Overlapping thin-section fast spin-echo MR of the large vestibular aqueduct syndrome.

PURPOSE: To evaluate a high-resolution, thin-section fast spin-echo MR imaging technique of the inner ear to identify the large vestibular aqueduct syndrome seen on temporal bone CT scans. METHODS: We retrospectively reviewed the temporal bone CT scans of 21 patients with hearing loss and enlarged bony vestibular aqueducts by CT criteria. High-resolution fast spin-echo MR imaging was then performed on these patients using dual 3-inch phased-array receiver coils fixed in a temporomandibular joint holder and centered over the temporal bones. MR imaging included axial and oblique sagittal fast spin-echo sequences. The diameter of the midvestibular aqueduct on CT scans and the signal at the level of the midaqueduct on MR images were measured on axial sequences, then compared. High-resolution MR imaging with the same protocol was performed in 44 control subjects with normal ears, and similar measurements were taken. RESULTS: The average size of the enlarged bony vestibular aqueduct on CT scans was 3.7 mm, and the average width of the signal from within the enlarged aqueduct on MR images was 3.8 mm. Statistical analysis showed excellent correlation. MR images alone displayed the enlarged extraosseous endolymphatic sac, which accompanies the enlarged aqueduct in this syndrome. Five ears in three patients with enlarged bony vestibular aqueducts on CT scans showed no evidence of an enlarged endolymphatic duct or sac on MR images. An enlarged endolymphatic sac was seen on MR images in one patient with a bony vestibular aqueduct, which had normal measurements on CT scans. MR imaging alone identified a single case of mild cochlear dysplasia (Mondini malformation). In the 88 normal ears studied, the average size of the endolymphatic sac at its midpoint between the common crus and the external aperture measured on MR images was 0.8 mm (range, 0.5 to 1.4 mm). In 25% of the normal ears, no signal was seen from within the vestibular aqueduct. CONCLUSION: Thin-section, high-resolution fast spin-echo MR imaging of the inner ear is complementary to CT in studying patients with the large vestibular aqueduct syndrome, as MR imaging better displays the soft tissue and fluid of the membranous labyrinth.

Osseointegration and growth effects of temporal bone percutaneous pedestals.

The percutaneous temporal bone pedestal has shown significant utility for the attachment of bone-anchored hearing aids, attachment of cosmetic auricular prostheses, and as connector between external sound processors and implanted cochlear implants. The biological acceptance of these implants by temporal bone hosts is affected by many factors including the maturity of the bone, the design of the pedestal-fixation system, and the pedestal-construction material. The first phase of this study evaluated the effect of the pyrolized graphite pedestal fixation on maturing temporal bones. Pedestals were implanted in young swine temporal bones using single screw and multiple screw fixation systems. The effect on temporal bone growth is demonstrated with photomicrographs and gross photography showing acceptable host-tissue response to the presence of multiple and single screw attachment techniques. Osseointegration of the attaching screws occurred. The second phase of the study evaluated osseointegration of smooth, beaded, and textured titanium pedestals in feline temporal bones. High-resolution temporal bone/pedestal sectioning has been accomplished with high-performance microtomes, showing the osseointegration of the pedestal by the temporal bone. This is demonstrated with tetracycline labeling and histologic assessment. Percutaneous pedestals are of increasing importance in otologic practice. This study assists in the understanding of biologic acceptance of pedestals as influenced by the pedestal composition and fixation design. This basic understanding is essential for design improvements in percutaneous temporal bone pedestals.

Low-cost high-resolution fast spin-echo MR of acoustic schwannoma: an alternative to enhanced conventional spin-echo MR?

