Pediatric head and neck emergencies.

PURPOSE: Head and neck emergencies in children are frequent cause of visits to the hospital. Imaging plays a critical role in the management of these patients. This review article aims to familiarize radiologists with the common clinical presentations encountered, imaging characteristics of nontraumatic pediatric head and neck emergencies, and improve their ability to recognize associated complications as well as be aware of common mimics. METHODS: We researched our database for commonly encountered nontraumatic head and neck emergencies in children. A literature search was done to compare and complete the list of conditions to be discussed in this review. RESULTS: The review was organized according to anatomical location of the emergent condition. Relevant anatomy has been discussed along with clinical presentation, imaging characteristics and complications. We have presented common mimics with each set of disorders. Key imaging characteristics have been delineated using radiology images. CONCLUSION: Familiarity with the known complications of head and neck emergencies allows the radiologist to actively search for such findings, encourage early institution of appropriate therapy, and improve outcomes.

Non-accidental trauma: the role of radiology.

Non-accidental trauma is a significant source of morbidity and mortality in the pediatric population. Given the vulnerable state of the child, the radiologist can often provide valuable diagnostic information in the setting of suspected abuse. This review focuses on common findings of abusive trauma and serves as a guide to aid in clinical decision-making for providers of emergency medicine and pediatrics. Amid this discussion is an assessment of modern controversies regarding reported mimicking pathologies, recapitulation of the current state of evidence with respect to radiologic findings of abuse, and examination of the contribution that spine imaging may add to the diagnosis of possible abusive head trauma in the acutely injured child. Recommendations for avoiding pitfalls regarding the dating of intracranial injuries are discussed, and illustrated depictions of perpetrator-induced pathology are provided to aid in the understanding of these injuries. Through the use of the appropriate approach to imaging and evidence-based guidelines regarding radiologic findings, the role of radiology is to provide fundamental clues to diagnose and prevent recurrence of abusive injury in patients who cannot speak for themselves.

Nonrandomized comparison of neurofibromatosis type 1 and non-neurofibromatosis type 1 children who received carboplatin and vincristine for progressive low-grade glioma: A report from the Children's Oncology Group.

BACKGROUND: To evaluate tumor responses, event-free survival (EFS), overall survival (OS), and toxicity of chemotherapy, children with neurofibromatosis type 1 (NF1) and progressive low-grade glioma were enrolled into the Children's Oncology Group (COG) A9952 protocol and treated with carboplatin and vincristine (CV). METHODS: Non-NF1 patients were randomized to CV or thioguanine, procarbazine, 1-(2-chloroethyl)-3-cyclohexyl-1-nitrosourea, and vincristine in COG A9952. NF1 patients were assigned to CV only. NF1 patients and non-NF1 patients who were treated with CV were compared with respect to baseline characteristics, toxicity, tumor responses, EFS, and OS. RESULTS: A total of 127 eligible patients with NF1 were nonrandomly assigned to CV: 42 NF1 patients (33%) had events, and 6 (4.7%) died. The 5-year EFS rate was 69% ± 4% for the CV-NF1 group and 39% ± 4% for the CV-non-NF1 group (P < .001). In a univariate analysis, NF1 children had a significantly higher tumor response rate and superior EFS and OS in comparison with CV-treated children without NF1. NF1 patients and non-NF1 patients differed significantly in amount of residual tumor, extent of resection, tumor location, and pathology. According to a multivariate analysis, NF1 was independently associated with better EFS (P < .001) but not with OS. NF1 patients also had a decreased risk of grade 3 or 4 toxicities in comparison with non-NF1 patients. Three second malignant neoplasms occurred in NF1 patients receiving CV (CV-NF1 group) at a median of 7.8 years (range, 7.3-9.4 years) after enrollment, but there were none in the non-NF1 group. CONCLUSIONS: Children with NF1 tolerated CV well and had tumor response rates and EFS that were superior to those for children without NF1. Cancer 2016;122:1928-36. © 2016 American Cancer Society.

MRI of the petromastoid canal in children.

