Pornthep Kasemsiri

Endoscopic endonasal transpterygoid approaches: Anatomical landmarks for planning the surgical corridor†

Endoscopic endonasal transpterygoid approaches (EETA) use the pneumatization of the sinonasal corridor to control lesions of the middle and posterior skull base. These surgical areas are complex and the required surgical corridors are difficult to predict.

Reconstruction of the pedicled nasoseptal flap donor site with a contralateral reverse rotation flap: Technical modifications and outcomes

A pedicled nasoseptal flap is our preferred reconstructive technique after endoscopic endonasal skull base surgery. Its harvesting implies that the donor site (septal cartilage) is left bare. Secondary healing leads to crusting at the donor site that negatively affects the patients quality of life and requires multiple outpatient debridements. A nasoseptal reverse rotation flap was designed to eliminate this problem; however, its outcomes have not been reported.

Endonasal Endoscopic Approaches to the Paramedian Skull Base

OBJECTIVE To describe the technical and anatomic nuances related to endoscopic endonasal approaches (EEAs) to the paramedian skull base. METHODS Surgical indications, limitations, and technical aspects pertaining to EEAs designed to access areas oriented in the coronal plane are systematically reviewed with special attention to caveats, pitfalls, and common complications and how to avoid them. Case examples are presented. RESULTS The paramedian skull base may be divided into anterior (corresponding to the orbit and its contents), middle (corresponding to the middle cranial, pterygopalatine, and infratemporal fossae), and posterior (includes the craniovertebral junction lateral to the occipital condyles and the jugular foramen) segments. EEAs to the anterior segment offer access to the intraconal orbital space and the optic canal. A transpterygoid corridor typically precedes EEAs to the middle and posterior paramedian approaches. EEAs to the middle segment provide wide exposure of the petrous apex, middle cranial fossa (including cavernous sinus and Meckel cave), and infratemporal and pterygopalatine fossae. Finally, EEAs to the posterior segment access the hypoglossal canal, occipital condyle, and jugular foramen. CONCLUSIONS Approaches to the paramedian skull base are the most challenging and complex of all endoscopic endonasal techniques. Because of their technical complexity, it is recommended that surgeons master endoscopic endonasal anatomic approaches oriented to median structures (sagittal plane) before approaching paramedian (coronal plane) pathologies.

Control of bleeding in endoscopic skull base surgery: current concepts to improve hemostasis.

Hemostasis is critical for adequate anatomical visualization during endoscopic endonasal skull base surgery. Reduction of intraoperative bleeding should be considered during the treatment planning and continued throughout the perioperative period. Preoperative preparations include the optimization of comorbidities and cessation of drugs that may inhibit coagulation. Intraoperative considerations comprise anesthetic and surgical aspects. Controlled hypotension is the main anesthetic technique to reduce bleeding; however, there is controversy regarding its effectiveness; what the appropriate mean arterial pressure is and how to maintain it. In extradural cases, we advocate a mean arterial pressure of 65–70 mm Hg to reduce bleeding while preventing ischemic complications. For dealing intradural lesion, controlled hypotension should be cautious. We do not advocate a marked blood pressure reduction, as this often affects the perfusion of neural structures. Further reduction could lead to stroke or loss of cranial nerve function. From the surgical perspective, there are novel technologies and techniques that reduce bleeding, thus, improving the visualization of the surgical field.

Technical nuances of commonly used vascularised flaps for skull base reconstruction.

BACKGROUND AND METHODS Reconstruction with a vascularised flap provides the most reliable outcome, with post-operative cerebrospinal fluid leak rates of less than 5 per cent. This article aims to review and summarise the critical technical aspects of the vascularised flaps most commonly used for skull base reconstruction. RESULTS Vascularised flaps are classified as intranasal or extranasal. The intranasal group includes the Hadad-Bassagaisteguy nasoseptal flap, the Caicedo reverse nasoseptal flap, the nasoseptal rescue flap, the posteriorly or anteriorly based lateral wall flaps, and the middle turbinate flap. Extranasal flaps include the transfrontal pericranial and transpterygoid temporoparietal flaps. CONCLUSION The Hadad-Bassagaisteguy nasoseptal flap is overwhelmingly favoured for reconstructing extensive defects of anterior, middle and posterior cranial base. Its pertinent technical features are described. However, it is essential to master the skills required for the various extranasal or regional vascularised flaps because each can offer a reconstructive alternative for specific patients, especially when open approaches are needed and/or intranasal vascularised flaps are not feasible.

Endoscopic endonasal technique: treatment of paranasal and anterior skull base malignancies

UNLABELLED Technical and technological innovations have spearheaded the expansion of the indications for the use of endoscopic endonasal approaches to extirpate malignancies of the sinonasal tract and adjacent skull base. OBJECTIVE Critical review of the available literature regarding the use of endoscopic endonasal approaches including indications, limitations, surgical techniques, oncologic outcome, and quality of life. METHOD Various endoscopic endonasal techniques are reviewed according to the origin and local extension of sinonasal and skull base malignancies including anterior cranial base, nasopharynx, clivus, and infratemporal fossa. In addition, the available literature is reviewed to assess outcomes. CONCLUSION Endoscopic endonasal approaches are an integral part of the armamentarium for the treatment of the sinonasal tract malignancies and skull base. In properly selected cases, it affords similar oncologic outcomes with lower morbidity than traditional open approaches. Nonetheless, these minimal access approaches should be considered a complement to well-established open approaches, which are still necessary in most advanced tumors.

A Tablet-Based Mobile Hearing Screening System for Preschoolers: Design and Validation Study

Background Hearing ability is important for children to develop speech and language skills as they grow. After a mandatory newborn hearing screening, group or mass screening of children at later ages, such as at preschool age, is often practiced. For this practice to be effective and accessible in low-resource countries such as Thailand, innovative enabling tools that make use of pervasive mobile and smartphone technology should be considered. Objective This study aims to develop a cost-effective, tablet-based hearing screening system that can perform a rapid minimal speech recognition level test. Methods An Android-based screening app was developed. The screening protocol involved asking children to choose pictures corresponding to a set of predefined words heard at various sound levels offered in a specifically designed sequence. For the app, the set of words was validated, and their corresponding speech power levels were calibrated. We recruited 122 children, aged 4-5 years, during the development phase. Another 63 children of the same age were screened for their hearing abilities using the app in version 2. The results in terms of the sensitivity and specificity were compared with those measured using the conventional audiometric equipment. Results For screening purposes, the sensitivity of the developed screening system version 2 was 76.67% (95% CI 59.07-88.21), and the specificity was 95.83% (95% CI 89.77-98.37) for screening children with mild hearing loss (pure-tone average threshold at 1, 2, and 4 kHz, >20 dB). The time taken for the screening of each child was 150.52 (SD 19.07) seconds (95% CI 145.71-155.32 seconds). The average time used for conventional play audiometry was 11.79 (SD 3.66) minutes (95% CI 10.85-12.71 minutes). Conclusions This study shows the potential use of a tablet-based system for rapid and mobile hearing screening. The system was shown to have good overall sensitivity and specificity. Overall, the idea can be easily adopted for systems based on other languages.