PURPOSE: To determine whether unenhanced high-resolution T2-weighted fast spin-echo MR imaging provides an acceptable and less expensive alternative to contrast-enhanced conventional T1-weighted spin-echo MR techniques in the diagnosis of acoustic schwannoma. METHODS: We reviewed in a blinded fashion the records of 25 patients with pathologically documented acoustic schwannoma and of 25 control subjects, all of whom had undergone both enhanced conventional spin-echo MR imaging and unenhanced fast spin-echo MR imaging of the cerebellopontine angle/internal auditory canal region. The patients were imaged with the use of a quadrature head receiver coil for the conventional spin-echo sequences and dual 3-inch phased-array receiver coils for the fast spin-echo sequences. RESULTS: The size of the acoustic schwannomas ranged from 2 to 40 mm in maximum dimension. The mean maximum diameter was 12 mm, and 12 neoplasms were less than 10 mm in diameter. Acoustic schwannoma was correctly diagnosed on 98% of the fast spin-echo images and on 100% of the enhanced conventional spin-echo images. Statistical analysis of the data using the kappa coefficient demonstrated agreement beyond chance between these two imaging techniques for the diagnosis of acoustic schwannoma. CONCLUSIONS: There is no statistically significant difference in the sensitivity and specificity of unenhanced high-resolution fast spin-echo imaging and enhance T1-weighted conventional spin-echo imaging in the detection of acoustic schwannoma. We believe that the unenhanced high-resolution fast spin-echo technique provides a cost-effective method for the diagnosis of acoustic schwannoma.

Cerebellopontine angle glioneuronal hamartoma.

Roughly 90% of cerebellopontine angle tumors are acoustic neuromas. Other prevalent lesions include meningiomas and epidermoid tumors; additional lesions are rare. We describe a patient with a neuroglial hamartomatous mass of the internal auditory canal who was thought to have a schwannoma preoperatively. In this case, the hamartomatous tissue containing neuroectodermal elements may have become separated from the developing neuraxis during neural migration. Hamartomas should be considered when masses are discovered originating from eighth nerve branches other than the superior vestibular nerve and when magnetic resonance signal characteristics vary from the T1 enhancement typically seen with schwannomas and meningiomas.

Frequency discrimination and speech recognition by patients who use the Ineraid and continuous interleaved sampling cochlear-implant signal processors.

Patients who use the Ineraid cochlear implant were tested in four experiments with materials which assessed frequency discrimination and speech understanding. In each experiment both frequency discrimination and speech recognition varied among patients. Correlations between the two measures were significant and ranged from 0.60 to 0.83. Most generally, frequency discrimination was better in the frequency domain of F1 than in the domain of F2. In experiment 5, both the Ineraid signal processing strategy and a continuous interleaved sampling (CIS) strategy were implemented for a single patient. The CIS strategy improved frequency discrimination in the domain of F2 and improved speech understanding.

Advanced techniques in magnetic resonance imaging in the evaluation of the large endolymphatic duct and sac syndrome.

The purpose of this report is to compare temporal bone computed tomography (CT) to high-resolution magnetic resonance (MR) imaging using a novel thin-section fast spin echo (FSE) pulse sequence in identifying and characterizing patients with large vestibular aqueduct syndrome. Sixteen patients with sensorineural hearing loss and a CT diagnosis of large vestibular aqueduct(s) underwent high-resolution fast spin echo magnetic resonance imaging with dual, 3-in phased array receiver coils centered over the external auditory canals. Magnetic resonance imaging parameters included axial and oblique sagittal fast spin echo with an effective slice thickness of 1 mm contiguous. Thirty-eight patients with 76 normal inner ears who underwent MR imaging using this technique had their endolymphatic duct measured. MR alone identified the enlarged endolymphatic sac seen along with the large endolymphatic duct in all cases. Three cases (five inner ears) with enlarged bony vestibular aqueducts on CT showed no evidence of endolymphatic duct or sac enlargement on MR. MR alone identified a single case of mild cochlear anomaly in conjunction with an enlarged endolymphatic duct and sac. In the normal population the size of the normal endolymphatic duct at its midpoint measured from 0.1 to 1.4 mm. Thin-section, high-resolution fast spin echo MR imaging of the inner ear may be superior to CT in the evaluation of patients with the large vestibular aqueduct syndrome.

