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Biomedical subjects

M Luntz

Publications and source records attributed to M Luntz.

At least 19 recordsLinked to original sources
PubMed2005

Width of the extended facial recess: a numerical study of ultrahigh-resolution computed tomography and its implications in minimally invasive otologic surgery.

BACKGROUND: Methods of minimally invasive computer-assisted otologic surgery lag behind other fields. The reason seems to be the extremely small dimensions of the corridors between important structures in the temporal bone and the fact that these structures are encased in bony frameworks, are obscured before drilling, and are not movable. The extended facial recess is a surgical pass to the tympanic cavity. It is bounded medially by the facial nerve and laterally by the tympanic annulus, and varies among individuals. For computer-assisted, minimally invasive temporal bone surgery, high-resolution definition is critically important. AIMS: To determine the width of the extended facial recess and evaluate the computerized findings as a pre- and intraoperative aid to otologic surgery planning. METHODS: Bilateral temporal bone high-resolution computed tomographic images of 100 male and 100 female patients were measured twice at five levels (caudal to cephalic), first using a window-independent algorithm (extended facial recess, full-width at half-maximum), implemented in a computed tomographic image-processing workstation, and then manually with calipers on the same axial computed tomographic images. RESULTS: As expected, the extended facial recess, full-width at half-maximum method yielded the widest values superiorly (4.15 +/- 0.41 mm in the female patients and 4.32 +/- 0.54 mm in the male patients). From this level down, the extended facial recess, full-width at half-maximum method yielded values that tapered gradually to 2.50 +/- 0.56 mm in the female patients and 2.42 +/- 0.46 mm in the male patients at the most interior level. The manual method (extended facial recess, computed tomographic images) yielded a significantly higher value than that obtained with the objective, window-independent method at all levels, and at some levels was higher by as much as one-third. At Level 2, which corresponded roughly to the round window, the extended facial recess was 4.00 +/- 0.65 in the female study group and 4.11 +/- 0.67 mm in the male study group. CONCLUSION: Image processing methods such as extended facial recess, full-width at half-maximum method might lead to fine tuning and thus improvement of computer-assisted otologic surgery. Before clinical application and complete dependence on these automated methods during otologic surgery, their reliability should be further validated.

Adolescent↗
PubMed2001

Acute mastoiditis--the antibiotic era: a multicenter study.

OBJECTIVES: To evaluate the clinical course and identify the causative organisms of acute mastoiditis in a community where most of the patients who develop acute otitis media are treated with antibiotics. METHODS: A multicenter retrospective review of a series of 223 consecutive cases of acute mastoiditis. SETTING: Nine secondary or tertiary academic or non-academic referral centers. RESULTS: Prior to the diagnosis of acute mastoiditis, 121 of the patients (54.3%) had been receiving oral antibiotic treatment for acute otitis media for periods ranging from 1 to 21 days (mean 5.3 days). Samples for bacterial culture were obtained from 152 patients. Cultures were negative in 60 patients. The organisms isolated in the 92 positive cultures were: Streptococcus pneumoniae (15 patients), Streptococcus pyogenes (14 patients), Staphylococcus aureus (13 patients), Staphylococcus coagulase negative (three patients), Pseudomonas aeruginosa (eight patients), Haemophilus influenzae (four patients), Proteus mirabilis (two patients), Escherichia coli (two patients), Klebsiella pneumoniae (one patient), Enterobacter (one patient), Acinetobacter (one patient), anaerobic gram-negative bacilli (one patient), and fungi (two patients). Ten patients had mixed flora. Sixteen patients presented with complications (cerebellar abscess, perisinus empyema, subdural abscess or empyema, extradural abscess, cavernous sinus thrombosis, lateral sinus thrombosis, bacterial meningitis, labyrinthitis, petrositis, or facial nerve palsy). CONCLUSIONS: Antibiotic treatment cannot be considered an absolute safeguard against the development of acute mastoiditis. Early myringotomy for acute otitis media seems to decrease the incidence of complications. The distribution of causative organisms in acute mastoiditis differs from that in acute otitis media. Intracranial complications in acute mastoiditis are not rare. Because of the diversity of causative organisms in acute mastoiditis and the growing resistance of bacteria to the various antibiotics, all means to obtain a sample for culture prior to antibiotic treatment, including general anesthesia.

