Keyhole Approach for Clipping Anterior Circulation Aneurysms: Clinical Outcomes and Technical Note

Purpose: Keyhole craniotomy is a minimally invasive approach for the treatment of anterior circulation aneurysm. In this study, we evaluated the benefits and value of the keyhole approach by analyzing the surgical results in 235 patients with anterior circulation aneurysm treated by the keyhole approach and identifying lessons learned from addressing various complications in this approach.Patients and Methods: This was a retrospective study in a single institution of 235 surgical patients with 248 anterior circulation aneurysms who had the supraorbital keyhole approach (SKA) or pterional keyhole approach (PKA) between January 2016 and January 2021. The modified Rankin Scale (mRS) was used to measure long-term results during follow up.Results: All 235 patients' aneurysms were fully clamped and have not recurred. Among them, 31 (13.2%) had intraoperative aneurysm rupture, 8 (3.4%) had cerebral vascular spasm, and 4 (1.7%) had intraoperative brain edema. There were seven (3.0%) cases of postoperative infection, eight (3.4%) cases of postoperative cerebral infarction, one (0.4%) case of postoperative hematoma, and two (0.8%) patients had some form of cognitive impairment after surgery. Follow up after surgery demonstrated that 189 out of the 235 patients (80.4%) had favorable outcomes (mRS score 0–2), and 43 (18.3%) had poor outcomes (mRS from 3–5). There were three deaths (1.28%).Conclusions: The keyhole approach has a quick postoperative recovery, a mild postoperative response, and a good surgical outcome. Our findings indicate that the keyhole approach is a safe and effective surgical method for the treatment of anterior circulation aneurysm.

A randomized controlled study comparing microsurgical clipping via the keyhole approach, conventional craniotomy, and endovascular coiling for ruptured anterior circulation aneurysms

Objective: Few prospective randomized controlled studies have investigated the efficacy of endovascular treatment and microsurgical clipping of intracranial aneurysms, especially via microsurgical keyhole approach. We compared the efficacy of three techniques in treating patients with ruptured anterior circulation aneurysms to provide surgeons with a more objective basis for treatment selection. Methods: 150 patients with ruptured anterior circulation aneurysms were randomly assigned to endovascular treatment, conventional craniotomy, and keyhole approach groups. Aneurysm occlusion, surgical time, hospitalization time, hospitalization expenses, and surgical complications were compared between groups. Results: The complete occlusion rates of aneurysms at discharge were 90% in the endovascular group, 94% in the conventional group, and 96% in the keyhole group. No significant differences in complete occlusion rates or Glasgow Outcome Scale scores were found between groups. In the keyhole approach, conventional craniotomy, and endovascular groups, the overall surgical times were 161.78±34.51 min, 201.55±38.79 min, and 85.86±58.57 min, respectively; the hospitalization times were 11.42±6.64 d, 18.03±7.14 d, and 10.57±8.67 d; hospitalization expenses were 10574.25±4154.25 USD, 13214.54±5487.65 USD, and 20134.58±6587.61 USD; and the incidence rates of postoperative complications such as intracranial infection, cerebral vasospasm, hydrocephalus, intracranial hematoma, and epilepsy were 8%, 28%, and 20%. Conclusions: Endovascular coiling and the microsurgical keyhole approach have the advantages of simple execution, time savings, and short hospitalization. Microsurgical clipping of intracranial aneurysms needs to be updated to a minimally invasive procedure to maintain its complementary value with endovascular treatment.Clinical trial registration: The study has been retrospectively registered in clinicaltrial.org (NCT05049564) in Sep. 8th, 2021.