PURPOSE: To characterize the MRI features of the petromastoid canal in children with sensorineural hearing loss (SNHL) and in normal infants. MATERIALS AND METHODS: High resolution MRI examinations of 564 children who were evaluated for SNHL and brain MRI examinations of 112 infants who had normal studies were studied independently by two reviewers. RESULTS: In SNHL group, visibility of the PMC decreased for right and left PMC (P < 0.001). The width of the right PMC significantly decreased as age increased (P < 0.0001). There was no relation between abnormalities of membranous labyrinth and cochlear nerve and PMC visibility in children with SNHL (p > 0.05). In the normal group, the PMC visibility decreased with increasing age (right P = 0.0001, left P = 0.001). In the normal group also, as age increased, the PMC width decreased for both PMCs (right, P = 0.0006; left, P = 0.03). CONCLUSION: The PMC is more frequently visualized in young children. Its visibility and width are not associated with abnormalities of membranous labyrinth and cochlear nerves.

High-resolution 3-D T2-weighted imaging in the diagnosis of labyrinthitis ossificans: emphasis on subtle cochlear involvement.

BACKGROUND: Meningitis is the most common cause of acquired sensorineural hearing loss (SNHL) in children. Labyrinthitis ossificans develops in a significant number of patients with meningitis-related SNHL. Reduced T2 signal on MRI within the membranous labyrinth is often noted in the fibrous and ossifying stages of labyrinthitis ossificans. OBJECTIVE: The purpose of this study is to demonstrate the distribution and extent of involvement of the cochlea in children being evaluated for labyrinthitis ossificans; using high-resolution 3-D T2-weighted imaging, and to evaluate for subtle involvement of the scala tympani within the basal turn of the cochlea. MATERIALS AND METHODS: A retrospective review from 2002 to 2012 was performed using a cochlear implant database and PACS search function. Twenty-four patients were found to have MR findings consistent with labyrinthitis ossificans, 13 previously reported. Axial 3-D T2-weighted sequences were obtained in all patients. The presence of abnormal decreased T2 signal within the scala tympani and vestibuli of the cochlea was noted and graded according to the extent. The electronic medical record was reviewed for audiometry and risk factors as well as correlative operative findings. RESULTS: The average age at imaging was 4.2 years. M:F ratio = 5:1. Eighty-eight percent (21/24) of patients had bilateral SNHL. The most common risk factor for labyrinthitis ossificans was meningitis (19/24 or 79%). Eighteen (75%) patients had a history of bacterial meningitis. The mean age for the onset of labyrinthitis was 1.2 years with an average of 2.2-year interval to imaging. Nineteen patients (79%) underwent placement of a cochlear implant. Cochlear obstruction was documented in 83% (40/48) of the ears. Lower grade (1) cochlear obstruction was present in 14 ears and limited to the scala tympani. Statistical analysis was performed correlating MRI imaging and surgical findings. CONCLUSION: Subtle, isolated involvement of the scala tympani within the proximal basal turn is a common finding in labyrinthitis ossificans and history typical for meningitis is not uniformly present. The extent of cochlear obstruction is important and has surgical implications.

Congenital Cystic Neck Masses.

Congenital cystic masses are commonly encountered when imaging a patient presenting with a neck mass. Congenital cysts are present at birth; however, these cysts may not present until later in life with some growing slowly and others rapidly increasing in size due to hemorrhage of infection. A neonatal presentation is rare but when present may allow a narrower differential diagnosis. Imaging plays a significant role in defining a lesion as cystic, assessing location, and directing the next step in evaluation and or intervention.

Cervical spine evaluation in pediatric trauma.

OBJECTIVE: This article will review the current literature as it relates to imaging of the child suspected to have cervical spine injury (CSI) and the imaging findings of pediatric CSI, focusing on strategies to minimize radiation dose while maximizing diagnostic yield. CONCLUSION: Although CSI is uncommon in children, the clinical implications of failure to correctly diagnose CSI are significant. Clinical decision rules proven effective in predicting CSI in adults cannot be uniformly applied to children.

Children's Oncology Group Phase III Trial of Reduced-Dose and Reduced-Volume Radiotherapy With Chemotherapy for Newly Diagnosed Average-Risk Medulloblastoma.