Acute Disease↗
PubMed2001

Cochlear implantation in healthy and otitis-prone children: a prospective study.

OBJECTIVE: To evaluate and compare the timing of surgery, intraoperative findings, and otitis media-related outcome of cochlear implantation in children who are otitis-prone with their counterparts who are not otitis-prone. STUDY DESIGN: Prospective. METHODS: Children referred for cochlear implantation were assigned to a non-otitis-prone group (group A: normal otoscopy on their first visit after referral) or an otitis-prone group (group B: current or a recent history of otitis media at referral). Group B patients were managed using a structured protocol aimed at preimplantation otitis media control. The study reviewed pre-, intra-, and postoperative data. RESULTS: Of the 18 children studied, 8 were assigned to group A (mean age at referral, 40.6 mo) and 10 to group B (mean age at referral, 31.6 mo). For otitis media control, all otitis-prone children underwent ventilating tube insertion (various numbers of procedures before implantation). Only one otitis-prone child required cortical mastoidectomy also. Time from referral to implantation was similar in the two groups (mean, 6.6 mo). High-resolution computed tomography data showed mastoid pneumatization to be significantly smaller in the otitis-prone group, but the facial recess was not smaller in this group. During implantation, 10 children had inflamed middle ear mucosa. Seven of these belonged to group B. All of these seven children had a round window niche obliterated by the inflamed mucosa, which had to be removed for round window membrane identification. After implantation, only one child had drainage through the ventilating tube for more than 1 week. Two children in group B developed otitis media (1 year postimplantation) that was overcome within 1 week. There were no otitis media-related complications. CONCLUSIONS: If a structured protocol is used for the control of otitis media before cochlear implantation, otitis media should not require a delay in implantation. In otitis media-prone children, the round window niche is often obscured by inflamed mucosa. Its removal is mandatory for identification of the round window membrane. After cochlear implantation, otitis media is not a frequent occurrence.

Acute Disease↗
PubMed2001

Volume of mastoid pneumatization: three-dimensional reconstruction with ultrahigh-resolution computed tomography.

The volume of the mastoid air cell system was measured in 69 patients with normal middle ears. All patients underwent axial ultrahigh-resolution computed tomography. Mastoid pneumatization was marked on each axial slice, and 3-dimensional reconstruction was performed. The volumes were measured with a volumetric algorithm. A polyethylene tubing phantom with a density similar to that of bone on computed tomography was devised. The polyethylene tubing was tied in a particular fashion so as to create interconnecting air spaces with a known volume. The phantom was scanned with the imaging parameters used for scanning the temporal bone. The air in the tubing was marked, and 3-dimensional reconstruction for the marked phantom air was performed. The volume of the interconnecting air spaces was measured and found to be identical to its known volume, thereby verifying the accuracy of the method used. The mean mastoid volume was 6.61 cm3. The smallest volume measured was 1.3 cm3, and the largest was 12.7 cm3. The importance of this technique lies in its high accuracy, ease of use, and ability to directly correlate mastoid size and clinical findings.

Adult↗
PubMed2001

Tinnitus as a prognostic sign in idiopathic sudden sensorineural hearing loss.

Idiopathic sudden sensorineural hearing loss remains a controversial problem with respect to etiology and the factors that might predict a favorable prognosis. This study evaluated the possible prognostic factors of recovery in 67 patients with idiopathic sensorineural hearing loss treated with steroids (prednisone), plasma expanders (intravenous dextran), and vasodilators (papaverine). Clinical recovery was estimated by contrasting the audiometric results on admission and those at discharge 10 days later. The correlation between various potential prognostic factors and audiological improvement was calculated. Only two factors were found to be associated significantly with hearing improvement: tinnitus (p < .04) and the slope of audiogram on admission (p < .045). Tinnitus and the presence of an ascending audiogram were found to be correlated with a favorable outcome in idiopathic sensorineural hearing loss.

Adult↗
PubMed2000

The anatomic relationship between the second genu of the facial nerve and the incus: a high-resolution computed tomography study.

