Retrosigmoid Approach: Investigating the Role of a C-Shaped Skin Incision and Muscle Flaps in Improving Functional Outcome and Reducing Postoperative Pain

A novel 3D anatomical visualization system to avoid injuries of nerves in retrosigmoid approach

The retro-sigmoid approach (RA), widely used during different neurosurgical procedures, is burdened by the risk of injuries of the nerves that cross that region contributing to possible postoperative complications. By using, anatomage table (AT), a novel 3D anatomical visualization system, we described the nerves passing through the retromastoid area including the great occipital nerve (GON), the lesser occipital nerve (LON) and the great auricular nerve (GAN), and their courses from the origins, till terminal branches. Moreover, using dedicated software, we measured distances between the nerves and well-recognizable bony landmarks. After identifying the nerves and their distances from bony landmarks, we observed that the safest and risk-free skin incision should be made in an area delimited, superiorly from the superior nuchal line (or slightly higher), and inferiorly from a plane passing at 1-1.5 cm above the mastoid tip. The lateral aspect of such an area should not exceed 9.5-10 cm from the inion, while the medial one should be more than 7 cm far from the inion. This anatomical information has been useful in defining anatomical landmarks and reducing the risk of complications, mainly related to nerve injury, in RA. In-depth neuroanatomic knowledge of the cutaneous nerves of the retromastoid area is essential to minimize the complications related to their injury during different neurosurgical approaches. Our findings suggest that the AT is a reliable tool to enhance understanding of the anatomy, and thus contributing to the refinement of surgical techniques.

Linear Scalp Incision in Brain Tumor Surgery: Intraoperative and Postoperative Considerations

BACKGROUND

Although the linear scalp incision is commonly used in neurosurgical practice, a systematic study elucidating its pros and cons in a specific surgical setting is lacking. Herein, we analyzed our experience with linear scalp incision in brain tumor surgery and the impact on intraoperative variables and postoperative complications.

METHODS

Patients undergoing brain tumor surgery (January 2014-December 2021) at 2 neurosurgical departments were included and divided into 2 groups: linear or flap scalp incision. Patients' demographics characteristics, surgical variables, and wound-related complications were analyzed.

RESULTS

More than a total of 1036 craniotomies, linear incision (mean length 6cm) was adopted in 282 procedures (27.2%). Mean maximum diameter of the craniotomy was 5.25 cm, with no statistical difference between the 2 groups. In emergency surgery (36 cases), the linear and flap incisions were used indifferently. Linear incision was predominant in supratentorial and suboccipital lesions. Flap incision was significantly more frequent among meningiomas (P < 0.01). Neuronavigation, operative microscope, and subgaleal drain were more frequently used in the flap scalp incision group (P = 0.01). Overall complication rate was comparable to flap scalp opening (P = 0.40).

CONCLUSIONS

The use of the linear incision was broadly applied for the removal of supratentorial and suboccipital tumors granting adequate surgical exposure with a low rate of postoperative complications. Tumors skull base localization resulted the only factor hindering the use of the linear incision. The choice of 1 incision over another didn't show to have any impact on intraoperative and postoperative variables, and it remains mainly based on surgeon expertise/preference.

Case report: Fully endoscopic microvascular decompression for glossopharyngeal neuralgia

With the advances in endoscopic technology, endoscopy is widely used in many neurosurgical procedures, such as microvascular decompression, which is an effective method to treat glossopharyngeal neuralgia, trigeminal neuralgia, and facial spasm. The purpose of this study was to determine the efficacy of fully endoscopic microvascular decompression in the treatment of glossopharyngeal neuralgia. We managed a patient with glossopharyngeal neuralgia in our department, whose main clinical manifestation was recurrent left ear and facial pain for 3 years. The patient underwent a fully endoscopic microvascular decompression. The pain in the left ear and face was significantly relieved postoperatively, and there was no recurrence at the 6-month follow-up evaluation. We describe a case of glossopharyngeal neuralgia that was successfully treated by fully endoscopic microvascular decompression, which showed that endoscopy has advantages in microvascular decompression, and fully endoscopic microvascular decompression is an effective method for glossopharyngeal neuralgia.

