From CT scanning to 3D printing technology: a new method for the preoperative planning of a transcutaneous bone-conduction hearing device

SUMMARY

The aim of the present study was to assess the feasibility and utility of 3D printing technology in surgical planning of a transcutaneous bone-conduction hearing device (Bonebridge^®) (BB), focusing on the identification of the proper location and placement of the transducer. 3D printed (3DP) models of three human cadaveric temporal bones, previously submitted to CT scan, were created with the representation of a topographic bone thickness map and the sinus pathway on the outer surface. The 3DP model was used to detect the most suitable location for the BB. A 3DP transparent mask that faithfully reproduced the surface of both the temporal bone and the 3DP model was also developed to correctly transfer the designated BB area. The accuracy of the procedure was verified by CT scan: a radiological marker was used to evaluate the degree of correspondence of the transducer site between the 3DP model and the human temporal bone. The BB positioning was successfully performed on all human temporal bones, with no difficulties in finding the proper location of the transducer. A mean error of 0.13 mm was found when the transducer site of the 3DP model was compared to that of the human temporal bone. The employment of 3D printing technology in surgical planning of BB positioning showed feasible results. Further studies will be required to evaluate its clinical applicability.

Bickerstaff Brainstem Encephalitis and overlapping Guillain-Barré syndrome in children: Report of two cases and review of the literature

Bickerstaff Brainstem Encephalitis (BBE) is a rare autoimmune encephalitis, characterized by acute ophthalmoplegia, ataxia and altered state of consciousness. Together with Guillan-Barrè Syndrome (GBS) and Miller-Fisher Syndrome, it forms a spectrum of post-infectious demyelinating diseases. Overlapping forms between BBE and GBS (BBE/GBS) are described in patients with lower limbs weakness and typical signs of BBE, suggesting a combined involvement of Central and Peripheral Nervous System (PNS), but only few reported cases are focused on pediatric population. We reviewed all cases of pediatric BBE in the literature, to determine if any patient showed features suggestive for BBE/GBS. Data analysis focused on the diagnostic tests performed (e.g. anti-GQ1b antibodies), neuroimaging and nerve conduction studies (NCS). Further attention was given to the therapeutic management and to patients' outcome. We additionally present two previously unreported pediatric cases. Our review retrieved 19 cases of BBE/GBS, only 2 of which were originally and correctly diagnosed by the authors. The prevalence was higher in male subjects (ratio 3:1) and median age at diagnosis was 8 years. Anti-GQ1b were positive in 46% of the patients, while NCS were altered in 64%. Only 25% of the patients that underwent brain MRI showed abnormal findings. The incidence of BBE/GBS has been underrated in the past, mostly due to an underestimation of the PNS involvement. We therefore suggest to investigate all patients with a clinical picture suggestive of BBE/GBS through electroencephalogram, NCS, brain and spine MRI in order to promptly achieve the correct diagnosis.