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Biomedical subjects

Ritvik P Mehta

Publications and source records attributed to Ritvik P Mehta.

13 recordsLinked to original sources
PubMed2006

Mastoid obliteration.

Mastoid obliteration is commonly performed to reduce the size of mastoidectomy cavity following canal wall-down tympanomastoidectomy for chronic otitis media. The indications and techniques for mastoid obliteration as well as total tympanomastoid obliteration will be reviewed. The vast majority of obliteration techniques consist of either local flaps or free grafts (bone, cartilage, fat, hydroxyapatite). The radiographic and histopathologic features of mastoid obliteration will also be reviewed.

Chronic Disease↗
PubMed2006

Determinants of hearing loss in perforations of the tympanic membrane.

BACKGROUND: Although tympanic membrane perforations are common, there have been few systematic studies of the structural features determining the magnitude of the resulting conductive hearing loss. Our recent experimental and modeling studies predicted that the conductive hearing loss will increase with increasing perforation size, be independent of perforation location (contrary to popular otologic belief), and increase with decreasing size of the middle-ear and mastoid air space (an idea new to otology). OBJECTIVE: To test our predictions regarding determinants of conductive hearing loss in tympanic membrane perforations against clinical data gathered from patients. STUDY DESIGN: Prospective clinical study. SETTING: Tertiary referral center. INCLUSION CRITERIA: Patients with tympanic membrane perforations without other middle-ear disease. MAIN OUTCOME MEASURES: Size and location of perforation; air-bone gap at 250, 500, 1,000, 2,000, and 4,000 Hz; and tympanometric estimate of volume of the middle-ear air spaces. RESULTS: Isolated tympanic membrane perforations in 62 ears from 56 patients met inclusion criteria. Air-bone gaps were largest at the lower frequencies and decreased as frequency increased. Air-bone gaps increased with perforation size at each frequency. Ears with small middle-ear volumes, < or = 4.3 ml (n = 23), had significantly larger air-bone gaps than ears with large middle-ear volumes, > 4.3 ml (n = 39), except at 2,000 Hz. The mean air-bone gaps in ears with small volumes were 10 to 20 dB larger than in ears with large volumes. Perforations in anterior versus posterior quadrants showed no significant differences in air-bone gaps at any frequency, although anterior perforations had, on average, air-bone gaps that were smaller by 1 to 8 dB at lower frequencies. CONCLUSION: The conductive hearing loss resulting from a tympanic membrane perforation is frequency-dependent, with the largest losses occurring at the lowest sound frequencies; increases as size of the perforation increases; varies inversely with volume of the middle-ear and mastoid air space (losses are larger in ears with small volumes); and does not vary appreciably with location of the perforation. Effects of location, if any, are small.

Acoustic Impedance Tests↗
PubMed2005

Pediatric deaths due to otolaryngologic causes: a population-based study in Massachusetts, 1990-2002.

OBJECTIVE: To identify the most common otolaryngologic causes of mortality in the 0 to 19 age group in the state of Massachusetts and to estimate the pediatric otolaryngologic mortality rate based on population data. STUDY DESIGN: Population-based retrospective cohort study. METHODS: The Massachusetts State Registry of Vital Records and Statistics electronic database was searched for all otolaryngology related causes of death from 1990 to 2002 for children aged 0 to 19. The individual death certificates were then reviewed, and a database of otolaryngology related pediatric deaths was created. RESULTS: A total of 59 otolaryngology related deaths were identified in the pediatric population from 1990 to 2002. Eighty-one percent of deaths occurred because of airway compromise caused by infection, anatomic obstruction, or congenital anomaly. The remaining 19% of deaths occurred because of aspiration, nonairway infections, and malignant neoplasms. Ninety-five percent of deaths in the children under age 10 were caused by airway compromise. Six of seven deaths (86%) in the age 15 to 19 group occurred because of malignant neoplasms. The overall mortality rate caused by otolaryngologic causes was estimated to be 0.28 per 100,000 population. CONCLUSIONS: The overall mortality rate for otolaryngology related deaths is low in the pediatric population. The vast majority of deaths are caused by airway compromise, primarily because of laryngotracheobronchitis or other upper airway obstruction. In older children (ages 15-19), malignant head and neck neoplasms are the leading cause of otolaryngology related deaths.

Adolescent↗
PubMed2004

Cervical bronchogenic cysts: a consideration in the differential diagnosis of pediatric cervical cystic masses.

OBJECTIVE: To discuss the clinical and histopathologic features of cervical bronchogenic cysts. METHODS: Retrospective case series. RESULTS: A 22-year pathology database search identified 24 patients 18 years of age and younger with bronchial/bronchogenic cysts, four of which presented in the cervical region. CONCLUSION: Cervical bronchogenic cysts are rare in the pediatric population but deserve inclusion in the differential diagnosis of cystic neck masses. Such cysts result from abnormal tracheobronchial tree development with characteristic pathology including respiratory-type epithelium, mural cartilage, smooth muscle, and seromucinous glands. Definitive treatment requires surgical excision.