Acute leukemia and the transient myeloproliferative disorder associated with Down syndrome: morphologic, immunophenotypic and cytogenetic manifestations.

Individuals with Down syndrome have an increased incidence of leukemia compared to the general population. In addition, Down syndrome children may acquire a myeloproliferation that resembles acute leukemia that undergoes a spontaneous, durable remission. To clarify the relationship between these two disorders, the morphologic, immunophenotypic and cytogenetic characteristics of 28 patients with Down syndrome and the morphologic manifestations of acute leukemia were examined. Three cytomorphological groups were discerned. The first two groups consisted of five patients with acute lymphoblastic leukemia (group I) and three patients with acute myeloid leukemia (group II). These leukemias resembled those of non-Down individuals. The third and largest group (group III) consisted of 20 cases of acute myeloid leukemia that showed prominent megakaryocytic and/or erythroid differentiation and occurred in children under 6 years of age. The blasts in this group were non-reactive for myeloperoxidase or non-specific esterase and expressed CD7, CD34 and CD36 with variable expression of CD61, CD13 and CD33. Four patients in this group had an acquired trisomy 8. Four group III leukemias underwent a durable, spontaneous remission within 2 months of diagnosis. There were no morphologic differences between those leukemias in this group that progressed and those that remitted; however, all remissions occurred in newborns. It is concluded that Down syndrome children acquire a characteristic acute myeloid leukemia that has prominent megakaryocytic and/or erythroid differentiation and an unusual immunophenotype. This group of leukemias may undergo a durable, spontaneous remission in the newborn period.

Multichannel cochlear implantation with percutaneous pedestal.

In a prospective study by Cohen et al, the superiority of multichannel cochlear implant patient performance over single-channel cochlear implant performance was demonstrated. The Ineraid system described in this paper includes a percutaneous pedestal which has had a satisfactory patient experience. Only one pedestal removal has been necessary because of specific pedestal problems. Other less serious pedestal problems decrease in frequency with increasing time post-implantation. The auditory performance indicates significant communication skills improvement in patients with multichannel cochlear implants.

The pitch of electrically presented sinusoids.

A patient who uses the Ineraid cochlear implant, and who has hearing thresholds less than 50 dB HL for frequencies under 500 Hz in his nonimplanted ear, was asked to match the pitch of low-frequency signals presented to his two ears. The patient produced pitch matches, for frequencies of 125, 200, and 300 Hz presented to his most apical electrode, that were slightly higher than the reference frequency. When signals of fixed frequency were presented to electrodes located in successively more basal cochlear locations, pitch increased in an orderly fashion--an average of 57 Hz (range = 31-87 Hz) for each change in electrode location.

Morphologic and quantitative changes in blood and marrow cells following growth factor therapy.

Sequential blood and bone marrow specimens from 53 patients receiving recombinant granulocyte (G-CSF) or granulocyte macrophage colony stimulating growth factor (GM-CSF) for neutropenia were evaluated. The blood findings were marked by a neutrophilia with a prominent left shift, increased azurophilic granulation, Döhle bodies, and an elevated leukocyte alkaline phosphatase; circulating myeloblasts were observed but did not exceed 2% of the leukocytes. Nuclear segmentation abnormalities consisting of hyposegmentation, hypersegmentation, and ring nuclei were noted but were not a prominent finding. A leukoerythroblastosis was present in 54% of patients. No consistent effect on cell lines other than neutrophils was found. A monocytosis was present in 12 patients, a transient lymphocytosis in 2 and an eosinophilia in 1. No effect was evident on basophils. The morphologic changes in the neutrophils in the bone marrow specimens were most pronounced in the early period of growth factor therapy with a relative neutrophil hyperplasia with a marked increase in promyelocytes and myelocytes. With increasing duration of therapy, the myeloid to erythroid ratio normalized and the percentage of promyelocytes decreased while myelocytes and band neutrophils increased. Thirteen patients had no response to growth factor. The nonresponding patients were clinically diverse; all bone marrow biopsy specimens in this group were virtually acellular. No differences were noted between G-CSF and GM-CSF.