PURPOSE: Children with average-risk medulloblastoma (MB) experience survival rates of ≥ 80% at the expense of adverse consequences of treatment. Efforts to mitigate these effects include deintensification of craniospinal irradiation (CSI) dose and volume. METHODS: ACNS0331 (ClinicalTrials.gov identifier: NCT00085735) randomly assigned patients age 3-21 years with average-risk MB to receive posterior fossa radiation therapy (PFRT) or involved field radiation therapy (IFRT) following CSI. Young children (3-7 years) were also randomly assigned to receive standard-dose CSI (SDCSI; 23.4 Gy) or low-dose CSI (LDCSI; 18 Gy). Post hoc molecular classification and mutational analysis contextualized outcomes according to known biologic subgroups (Wingless, Sonic Hedgehog, group 3, and group 4) and genetic biomarkers. Neurocognitive changes and ototoxicity were monitored over time. RESULTS: Five hundred forty-nine patients were enrolled on study, of which 464 were eligible and evaluable to compare PFRT versus IFRT and 226 for SDCSI versus LDCSI. The five-year event-free survival (EFS) was 82.5% (95% CI, 77.2 to 87.8) and 80.5% (95% CI, 75.2 to 85.8) for the IFRT and PFRT regimens, respectively, and 71.4% (95% CI, 62.8 to 80) and 82.9% (95% CI, 75.6 to 90.2) for the LDCSI and SDCSI regimens, respectively. IFRT was not inferior to PFRT (hazard ratio, 0.97; 94% upper CI, 1.32). LDCSI was inferior to SDCSI (hazard ratio, 1.67%; 80% upper CI, 2.10). Improved EFS was observed in patients with Sonic Hedgehog MB who were randomly assigned to the IFRT arm (P = .018). Patients with group 4 MB receiving LDCSI exhibited inferior EFS (P = .047). Children receiving SDCSI exhibited greater late declines in IQ (estimate = 5.87; P = .021). CONCLUSION: Reducing the radiation boost volume in average-risk MB is safe and does not compromise survival. Reducing CSI dose in young children with average-risk MB results in inferior outcomes, possibly in a subgroup-dependent manner, but is associated with better neurocognitive outcome. Molecularly informed patient selection warrants further exploration for children with MB to be considered for late-effect sparing approaches.

Efficacy of High-Dose Chemotherapy and Three-Dimensional Conformal Radiation for Atypical Teratoid/Rhabdoid Tumor: A Report From the Children's Oncology Group Trial ACNS0333.

PURPOSE: Atypical teratoid/rhabdoid tumor (AT/RT) is an aggressive, early-childhood brain tumor without standard effective treatment. To our knowledge, we conducted the first AT/RT-specific cooperative group trial, ACNS0333, to examine the efficacy and safety of intensive postoperative chemotherapy and focal radiation to treat AT/RT. PATIENTS AND METHODS: Patients from birth to 22 years of age with AT/RT were eligible. After surgery, they received 2 courses of multiagent chemotherapy, followed by 3 courses of high-dose chemotherapy with peripheral blood stem cell rescue and involved-field radiation therapy. Timing of radiation was based on patient age and disease location and extent. Central testing of tumor and blood for SMARCB1 status was mandated. Tumor molecular subclassification was performed retrospectively. The primary analysis was event-free survival (EFS) for patients < 36 months of age compared with a cooperative groups' historical cohort. Although accrual was based on the therapeutic question, potential prognostic factors, including age, tumor location, M stage, surgical resection, order of therapy, germline status, and molecular subtype, were explored. RESULTS: Of 65 evaluable patients, 54 were < 36 months of age. ACNS0333 therapy significantly reduced the risk of EFS events in patients < 36 months of age compared with the historical cohort (P < .0005; hazard rate, 0.43; 95% CI, 0.28 to 0.66). Four-year EFS and overall survival for the entire cohort were 37% (95% CI, 25% to 49%) and 43% (95% CI, 31% to 55%), respectively. Timing of radiation did not affect survival, and 91% of relapses occurred by 2 years from enrollment. Treatment-related deaths occurred in 4 patients. CONCLUSION: The ACNS0333 regimen dramatically improved survival compared with historical therapies for patients with AT/RT. Clinical characteristics and molecular subgrouping suggest prognostic differences. ACNS0333 results lay a foundation on which to build future studies and incorporate testing of new therapeutic agents.

ACR Appropriateness Criteria® Scoliosis-Child.

