A Study of Round Window and its Adjacent Anatomy to Guide the Cochlear Implant Electrode Insertion.

Introduction: Residual hearing preservation has gained attention now which has brought round window membrane into the light, as a port for cochlear implantation. Atraumatic insertion of electrodes can be achieved by study of anatomical variations of round window and its forms which can guide the surgeon. Objective: This study was undertaken to examine the anatomical variations of round window and its adjacent structures and their impact on surgical approach during cochlear implantation. Methods: A series of 40 adult human temporal bones underwent high-resolution CT scanning and were further dissected for microscopic study of the round window. Results: The antero posterior dimensions of RW ranged from 1.22 to 2.51 mm on radiology and on dissection 1.76 mm +/- 0.3 mm. Shape of round window in 72.5% of bones was oval, and in 27.5% bones it was round shaped. As per Saint Thomas hospital classification for Round window visualization we found 82.5% bones had type I RW visualization and 17.5% had type IIa RW visualization. Area of crista fenestra on dissection was ranging from 0.41 to 0.69 mm2. Conclusion: Residual hearing preservation has become a new motto for surgeons. Therefore thorough anatomic knowledge of round window is must for careful insertion, as round window is closely related to the sensitive inner ear structures.

Correlation of Preoperative High-resolution Computed Tomography Temporal Bone Findings with Intra-operative Findings in Various Ear Pathologies.

High resolution computed tomography (HRCT) is a tool which provide fine details of temporal bone and its associated pathologies which are of extreme use in making diagnosis, to evaluate extension of disease and most important to plan surgical approach. Aim of the present study was to correlate HRCT findings with operative findings in different ear pathologies. This observational, prospective study enrolled 70 patients of different ear pathologies required surgical intervention. They were subjected to HRCT temporal bone and its findings were correlated with surgical findings. Mean age of the study population was 20.3 ± 12.04 years with M: F = 1.12: 1. HRCT showed specificity and sensitivity of 100% and 92.31% respectively in detecting ossicular erosion. It was 100% sensitive and 98.51% specific in detecting LSCC erosion, 85.71% sensitive and 96.83% specific in detecting facial canal dehiscence, 100% sensitive and 98.11% specific in detecting scutum erosion, 75% sensitive and 96.97% specific to detect tegmen erosion, 100% sensitive and 97.01% specific in detecting sinus plate erosion, 100% sensitive and 95.38% specific in detecting high jugular bulb, sensitivity and specificity both are 100% in detecting labyrinthitis ossificans and 100% sensitive in detecting otosclerotic foci. HRCT findings showed a good association with operative findings in terms of sensitivity and specificity. Thus, HRCT is a acceptable tool to make diagnosis and to plan surgical approach.

Newborn Hearing Screening: Time to Act!

The present study was carried out with the aim of assessing the outcomes of otoacoustic hearing screening in newborns coupled with the three stage protocol. It was a hospital based observational study which was conducted over a time period of twelve months at a tertiary care institute to screen 2000 live neonates for congenital hearing impairment using OAE, followed up by tympanometry and BERA, if required. 2000 neonates were screened for hearing impairment. 406 were in high risk group and the rest in non-high risk group. Seven neonates had absent V wave on BERA. Five of them were high risk babies and the rest two were non-high risk ones. In order to ensure that early detection and effective intervention are possible for all neonates with hearing impairment, UNHS should be performed. Three stage UNHS protocol using OAE and BERA showed that the implementation of UNHS for congenital childhood hearing loss for all neonates would be beneficial.

Soft tissue reactions following cochlear implantation.

INTRODUCTION: Cochlear implantation is a boon to children with hearing loss. Rarely, it can be associated with complications. Soft tissue reaction can be a particularly distressing complication. MATERIALS AND METHODS: The study was conducted on all patients presenting with soft tissue reaction post-cochlear implant in a tertiary care referral institute from March 2011 to June 2018. We graded the severity of soft tissue reaction as per the severity and then managed these patients accordingly. RESULTS: Thirty-five patients were included in this study. Grade 1 had 12 patients, grade 2 had 9, grade 3 had 4 and grade 4 had 9 patients. Grade 1, 2 and 3 reactions were managed conservatively, while grade 4 required surgery. The incidence of explantations increased with the grade severity. CONCLUSION: Soft tissue reaction post-cochlear implant is a rare, but distressing complication. Grading and analyzing them can help us manage them in a better way.