New Osia® OSI200 active transcutaneous bone-anchored hearing device: how I do it

INTRODUCTION

The new Osia® OSI200 implant incorporates a receiver coil and Piezo Power™ Transducer into one monolithic unit. Appropriate planning and surgical approach is needed for suitable positioning of the device.

METHOD

To optimise the surgical field and provide tension-free wound closure our team have adopted a versatile 'Sheffield-S' post-auricular incision which remains hidden within the hairline.

CONCLUSION

This incision provides adequate exposure for device placement and bone polishing/recessing. The soft tissue approach has resulted in improved operative efficacy particularly in those patients with irregular cortical bone or where pre-existing osseointegrated implants need to be removed or avoided.

A Laboratory Investigation on a Tailored Skin and Muscle Flap Variant for the Retrosigmoid Approach

Introduction An anatomical study was conducted to test a modified C-shaped flap designed for patients undergoing a keyhole approach and/or minicraniotomy for retrosigmoid approach (KRSA).

Materials and Methods Ten heads specimens were used. The surgical technique investigated was based on a 4-cm C-shaped skin incision with medial convexity (placed 8 cm laterally to the external occipital protuberance, with the lower edge terminating 1.5 to 2 cm above the mastoid tip), which followed by careful subperiosteal dissection and completed by reflecting and securing the skin flap layer anteriorly and the muscle flaps superiorly and inferiorly by stitches. Anatomical findings, including depth of surgical corridor till to the cerebellopontine cistern (CPC) as well as the sparing of neurovascular structures, were evaluated in every specimen.

Results Twenty surgical approaches to CPC were conducted, resulting in a short working distance to the target (32 mm) without any need for a self-retaining retractor. In every specimen, the integrity of occipital muscles and cutaneous nerves was maintained, and a solid multilayer closure was always achieved. These data suggest that landmarks-based design of this C-shaped incision could be helpful in avoiding damages to the soft tissues encountered during KRSA.

Conclusion This modified approach provides a wide surgical corridor to access the CPC while ensuring the minimal invasiveness of the standard S-shaped incision. Compared with the latter, it preserves better the integrity of the surrounding soft tissues and appears less likely to cause any iatrogenic injury to occipital muscles and cutaneous nerves.

Modified Skin Incision and Location of Burr-Hole Surgery via a Retrosigmoid Approach: An Anatomical Study

Objective  This study aims to reduce the tissue damage during craniotomy with retrosigmoid approach. A modified sickle-shaped skin incision was developed, and a new burr-hole positioning method was proposed. Methods  Five adult cadaveric heads (10 sides) were used in this study. The sickle-shaped skin incision was performed during craniotomy. The nerves, blood vessels, and muscles were observed and measured under a microscope. Additionally, 62 dry adult skull specimens (left sided, n  = 35; right sided, n  = 27) were used to measure the distance between the most commonly used locating point (asterion [Ast] point) and the posteroinferior point of the transverse sigmoid sinus junction (PSTS) (Ast-PSTS), as well as the distance between the new locating O point and the PSTS (O-PSTS). Then, the reliability of the new locating O point was validated on the same five adult cadaveric heads (10 sides) used for the sickle-shaped skin incision. Results  The sickle-shaped skin incision reduced the damage to the occipital nerves, blood vessels, and muscles during the surgery via a retrosigmoid approach. The dispersion and variability of O-PSTS were smaller than those of Ast-PSTS. Conclusion  The sickle-shaped skin incision of the retrosigmoid approach can reduce the tissue damage and can completely expose the structures in the cerebellopontine angle. The modified O point is a more reliable locating point for a burr-hole surgery than the Ast point.

Vestibular schwannoma: care for soft tissues and subperineural dissection: how I do it

BACKGROUND

Recognition of the right surgical cleavage plane of a vestibular schwannoma is mandatory to preserve the facial nerve function.