Scoliosis is frequently encountered in childhood, with prevalence of 2%. The majority is idiopathic, without vertebral segmentation anomaly, dysraphism, neuromuscular abnormality, skeletal dysplasia, tumor, or infection. As a complement to clinical assessment, radiography is the primary imaging modality used to classify scoliosis and subsequently monitor its progression and response to treatment. MRI is utilized selectively to assess for neural axis abnormalities in those at higher risk, including those with congenital scoliosis, early onset idiopathic scoliosis, and adolescent idiopathic scoliosis with certain risk factors. CT, although not routinely employed in the initial evaluation of scoliosis, may have a select role in characterizing the bone anomalies of congenital scoliosis and in perioperative planning. The American College of Radiology Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed annually by a multidisciplinary expert panel. The guideline development and revision include an extensive analysis of current medical literature from peer reviewed journals and the application of well-established methodologies (RAND/UCLA Appropriateness Method and Grading of Recommendations Assessment, Development, and Evaluation or GRADE) to rate the appropriateness of imaging and treatment procedures for specific clinical scenarios. In those instances where evidence is lacking or equivocal, expert opinion may supplement the available evidence to recommend imaging or treatment.

ACR Appropriateness Criteria® Suspected Spine Trauma-Child.

Choosing the appropriate imaging in children with accidental traumatic spine injuries can be challenging because the recommendations based on scientific evidence at this time differ from those applied in adults. This differentiation is due in part to differences in anatomy and physiology of the developing spine. This publication uses scientific evidence and a panel of pediatric experts to summarize best current imaging practices for children with accidental spine trauma. The American College of Radiology Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed annually by a multidisciplinary expert panel. The guideline development and revision include an extensive analysis of current medical literature from peer reviewed journals and the application of well-established methodologies (RAND/UCLA Appropriateness Method and Grading of Recommendations Assessment, Development, and Evaluation or GRADE) to rate the appropriateness of imaging and treatment procedures for specific clinical scenarios. In those instances where evidence is lacking or equivocal, expert opinion may supplement the available evidence to recommend imaging or treatment.

ACR Appropriateness Criteria® Sinusitis-Child.

Sinusitis is common in children that usually resolves spontaneously. Imaging is not part of the standard of care for initial diagnosis, however may be necessary in cases with persistent or chronic sinusitis to guide surgical intervention, or to rule out intracranial and vascular complications of sinusitis. Computed tomography (CT) and magnetic resonance imaging (MRI) are the leading imaging modalities. In this article, appropriateness in use of imaging modalities are discussed under common/clinically relevant scenarios. The American College of Radiology Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed annually by a multidisciplinary expert panel. The guideline development and revision include an extensive analysis of current medical literature from peer reviewed journals and the application of well-established methodologies (RAND/UCLA Appropriateness Method and Grading of Recommendations Assessment, Development, and Evaluation or GRADE) to rate the appropriateness of imaging and treatment procedures for specific clinical scenarios. In those instances where evidence is lacking or equivocal, expert opinion may supplement the available evidence to recommend imaging or treatment.

ACR Appropriateness Criteria® Headache-Child.

Headaches in children are not uncommon and have various causes. Proper neuroimaging of these children is very specific to the headache type. Care must be taken to choose and perform the most appropriate initial imaging examination in order to maximize the ability to properly determine the cause with minimum risk to the child. This evidence-based report discusses the different headache types in children and provides appropriate guidelines for imaging these children. The American College of Radiology Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed annually by a multidisciplinary expert panel. The guideline development and revision include an extensive analysis of current medical literature from peer reviewed journals and the application of well-established methodologies (RAND/UCLA Appropriateness Method and Grading of Recommendations Assessment, Development, and Evaluation or GRADE) to rate the appropriateness of imaging and treatment procedures for specific clinical scenarios. In those instances where evidence is lacking or equivocal, expert opinion may supplement the available evidence to recommend imaging or treatment.

Variability of Ponto-cerebellar Fibers by Diffusion Tensor Imaging in Diverse Brain Malformations.