OBJECTIVE: This study defines the three-dimensional location of the posterior-most point of the tympanic segment of the facial nerve (TSFN) relative to the posterior-most point of the short process of the incus, using ultrahigh-resolution computed tomography (CT) of the temporal bone. STUDY DESIGN, SETTING, AND PATIENTS: Included were patients who had been referred for CT of the temporal bone for various reasons other than suspected pathologic conditions of the middle ear. The decision whether to include a patient in the study was based on the referring physician's referral note for the examination. INTERVENTION: All of the patients underwent axial CT of the temporal bone, with consecutive slices of 1.1 mm width and 0.5-mm increments. MAIN OUTCOME MEASURES: The posterior-most point of the short process of the incus was identified on axial CT and was superimposed onto a lower axial slice in which the posterior-most point of the TSFN was identified. Its shortest distance to the TSFN was measured. Afterward, the length of the TSFN that remained posterior to the perpendicular of the posterior-most point of the short process of the incus was measured by measuring the length of TSFN that could be seen posterior to the point of bisection of the line marking the shortest distance between the posterior-most point of the short process of the incus and the FN in the previous measurement. The measurements were performed on 30 normal temporal bones. RESULTS: The shortest distance measured between the posterior-most point of the short process of the incus and the TSFN was, on average, 3.31 mm for all 30 ears (range 2-4.8 mm). The length of TSFN that could be seen posterior to the perpendicular of the most posterior point of the short process of the incus was, on average, 2.70 mm (range 1.80-3.90 mm). CONCLUSIONS: In addition to defining the spatial location of the posterior-most point of the TSFN, this study also offers a practical method by which the surgeon can evaluate, preoperatively, how far medial to the incus and how much posterior to the posterior-most point of the short process of the incus the facial nerve is located.

Adult↗
PubMed1999

Supracochlear approach to the petrous apex: case report and anatomic study.

OBJECTIVE: The case of an 11-month old infant with petrous apex abscess drained through the supracochlear air cells prompted an anatomic study of the dimensions of this approach. Of the various approaches to the petrous apex, the supracochlear dissection has been the least described. STUDY DESIGN: Twenty temporal bones were dissected to completely expose the epitympanum. This required mastoidectomy, exenteration of zygomatic root and epitympanic air cells, and removal of the incus. Measurements were taken from three sides of a triangle described by the tegmen tympani (TT), tympanic facial nerve (TFN), and superior semicircular canal (SSCC). Similar measurements were obtained from standard coronal computerized tomographic (CT) scans from a random series of 20 patients. RESULTS: Mean lengths of the sides of the triangle were 7.0 mm (TT), 5.3 mm (TFN), and 4.8 mm (SSCC). The superior petrous apex air cells or marrow space was accessible through the supracochlear exposure in all specimens. Mean lengths from the coronal CT images were 4.2 mm (TT), 3.2 mm (TFN), and 8.45 mm (SSCC). CONCLUSIONS: The authors conclude that the supracochlear approach may provide adequate access to the superior petrous apex for drainage and biopsy in selected cases.

Abscess↗
PubMed1998

Surgical technique for implantation of the totally ossified cochlea.

OBJECTIVES: Among the technical challenges of cochlear implant surgery is electrode insertion into the fully ossified cochlea. Earlier drill-out techniques have two significant drawbacks: 1. up to one half fail when the electrode pulls away from the cochlea; and 2. extended radical mastoidectomy, abdominal fat graft for obliteration, and closure of the external auditory meatus are required. A simplified technique is described that allows positive fixation of the cochlear implant electrode and in selected cases avoids a radical cavity with obliteration. STUDY DESIGN: Technical description with case reports and hearing outcomes. METHODS: Ten cadaver temporal bones were dissected to determine middle ear landmarks that overlie the basal turn of the cochlea from the transcanal approach and to establish the feasibility of the intact canal wall procedure. Surgery was performed on four patients who had preoperative imaging evidence of full ossification, two with the canal wall down, and two with canal wall up. Standard measures of speech recognition were used to evaluate hearing. RESULTS: Critical surgical landmarks are the round window, carotid artery, cochleariform process, and oval window. The procedure was successfully performed on four patients and open-set speech recognition is present in each. CONCLUSIONS: This canal wall up procedure allows long electrode insertion without radical cavity/obliteration in patients with fully ossified cochleas and prevents distraction of the electrode from the cochlea. While open-set word recognition was achieved by all subjects, results are poorer than expected for patients with limited or no ossification.