Cochlear implant in Thalassemia patient - Case report.

INTRODUCTION: Beta-thalassemias are a group of hereditary blood disorders characterized by anomalies in the synthesis of the beta chains of hemoglobin. Iron overload occurs in thalassemia, with blood transfusion therapy being the major cause. Deferoxamine continues to be the mainstay of therapy to remove excess iron in patients requiring long-term transfusions. One of the most important complications of deferoxamine therapy is neurosensory toxicity, including sensorineural hearing loss (SNHL). Labyrinthine hemmorhage (LH) is thought to result from altered capillary hemodynamics or reperfusion injury. It is theorized that LH incites a reparative response that cascades from fibrosis to sclerosis and ultimately ossification of the inner ear structures. CASE PRESENTATION: We present a case of 3-year-old thalassemic child with bilateral profound sensorineural hearing loss. Patient was on regular blood transfusions with chelation therapy. HRCT temporal bone and MRI brain and temporal bone had features of labyrinthitis ossificans (LO). Child underwent uniateral cochlear implantation and postimplantation speech perception and production outcomes were normal. DISCUSSION: This case illustrates the unique feature of labyrinthitis ossificans in a thalassemia patient which has not yet reported in the English literature. Hearing screening of all thalassemia patients and therefore early diagnosis of SNHL prompts early intervention and improved quality of life.

Measuring cochlear duct length in Asian population: worth giving a thought!

INTRODUCTION: The anatomy of the cochlea forms the basis for a successful cochlear implantation. Cochlear duct length (CDL) is defined as the length of the scala media as measured from the middle of the round window to helicotrema. Preoperative measurement of CDL is particularly important when precise intracochlear electrode array placement is desired. It can be done both histologically and radiologically. Preoperative high-resolution computed tomography (HRCT) scan which forms an integral part of cochlear implant workup is a useful tool to calculate CDL using 3D reconstructions. METHOD: This study was done in SMS Medical College and Hospital, Jaipur, India, which is a tertiary care hospital and referral centre for cochlear implants. HRCT temporal bones of all children less than 6 years of age, with congenital bilateral severe-to-profound SNHL who were being worked up for cochlear implant were studied and analysed. 124 patients (56 females and 68 males) with hearing loss were evaluated for cochlear implantation. HRCT temporal bone of these patients was analysed and a variable A was measured which is defined as the linear measurement from the round window to the farthest point on the opposite wall of the cochlea on a reformatted CT scan slice. RESULTS: Mean of distance A for right ear of these patients was 8.10 mm (range 7.7-9.2 mm). Mean for the same in left ear of these patients was 8.14 mm (range 7.7-9.0 mm), giving an overall average of 8.12 mm. Using the formula, CDL = 4.16A-3.98, we calculated the length of cochlear duct. Mean cochlear duct length was 29.8 mm with a range from 28 to 34.3 mm. CONCLUSION: To the best of our knowledge, this is the first large sample study of cochlear length in population of this part of the world. A smaller cochlear length in this part of the world as compared to the Caucasian cochlear duct is a significant finding in understanding of the cochlear anatomy and physiology. It would also have great implications on the insertion depth in cochlear implantation.

Cochlear Implantation in Children with Anomalous Cochleovestibular Anatomy: Our Experience.

To report operative findings, postoperative course, and postimplantation performance in patients with cochlear malformations who underwent cochlear implantation. Seventeen patients with malformations which included enlarged vestibular aqueduct (n = 6), Mondini's dysplasia (n = 5) common cavity deformity (n = 3) and incomplete partition type 2 (n = 3) underwent cochlear implantation with Nucleus 22 straight array device at our center. Operative findings described facial nerve anatomy and cerebrospinal fluid leak. Standard tests of speech perception were used to evaluate the postoperative performance for each subject. Operative findings included cerebrospinal fluid leak (thirteen patients) all of which were repaired successfully with graft. None had abnormal facial nerve anatomy. No surgical complications occurred. All the patients except two with common cavity had complete insertion. Electrode thresholds and discomfort levels were variable for several months after implantation. All patients demonstrated improved performance after implantation. Patients with enlarged vestibular aqueduct fared better than patients with other inner ear malformations. Cochlear implantation can be a successful method of rehabilitation in patients with congenital deafness who have cochlear malformations.