Subarachnoid Space Measurements in Apparently Healthy Fetuses Using MR Imaging.

BACKGROUND AND PURPOSE: The fetal subarachnoid space size serves as an indicator of normal brain development. The subarachnoid space is commonly measured by an ultrasound examination. Introduction of MR imaging for fetal brain evaluation enables standardization of MR imaging-driven subarachnoid space parameters for a more accurate evaluation. This study aimed to determine the normal range of MR imaging-derived subarachnoid space size in fetuses according to gestational age. MATERIALS AND METHODS: A cross-sectional study based on a retrospective assessment of randomly selected brain MR images of apparently healthy fetuses performed between 2012 and 2020 at a large tertiary medical center was performed. Demographic data were collected from the mothers' medical records. Subarachnoid space size was measured at 10 reference points using the axial and coronal planes. Only MR imaging scans obtained between weeks 28 and 37 of pregnancy were included. Scans with low-quality images, multiple pregnancy, and cases with intracranial pathologic findings were excluded. RESULTS: Overall, 214 apparently healthy fetuses were included (mean maternal age, 31.2 [SD, 5.4] years). Good interobserver and intraobserver agreement was observed (intraclass correlation coefficient > 0.75 for all except 1 parameter). For each gestational week, the 3rd, 15th, 50th, 85th, and 97th percentiles of each subarachnoid space measurement were described. CONCLUSIONS: MR imaging-derived subarachnoid space values at a specific gestational age provide reproducible measurements, probably due to the high resolution of MR imaging and adherence to the true radiologic planes. Normal values for brain MR imaging could provide valuable reference information for assessing brain development, thus being an important tool in the decision-making process of both clinicians and parents.

Calculated versus measured pure tone bone conduction 3 kHz thresholds in sudden sensorineural hearing loss.

OBJECTIVE: To compare the measured bone conduction threshold at 3 kHz with the calculated threshold in newly diagnosed sudden sensorineural hearing loss. METHODS: A retrospective chart review was conducted of pure tone audiograms in confirmed sudden sensorineural hearing loss cases. RESULTS: Of 157 patients with sudden sensorineural hearing loss, 144 had idiopathic hearing loss, 8 had vestibular schwannoma and 5 had Ménière's disease. The r value for the correlation between the two methods of 3 kHz assessment for all patients was 0.887 (p < 0.001). The mean difference between the measured and calculated 3 kHz thresholds was 0.76 ± 7.96 dB, 0.4 ± 8.08 dB and 1.5 ± 1.8 dB in the sudden sensorineural hearing loss, idiopathic and Ménière's disease groups, respectively. The mean difference between the measured and calculated 3 kHz thresholds was significantly greater in the vestibular schwannoma group (6.86 ± 4.38 dB) than in the idiopathic group (p = 0.013). CONCLUSION: The 3 kHz frequency may encompass important audiometric information. A discrepancy between the measured and calculated bone conduction 3 kHz thresholds raises suspicion of an underlying vestibular schwannoma as an aetiology for sudden sensorineural hearing loss, and these thresholds should therefore be measured independently and routinely.

Pseudo-anticipation in Creutzfeldt-Jakob disease is due to a rhomboid-shaped artifact.

BACKGROUND AND PURPOSE: Previous studies have reported conflicting results regarding possible anticipation in familial E200K Creutzfeldt-Jakob disease (fCJD). Our objective was to use a large database to assess the age of disease onset (AODO) in CJD. METHODS: The study population included 477 CJD patients [266 with fCJD, 145 with sporadic CJD (sCJD) and 66 patients of Libyan origin but negative family history] from the Israeli registry of CJD conducted since 1954. In all patients, AODO in relatives and family trees was documented. Comparison of AODO was done using a paired t test and regression using Pearson correlation for birth and year of onset. RESULTS: The initial analysis in 52/73 families in which more than one generation was affected revealed an AODO of 63.30 ± 9.44 in the first generation compared to 56.96 ± 8.99 in the second generation (P < 0.001). However, inspection of individual AODO values plotted by year of birth showed a clear rhomboid methodological artifact generated by missing data of many young onset CJD patients who died before the database began to function in 1954 and of many late onset CJD patients missing at the present time since they will only develop the disease in the future. The 'generation' effect completely disappears if analysis is performed by year of disease onset or for the periods in which complete data are available. CONCLUSIONS: In this very large dataset, true anticipation in fCJD patients was not detected. It is plausible that previous reports supporting the presence of anticipation are biased by a rhomboid-shaped data availability artifact.