Audiometry, Speech↗
PubMed1998

Middle ear pressure variations during 50% N2O anesthesia as a function of mastoid pneumatization.

HYPOTHESIS: Mastoid size is a factor in middle ear (ME) pressure regulation. BACKGROUND: In a study investigating ME pressure variations during nitrous oxide (N2O) anesthesia, particularly high values of ME pressure increase rate (PIR) were observed in four patients with sclerotic mastoids. The current study is aimed at systematically assessing this observation. METHODS: Middle ear pressure was measured periodically in 30 patients during 50% N2O anesthesia using tympanometry. For each patient, a curve representing ME pressure during anesthesia was plotted. From the curve steepness, the PIR was calculated. Extent of mastoid pneumatization was assessed planimetrically using mastoid x-rays. Ears then were divided by the median into two groups: ears with small mastoids and ears with large mastoids. The difference between the mean PIR of both ear groups was statistically analyzed. RESULTS: A significant difference between the PIR was found among the two groups. In ears with mastoids smaller than 9.475 cm2 (the median), the PIR was significantly higher than in ears with mastoids > 9.475 cm2. CONCLUSIONS: These findings support the concept that the mastoid has a ME pressure buffering capability: the larger its volume, the better its buffering capability. It is therefore suggested, that the mastoid plays a role in ME pressure regulation.

Acoustic Impedance Tests↗
PubMed1997

Shrapnell membrane and mastoid pneumatization.

OBJECTIVE: To assess whether a correlation exists between the degree of pars flaccida (PF) retraction and the degree of mastoid pneumatization. DESIGN: The degree of PF retraction was defined by means of an operating microscope and a pneumatic otoscope. Degree of mastoid pneumatization was assessed planimetrically, using mastoid x-rays. SETTING: Private otologic clinic. PARTICIPANTS: A total of 595 ears, with intact pars tensa, of 332 adult patients. RESULTS: The degree of PF retraction was found to be inversely correlated to the level of mastoid pneumatization. Poorly pneumatized mastoids were associated with PF retractions. The poorer the pneumatization, the deeper the retraction. Well-pneumatized mastoids were associated with normal position of the PF. CONCLUSIONS: This study lends further support to the possibility that the mastoid pneumatic system functions as a middle ear pressure buffer. This possibility gives further explanation as to why ears with poorly pneumatized mastoids tend to develop tympanic membrane retractions and perforations, incus necrosis, or retraction pocket cholesteatoma, while ears with a large pneumatic system are rarely at such risk.

Adult↗
PubMed1997

Cochlear implants in children with congenital inner ear malformations.

OBJECTIVE: To describe clinical experiences with multichannel cochlear implantation in children with inner ear malformations, including surgical indications and techniques, imaging findings, and outcomes. DESIGN: A retrospective review of a series of 10 consecutive cases with a mean follow-up of 29 months, as well as a review of the literature. SETTING: Academic referral center. SUBJECTS: Ten children who underwent multichannel cochlear implantation for inner ear malformations. High-resolution computed tomographic scans demonstrated a common cavity deformity in 3, an incomplete cochlear partition in 4, and an enlarged vestibule in 1. Two had membranous anomalies as indicated by cerebrospinal fluid gushers at surgery, but the results of imaging were normal. INTERVENTION: All subjects received multichannel cochlear implants. Two subjects underwent mastoid obliteration at the time of implantation owing to preoperative recurrent meningitis or chronic otitis media with episodes of clinical mastoiditis. MAIN OUTCOME MEASURES: The 10 subjects were evaluated for electrode insertion and stability and auditory function for up to 7 years. RESULTS: All 22 electrodes are functional in each child with an incomplete partition, an enlarged vestibule, or a membranous anomaly. Of 3 subjects with common cavities, 2 had full insertion of electrodes and 1 had 16 electrodes inserted. All subjects had speech awareness thresholds detected at 25 dB or better. Three (75%) of the 4 subjects with at least 30 months of experience, including 1 subject with a common cavity, have developed open-set word recognition. CONCLUSIONS: Electrode insertion and hearing results in children with an incomplete partition, an enlarged vestibule, or a membranous anomaly are similar to those in children with normal cochleas. Specific surgical techniques are effective for children with a common cavity, and the results are less certain. Cerebrospinal fluid gushers were encountered frequently but were not difficult to control.

