Does Location of Intralabyrinthine Vestibular Schwannoma Determine Objective and Subjective Vestibular Function?

BACKGROUND AND OBJECTIVE

The incidence of intralabyrinthine schwannomas is increasing, and a growing attention is given to the detrimental effects on hearing function. On the contrary, the vestibular profile of intralabyrinthine vestibular schwannomas (VSs) is still not well understood. We aimed to investigate and report the observed relationships between the intralabyrinthine location of the schwannomas and objective and subjective vestibular profile of the patients.

METHODS

Retrospective cohort study of 20 consecutive individuals with sporadic intralabyrinthine schwannomas and grouped according to the intralabyrinthine location of the schwannomas. Vestibular testing consisted of the video head impulse test of all three semicircular canals, the caloric test, cervical and ocular vestibular evoked myogenic potentials, and the dizziness handicap inventory. A nonparametric unpaired t test was performed to compare groups, and Fisher's exact test was used for categorical data.

RESULTS

The median video head impulse test gains (lateral, anterior, posterior) were 0.40, 0.50, and 0.75 for intravestibular schwannomas and 0.93, 1.52, and 0.91 for intracochlear schwannomas ( p = 0.0001, p = 0.009, p = 0.33), respectively. Caloric unilateral weakness had a median of 100% for intravestibular schwannomas and 14% for intracochlear schwannomas ( p = 0.0001). The mean dizziness handicap inventory was 21 for intravestibular schwannomas and 1 for cochlear schwannomas ( p = 0.02). There were no significant differences in vestibular evoked myogenic potentials according to intralabyrinthine location.

CONCLUSION

By both objective and subjective measures, intralabyrinthine schwannomas with an intravestibular component has significantly worse vestibular function than schwannomas with purely cochlear involvement.

Transmastoid Surgery for Superior Canal Dehiscence: Prospective Longitudinal Objective and Patient-Reported Audiovestibular Outcomes

OBJECTIVE

We assess symptom control, reversal and stability of objective third-window indicators, and hearing and balance function after transmastoid superior canal dehiscence plugging. To do this, we combine patient self-assessment questionnaires with auditory and vestibular test data collected at a preoperative and multiple postoperative visits.

STUDY DESIGN

Prospective cohort study.

SETTING

Tertiary referral center.

PATIENTS

Patients who underwent transmastoid plugging for superior canal dehiscence from 2012 to 2020.

INTERVENTIONS

Plugging of the superior semicircular canal using the transmastoid approach.

MAIN OUTCOME MEASURES

Patients were evaluated preoperatively, 3-month postoperative, and at yearly follow-ups (up to 8 yr postoperative). Self-assessment questionnaires included Autophony Index, Dizziness Handicap Inventory, Tinnitus Handicap Inventory, and Hearing Handicap Inventory. Objective tests included audiometry, cervical vestibular evoked myogenic potential, ocular vestibular evoked myogenic potential, and video head impulse test.

RESULTS

There was a statistically significant improvement in Autophony Index and Hearing Handicap Inventory total scores from the preoperative evaluation to 1 year postoperative. Dizziness Handicap Inventory and Tinnitus Handicap Inventory total scores also improved but statistically insignificant. Cervical and ocular vestibular evoked myogenic potential amplitudes and low-frequency air-bone gap showed statically significant reversal of the third-window effect preoperative versus 1 year postoperative. Video head impulse test of the superior semicircular canal revealed cases of pathological function preoperative with postoperative recovery. Results were stable over time.

CONCLUSIONS

Superior canal dehiscence repair resolves symptoms of autophony and improves hearing disability. Objective third-window indicators reverse and show long-term stability. Auditory and vestibular function is preserved postoperative, even superior semicircular canal function may be normal. Data suggest that surgical outcomes should not be evaluated until 1 year postoperative.

Tinnitus suppression in a prospective cohort of 45 cochlear implant recipients: occurrence, degree and correlates

OBJECTIVE

To determine tinnitus prevalence and severity in a cohort of unselected first-time cochlear implant (CI) recipients whose primary motive for CI was sensorineural hearing loss (SNHL), and to evaluate the effect of CI on tinnitus after cochlear implantation.

METHODS

Prospective longitudinal study of 45 adult CI recipients with moderate to profound SNHL. Patients completed the Danish version of the Tinnitus Handicap Inventory (THI) and a visual analogue scale (VAS) for tinnitus burden before implantation, 4 months after implantation and 14 months after implantation.

