus age of 0-7 days were SE+, versus 7 of 30 (23.3%) segments with a thrombus age of 8 days or greater.

CONCLUSION

SEs from CVT can be detected with GRE imaging and are most prevalent in patients with hypointense thrombus on T2WI within 7 days after the symptom onset. This correlates with the paramagnetic effects of deoxyhemoglobin in acute stage thrombus. GRE imaging may be useful in detecting thrombus in this stage when difficult to detect on other pulse sequences.

Partially recanalized chronic dural sinus thrombosis: findings on MR imaging, time-of-flight MR venography, and contrast-enhanced MR venography

BACKGROUND AND PURPOSE

The imaging appearance of chronic, partially recanalized dural sinus thrombosis has been incompletely described. We sought to more fully characterize the imaging findings of this entity on MR imaging, time-of-flight MR venography (TOF-MRV), and elliptic centric-ordered contrast-enhanced MR venography (CE-MRV).

MATERIALS AND METHODS

From a data base of patients with cerebral venous thrombosis, 10 patients were identified with imaging and clinical findings consistent with the diagnosis of chronic, partially recanalized, dural sinus thrombosis. All patients had MR imaging of the brain without and with contrast. Nine patients underwent MRV, and 6 had both CE-MRV and TOF-MRV. Thirty-four venous segments were thrombosed and were assessed in detail for multiple imaging features.

RESULTS

Most thrombosed segments were isointense to gray matter on T1-weighted images (85%), and hyperintense to gray matter on T2-weighted images (97%). Visible serpiginous intrathrombus flow voids were visible in 23 segments (8/10 patients) corresponding with areas of flow signal intensity on TOF-MRV and enhancing channels on contrast MRV. Eighty-four percent of thrombosed segments enhanced equal to or greater than venographically normal venous sinuses. TOF-MRV and CE-MRV were abnormal in all patients, and CE-MRV more completely characterized the thrombosed segments. The imaging appearance did not change in those patients with follow-up imaging (average 13.6 months).

CONCLUSION

Chronic, partially recanalized, venous thrombosis has a characteristic appearance on MR and MRV. CE-MRV was abnormal in all cases, despite the intense enhancement of the thrombosed segments. Because of the highly selected nature of the cases reported, further study is required to determine whether these findings are present in all cases of this condition.

Osteomyelitis of the skull in early-acquired syphilis: evaluation by MR imaging and CT

We present an unusual case of acquired secondary syphilis manifesting as osteomyelitis of the skull in a patient with a history of human immunodeficiency virus infection, evaluated by CT, volumetric CT reconstructions, and MR imaging.

Dual-Porosity Expanded Polytetrafluoroethylene Implants for Lip, Nasolabial Groove, and Melolabial Groove Augmentation

OBJECTIVE

To evaluate the clinical outcomes with the use of a dual-porosity expanded polytetrafluoroethylene implant for midfacial rejuvenation.

DESIGN

An institutional review board-approved retrospective chart review was conducted of all patients who underwent implantation with the dual-porosity expanded polytetrafluoroethylene implant between 2001 and 2005.

RESULTS

A total of 170 patients, with 612 implants, were evaluated. Only 8 patients had minor complications, 3 of which necessitated implant removal. The overall results of independent observer analysis of outcomes were favorable in the majority of cases.

CONCLUSION

The dual-porosity expanded polytetrafluoroethylene implant is safe and reliable to use for midfacial implantation.

Four suture tip rhinoplasty: a powerful tool for controlling tip dynamics

OBJECTIVE

To evaluate the short-term effectiveness of using a 4-suture technique to control nasal tip dynamics. The 4 sutures include a medial crural suture, bilateral intradomal sutures, and an interdomal suture.

STUDY DESIGN AND SETTING

Retrospective photograph analysis of preoperative and postoperative photographs of 77 patients with respect to 7 dynamic variables: supratip break, projection, rotation, tip shape, tip definition, tip symmetry, and the presence of a double columellar break.

