Innovative computed tomography based mapping of the surgical posterior tympanotomy: An exploratory study.

Robotic devices have recently enhanced cochlear implantation by improving precision resulting in reduced intracochlear damage during electrode insertion. This study aimed to gain first insights into the expected dimensions of the cone-like workspace from the posterior tympanotomy towards the round window membrane. This retrospective chart review analyzed ten postoperative CT scans of adult patients who were implanted with a CI in the past ten years. The dimensions of the cone-like workspace were determined using four landmarks (P1-P4). In the anteroposterior range, P1 and P2 were defined on the edge of the bony layer over the facial nerve and chorda tympani nerve, respectively. In the inferosuperior range, P3 was defined on the bony edge of the incus buttress and P4 was obtained at a distance of 0.45 mm between the facial nerve and the chorda tympani nerve. After selecting the landmarks, the calculations of the dimensions of the surgical access space were done in a standardized coordinate system and presented using descriptive statistics. The cone-like space is limited by two maximal angles, α and ß. The average angle α of 19.84 (±3.55) degrees defines the angle towards the round window membrane between P1 and P2. The second average angle ß of 53.56 (±10.29) degrees defines the angle towards the round window membrane between P3 and P4. Based on the angles the mean anteroposterior range of 2.25 (±0.42) mm and mean inferosuperior range of 6.73 (±2.42) mm. The distance from the posterior tympanotomy to the round window membrane was estimated at 6.05 (±0.71) mm. These findings present data on the hypothetical maximum workspace in which a future robotically steered insertion tool can be positioned for an optimal automated electrode insertion. A larger sample size is necessary before generalizing these dimensions to a population. Further research including preoperative CT scans is needed for planning robotic-steered cochlear implantation.

Tophaceous Gout of the Middle Ear.

Tophaceous gout can rarely present in the middle ear as a mass-like lesion, causing conductive hearing loss. Noncontrast high-resolution computed tomography (HRCT) of the temporal bone plays a significant role in the diagnosis. Awareness of this condition among radiologists is important since it presents a distinctive appearance on HRCT. We present a case of tophaceous gout of the middle ear diagnosed with photon-counting computed tomography (PCCT). Teaching point: The presence of a partially calcified mass with a semolina-like appearance within the middle ear is highly suggestive of tophaceous gout, even in the presence of normal serum uric acid levels.

Fetal-onset Alexander disease with radiological-neuropathological correlation.

Alexander disease is a leukodystrophy caused by mutations in the GFAP gene, primarily affecting the astrocytes. This report describes the prenatal and post-mortem neuroimaging findings in a case of genetically confirmed, fetal-onset Alexander disease with pathological correlation after termination of pregnancy. The additional value of fetal brain magnetic resonance imaging in the third trimester as a complementary evaluation tool to neurosonography is shown for suspected cases of fetal-onset Alexander disease. Diffuse signal abnormalities of the periventricular white matter in association with thickening of the fornix and optic chiasm can point towards the diagnosis. Furthermore, the presence of atypical imaging findings such as microcephaly and cortical folding abnormalities in this case broadens our understanding of the phenotypic variability of Alexander disease.

Residual Splenic Volume after Main Splenic Artery Embolization is Independent of the Underlying Disease.

PURPOSE: To assess the safety and efficacy of main splenic artery embolization. To assess the potential difference post-embolization of the residual splenic volume in patients embolized for trauma versus those embolized for (pseudo)aneurysms. MATERIALS AND METHODS: A retrospective analysis was performed on a cohort of 65 patients (36 males) who underwent pre- and post-embolization computed tomography. Patients' demographics, pre- and post-interventional medical and radiological data were gathered. Splenic volume calculations were semi-automatically performed via a workstation. Patients with splenic aneurysms or pseudoaneurysms of the main splenic artery (group 1) were compared to those with splenic rupture (group 2) using Wilcoxon rank tests. RESULTS: The main indications for splenic artery embolization were splenic rupture (n = 22; 34%) and splenic pseudoaneurysm (n = 19; 29%). The technical success rate was n = 63; 97%. The procedure-related complication rate was n = 7; 11%, including abscess formation (n = 5; 8%), re-bleeding (n = 1; 1.5 %) and pseudoaneurysm re-opening (n = 1; 1.5%). The overall 30-day mortality was n = 7; 11%.Median follow-up for groups 1 and 2 was 1163 days (61-3946 days) and 702 days (43-2095 days) respectively. When processable (n = 23), the splenic volume in group 1 (n = 7) was 311 cm3 and 257 cm3 (p = 0.1591) before and after embolization respectively, and in group 2 (n = 16) it was 261 cm3 and 215 cm3 (p = 0.4688), respectively. CONCLUSIONS: Main splenic artery embolization is efficacious, with low procedure-related complication and 30-day mortality rates. No significant differences in residual post-embolization splenic volume were found between patients treated for splenic rupture versus those treated for splenic arterial (pseudo)aneurysm.