RESULTS

The study included 45 patients, of which 29 (64%) had pre-implant tinnitus. Median THI score (IQR) significantly decreased from 20 (34) to 12 (24) at first follow-up (p < 0.05) and to 6 points (17) at second follow-up (p < 0.001). Median VAS (IQR) for tinnitus burden decreased from 33 (62) to 17 (40; p = 0.228) and 12 (27, p < 0.05) at the first and second follow-ups, respectively. Tinnitus was totally suppressed in 19% of patients, improved in 48%, remained unchanged in 19% and worsened in 6%. 2 patients reported new tinnitus. At the second follow-up, 74% of patients had slight or no tinnitus handicap, 16% had mild handicaps, 6% had moderate handicaps, and 3% had severe handicaps. High pre-implant THI and VAS scores correlated with greater decrease in THI scores over time.

CONCLUSION

64% of the patients with SNHL had pre-implant tinnitus, which was decreased 4 and 14 months after implantation. Overall, 68% of patients with tinnitus improved their tinnitus handicap after CI. Patients with higher THI and VAS scores had a larger decline and the highest benefits in terms of tinnitus handicap improvement. The study findings demonstrate that the majority of patients with moderate to profound SNHL eligible for cochlear implantation benefit from complete or partial tinnitus suppression and improved quality of life after implantation.

Vestibular Function in Pendred Syndrome: Intact High Frequency VOR and Saccular Hypersensitivity

OBJECTIVE

Although Pendred syndrome involves anatomical abnormalities in the vestibular system and patient-perceived dizziness, the literature on vestibular function is scarce. The objective was to evaluate objective vestibular function in patients with PS using the video head impulse test (VHIT) and the cervical vestibular evoked myogenic potential (cVEMP) test, assessing the high frequency vestibulo-ocular reflex (VOR) and the saccular function, respectively.

METHODS

Twenty-six subjects (52 ears) with Pendred Syndrome and severe-to-profound hearing loss (cochlear implant candidacy) were studied retrospectively. Main outcome measures were VHIT VOR gain, refixation saccades, cVEMP stimulus thresholds and amplitudes.

RESULTS

In total, 4 of 52 ears (8%) had pathological VHIT outcomes (2 ears with low VHIT gain and 2 ears with saccades). The mean VHIT gain value was 0.96 (range 0.63-2.02). No patients had complete VOR loss. CVEMP responses were present in 76% of tested ears and absent in 24%. The mean cVEMP amplitude value was 192 μV. Absence of cVEMP response was associated with the presence of VHIT saccades (p = 0.038) and advanced age (rs = -0.34; p < 0.05). cVEMP amplitude was correlated with VHIT gain (rs = 0.46; p < 0.001).

CONCLUSION

Despite dysmorphic vestibular anatomy and severe loss of hearing, the VHIT VOR function is normal in patients with Pendred Syndrome. However, saccular function appears to be abnormally sensitive, as documented by low cVEMP thresholds and high amplitudes, which agrees with a "third window" effect secondary to the large vestibular aqueduct.

Nordic results of cochlear implantation in adults: speech perception and patient reported outcomes

BACKGROUND

Although cochlear implantation (CI) is widely performed in postlingually hearing-impaired adults in the Nordic countries, the literature on hearing outcomes remains scarce. Aims/objectives: To evaluate and correlate hearing outcomes after implantation.

METHODS

Prospective evaluation of 40 adult first-implantation recipients pre- and post-implantation with Dantale, the Danish Hearing in Noise Test (HINT), the Nijmegen Cochlear Implant Questionnaire (NCIQ) and the Speech, Spatial and Qualities of Hearing Scale (SSQ12).

RESULTS

Dantale_mean increased from 50% (95% CI [41.7,58.4])) to 73% (95% CI [66.6,80.1]) and 19% (95% CI [13.3,25.1]) to 40%(95% CI [32.1,46.7]) (quiet/noise). HINT_words increased from 71% (95% CI [58.8,83.8]) to 83% (95% CI [69.8,95.4]) and 59% (95% CI [46.2,70.6]) to 73% (95% CI [63.3,82.8]) (quiet/noise). NCIQ_mean changed from 277 (95% CI [252.4,301.6]) to 396 (95% CI [366.7,424.7]) and SSQ12_mean from 27 (95% CI [21.3,31.8]) to 48 (95% CI [39.4,55.6]). Correlations coefficients were r _s = 0.39-0.74 (p < .01) between Dantale/HINT, rs = 0.78 (p < .0001) between NCIQ/SSQ12, r _s = 0.41-0.59 (p < .01) between NCIQ/SSQ12 and Dantale and r _s = 0.24-0.41 (ns) between NCIQ/SSQ12 and HINT.