Bronchogenic Cyst↗
PubMed2004

Mandibular reconstruction in 2004: an analysis of different techniques.

PURPOSE OF REVIEW: The field of mandibular reconstruction has evolved dramatically over the past fifty years. Numerous advances in microsurgical technique, plating technology and instrumentation, and an understanding of donor site angiosomes have made consistent and reliable mandibular reconstruction possible. Refinements in technique continue to improve the functional and aesthetic outcomes of oromandibular reconstruction. This review discusses the current state-of-the-art techniques for mandibular reconstruction and highlights the latest innovations in technique. RECENT FINDINGS: The most common indication for oromandibular reconstruction remains ablative surgery for advanced neoplastic processes of the oral cavity and oropharynx. Reconstruction of these complex three-dimensional composite bony and soft-tissue defects is paramount for rehabilitation of form and function. Vascularized osseous free tissue transfer is the state-of-the-art for mandibular reconstruction. The long-term excellent functional and aesthetic outcomes of this technique have recently been reported. The most commonly used free flaps for mandibular reconstruction are the fibula, iliac crest, and scapula. Each of these typically accepts endosseous implants improving functional outcomes. The use of mandibular reconstruction plates and coverage with a soft-tissue flap remains a reconstructive option for selected patients. The latest refinements in technique include temporary intraoperative external fixation, the use of periosteal free flaps, distraction osteogenesis, and development of biodegradable biopolymer scaffolds for mandibular defects. SUMMARY: Oromandibular reconstruction, although a challenge for the head and neck reconstructive surgeon, is now reliable and highly successful with excellent long-term functional and aesthetic outcomes.

Bone Transplantation↗
PubMed2003

Diagnostic utility of laser-Doppler vibrometry in conductive hearing loss with normal tympanic membrane.

HYPOTHESIS: It was hypothesized that laser-Doppler vibrometry measurements of umbo velocity in aerated middle ears with conductive loss can differentiate ossicular interruptions, stapes fixations, and mallear fixations. More generally, we hypothesize that laser-Doppler vibrometry measurements of umbo velocity can give information about how differences in the impedance that the ossicles work against affect middle-ear function. BACKGROUND: Laser-Doppler vibrometry is a well-established research tool for exploring middle-ear function. The authors wished to investigate its potential as a clinical tool for differential diagnosis of the cause of conductive hearing loss. METHODS: Laser-Doppler vibrometry was used to investigate the relationship between the sound-induced velocity of the tympanic membrane at the umbo and the cause of conductive hearing loss when the tympanic membrane was normal and the middle ear was aerated. The results of measurements in 17 adult ears before exploratory tympanotomy were compared with the surgically determined cause of the hearing loss. The authors also measured the motion of the umbo in 10 patients who had undergone successful small-fenestra stapedectomy procedures. In all the studied ears, pure-tone audiograms were measured at the time of laser-Doppler vibrometry testing. RESULTS: There were clear statistical differences between the umbo velocity in normal ears and in ears with different ossicular pathologic conditions. There was also a clear separation of the results between ears with ossicular interruptions and ossicular fixation. The pattern of laser-Doppler vibrometry measurements in poststapedectomy ears approximated the pattern in ears with ossicular interruptions. CONCLUSION: Comparison of laser-Doppler vibrometry results and audiometry may be a sensitive and selective indicator of ossicular pathologic conditions as well as a useful tool for investigating middle ear function.

Audiometry, Pure-Tone↗
PubMed2003

Middle-ear mechanics of Type III tympanoplasty (stapes columella): I. Experimental studies.