RESULTS

Seventy-four patients underwent primary rhinoplasty and had an overall average score of 5.2 on a -7 to +7 scale, with a mean follow-up period of 3.8 months. The 3 patients undergoing revision rhinoplasty had an overall average score of 5.0 and a mean follow-up of 8.7 months.

CONCLUSION

The 4-suture technique worked best with respect to projection and tip symmetry, although the technique proved to be an effective tool overall in controlling all 7 variables mentioned above.

EBM RATING

C-4.

Left vertebral artery origin from the thyrocervical trunk: a unique vascular variant

The vertebral artery normally arises from the subclavian artery, and variations in its origin have been described. We describe a unique case of the left vertebral artery arising from the thyrocervical trunk.

New techniques for management of the crooked nose

The crooked or twisted nose results from a complex deformity of the bony pyramid, the upper and lower cartilaginous vaults, and the septum and causes functional and aesthetic problems. The forces of scar contracture coupled with long-standing cartilage deformation may make the crooked nose resistant to conventional surgical intervention. The middle vault of the nose may exhibit deformities that are due to atrophy, deviations, and skewing in relationship to the other regions of the nose. We report a series of 79 cases of significantly crooked noses to highlight 5 techniques not widely discussed in the facial plastic surgery literature.

Techniques for improving ear definition in microtia reconstruction

Surgeons involved in microtia repair recognize the difficulty in creating a natural appearing ear. One key to successful reconstruction is to provide sufficient relief between the helix, scaphoid fossa and antihelix to create the illusion of thin skin overlying thin cartilage. Problems such as thick skin, hair-bearing skin and poor-quality cartilage serve to frustrate the surgeons attempt to achieve the desired result. Surgical techniques to improve cartilaginous framework definition in microtia repair are discussed.

Osteoinduction using bone morphogenic protein in irradiated tissue

OBJECTIVE

To prove the efficacy of bone morphogenic protein as an osteoinductive agent in irradiated tissue.

DESIGN

Prospective randomized controlled trial designed to test the effectiveness of recombinant bone morphogenic protein 2 (rBMP-2) combined with solid hydroxyapatite disks in an irradiated tissue bed.

SUBJECTS

Eighteen adult, male, white New Zealand rabbits weighing 3.0 to 3.5 kg.

INTERVENTION

The rabbits were randomly divided, with 9 receiving radiation treatment and 9 receiving no radiation treatment. Each animal underwent implantation of 2 hydroxyapatite disks onto the snout at 9 weeks following radiation treatment. One disk was impregnated with rBMP-2 and the other with buffer only. The animals were killed at 3, 6, or 20 weeks after implantation for analysis.

RESULTS

Histological analysis demonstrated that rBMP-2 was equally effective as an osteoinductive agent in the irradiated and nonirradiated tissue. We also found significantly increased new bone formation in the rBMP-2 group vs the buffer group.

CONCLUSIONS

This study supports the potential clinical utility of rBMP-2 and solid hydroxyapatite in irradiated tissue beds. These findings have interesting implications for patients with head and neck cancer who have undergone radiation therapy and need bony reconstruction.

Lateral thigh flap reconstruction in the head and neck

The lateral thigh free flap is a fasciocutaneous flap based on the cutaneous perforators of the deep femoral vessels. Although originally described in 1983, it has had very few reports in the literature. This article describes the flap and reports our findings and outcomes in nine cadavers (18 thighs) and 33 clinical cases. The position of the vascular pedicle may vary in each case but has always been found to be present. Successful transfer occurred in 30 of 33 cases. Flap loss was attributable to infection, fistula, and hematoma in three of four cases. The flap was especially useful in large defects, most commonly total and base-of-tongue defects. We have found this flap to be reliable and to result in minimal morbidity.

Prevention of flash fires during facial surgery performed under local anesthesia

As more surgical procedures are being performed under local anesthesia and intravenous sedation, complications associated with these techniques are more likely to be experienced. We report a case of an intraoperative flash fire that occurred while supplemental oxygen was being used in this scenario. A literature review and suggestions for prevention of this complication are discussed.