CONCLUSION

The study documents a high auditory performance and patient-perceived improvement after implantation and advocate broader awareness of implantation as treatment option in the growing population of severe-to-profound hearing-impaired adults. Correlations between hearing measures may influence future evaluation practices.

Lack of humoral immune response to the tetracycline (Tet) activator in rats injected intracranially with Tet-off rAAV vectors

The ability to safely control transgene expression from viral vectors is a long-term goal in the gene therapy field. We have previously reported tight regulation of GFP expression in rat brain using a self-regulating tet-off rAAV vector. The immune responses against tet regulatory elements observed by other groups in nonhuman primates after intramuscular injection of tet-on encoding vectors raise concerns about the clinical value of tet-regulated vectors. However, previous studies have not examined immune responses following injection of AAV vectors into brain. Therefore, rat striatum was injected with tet-off rAAV harboring a therapeutic gene for Parkinson's disease, either hAADC or hGDNF. The expression of each gene was tightly controlled by the tet-off regulatory system. Using an ELISA developed with purified GST-tTA protein, no detectable immunogenicity against tTA was observed in sera of rats that received an intrastriatal injection of either vector. In contrast, sera from rats intradermally injected with an adenovirus containing either tTA or rtTA, as positive controls, had readily detectable antibodies. These observations suggest that tet-off rAAV vectors do not elicit an immune response when injected into rat brain and that these may offer safer vectors for Parkinson's disease than vectors with constitutive expression.

A new modified bovine heterograft for vascular access in haemophiliacs

Because of poor venous access and failure of previous arteriovenous shunts due to thrombosis, two patients with severe coagulapathies had an arteriovenous fistula performed using a new chemically treated bovine carotid artery segment (Solcograft-P). To date, no complications have been noted after 16 and 17 months respectively. This treated heterograft maintains many of the physical characteristics observed in a normal bovine carotid artery. The theoretical advantages for using this heterograft in such patients are discussed.

Upstream flanking sequences and transcription of SINEs

SINEs, short interspersed repeated DNA elements, undergo amplification through retroposition and subsequent integration into a new location in the genome. Each new SINE insertion will be located in a new chromosomal environment, with different flanking sequences. Modulation of transcription by different flanking sequences may play an important role in determining which SINE elements are preferentially active in a genome. We evaluated the ability of upstream flanking sequences to regulate the transcription of three different SINEs (Alu, B2 and ID) by constructing chimeric constructs with known 5' flanking sequences of RNA polymerase III-transcribed genes. Upstream sequences from the 7SL RNA gene, U6 RNA gene, vault RNA gene, and BC1 gene increase transcription of Alu, B2 and BC1 in transient transfections of NIH3T3, HeLa, Neuro2a and C6 glioma cell lines. The 7SL sequence proved most efficient in increasing SINE transcription. The 7SL upstream fused to the BC1 RNA gene (an ID element) was used to create a transgenic mouse line. In contrast to the tissue-specific endogenous BC1 transcription, BC1 transgene transcripts were detected in all tissues tested. However, expression was much higher in those tissues that express the endogenous gene, demonstrating both transcriptional and post-transcriptional regulation. The BC1 RNA was detected in a similar ribonucleoprotein complex in the different tissues.

Unusually severe heterozygous beta-thalassemia: evidence for an interacting gene affecting globin translation

A common beta-thalassemia mutation in Asian populations is the C --> T substitution at position 654 of intron 2, which leads to the activation of two cryptic splicing sites and the incorporation of 73 extra nucleotides into the mutant mRNA. Like most beta-thalassemia mutations, it normally exhibits recessive inheritance. We investigated the unusually severe phenotype in two heterozygotes for this mutation, father and son, who had thalassemia intermedia and an apparent dominant mode of inheritance. An increased level of aberrantly spliced transcript in the reticulocytes of the probands compared with asymptomatic beta654 heterozygotes led us to investigate the production and processing of beta654 RNA. We showed that large amounts of the aberrant beta654 transcript were detectable in erythroblasts from one of the asymptomatic cases. The translation product of this mRNA was not detectable in vivo, and we were unable to demonstrate the translation of the mutant mRNA in a cell-free translation system. Although the reticulocyte alpha:beta mRNA ratios in the two probands were within the range observed in the asymptomatic heterozygotes, globin chain biosynthesis studies showed that the probands had considerably greater alpha:beta chain imbalance. These results imply that the more severe phenotype may be due to a second defect, possibly unlinked to the beta-globin cluster, that acts at the translational or posttranslational level.

