Cernea's classification of the External Branch of the Superior Laryngeal Nerve during Microscopic Thyroidectomy at Gandaki Medical College, Pokhara

Background: Preservation of the external branch of the superior laryngeal nerve (EBSLN) during thyroidectomy is important because its injury may lead to frequent occurrence of vocal fatigue and the inability to perform phonation. The objective of the study was to identify and classify the nerve as per Cernea's classification using operating microscope during thyroidectomy Method: Between January 2017 to December 2019, we evaluated 50 patients for the position of external branch of superior laryngeal nerve, who underwent microscopic thyroid surgeries in the department of ENT- head and neck surgery at Gandaki Medical College. Results: In our study, we dissected a total 59 superior poles of thyroid from 50 patients and identified the nerve in all the cases. Of the total superior poles, 36 (61.01%) had type IIa EBSLN among which 24 was on the right side and 12 on the left followed by 19 (32.20%) patients with type IIb EBSLN among which 8 on right and 11 on left side. There were only 4 poles (6.77%) of type I with 3 on the right and 1 on the left side. Conclusion: The EBSLN can be very efficaciously identified during a microscope assisted thyroidectomy. Cernea type 2a and 2b EBSLNs are in position to be at high risk of injury during ligation of the superior vascular pedicle, which can be avoided by prompt identification through a microscope and a meticulous extra capsular dissection technique.

400 Years after Thomas Willis: beyond the Polygon / 400 Anos depois de Thomas Willis: além do Polígono

Thomas Willis is famous for the cerebral arterial polygon that bears his name, but his contribution to neuroanatomy goes beyond that. Probably the first anatomist physician to attempt the study of the basal nuclei was Galenus. However, it was only in the 17th century that there was a leap in neuroanatomical knowledge of the region based on the studies by Willis, using a dissection technique with a caudal to cranial perspective.

P-BN28 The Consistency of Operative Safety Markers and the Critical View of Safety During Laparoscopic Cholecystectomy: A Pilot Study

Background Safe laparoscopic cholecystectomy(LC) depends on surgeon's experience, operative difficulty, utilisation of traditional safety markers, adapting the dissection technique and, where possible, displaying the critical view of safety (CVS) to confirm cystic pedicle structures prior to division. The Safe Cholecystectomy Multi-Society Practice Guidelines and State of the Art Consensus Conference on Prevention of Bile Duct Injury During Cholecystectomy identified no direct comparative evidence to support the CVS over other methods of anatomic identification. The aim of this study, therefore, was to examine the consistency of safety markers guiding the dissection and to determine the value of displaying the CVS. Methods A pilot study was conducted, reviewing video recordings of 241 LCs (144 retrospective and 97 prospective). The consistency of the Rouvier Sulcus (RS), the cystic lymph node (CLN), identification of the common bile duct (CBD) and duodenum and a new marker; the “cystic duct fold” (CDF), the peritoneal fold stretching between the retracted Hartman's Pouch and the CBD guiding the dissection at its distal end over the gallbladder neck, was documented. Data on the safety marker used to commence dissection, gallbladder condition, the LC difficulty grade, the selected technique and whether the CVS was achieved was recorded and analysed. Results Although the CBD and duodenum were visualised in 77%, the CDF was identifiable in 56% (CLN in 52.3%, RS in 50.2%) and the most consistently used to commence dissection in 51.4% (CLN 17.4%, CBD in 11.6% and RS in 6.6%). 12.8% required access to the infundibulum using sub-serosal or trans-vesical dissection (41% had acute cholecystitis, empyema or gangrenous gallbladders). Infundibular dissection was used in 88%. CVS was achievable in 56.8%. The CDF dropped form 87% in difficulty grades 1 and 2 to 16.5% in grades 4 and 5 with the CLN used in 21% of these difficult LCs. Conclusions A new safety marker, the CDF is proposed, being more reliable and safer on account of starting the dissection away from the CBD and potentially aberrant ducts, contrary to the line of RS. The CLN is more reliable in difficult LC, especially with acute inflammation. Infundibular dissection remains the default approach to “target identification” required to display the CVS. The true value of the CVS, as an end product of the process of dissection, lies in “target confirmation” before dividing any structures and in clearing the cystic plate to avoid injury to Couinaud Types C, F and hepato-cystic ducts.