Isolation from human placenta of the IgG transporter, FcRn, and localization to the syncytiotrophoblast: implications for maternal-fetal antibody transport

The IgG transporter responsible for ferrying maternal IgG across the human placenta to fetal circulation has not been identified, although the human homologue of the neonatal rat Fc receptor (FcRn), a heterodimer with pH-dependent IgG affinity, structurally similar to MHC Class I molecules, was recently proposed as a candidate. Affirming this hypothesis, we describe herein the specific copurification from human placenta of 46- and 14-kDa proteins by IgG affinity at acid pH. The larger protein, characterized by its amino acid sequence and by immunoblot, is the alpha-chain of human FcRn (hFcRn). The smaller is beta2-microglobulin. Their coisolation by ligand affinity suggests that they comprise the hFcRn heterodimer. Placenta sections stained immunohistochemically with anti-hFcRn alpha-chain peptide Abs show extensive expression of hFcRn in the syncytiotrophoblast and traces in the endothelium and other unidentified cells of the villus stroma. We find alpha-chain mRNA by Northern analysis in human placenta and in human trophoblast-like cell lines (JEG-3, ED27) but not in a human myelocytic cell line (HL60). We suggest that the placental hFcRn heterodimer may transport IgG to the fetus by a mechanism in which maternal IgG is pinocytosed nonspecifically and then carried to fetal tissues by a pH gradient from acidic endosomes to the pH-neutral basolateral surface of the syncytiotrophoblast. Furthermore, the known characteristics of FcRn suggest a wider function, that it is the receptor postulated by Brambell in the 1960s to regulate tissue and serum IgG concentrations by controlling IgG transport and catabolism.

Isolation from human placenta of the IgG transporter, FcRn, and localization to the syncytiotrophoblast: implications for maternal-fetal antibody transport

The IgG transporter responsible for ferrying maternal IgG across the human placenta to fetal circulation has not been identified, although the human homologue of the neonatal rat Fc receptor (FcRn), a heterodimer with pH-dependent IgG affinity, structurally similar to MHC Class I molecules, was recently proposed as a candidate. Affirming this hypothesis, we describe herein the specific copurification from human placenta of 46- and 14-kDa proteins by IgG affinity at acid pH. The larger protein, characterized by its amino acid sequence and by immunoblot, is the alpha-chain of human FcRn (hFcRn). The smaller is beta2-microglobulin. Their coisolation by ligand affinity suggests that they comprise the hFcRn heterodimer. Placenta sections stained immunohistochemically with anti-hFcRn alpha-chain peptide Abs show extensive expression of hFcRn in the syncytiotrophoblast and traces in the endothelium and other unidentified cells of the villus stroma. We find alpha-chain mRNA by Northern analysis in human placenta and in human trophoblast-like cell lines (JEG-3, ED27) but not in a human myelocytic cell line (HL60). We suggest that the placental hFcRn heterodimer may transport IgG to the fetus by a mechanism in which maternal IgG is pinocytosed nonspecifically and then carried to fetal tissues by a pH gradient from acidic endosomes to the pH-neutral basolateral surface of the syncytiotrophoblast. Furthermore, the known characteristics of FcRn suggest a wider function, that it is the receptor postulated by Brambell in the 1960s to regulate tissue and serum IgG concentrations by controlling IgG transport and catabolism.

Normal appearance of arachnoid granulations on contrast-enhanced CT and MR of the brain: differentiation from dural sinus disease

PURPOSE

To determine the imaging appearance and frequency with which arachnoid granulations are seen on contrast-enhanced CT and MR studies of the brain.

METHODS

We retrospectively reviewed 573 contrast-enhanced CT scans and 100 contrast-enhanced MR studies of the brain for the presence of discrete filling defects within the venous sinuses. An anatomic study of the dural sinuses of 29 cadavers was performed, and the location, appearance, and histologic findings of focal protrusions into the dural sinus lumen (arachnoid granulations) were assessed and compared with the imaging findings.