Reconstruction clipping of ruptured anterior circulation aneurysms via supraorbital lateral keyhole approach

Background Intracranial aneurysm(IA) is a serious disease.Analyze and review the cases of anterior circulation ruptured IA by supraorbital lateral keyhole approach, and summarize the experiences of this approach. Methods Retrospective analysis of 16 cases of ruptured anterior circulation IA in our department from January 2019 to June 2020, CT angiography (CTA) was performed before operation. Analyzing the IA’s parameters by 3D-CT reconstruction. The IA was clipped by supraorbital lateral keyhole approach combined with the 3D-skull reconstruction. Extraventricular drainage were performed before craniotomy. Intraoperative neurophysiological monitoring was performed during the operation. After operation, fluorescein angiography and vascular ultrasound were performed to check the clipping effect. Intracranial pressure monitor was performed postoperatively. CTA was reexamined one week after operation. The modified Rankin Scale (MRS) was performed 6 months after operation. Results There were 7 males (43.8%) and 9 females (56.2%) ,the average age is 52.3 years. Among them, 11 patients(68.8%) were anterior communicating artery aneurysms and 5 (31.2%) were middle cerebral artery aneurysms. All patients were out of hospital within 10 days without any death, without cerebral infarction, cerebrospinal fluid leakage and neurological impairments. About mRS score, after 6 months follow-up, 8 cases(50%) had 0 point, 4 cases (25%) had 1 point, 4 cases (25%) had 2 points. Conclusions For ruptured anterior circulation IA, the supraorbital lateral keyhole approach combined with ventricular drainage, intraoperative electrophysiological monitoring and intraoperative vascular ultrasound is a safe and minimally invasive treatment. The application of reconstruction clipping can reconstruct the diameter of parent vessel and reduce the recurrence rate of IA.

Developing a Method to Precisely Locate the Keypoint During Craniotomy Using the Retrosigmoid Keyhole Approach: Surgical Anatomy and Technical Nuances

Objective: To explore the precise location of the keypoint during craniotomy using the retrosigmoid keyhole approach.Methods: This study included 20 dry skulls and 10 wet cadaveric specimens. On the inner surface of dry skulls, the junction between the inferior margin of the transverse sinus (ITS) and the posterior margin of the sigmoid sinus (TSJ) was marked. The keypoint (D) was identified as the TSJ's corresponding point on the external surface of the temporal mastoid process (MP). The distance from the keypoint to the top point of the digastric groove, mastoidale, and asterion were noted (AD, BD, CD, respectively). A method to accurately locate the keypoint was developed based on these relationships. The developed method was used on the wet cadaveric specimens to evaluate its accuracy, safety, rapidity, and minimal invasion.Results: No significant difference was found between the AD, BD, and CD of the left and right sides. The drilling point was oriented on a straight line 12 mm above the top point of digastric groove, perpendicular to the Frankfort horizontal plane (FHP). In the cadaveric specimens, the operative area was clearly exposed. No venous sinus rupture occurred. The average craniotomy time was 28.74 ± 3.89 min.Conclusions: A potentially safe, accurate, and rapid craniotomy procedure was developed with the added advantage of preserving the visibility of the operating field and preventing venous sinus injury.

Endoscopic Keyhole Approach for Intracranial Epidermoid

Objective In contemporary neurosurgical practice, keyhole endoscopic approach has established its role in various neurosurgical pathologies. Intracranial epidermoid is an ideal pathology for endoscopic keyhole approach as epidermoid is well encapsulated, extra-axial, avascular, and easily suckable. The objective of this study is to share our experience of endoscopic keyhole approach for intracranial epidermoids at various locations as a new minimally invasive neurosurgical approach to deal with these lesions. Materials and Methods We conducted a retrospective study on 26 patients who underwent keyhole pure endoscopic excision of intracranial epidermoid between July 2015 and December 2019. Patient's demographics, clinical features, radiological imaging, and postoperative complications were noted. Follow-up outcome of preoperative symptoms and postoperative complications were also analyzed. Results The mean age of the study population was 30.5 years with a mean follow-up of 30 months. The common presenting features were headache, hearing loss, and trigeminal neuralgic pain. Gross total resection was achieved in 73.1% cases, while near total resection and subtotal resection were achieved in 19.2 and 7.7% cases, respectively. In the follow-up, maximal improvement was seen in trigeminal neuralgic pain (83%) and headache (66.7%). Major postoperative complications were facial nerve paresis, lower cranial nerve paresis, and transient facial hypoesthesia, most of which improved over time. None of the patients required resurgery till date. Statistical Analysis Patients' data were analyzed using SPSS software version 23 (Statistical Package for Social Sciences, IBM, Chicago, United States). Conclusion This study demonstrates that with careful patient selection, endoscopic keyhole excision of epidermoid is a good alternative to conventional microsurgical excision with comparable surgical and functional outcomes.