Suprafascial dissection for pterional craniotomy to preserve the frontotemporal branch of the facial nerve with less temporal hollowing

Background: To protect the frontotemporal branch of the facial nerve (FTFN) when performing pterional craniotomy, several reports suggest the subfascial or interfascial dissection technique. However, the reports of postoperative frontalis paralysis and temporal hollowing, which are common complications, were relatively limited. This study reports the incidence of postoperative frontalis paralysis and temporal hollowing after pterional craniotomy using the suprafascial and interfascial techniques. Methods: Patients who underwent pterional craniotomy, using the suprafascial technique (leaving the muscle cuff and not leaving the muscle cuff) and the interfascial technique, between November 2015 and September 2018 were retrospectively evaluated for postoperative frontalis paralysis and temporal hollowing using Chi-squared/ Fisher exact test. Results: Seventy-two patients underwent pterional craniotomy, using the suprafascial technique in 54 patients (leaving the muscle cuff in 21 patients and not leaving the muscle cuff in 33 patients) and the interfascial technique in 18 patients. Eleven patients (20.4%) in the suprafascial group and 1 patient (5.6%) in the interfascial group developed transient frontalis paralysis (P = 0.272). No permanent frontalis paralysis was observed. Obvious temporal hollowing occurred in 18.2% of patients in the suprafascial group without the muscle cuff, in 64.3% of patients in the suprafascial group with the muscle cuff, and in 72.7% of patients in the interfascial group (P = 0.003). Conclusion: The suprafascial dissection technique does not cause permanent injury of the FTFN, and this approach results in a significantly lower incidence of postoperative temporal hollowing than interfascial dissection, especially without leaving a temporalis muscle cuff.

Deep anterior lamellar and penetrating keratoplasty in developed and advanced stages of keratoconus

This article presents the results of surgical treatment of 30 patients (30 eyes) with keratoconus stage 3-4, which were divided into two groups depending on the performed surgery technique. Deep anterior lamellar keratoplasty (DALK) was performed on 20 eyes using a femtosecond laser and the surgery technique including separation of the residual corneal stroma using the "big bubble" technique, and in some cases using the manual dissection technique. In 25% of cases (5 out of 20 eyes), the DALK operation was complicated by Descemet's membrane perforation and therefore, the surgical intervention was completed by switching to penetrating keratoplasty (PK). These patients were excluded from the DALK group and included in the PK group, who underwent penetrating keratoplasty (15 eyes). The maximum follow-up period was 2 years. After DALK transparent engraftment was achieved in all cases, and after PK in 93.4% of cases, in one case (6.6%) graft rejection was observed. Key words: keratoconus, surgical treatment, deep anterior lamellar keratoplasty, penetrating keratoplasty.

Endoscopic-assisted microsurgical resection of giant vestibular schwannoma in semi-sitting position

The main objectives of microsurgery for vestibular schwannoma are total tumor removal and preservation of facial and cochlear nerve function. For giant tumors, total tumor removal and facial nerve function preservation are challenging. The semisitting position has some advantages. In this video the authors show the removal of a giant vestibular schwannoma with the patient in a semisitting position. They demonstrate the advantages of the semisitting technique, such as the two-handed microsurgical dissection technique and a clear operative field. Finally, a small residual tumor in the internal auditory canal was removed by endoscopy. The patient’s facial function was House-Brackmann grade I at discharge. The video can be found here: https://stream.cadmore.media/r10.3171/2021.7.FOCVID2176

Diamond knife dissection technique for nerve preservation during resection of large vestibular schwannomas

Facial and cochlear nerve preservation in large vestibular schwannomas is a major challenge. Bimanual pincers or plate-knife dissection techniques have been described as crucial for nerve preservation. The authors demonstrate a recently applied diamond knife dissection technique to peel the nerves from the tumor capsule. This technique minimizes the nerve trauma significantly, and complete resection of a large vestibular schwannoma without any facial nerve palsy and hearing preservation is possible. The authors illustrate this technique during surgery of a 2.6-cm vestibular schwannoma in a 27-year-old male patient resulting in normal facial function and preserved hearing postoperatively. The video can be found here: https://stream.cadmore.media/r10.3171/2021.7.FOCVID21104

Retrosigmoid approach for giant cystic vestibular schwannoma: subperineural dissection technique for facial nerve preservation

In this illustrative video, the authors demonstrate retrosigmoid resection of a giant cystic vestibular schwannoma using the subperineural dissection technique to preserve facial nerve function. This thin layer of perineurium arising from the vestibular nerves is used as a protective buffer to shield the facial and cochlear nerves from direct microdissection trauma. A near-total resection was achieved, and the patient had an immediate postoperative House-Brackmann grade I facial nerve function. The operative nuances and pearls of technique for safe cranial nerve and brainstem dissection, as well as the intraoperative decision and technique to leave the least amount of residual adherent tumor, are demonstrated. The video can be found here: https://stream.cadmore.media/r10.3171/2021.7.FOCVID21128