RESULTS

Discrete filling defects within the dural sinuses were found on 138 (24%) of the contrast-enhanced CT examinations. A total of 168 defects were found, the majority (92%) within the transverse sinuses. One third were isodense and two thirds were hypodense relative to brain parenchyma. Patients with filling defects were older than patients without filling defects (mean age, 46 years versus 40 years). Discrete intrasinus signal foci were noted on 13 (13%) of the contrast-enhanced MR studies. The foci followed the same distribution as the filling defects seen on CT scans and were isointense to hypointense on T1-weighted images, variable in signal on balanced images, and hyperintense on T2-weighted images. Transverse sinus arachnoid granulations were noted adjacent to venous entrance sites in 62% and 85% of the CT and MR examinations, respectively. Arachnoid granulations were found in 19 (66%) of the cadaveric specimens, in a similar distribution as that seen on the imaging studies.

CONCLUSION

Discrete filling defects, consistent with arachnoid granulations, may be seen in the dural sinuses on 24% of contrast-enhanced CT scans and on 13% of MR studies. They are focal, well-defined, and typically located within the lateral transverse sinuses adjacent to venous entrance sites. They should not be mistaken for sinus thrombosis or intrasinus tumor, but recognized as normal structures.

Imaging evaluation of cervical spine trauma

Plain radiography remains the standard imaging modality for initial evaluation of cervical spine trauma. CT and MR imaging play an important role in additional evaluation for patients with known or suspected injuries. The role of conventional tomography and myelography is limited.

Total potentially available nucleosides of human milk by stage of lactation

Human milk-borne ribonucleotides reportedly have important physiological roles in breast-fed infants. Previous studies measured the free nucleotide content of human milk. To more fully evaluate the physiological capacity of nucleotides in human milk, we determined the monomeric and polymeric ribonucleotide and ribonucleoside content of milk pooled from 11 American women. Subsequently, we determined the total potentially available nucleosides (TPAN) of pooled and individual milk samples segregated by stage of lactation from 100 women in three European countries to test for effect of culture and diet. The methodology simulated in vivo digestion. Polymeric ribonucleotide (primarily RNA), monomeric ribonucleotide, and ribonucleoside-containing adducts (eg, uridine diphosphate hexose) were enzymatically hydrolyzed to their constituent ribonucleosides, the preferred form for absorption. Free and enzymatically liberated nucleosides were then measured by HPLC to yield the TPAN value. The mean (+/- SD) TPAN concentration of the 16 pooled European samples, derived from the 100 individual samples, was 189 +/- 70 mumol nucleoside/L human milk (range 82-402 mumol/L). The means (mumol/L human milk) of each nucleoside were 38 for uridine, 88 for cytidine, 31 for guanosine, and 32 for adenosine. These values included the contribution from the cellular portion of human milk. Only one of the 16 pooled samples contained a measurable amount of inosine (4 mumol/L). The potentially available ribonucleosides in the human milk samples were predominantly present as monomeric (36 +/- 10%) and polymeric (48 +/- 8%) nucleotides.(ABSTRACT TRUNCATED AT 250 WORDS)

Endoscopic resection of the intranasal frontal sinus floor

The current accepted treatment for chronic frontal sinus disease unresponsive to medical management and endoscopic surgery is an external approach to either obliterate the sinus or restore communication to the nasal cavity. Here reported is an endoscopic approach for resection of the intranasal frontal sinus floor, a modification of a procedure first described by Lothrop in 1899. Eleven patients underwent this operation from April 1993 to December 1993. One complication, a cerebrospinal fluid leak treated successfully endoscopically, has occurred. Of the 7 patients followed up 3 months or longer after surgery, only 1 has developed symptoms of recurrent frontal sinusitis. On the basis of this limited preliminary experience, the endoscopic Lothrop procedure shows promise as an effective operation designed to establish a physiologic communication between the frontal sinus and the nasal cavity in selected patients who would otherwise be candidates for an external approach.