Double heterozygosity for mutations in the platelet glycoprotein IX gene in three siblings with Bernard-Soulier syndrome

Bernard-Soulier syndrome (BSS) giant platelets have defective and/or deficient glycoprotein (GP) Ib/IX complexes, causing absent ristocetin-induced aggregation, defective interaction with von Willebrand factor, morphologic abnormality, and a clinical bleeding tendency. Recently several mutations have been described in the platelet GPIb alpha gene in individuals exhibiting the BSS phenotype. We have studied a family with classical BSS, and have excluded lesions at the GPIb alpha locus by restriction fragment length polymorphism linkage analysis. Analysis of the genes for two other components of the platelet GPIb:IX complex, namely GPIb beta and GPIX, showed two different missense mutations in the coding region of the GPIX gene: an A-->G transition in codon 21 results in conversion of an aspartic acid to glycine and an A-->G change in codon 45 converts an asparagine residue to serine. Three affected individuals are doubly heterozygous for these mutations, which alter conserved residues in or flanking the GPIX leucine-rich glycoprotein motif. Both mutations create new recognition sites for the enzyme Fnu 4H1; therefore, this enzyme was used to screen 60 normal subjects (120 alleles). Neither mutation was detected in any subject other than direct relatives of the affected individuals. Although low levels of GPIb were demonstrable by both flow cytometry and immunoblot analysis in an affected individual's platelets, there was no evidence of GPIX immunoreactivity. We propose that expression of abnormal GPIX prevents stable assembly of the GPIb/IX complex, causing BSS in the doubly heterozygous individuals in this family.

A regional experience of red cell aplasia

The incidence and current management of red cell aplasia in children was determined from a retrospective survey of haematologists and paediatricians in the northern health region of England over a 7-year period. Thirty-three children were diagnosed: 4 had Diamond Blackfan anaemia, 22 transient erythroblastopenia of childhood, and 7 parvovirus B19 aplasia, with annual incidences of 1, 5 and 2 per 1,000,000 children respectively. Many were over-investigated. Three with Diamond Blackfan anaemia were steroid responsive. One with transient erythroblastopenia was retrospectively diagnosed because anaemia did not recur after steroids were stopped. Transient erythroblastopenia is the most common single cause of red cell aplasia in immunocompetent children. Time, observation and bone marrow examination before steroid therapy are the ways to distinguish transient erythroblastopenia from Diamond Blackfan anaemia or leukaemia. Interpretation of red cell indices using age-related percentiles may reduce the number of inappropriate investigations of the anaemia, but is often unhelpful in distinguishing the various causes of red cell aplasia.

Parvovirus infection associated with aplastic crisis in a patient with HEMPAS

An aplastic crisis associated with parvovirus infection occurred in a patient suffering from hereditary erythrocytic multinuclearity associated with a positive acidified (Hams) test (HEMPAS). This case emphasises that any patient who has a shortened red cell survival is susceptible to an aplastic crisis induced by parvovirus.

Interdonor incompatibility due to anti-Kell antibody undetectable by automated antibody screening

A unit of whole donor blood, the plasma of which contained anti-Kell antibody, was transfused into a Kell-negative patient who had received a unit of Kell-positive blood 4 weeks previously. A haemolytic transfusion reaction ensued. The antibody had gone undetected in routine automated screening of the donor blood. Automated antibody detection techniques do not offer reliable detection of anti-Kell antibodies.

IgE myeloma associated with plasma cell leukaemia

A patient presented with plasma cell leukaemia and was found to have an IgE secreting multiple myeloma. IgE myeloma is very rare with only 18 cases recorded. However, this case is the fifth recorded of IgE myeloma associated with plasma cell leukaemia. Since plasma cell leukaemia only occurs in 1.6% of all cases of myeloma, it seems certain that this is a significant association.