Study of anatomical variations of pterion in Karnataka population

The Pterion is a point of sutural confluence formed by frontal, parietal, temporal and sphenoid bones. Center of pterion is located 4cms above the midpoint of zygomatic arch and 3.5cms behind the fronto-zygomatic suture. Pterion is a reference landmark for many regions of the brain. Knowledge of various types of pterion is important in neurosurgeries as pterion keyhole approach has several advantages over traditional craniotomy; it has got radiological significance in interpretation of radiographs; in forensic medicine, it has been used for estimation of age and stature; and types of pterion has racial variations, hence it has got anthropological significance. Hence, the present study was taken to assess various types of pterion in South Indian adult human skulls. To classify the types of pterion based on Murphy’s classification and compare the right and left sides.The study was conducted on 100 adult dry human skulls collected from Kempegowda Institute of Medical Sciences & Research center, Bangalore. The various types of pterion were noted. All the readings were tabulated and subjected to analysis. All measurements and frequencies of the data were tabulated. The mean, standard deviation for each of the measurements were assessed. Statistical software SPSS version 16 was used. Right and left side were compared using One-Way ANOVA (Analysis of Variance). Various types of pterion were observed. Spheno-parietal was the most predominant (78%) type, followed by epipteric (16%), stellate (4%) and fronto-temporal (2%).: The results of the present study can be utilized by neurosurgeons, radiologists, anthropologists and forensic experts. The findings can be used in future for comparing various types of pterion from a different population, race or species altogether.

Fully endoscopic transcranial removal of anterior fossa meningioma through the minipterional keyhole approach in case with marked frontal sinuous pneumatization: clinical case

Transcranial surgery of skull base meningiomas currently remains the main method of treatment. Transnasal removal is possible in a number of cases, but it is associated with the risk of postoperative CSF-leak as a result of insolvency of the reconstruction of the skull base defect. Minimally invasive (keyhole) accesses provide a tumor overview comparable to standard accesses in most cases. The anterior-medial part of the anterior cranial fossa and the olfactory fossa is not accessible to the direct view from the minipterional craniotomy. The use of angular endoscopic optics in combination with additional resection or thinning of the bones in the orbital roof provides an overview sufficient to remove the tumor, but manipulations in this area require the use of specific tools. Aspirators, dissectors and coagulators should have bends of different expressions. The application of the described technique is advisable only in certain specially selected cases.

How Safe and Effective Is Shifting from Pterional to Supraorbital Keyhole Approach for Clipping Ruptured Anterior Circulation Aneurysms? A Surgeon’s Transition Phase Comparative Study

Background Comparative studies between standard pterional and supraorbital keyhole approaches for aneurysms had potential biases with the heterogeneity of patient selection, differences among surgeons, or varying expertise across the surgeon’s learning curve. This is a study of a surgeon’s transition from pterional to keyhole approach for early clipping of selected consecutive ruptured anterior circulation aneurysms. Methods Patients more than 18 years, presenting within 72 hours of ictus, in good clinical grades 1 to 3, no midline shift, with saccular aneurysms less than 25 mm at either communicating segment of internal carotid artery, anterior communicating artery, or middle cerebral artery segment till bifurcation were studied between the last 25 cases of pterional and first 25 cases of the keyhole, for the intraoperative and postoperative surgical outcome parameters. Results There was no significant difference among baseline parameters, including the location of aneurysms across both groups. While only four cases of pterional had an intraoperative ventricular puncture, the lumbar drain was electively inserted in all keyhole patients. The intraoperative parameters, such as a dural tear, adequate parent vessel exposure, temporary clipping, and intraoperative rupture, did not show any significant difference. None had immediate postoperative deficits. While delayed cerebral ischemia and wound complaints were similar in both groups, temporal hollowing and chewing difficulty were significantly more in pterional patients(p = 0.01). Conclusion A surgeon experienced in pterional approach can comfortably and safely shift to the keyhole for early clipping of selected ruptured aneurysms less than 25 mm, with a comparable surgical outcome but better cosmesis and mastication.