Reliability of microvascular free flaps in head and neck reconstruction

Reliable reconstructive techniques are essential in the surgical treatment of head and neck cancer patients. Free flaps have often been used as reconstructive options of last resort in the head and neck because of the need for added technical skill, a longer operating time, and a perception of poor reliability. This study reviews our experience with 39 free flaps performed by the Otolaryngology-Head and Neck Surgery Service. For the first 17 cases, an interrupted anastomotic technique was used; a running technique was performed in the remaining 22 cases. The average total ischemic time (3.7 vs. 2.7 hours; p < 0.001) was significantly less with a running technique. There were 10 complications: 7 minor would problems, 1 death from aspiration without surgical wound/flap problem, and 2 cases requiring second flaps (1 flap necrosis, 1 fistula with healthy free flap). No statistical correlation was found between complications and ischemic time, suture technique, age, or hospital (five hospitals). Free flaps are reliable and may obviate the need for sacrifice of trunk muscles for wound closure (e.g., fascicocutaneous free flaps instead of myocutaneous flaps); therefore we recommend revascularized free flaps as the primary mode of reconstruction for head and neck defects.

Pericyte degeneration and thickening of basement membranes of cerebral microvessels in complex partial seizures: electron microscopic study of surgically removed tissue

Complex partial seizures are associated with alterations in regional cerebral blood flow in abnormally spiking foci, as shown by positron emission tomography and single photon emission computed tomography, with an increase in flow ictally and a decrease interictally. Alterations of vasoregulation during ictal periods have also been described in animal seizure models. An electron microscopic study on human brain tissue from seven patients undergoing resections for the treatment of intractable complex partial seizures was performed to examine ultrastructural changes of the microvasculature and their locations within the microvessel wall. Biopsies were obtained intraoperatively from temporal lobe regions with electrocorticographically detected abnormal spiking and from regions without abnormality on electrocorticograms (control samples) removed as part of the therapeutic resection. A total of 539 microvessels from three regions were evaluated: spiking mesial temporal lobe, spiking lateral temporal cortex, and nonspiking (control) cortex. Evidence of pericyte degeneration (aggregates of cellular debris within the basement membrane) was noted in the majority of spiking area microvessels (76.7% in spiking mesial temporal cortex; 69.8% in spiking lateral temporal cortex) as compared with 37.8% of control microvessels (P less than 0.0005). Morphometric studies revealed a significant increase in total wall thickness, pericyte-basement membrane unit thickness, pericyte cytoplasmic density, basement membrane density, and basement membrane thickness in microvessels from spiking (mesial and lateral temporal cortex), as compared to control areas (P less than 0.01). No statistically significant difference was noted in pericyte coverage or pericyte or endothelial mitochondrial densities between microvessels in spiking and control regions. This study shows degeneration of pericytes, cells thought to play an essential role in microvascular hemodynamics, and thickening of microvessel walls in abnormally spiking brain regions in patients with intractable complex partial seizures. The pericyte degeneration and basement membrane thickening in abnormally spiking areas may explain alterations in vasoregulation, by a decrease in the microvascular compliance and in cross-capillary diffusion.

Effect of topical fosfomycin on polymyxin B ototoxicity

Fosfomycin is an antibiotic that has been found to reduce the ototoxicity of aminoglycoside antibiotics and cisplatin when systemically coadministered. Polymyxin B, an antibiotic frequently used in ototopical preparations, has been shown to be ototoxic in experimental studies. To investigate the effect of fosfomycin on polymyxin B ototoxicity, topical administration of the two agents into the middle ear cavity was performed. Two groups of chinchillas were used. One group received applications of polymyxin B alone, and the second group received polymyxin B combined with fosfomycin. It was found that application of polymyxin B produces severe damage to the cochlea. However, when polymyxin B was given in combination with fosfomycin, cochlear damage was dramatically reduced. It is likely that in clinical use, a combination of polymyxin B and fosfomycin would demonstrate reduced risk of ototoxicity.