Comparison of depth of electrode insertion between cochleostomy and round window approach: a cadaveric study.

INTRODUCTION: Round window approach and cochleostomy approach can have different depth of electrode insertion during cochlear implantation which itself can alter the audiological outcomes in cochlear implant. OBJECTIVE: The current study was conducted to determine the difference in the depth of electrode insertion via cochleostomy and round widow approach when done serially in same temporal bone. METHODOLOGY: This is a cross-sectional study conducted in the Department of Otorhinolaryngology in conjunction with Department of Anatomy and Department of Diagnostic and Interventional Radiology over a period of 1 year. 12-electrode array insertion was performed via either approach (cochleostomy or round window) in the cadaveric temporal bone. HRCT temporal bone scan of the implanted temporal bone was done and depth of insertion and various cochlear parameters were calculated. RESULT: A total of 12 temporal bones were included for imaging analysis. The mean cochlear duct length was 32.892 mm; the alpha and beta angles were 58.175° and 8.350°, respectively. The mean angular depth of electrode insertion via round window was found to be 325.2° (SD = 150.5842) and via cochleostomy 327.350 (SD = 112.79) degree and the mean linear depth of electrode insertion via round window was found to be 18.80 (SD = 4.4962) mm via cochleostomy 19.650 (SD = 3.8087) mm, which was calculated using OTOPLAN 1.5.0 software. There was a statically significant difference in linear depth of insertion between round window and cochleostomy. Although the angular depth of insertion was higher in CS group, there was no statistically significant difference with round window type of insertion. CONCLUSION: The depth of electrode insertion is one of the parameters that influences the hearing outcome. Linear depth of electrode insertion was found to be more in case of cochleostomy compared to round window approach (p = 0.075) and difference in case of angular depth of electrode insertion existed but not significant (p = 0.529).

Carrier Screening and Diagnosis for Spinal Muscular Atrophy Using Droplet Digital PCR Versus MLPA: Analytical Validation and Early Test Outcome.

Background: Spinal muscular atrophy (SMA) is an autosomal recessive neuromuscular life-threatening disorder. Owing to high carrier frequency, population-wide SMA screening to quantify the copy number of SMN gene is recommended by American College of Medical Genetics and Genomics. An accurate, reliable, short runaround time and cost-effective method may be helpful in mass population screening for SMA. Methods: Multiplex ligation-dependent probe amplification (MLPA) is a gold standard to estimate the copy number variation (CNV) for SMN1 and SMN2 genes. In this study, we validated droplet digital polymerase chain reaction (ddPCR) for the determination of CNV for both SMN1 and SMN2 exon 7 for a diagnostic purpose. In total, 66 clinical samples were tested using ddPCR, and results were compared with the MLPA as a reference test. Results: For all samples, CNV for SMN1 and SMN2 exon 7 was consentaneous between ddPCR and MLPA test results (κ = 1.000, p < 0.0001). In addition, ddPCR also showed a significant acceptable degree of test repeatability, coefficient of variation < 4%. Conclusion: ddPCR is expected to be utilitarian for CNV detection for carrier screening and diagnosis of SMA. ddPCR test results for CNV detection for SMN1/SMN2 exon 7 are concordant with the gold standard. ddPCR is a more cost-effective and time-saving diagnostic test for SMA than MLPA. Furthermore, it can be used for population-wide carrier screening for SMA.

Anomalous retrogressive palmaris longus.

An interesting case of unusual unilateral variant of palmaris longus (PL) tendon of forearm was noticed by us. We found two bellies of PL as well as their different insertions. These observations will help in understanding morphological variations of this muscle and its clinical implications. PL is a fusiform muscle in the superficial flexor group of muscles of forearm. It originates from medial epicondyle of humerus by common flexor tendon. We found PL having one origin, i.e., from medial epicondyle from common tendinous origin of flexor muscles and then it divided to form two bellies having two long tendons distally. Understanding of presence or absence or anomalies of PL is not only important for medical professionals but also for evolutionary biologists. Awareness of anatomy and variations of flexor tendons is important for health care practitioners for the correct diagnosis and management of pain, disease, and trauma of forearm and hand.

Résumé Nous avons remarqué un cas intéressant de variante unilatérale inhabituelle du tendon du long palmaire (PL) de l'avant-bras. Nous avons retrouvé deux ventres de PL ainsi que leurs différentes insertions. Ces observations aideront à comprendre les variations morphologiques de ce muscle et ses implications cliniques. Le PL est un muscle fusiforme du groupe des muscles fléchisseurs superficiels de l'avant-bras. Il provient de l'épicondyle médial de l'humérus par le tendon fléchisseur commun. Nous avons trouvé que le PL avait une origine, c'est-à-dire de l'épicondyle médial provenant de l'origine tendineuse commune des muscles fléchisseurs, puis il s'est divisé pour former deux ventres ayant deux longs tendons distalement. Comprendre la présence, l'absence ou les anomalies de PL est non seulement important pour les professionnels de la santé mais également pour les biologistes évolutionnistes. La connaissance de l'anatomie et des variations des tendons fléchisseurs est importante pour les praticiens de la santé afin de diagnostiquer et de gérer correctement la douleur, la maladie et les traumatismes de l'avant-bras et de la main. Mots-clés: Palmaris longus, greffe tendineuse, variation, contracture ischémique de Volkmann.