OBJECTIVE: To investigate the mechanics of Type III tympanoplasty by developing a cadaveric temporal bone model. BACKGROUND: Type III stapes columella tympanoplasty involves the placement of a tympanic membrane graft, usually made of temporalis fascia, directly onto the stapes head. The procedure is usually done in conjunction with a canal wall down mastoidectomy. Postoperative hearing results vary widely, with air-bone gaps of 10 to 60 dB. The structural features responsible for the wide range in hearing results have not been systematically investigated. METHODS: Canal wall down Type III procedures were performed in eight cadaveric temporal bones. Acoustic stimuli were presented in the ear canal, and round window velocity VRW (used as an index of hearing) was measured, while systematically varying stapes mobility, mechanical properties of tympanic membrane graft, and tightness of connection between tympanic membrane graft and stapes. The effect of interposing a thin cartilage disc between the tympanic membrane graft and stapes head was also assessed. RESULTS: When the middle ear was aerated and the stapes was mobile, VRW was 15 to 30 dB lower than in an intact, normal ear. Stapes fixation led to a significant reduction in VRW; reduction was greatest at low frequencies. There was little effect of varying the tightness of connection between the tympanic membrane graft and stapes head. Sound energy was transmitted from the graft to the stapes as long as the graft was in physical contact with the stapes head. Different tympanic membrane graft materials with a range of mechanical properties (stiffness and mass) resulted in little variation in VRW. Interposing a thin cartilage disc between the tympanic membrane graft and stapes improved VRW in the lower frequencies by 5 to 10 dB. The authors hypothesize that the disc acted to increase the effective vibrating area of the graft. CONCLUSIONS: The feasibility of using a cadaveric temporal bone model to study the mechanics of Type III tympanoplasty was demonstrated. A mobile stapes and aerated middle ear were essential for a successful Type III tympanoplasty. There was little effect of varying the mechanical properties of the tympanic membrane graft or changing the tightness of connection between the graft and stapes head. Improved results were achieved by interposing a thin cartilage disc between the graft and stapes head to increase the effective vibrating area of the graft.

Aged↗
PubMed2003

Middle ear mechanics of Type III tympanoplasty (stapes columella): II. Clinical studies.

OBJECTIVES: To determine the structural features that are responsible for the large variation in postoperative hearing results after Type III stapes columella tympanoplasty, to compare the clinical results after Type III tympanoplasty with predictions based on experimental investigations using a temporal bone model, and to investigate the effectiveness of a modification in surgical technique for Type III reconstruction. STUDY DESIGN: Retrospective case review. SETTING: Tertiary referral center. INCLUSION CRITERIA: The ear was healed with an intact tympanic membrane graft; the status of the stapes was known, whether mobile or fixed; and the postoperative status of aeration of the middle ear was known, whether aerated or not. MAIN OUTCOME MEASURE: Air-bone gap at frequencies 250, 500, 1,000, 2,000 and 4,000 Hz. RESULTS: In ears with temporalis fascia graft onto stapes head: mobile stapes and aerated middle ear (n = 34), mean air-bone gaps at audiometric frequencies were 15 to 30 dB, consistent with predictions of the experimental model; mobile stapes and nonaerated middle ear (n = 16), large air-bone gaps of 35 to 55 dB; fixed stapes and aerated middle ear (n = 4), large air-bone gaps of 30 to 50 dB; fixed stapes and nonaerated middle ear (n = 2), large air-bone gaps of 30 to 70 dB. In ears with a fascia-cartilage graft onto stapes head, where a thin disc of meatal cartilage, 0.3 to 0.5 mm thick and 4 to 6 mm in diameter was interposed between the fascia graft and the stapes head: mobile stapes and aerated middle ear (n = 9), mean air-bone gaps at audiometric frequencies were 10 to 25 dB, about 5 dB better at 250, 500, and 2,000 Hz than in ears with only a fascia graft ( <0.05), improvement consistent with that observed experimentally when a thin cartilage disc was used in the temporal bone model, hypothesis that the cartilage increased the effective vibrating area of the graft; mobile stapes and nonaerated middle ear (n = 2), air-bone gaps were 40 to 50 dB. CONCLUSIONS: Large air-bone gaps of 30 to 70 dB occurred as a result of stapes fixation, nonaeration of the middle ear, or both. When the stapes was mobile and the middle ear was aerated, a fascia graft resulted in air-bone gaps of 15 to 30 dB. Interposing a thin disc of cartilage between the fascia graft and stapes head to improve the effective vibrating graft area gave better hearing, with air-bone gaps of 10 to 25 dB. The clinical Type III results were consistent with predictions based on experimental investigations of mechanics of the Type III procedure in a temporal bone model.

Acoustic Impedance Tests↗
PubMed2002

Malleus fixation: clinical and histopathologic findings.

The goals of this study were to review important clinical and histopathologic features of malleus fixation. Ten clinical cases and 10 histopathologic cases of malleus fixation were identified. For the clinical cases, preoperative clinical data, surgical findings, and preoperative and postoperative audiometric findings were reviewed. Ninety percent of the clinical cases achieved significant reduction of the air-bone gap after operation. Two thirds of these cases had an air-bone gap of 10 dB or less, and the remainder had air-bone gaps between 20 and 28 dB after operation. For the temporal bone cases, clinical data, histopathologic findings, and other otologic diagnoses were reviewed. Malleus fixation can be idiopathic or a result of trauma, chronic otitis media, or developmental anomalies. It is a cause of hearing loss that is likely to be more common than the number of diagnoses would indicate. Certain audiometric findings may lead one to suspect the diagnosis. The surgical approach used depends on the individual anatomy, and surgery is usually highly effective in improving hearing.

Adult↗