METHOD

We describe here our surgical technique that is focused on soft tissues preservation and on subperineural dissection, avoiding direct exposure of the acoustico-facial complex in order to preserve facial nerve function.

CONCLUSION

Soft tissue dissection helps in reducing patient's postoperative discomfort. Meticulously keeping a subperineural plan of dissection enables to preserve facial nerve function while offering satisfying resection rates.

Impact of C-shaped skin incision on surgical operability in the retrosigmoid approach: when a good start is half of the job

BACKGROUND

The retrosigmoid approach (RSA) is one of the routes of choice to approach tumors and vascular lesions of the cerebellopontine angle. Among different types of skin incisions and soft tissue dissection techniques, the most widely used variants comprise the straight/lazy S-shaped and the C-shaped incisions. Several reports discuss advantages in terms of functional and clinical outcomes of the C-shaped incision, but scientific considerations about the critical impact of this kind of incision on surgical operability are still extremely limited.

OBJECT

Authors comparatively analyze the advantage provided by C-shaped incision in RSA in terms of anatomic exposure and surgical operability, compared with straight/lazy S-shaped one.

METHODS

A comparative microanatomical laboratory investigation was conducted. The operability score (OS) was applied for quantitative analysis of surgical operability.

RESULTS

C-shaped incision, providing a significant reduction of the overall working distance (-13%) together with an overall increase of the maneuverability area (+ 204.9%), did improve the conizing effect on the surgical corridor. It optimized overall maneuverability of surgical instruments, in terms of angle of attack (+ 27.7%), as well as maneuverability arc (+ 122%), on the entire surgical field. C-shaped incision ensured good operability on all surgical targets (OS ranging from 2 to 3), most significantly improving surgical maneuverability at the porus trigeminus and internal acoustic meatus.

CONCLUSION

C-shaped incision in the RSA significantly improves anatomic exposure and surgical operability as compared with straight/lazy S-shaped incision.

The Efficacy and Safety of <2 cm Micro-Keyhole Microvascular Decompression for Hemifacial Spasm

Objective: Microvascular decompression (MVD) surgery has been accepted as a minimally invasive surgical modality for the treatment of hemifacial spasm (HFS). However, the size of the bone window does not match the concept of minimally invasive. This study is aimed at evaluating the efficacy and safety of <2 cm micro-keyhole MVD.

Methods: A total of 148 patients with HFS diagnosed in the First Affiliated Hospital of Chongqing Medical University from January 1, 2019, to July 1, 2020, who underwent MVD in the neurosurgery department of the hospital were collected. Surgery was performed by a retrosigmoid keyhole approach with the bone hole diameter <2 cm, which was named micro-keyhole MVD. The efficacy and safety of the micro-keyhole MVD were evaluated by statistical analysis of the efficacy of the micro-keyhole MVD and the incidence of postoperative complications.

Results: The effect of micro-keyhole MVD was satisfying (cure or partial remission) in 97.2% (n = 144). The failure and recurrence rates were 2.7% (n = 4) and 0.6% (n = 1), respectively. Among them, immediate facial palsy, delayed facial palsy, hearing loss, and cerebrospinal fluid (CSF) leakage were found in 0.6% (n = 1), 8.1% (n = 12), 4.7% (n = 7), and 1.3% (n = 2). Only one patient developed cerebellar infarction, which was complicated by “moyamoya disease.” The micro-keyhole MVD in the treatment of HFS can achieve a high remission rate and reduce the incidence of surgical complications.

Conclusion: Micro-keyhole MVD is a safe and effective minimally invasive treatment for HFS. This technique does not increase the incidence of cranial nerve injury. Meanwhile, it reduces the incidence of CSF leakage and hearing loss (HL).

A Novel Technical Refinement of Microvascular Decompression: Pain Relief and Complication Rate in a Consecutive Series of Patients With Trigeminal Neuralgia

BACKGROUND

Microvascular decompression (MVD) represents a milestone for the treatment of trigeminal neuralgia (TN). Nevertheless, several complications still occur and may negatively affect the outcome. We recently proposed some technical nuances for complication avoidance related to MVD.