Endoscopic Endonasal and Supraorbital Removal of Tuberculum Sellae Meningiomas: Anatomic Guides and Operative Nuances for Keyhole Approach Selection

BACKGROUND With growing worldwide endoscopy experience, endonasal and supraorbital removal of tuberculum sellae meningiomas (TSM) has increased. OBJECTIVE To describe anatomic factors for guiding approach selection and outcomes. METHODS Retrospective analysis of patients undergoing endonasal or supraorbital TSM resection: approach criteria, clinical outcomes, acute magnetic resonance imaging (MRI) fluid-attenuated inversion-recovery (FLAIR)/T2 changes. RESULTS From 2008 to 2020, 33 patients (mean age 55 ± 11 yr) were identified: 20 (61%) had endonasal and 13 (39%) supraorbital removal. Comparing endonasal and supraorbital approaches, mean tumor volume (3.7 ± 3.5 cm3 vs 7.7 ± 8.5 cm3, P = .07); percent tumor above planum (42% vs 65%, P = .02), and lateral tumor beyond supraclinoid internal carotid arteries (1.4 ± 2.0 mm vs 4.0 ± 3.2 mm, P = .006) were greater for supraorbital route. Sellar depth was greater for endonasal route tumors (12.2 ± 2.6 mm vs 9.3 ± 2.4 mm, P = .003). Endoscopy, used in 10/13(77%) supraorbital cases, was helpful in additional tumor removal in 4/10(40%). Gross total removal and mean volumetric tumor resection were 16/20(80%) and 97.5% by endonasal, and 5/13(39%) and 96% by supraorbital route. Vision improved in 12/17 (71%) endonasal, 6/8 (75%) supraorbital operations, and worsened in 1 (3%) supraorbital case. Endonasal approach with optic canal decompression increased over study period: 15/20 (75%) endonasal patients vs 1/13(8%) supraorbital (P < .001). Postoperative FLAIR/T2 MRI changes occurred in 2/12 supraorbital and 0/20 endonasal cases. CONCLUSION In our experience, both endonasal and supraorbital routes are safe and effective for TSM removal. Greater tumor extension below planum and medial optic canal invasion favor endonasal route, while larger size and lateral extension favor supraorbital route. Given high frequency of TSM growth into optic canals and better access for medial optic canal tumor removal, endonasal route may be preferred for most TSMs.

Endoscopic-Assisted Keyhole Resection of a Recurrent Epidermoid Tumor: 2-Dimensional Operative Video

Epidermoid tumors are benign lesions. Surgical resection is the only treatment option available for these lesions.1 The surgical approach should be tailored to the clinical and anatomic findings to achieve radical resection, preferably total removal of the content and the capsule to prevent recurrences.2 Total resection is frequently possible in de novo lesions using tailored skull base approaches and their combination as well as modern microsurgical techniques, including the endoscope-assisted tools.2,3 Giant recurrent tumors, however, are not amenable for total resection. Hence, the severe adhesions will lead to a higher morbidity as the epidermoid capsule becomes thicker and more fibrous after prior resections attempts.2,4 The extent of the resection should still be safely extended as much as possible to delay the interval between surgeries. Endoscopic techniques are of great help in achieving such results through a keyhole approach when conservative surgery is decided.3 We present the case of a 69-yr-old male with a past medical history of coronary heart disease, hypertension, hypothyroidism, and recurrent giant epidermoid cyst in the left cerebellopontine angle, with significant compression of the brainstem and extended into Meckel's cave, internal auditory canal, and jugular fossa. He underwent resection in 1983, 2004, and 2012. He presented with worsening gait, and multiple cranial nerves deficits. A minimally invasive approach through a keyhole craniotomy was performed given the age, comorbidity, and multirecurrent nature of his lesion. The patient consented to the intervention and publication of his image. He had a satisfying evacuation of his cyst content with transient facial and lower cranial nerve postoperative worsening.