Loudness balance between acoustic and electric stimulation by a patient with a multichannel cochlear implant.

Estimates of loudness balance were obtained for acoustically and electrically presented 250 Hz sine signals from a patient who uses the Ineraid multichannel cochlear implant. Acoustic and electric loudness matching was possible because the patient evidenced a 25 dB HL threshold at 250 Hz in his nonimplanted ear. The level of the electrical stimulus in microamperes required for a balance of loudness grew linearly with equal increments in decibels for the acoustic stimulus. These data, in concert with the very limited data from previous studies, provide a rationale for using a logarithmic transformation of acoustic to electric intensity in signal processors for cochlear implants.

Multichannel (Ineraid) cochlear implant update.

From April 1984 to May 1991, 49 profoundly deaf patients received implantation of the Ineraid multichannel cochlear implant at the University of Utah. The auditory results of 48 patients indicated improvement in mean pure-tone performance to 500 Hz (32.9 +/- 10.1 dB), 1000 Hz (27.1 +/- 10.0 dB), and 2000 Hz (30.1 +/- 9.8 dB). This group of patients had mean performances of 61.2% on auditory-only environmental sounds (Minimum Auditory Capabilities [MAC] battery), 48.8% on auditory-only CID sentences, and 95.5% on auditory-plus-visual CID sentences. The percutaneous pedestal has been well-tolerated. Changes in the surgical skin incisions have been made. A home use speech therapy program has been developed on VHS tapes.

Tumor necrosis factor induces enzymatic changes in liver comparable to those in extrahepatic cancer.

Human recombinant tumor necrosis factor was administered to rats in small doses to determine whether it causes changes in the activity of liver enzymes similar to those observed in cancer growing extrahepatically. Intraperitoneal injection of increasing doses of tumor necrosis factor (20-100 micrograms/kg/day for 5 days) resulted in a 20-50% decrease in hepatic alanine aminotransferase (P < or = 0.05), a 10-20% decrease in aspartate aminotransferase (P < or = 0.04), and a 50-200% increase in alkaline phosphatase (P < or = 0.02). The activity of hepatic 5'-nucleotidase was unchanged. In the serum, there was no significant change in the activity of any of the enzymes. Histologically, there was no damage detectable by light or electron microscopic examination of the liver, and no evidence of biliary obstruction. However, in frozen liver sections stained histochemically for alkaline phosphatase, there was a dramatic increase in the activity of this enzyme in hepatocytes, which was confined to the bile canaliculi. There was also a 3- to 9-fold increase in the mitotic activity of hepatocytes. Comparable changes have been reported in the tumor-free liver of animals with cancer.

Long-term measures of electrode impedance and auditory thresholds for the Ineraid cochlear implant.

Measures of electrode impedance and of detection thresholds for electrical stimuli were extracted from the records of patients implanted with the Ineraid cochlear prosthesis. An analysis of impedance measures, obtained at 1, 12, 24, and 36 months after surgery, demonstrated (a) a significant decrease in impedance over the first year for electrodes that carried current and (b) significant increases in impedance at 24 and 36 months for electrodes that did not carry current. An analysis of detection thresholds, obtained at the same times as the impedance measures, demonstrated that averaged thresholds for the current-carrying electrodes varied no more than 0.5 dB over the 3-year period. These results support the conclusion that stimulation with the Ineraid device does not produce deleterious changes in the electrodes or in the target neural tissue.

Tumor necrosis factor/cachectin decreases catalase activity of rat liver.