Adolescent↗
PubMed1997

Correlation between retractions of the pars flaccida and the pars tensa.

Retractions of the pars flaccida (PF) and the pars tensa (PT) were assessed in 250 atelectatic ears in an attempt to find out the way in which the differences in mechanical properties of the two parts of the tympanic membrane are reflected clinically. Retraction of PF was found in 217 ears (86.8 per cent) and retraction of PF in 150 (60 per cent). The concomitant presence of both types of retraction was observed in 117 ears (46.8 per cent) while 133 (53.2 per cent) had only one type, 100 of them (75.1 per cent) PF retraction and 33 (24.9 per cent) PT retraction. When only one type of retraction was present, the empirical probability of having a PF retraction was 75.1 per cent, while the probability of having a PT retraction was only 24.9 per cent. Clinically, the more frequent occurrence of PF retraction in the absence of PT retraction than vice versa reflects the greater collapsibility of the PF. When both types of retractions were present, we found a positive correlation between their severity.

Ear Diseases↗
PubMed1997

Necrotizing external otitis in patients with AIDS.

In a retrospective review of seven patients with AIDS who were diagnosed with necrotizing external otitis between 1990 and 1995, it was found that the presentation of necrotizing external otitis in patients with AIDS differed from the classic description of malignant external otitis in several respects. The patient population was significantly younger and nondiabetic. Granulation tissue was usually absent from the external auditory canal and Pseudomonas aeruginosa was not the predominant pathologic organism. Also, outcome was found to be significantly worse. Thus a high index of suspicion must be entertained and vigorous local and systemic treatment initiated early in the course of disease to achieve a satisfactory outcome.

AIDS-Related Opportunistic Infections↗
PubMed1997

Dependence of middle ear gas composition on pulmonary ventilation.

The middle ear (ME) steady state gas composition resembles that of mixed venous blood. We changed arterial and venous blood gases by artificially ventilating anesthetized guinea pigs and measured simultaneous ME gas changes during spontaneous breathing, hyperventilation, and hypoventilation. During hyperventilation, PaCO2 and PvCO2 (a = arterial, v = venous) decreased from 46.0 and 53.0 mm Hg to 17.9 and 37.5 mm Hg, respectively, while PaO2 and PvO2 (85.6 and 38.2 mm Hg) did not change. This was accompanied by an ME PCO2 decrease from 70.4 to 58.8 mm Hg and a PO2 decrease from 36.8 to 25.4 mm Hg. During hypoventilation, PaCO2 and PvCO2 increased to 56.8 and 66.4 mm Hg, while PvO2 decreased to 21.8 mm Hg. The ME PCO2 increased simultaneously to 88.8 mm Hg and the ME PO2 decreased to 25.4 mm Hg. The ME PO2 decrease during hyperventilation may be explained by a 33% decrease in ME mucosa perfusion, calculated from the ME ventilation-perfusion ratio. This study shows that ME gas composition follows fluctuations of blood gas levels and thus may affect total ME pressure.

Animals↗
PubMed1997

Intact canal wall drill-out procedure for implantation of the totally ossified cochlea.

OBJECTIVE: To describe a simplified drill-out technique for insertion of a multichannel electrode in the completely ossified cochlea without radical mastoidectomy and obliteration. STUDY DESIGN: Description of a new surgical technique and case report. SETTING: Temporal bone dissection laboratory and tertiary referral center. PATIENTS: Adult and pediatric cochlear implant (CI) recipients. MAIN OUTCOME MEASURES: Access for circum-modular drill-out and electrode insertion without radical mastoidectomy and adequate function of multichannel CI. RESULTS: Dissection of 10 cadaver temporal bones demonstrated feasibility of this technique. Highlights include facial recess cochleostomy and 8 mm tunnel; elevation of superiorly based tympanomeatal flap; removal of incus, cochleariform process, and tensor tympani; and identification of carotid canal and use of facial nerve monitor. A case report of an 11-year-year old child with total cochlear ossification and previous failure of a short (8 electrode) CI electrode insertion is presented. Complete insertion of a 22-channel electrode was successful and open-set word recognition is commencing. CONCLUSIONS: The canal wall-up drill-out procedure allows complete electrode insertion without mastoid obliteration in patients with obliterated cochleas. Appropriate attention to the carotid artery and facial nerve is essential.

Child↗