Usefulness of bilateral mucoplasty plus reboot surgery in severe type-2 chronic rhinosinusitis with nasal polyps.

BACKGROUND: Although extended endoscopic sinus surgery (ESS) constitutes an alternative approach in patients with Chronic Rhinosinusitis with Nasal Polyps (CRSwNP), the surgical techniques proposed so far do not allow for an optimal control of the disease. This study introduces bilateral mucoplasty as a complementary technique to extended ESS such as reboot surgery, analyzing its benefits in healing and quality of life (QoL). METHODS: Patients diagnosed with severe Type-2 CRSwNP were selected for a prospective cohort study in two surgery groups: reboot surgery plus bilateral mucoplasty versus reboot surgery only. In the first group, an autologous endonasal mucosal graft from the nostril floor was placed bilaterally onto the ethmoidal roof. Endoscopic, radiological and QoL outcomes were compared before and one year after surgery between the two groups using Modified Lund Kennedy (LKM), Meltzer and Lund Mackay (LM) scores, and the Sino-Nasal Outcome Test 22 (SNOT-22). RESULTS: 64 patients with homogeneous baseline characteristics were included: 17 patients underwent a reboot surgery plus a bilateral mucoplasty and 47 a reboot surgery only. LKM, Meltzer and SNOT-22 scores showed significant differences before and after surgery in both groups, with higher improvement in the mucoplasty group. A greater mean improvement of 20.5 ± 6.4 points in SNOT-22 change was associated with bilateral mucoplasty. CONCLUSION: Bilateral mucoplasty plus reboot surgery constitutes a useful surgical resource in Type-2 CRSwNP patients, showing improved endoscopic, radiological and QoL outcomes one year after surgery. Further studies are needed to determine their long-term benefits.

A comprehensive analysis of the impact of head model extent on electric field predictions in transcranial current stimulation.

Objective.MRI-based head models are used to predict the electric field (E-field) in the brain in transcranial current stimulation. The standard field of view of clinical MRI often only covers the head down to the skull base, which has usually lead to models truncated at the level of the nose. Although recent pipelines can artificially extend the head model to the neck, the need for implementing full head models preserving skull holes such as the foramen magnum remains controversial. The objective of this work is to analyse the impact of head model extent on E-field accuracy, with emphasis on specific electrode montages.Approach. A full head model containing an open foramen magnum and a cut head model with closed skull were compared in terms of predicted E-field. Several electrode montages, including fronto-occipital montages recently used in validation studies, were simulated. Local and global metrics were used to evaluate the error for both E-field magnitude and distribution, along with tangential and normal components over different cortical areas. The percentage of current flowing through the lower head was also computed.Results. Regarding E-field magnitude, small relative differences (RDs) below 7% were found in grey matter for classical montages. Although considerably higher RDs near 50% were found for fronto-occipital montages, absolute errors of 0.1 V m-1were only found in non-targeted regions such as the cerebellum. Differences in tangential and normal E-fields were similar and followed the same trend observed for E-field magnitude. Our results also showed a high correlation between the percentage of current shunted through the lower head and the absolute E-field differences.Significance. The influence of head model extent on E-field accuracy depends on electrode montage. Standard cut head models provide sufficiently accurate predictions for both E-field magnitude and distribution in targeted brain areas. However, fronto-occipital montages exhibited larger errors, which might be considered in further validation studies.

A Computational Analysis of the Electric Field Components in Transcranial Direct Current Stimulation.

Realistic electric field (E-field) models of the brain have cast doubt on classical targeting approaches used in transcranial direct current stimulation (tDCS). In apparent contradiction with physiological results, modeling studies predict similar or even higher E-field values in regions between the electrodes distant to the presumed targeted areas. As an explanation, not only the magnitude, but the direction of the E-field over specific cortical structures, have been shown to be determinant for the stimulation outcome. This work examines the magnitude and distribution of tangential and normal E-field components over different cortical areas in a representative brain atlas for various electrode montages commonly used in clinical applications. We have confirmed a general trend in the distribution of tangential and normal E-fields on gyri and sulci areas, respectively, partially independent of electrode configuration. The differences found between the various montages are also discussed.