Tumor bearing hosts and animals treated with endotoxin commonly show a decrease in the catalase activity of the liver and kidney. Since tumor necrosis factor (TNF)/cachectin may play a significant role in these conditions, we investigated its effects on the catalatic and peroxidatic activity of catalase in the liver and kidney of the rat. The activities of glucose-6-phosphate dehydrogenase and lactate dehydrogenase were measured simultaneously to monitor the pentose phosphate and glycolytic pathways, respectively. Injection i.p. of 100 micrograms/kg/day human recombinant TNF-alpha for 5 days resulted in a significant (P less than 0.01) decrease in the catalatic activity of the liver when compared to rats fed ad libitum. The decrease in four experiments ranged from 21 to 56%. A significant decrease (18%; P = 0.01) in liver catalatic and peroxidatic activity was also observed in another experiment using pair fed rats as controls. The peroxidatic activity of catalase with ethanol as hydrogen donor closely paralleled the catalatic activity. TNF treatment had no detectable effect on the catalatic or peroxidatic activity of catalase in the kidney. The activity of glucose-6-phosphate dehydrogenase increased (31-80%) significantly (P less than or equal to 0.02) in the liver and, to a lesser extent, in the kidney (5-27%, P = 0.05). Lactate dehydrogenase activity decreased (14-19%) significantly (P less than or equal to 0.05) in the liver and kidney but mainly in rats treated with TNF and additionally fasted for 24 h. Electron microscopic examination of liver sections showed that the hepatocytes of TNF-treated rats were undamaged but contained fewer and smaller peroxisomes than those of the control rats.

Acute basophilic leukemia. A clinical, morphologic, and cytogenetic study of eight cases.

The authors describe eight cases of acute basophilic leukemia. In six of the eight cases, basophilic involvement was not apparent by light microscopic examination. The cases were identified on the basis of ultrastructural evidence for basophil/mast cell differentiation of the blasts with little or no differentiation into other lineages. Ultrastructural analysis revealed immature basophil granules in blasts in all eight cases and theta granules in blasts in four cases. In three cases, ultrastructural evidence of mast cell differentiation also was present, with rare cells showing evidence for both basophil and mast cell differentiation. No clinical features distinguished this group of patients from others with acute myeloid leukemia. Cytogenetically, the cases were heterogeneous. Three had a Philadelphia chromosome; none had a t(6;9). The authors conclude that ultrastructural analysis usually must be used to diagnose acute basophilic leukemia, that acute basophilic leukemia is associated frequently with the Philadelphia chromosome, and that the ultrastructural findings provide evidence for a common origin of basophils and mast cells.

Vowel and consonant recognition with the aid of a multichannel cochlear implant.

In this report we review the vowel and consonant recognition ability of patients who use a multichannel cochlear implant and who achieve relatively good word identification scores. The results suggest that vowel recognition is accomplished by good resolution of the frequency of the first formant (F1) combined with poor resolution of the frequency of the second formant (F2). The results also suggest that consonant recognition is accomplished (1) by using information from the amplitude envelope, including periodicity/aperiodicity, as cues to manner and voicing, (2) by using F1 as an aid to the identification of manner and voicing, and (3) by using information from cochlear place of stimulation to provide a very crude indication of the shape of the frequency spectrum above 1 kHz.

Auditory performance with simultaneous intracochlear multichannel stimulation.

Different sound processing strategies are used in the various cochlear implant designs. This report presents auditory data on 35 patients implanted at the University of Utah from April 1984 to April 1989. A multichannel monopolar electrode system is inserted intracochlearly. During daily use and auditory performance testing, four electrodes receive simultaneous input. The incoming acoustic signal is amplified and routed to the different electrodes through a band-pass filter system. Mean pure-tone performances were: 500 Hz-29.6 +/- 9.4 dB; 1000 Hz-23.5 +/- 13.2 dB; 2000 Hz-25.4 +/- 9.6 dB; 4000 Hz-32.1 +/- 11.5 dB; and 6000 Hz-42.2 +/- 7.7 dB. Audio-only CID sentence testing showed 51.4% of patients scoring better than 60% and 40% scoring better than 80%. The percutaneous pedestal is well tolerated; patients have had the systems in place for 13 and 15 years.