OBJECTIVE

To verify the efficacy of the proposed refinement of the standard MVD technique in terms of resolution of the pain and reduction of complication rates.

METHODS

We analyzed surgical and outcome data of patients with TN using a novel surgical refinement to MVD, over the last 4 yr. Outcome variables included pain relief, facial numbness, muscular atrophy, local cutaneous occipital and temporal pain or numbness, cerebellar injury, hearing loss, cranial nerve deficits, wound infection, and cerebrospinal fluid (CSF) leak. Overall complication rate was defined as the occurrence of any of the aforementioned items.

RESULTS

A total of 72 consecutive patients were enrolled in the study. Pain relief was achieved in 91.6% and 88.8% of patients at 1- and 4-yr follow-up, respectively. No patient reported postoperative facial numbness during the entire follow-up period. The incidence of CSF leak was 1.4%. One patient developed a complete hearing loss and another a minor cerebellar ischemia. There was no mortality. The overall complication rate was 5.6%, but only 1.4% of patients experienced permanent sequelae.

CONCLUSION

The proposed refinement of the standard MVD technique has proved effective in maintaining excellent results in terms of pain relief while minimizing the overall complication rate associated with this surgical approach.

Endoscopic Endonasal Approach to the Ventral-Medial Portion of Posterior Paramedian Skull Base: A Morphometric Perspective of Surgical and Radiologic Anatomy

OBJECTIVE

This study aims to provide morphometric analysis of endoscopic endonasal approach (EEA) to the ventral-medial portion of posterior paramedian skull base. Furthermore, it aims to investigate the surgical exposure obtained through EEA with and without eustachian tube (ET) removal, emphasizing the role of contralateral nostril (CN) access.

METHODS

Five fresh adult head specimens were prepared for dissection. A predissection and a postdissection computed tomography study was performed. A surgically oriented classification into 4 regions was used: 1) tubercular region; 2) occipital condyle region; 3) parapharyngeal space (PPhS) region; and 4) jugular foramen (JF) region. The Student t-test was used to compare angulations and measures of EEA with access from the ipsilateral and CN, respectively, with and without ET removal.

RESULTS

EEA to the ventral-medial portion of posterior paramedian skull base encompasses 2 medial trajectories (transtubercular and transcondylar) and 2 lateral pathways to the PPhS and JF. The CN access, without removal of the ET, allows a complete exposure of the petrous and intrajugular portion of the JF and superior PPhS without exposition of the parapharyngeal segment of internal carotid artery. The ipsilateral nostril approach with ET removal allows to obtain a wider exposure, reaching the medial sigmoid part of the JF. No significant differences exist in regard to transtubercular and transcondylar approaches.

CONCLUSIONS

This study suggests that EEA to posterior paramedian skull base allows the realization of a corridor directed to the jugular tubercle, occipital condyle, medial PPhS, and ventral-medial JF. The CN approach with ET preservation can expose the petrous and intrajugular parts of the JF and PPhS. Case series are needed to demonstrate benefits and drawbacks of these approaches.

A Standard Operation Procedure of Clean and Fast Craniotomy Technique for Retrosigmoid Approach

Clean and fast craniotomy and closure (CAC) for retrosigmoid approach with safe and satisfactory exposure remains our primary goal. A standard operation procedure (SOP) of retrosigmoid approach was developed and reviewed. Between January 2015 and January 2017, 97 patients suffering various lesions underwent surgeries using this technique in the Department of Neurosurgery, Qilu Hospital of Shandong University. The records concerning time of craniotomies, blood losses, and complications were reviewed. By applying this SOP, a craniotomy generally took 15 to 35 minutes, with an average of around 25 minutes. Six cases had a blood loss of more than 30 mL during craniotomy. One patient had cerebrospinal fluid rhinorrhea and another case had subcutaneous effusion. There was no record of venous sinus injury or wound infection. To sum up, the SOP of retrosigmoid approach is simple, reliable and bloodless. In addition to avoiding complications such as venous sinus injury effectively, the SOP also benefits training of residents and early recovery after surgery (ERAS).