To describe pontine axonal anomalies across diverse brain malformations. Institutional review board-approved review of magnetic resonance imaging (MRI) and genetic testing of 31 children with brain malformations and abnormal pons by diffusion tensor imaging. Anomalous dorsal pontocerebellar tracts were seen in mid-hindbrain anomalies and in diffuse malformations of cortical development including lissencephaly, gyral disorganization with dysplastic basal ganglia, presumed congenital fibrosis of extraocular muscles type 3, and in callosal agenesis without malformations of cortical development. Heterotopic and hypoplastic corticospinal tracts were seen in callosal agenesis and in focal malformations of cortical development. There were no patterns by chromosomal microarray analysis in the non-lissencephalic brains. In lissencephaly, there was no relationship between severity, deletion size, or appearance of the pontocerebellar tract. Pontine axonal anomalies may relate to defects in precerebellar neuronal migration, chemotactic signaling of the pontine neurons, and/or corticospinal tract pathfinding and collateral branching not detectable with routine genetic testing.

Pediatric Langerhans cell histiocytosis of the lateral skull base.

OBJECTIVE: Describe the presentation, imaging characteristics, management, and outcomes of pediatric patients with Langerhans cell histiocytosis (LCH) of the temporal bone. METHODS: A retrospective chart review was performed between 2000 and 2014 at a single tertiary care children's hospital. Fourteen patients were identified with a diagnosis of LCH and involvement of the temporal bone. RESULTS: Ten patients were female and ten were Caucasian. Mean age at diagnosis was 3 years (range 0.3-9.6 years). The most common presenting symptoms were scalp lesions, postauricular lesions, otalgia, and persistent ear infections. Three patients had documented hearing loss. Four cases had otic capsule invasion. Computed tomography demonstrated a lytic temporal bone lesion within the following subsites: mastoid, squamous temporal bone, external auditory canal, middle ear, and petrous apex. Four patients had intracranial disease. Extent and location of disease prompted all patients to be initially managed with chemotherapy. Surgical excision was limited to one case of localized recurrence. After a mean follow-up of 85.2 months (SD 42.4 months) there were no deaths but eight patients had a recurrence. Two patients developed long-term otologic sequelae requiring surgery. One patient developed labyrinthitis ossificans. CONCLUSION: LCH has a varied presentation, age distribution, and treatment algorithm. This series of 14 pediatric patients with temporal bone involvement supports a limited role for surgical resection. Long-term follow-up is critical for detection of local and disseminated disease, and for monitoring of otologic complications.

ACR Appropriateness Criteria® Back Pain-Child.

It is now generally accepted that nontraumatic back pain in the pediatric population is common. The presence of isolated back pain in a child has previously been an indication for imaging; however, recently a more conservative approach has been suggested using clinical criteria. The presence of constant pain, night pain, and radicular pain, alone or in combination, lasting for 4 weeks or more, constitute clinical red flags that should prompt further imaging. Without these clinical red flags, imaging is likely not indicated. Exceptions include an abnormal neurologic examination or clinical and laboratory findings suggesting an infectious or neoplastic etiology, and when present should prompt immediate imaging. Initial imaging should consist of spine radiographs limited to area of interest, with spine MRI without contrast to evaluate further if needed. CT of the spine, limited to area of interest, and Tc-99m bone scan whole body with single-photon emission computed tomography may be useful in some patients. The addition of intravenous contrast is also recommended for evaluation of a potential neoplastic or infectious process. The American College of Radiology Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed annually by a multidisciplinary expert panel. The guideline development and revision include an extensive analysis of current medical literature from peer reviewed journals and the application of well-established methodologies (RAND/UCLA Appropriateness Method and Grading of Recommendations Assessment, Development, and Evaluation or GRADE) to rate the appropriateness of imaging and treatment procedures for specific clinical scenarios. In those instances where evidence is lacking or equivocal, expert opinion may supplement the available evidence to recommend imaging or treatment.

ACR Appropriateness Criteria® Suspected Physical Abuse-Child.

The youngest children, particularly in the first year of life, are the most vulnerable to physical abuse. Skeletal survey is the universal screening examination in children 24 months of age and younger. Fractures occur in over half of abused children. Rib fractures may be the only abnormality in about 30%. A repeat limited skeletal survey after 2 weeks can detect additional fractures and can provide fracture dating information. The type and extent of additional imaging for pediatric patients being evaluated for suspected physical abuse depends on the age of the child, the presence of neurologic signs and symptoms, evidence of thoracic or abdominopelvic injuries, and social considerations. Unenhanced CT of the head is the initial study for suspected intracranial injury. Clinically occult abusive head trauma can occur, especially in young infants. Therefore, head CT should be performed in selected neurologically asymptomatic physical abuse patients. Contrast-enhanced CT of the abdomen/pelvis is utilized for suspected intra-abdominal or pelvic injury. Particular attention should be paid to discrepancies between the patterns of injury and the reported clinical history. Making the diagnosis of child abuse also requires differentiation from anatomical and developmental variants and possible underlying metabolic and genetic conditions. The American College of Radiology Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed annually by a multidisciplinary expert panel. The guideline development and revision include an extensive analysis of current medical literature from peer-reviewed journals and the application of well-established methodologies (RAND/UCLA Appropriateness Method and Grading of Recommendations Assessment, Development, and Evaluation or GRADE) to rate the appropriateness of imaging and treatment procedures for specific clinical scenarios. In those instances where evidence is lacking or equivocal, expert opinion may supplement the available evidence to recommend imaging or treatment.

Parotid swelling and chronic recurrent multifocal osteomyelitis of mandible in children.

OBJECTIVE: Chronic recurrent multifocal osteomyelitis (CRMO) is an aseptic inflammatory disorder of unknown etiology. CRMO involving the mandible is a diagnostic challenge due to a propensity for solitary involvement and lack of definitive radiologic or pathologic diagnosis. The purpose of this study is to report clinical and imaging findings in cohort of children with CRMO of the mandible. MATERIALS AND METHODS: A retrospective search of the Picture Archiving Communication System (PACS) and accompanying reports was performed for studies with suspected osteomyelitis of the mandible. The electronic medical record, histopathology results, and imaging findings were also reviewed. Inclusion criteria included presentation and course as well as surgical biopsy consistent with CRMO. Four children satisfied our inclusion criteria. Mean age was 9.1 years (range 3.5-12). M:F ratio=1:3. RESULTS: Patients presented with mild pain and swelling in the parotid region (n=4), mildly elevated sedimentation rate (n=3), and negative biopsy culture (n=4). A positive response to non-steroidal anti-inflammatory medication was noted in all patients. Imaging demonstrated a predominately sclerotic lesion in the posterior mandible associated with solid periosteal reaction in all patients. Cortical expansion (n=3) was commonly present. The clinical course was prolonged in the patients in whom a diagnosis of CRMO was not initially entertained. CONCLUSIONS: Parotid mass or swelling is a common presentation of CRMO involving the mandible. The possibility of this diagnosis should be raised when typical clinical and imaging features are present. Whole body imaging may be helpful to evaluate for additional lesions. While biopsy is necessary with isolated mandibular involvement, repeated biopsies and prolonged antibiotic therapy should be avoided.

The Impact of Postmeningitic Labyrinthitis Ossificans on Speech Performance After Pediatric Cochlear Implantation.

OBJECTIVE: 1) To characterize pediatric cochlear implant performance in patients with hearing loss secondary to bacterial meningitis. 2) To evaluate performance differences in patients with and without labyrinthitis ossificans (LO). STUDY DESIGN: Retrospective case review. SETTING: A large university-based multidisciplinary cochlear implant program. PATIENTS: Forty-nine patients with hearing loss from bacterial meningitis who received cochlear implants from 1991 to 2011. Thirty-nine patients had adequate data for analysis. INTERVENTION: Cochlear implantation with postoperative performance evaluation. MAIN OUTCOME MEASURE(S): Speech perception category (SPC). RESULTS: Nineteen (48.7%) patients had intraoperative evidence of LO. Fourteen patients (70.0%) without LO compared with seven (36.8%) with LO developed open-set speech after implantation. There was a trend toward better postimplant SPC outcomes in patients without LO that did not reach statistical significance (p = 0.17). The presence of LO negatively correlated with classroom placement (p < 0.05). Analysis of each group individually demonstrated statistically significant improvement in pre- versus postimplant SPC outcomes (p < 0.001). CONCLUSION: The presence of LO may negatively affect performance in pediatric patients receiving a cochlear implant for hearing loss secondary to bacterial meningitis.