Abstract

Background: This document serves as a follow-up to our publication entitled, “Neurosurgical Treatment of Cerebellar Infarct: Open Craniectomy Versus Endoscopic Surgery,” and seeks to offer a comprehensive analysis of this surgical approach.

Methods: This technical note outlines a minimally invasive endoscopic technique for the excision of necrotic tissue in patients suffering from extensive cerebellar infarcts.

Results: Our minimally invasive endoscopic evacuation of necrotic tissue (MENT) technique has been utilized successfully since 2014 as a substitute for conventional decompressive craniotomy. The procedure is distinguished by a mini-keyhole access and a 2-cm incision, which is subsequently utilized for the endoscopic extraction of necrotic material under C-arm guidance.

Conclusion: This approach presents numerous advantages, including reduced surgical duration, smaller incision size, and a lower risk of infection. Our comparative analysis with traditional craniotomy revealed similar outcomes regarding the scale for the assessment and rating of ataxia (SARA) scale and Glasgow Coma Scale score, when employing a less invasive method. MENT is particularly beneficial for elderly patients with pre-existing medical conditions, offering a safer and more effective treatment option for cerebellar and posterior fossa infarcts.

Keywords: Cerebellar infarct, Endoscopic surgery, Minimally invasive surgery, Neurovascular surgery, Suboccipital craniotomy

INTRODUCTION

Cerebellar infarcts are relatively rare, accounting for approximately 1.5–3% of all ischemic strokes, although this rate may be higher in certain subgroups.[ 15 , 20 ] For instance, among patients initially presenting with symptoms resembling vestibular neuritis, up to 10% were later found to have isolated cerebellar infarctions based on imaging findings.[ 8 ] While many cases can be managed conservatively, surgical intervention becomes necessary in the presence of neurological deterioration, brainstem compression, mass effect, or obstructive hydrocephalus.[ 1 - 7 ]

Since 2014, we have implemented a novel approach, minimally invasive endoscopic evacuation of necrotic tissue (MENT), in combination with traditional decompressive craniotomy for the treatment of large cerebellar infarcts. This technique has shown significant advantages over conventional surgery, particularly in terms of reduced operative time and faster postoperative recovery. The only additional requirement is the use of intraoperative C-arm imaging to precisely localize the infarct, which adds only 4–5 min to the procedure. The keyhole approach allows access through a small, juxtamedian incision, avoiding the relatively avascular midline, which facilitates faster healing and reduces scarring.[ 14 ]

Our method integrates keyhole surgery with endoscopic visualization, allowing for efficient drainage of necrotic tissue when minimizing surgical trauma, a benefit well-supported by previous studies.[ 9 - 16 ] Although keyhole and burr-hole microsurgical techniques have been successfully employed in various intracranial procedures,[ 13 , 18 ] their use in the posterior fossa remains limited due to anatomical constraints.[ 2 ] In the present study, we present the anatomical rationale, surgical steps, and technical considerations of our combined keyhole-endoscopic approach, which offers a minimally invasive yet effective solution for managing massive cerebellar infarcts.

SURGICAL PROCEDURE AND ANATOMICAL CONSIDERATION

The patient is placed in the prone position with the head rotated approximately 45° to the contralateral side and secured using either a Mayfield or round headrest [ Figure 1 ]. The upper body is elevated at a 30° angle relative to the horizontal to optimize surgical exposure. Intraoperative imaging with a C-arm is utilized to precisely localize the lesion and determine the optimal trajectory for the endoscopic approach.

Figure 1:

Patient position.

A 2 cm vertical skin incision is made 3–4 cm lateral to the midline, depending on the side and position of the necrotic lesion [ Figure 2 ]. Care is taken to avoid injury to the greater occipital nerve and its branches to prevent postoperative complications such as nuchal numbness or painful deafferentation. After skin incision, a BECKMANN retractor is used for exposure, and a keyhole craniotomy is created using a burr or craniotome [ Figure 3 ]. Following bipolar coagulation, the dura mater is opened with a scalpel or preferably an electric cautery device, which allows simultaneous coagulation of dural vessels during incision.

Figure 2:

A 2 cm vertical incision is made centered over the necrotic region (indicated by the yellow arrow). Red arrows illustrate the direction of head rotation to optimize surgical access.

Figure 3:

Exposed bone prepared for the keyhole. The blue line indicates the diameter of the keyhole.

Due to increased intracranial pressure from cerebellar edema, the cerebellar tissue often bulges through the dural opening. To mitigate this, we recommend administering corticosteroids approximately 10 min before the incision or immediately after intubation. An incision is made in the cerebellar cortex using bipolar energy to allow endoscope insertion. The endoscopic tube is then carefully advanced into the lesion, enabling direct visualization and targeted evacuation of necrotic tissue, which is typically distinguishable from healthy parenchyma [ Figures 4 - 8 ]. If anatomical uncertainty arises, the C-arm may be re-employed to confirm endoscope positioning.

Figure 4:

Endoscopic intraoperative view. Light green arrows indicate cerebellar tissue, the orange arrow highlights necrotic tissue, and the yellow arrow points to the dura mater.

Figure 5:

Intraoperative view showing tissue differentiation. The yellow arrow indicates cerebellar tissue, the blue arrow points to necrotizing tissue, the green arrow marks normal cerebellar tissue, and the white arrow highlights necrotic tissue within the surgical field.

Figure 6:

Surgical field anatomy. The blue arrow indicates the dura mater, the white arrow shows normal cerebellar tissue, and the red arrow highlights necrotic tissue.

Figure 7:

Endoscopic view of the surgical site. The light blue arrow indicates the dura mater, the dark blue arrow points to cerebellar tissue adjacent to the necrotic area, and the green arrow highlights the necrotic tissue.

Figure 8:

The surgical field upon completion of the procedure, with green arrows indicating the evacuated necrotic area and a blue arrow denoting the cerebellar tissue.

Tissue evacuation proceeds circumferentially in a 360° fashion through rotation of the endoscope tube. Once debridement is complete and normal tissue is visualized, the cavity is thoroughly irrigated. Hemostasis is meticulously achieved, and a thrombin-based hemostatic agent is applied to the surgical field to minimize postoperative bleeding. The cranial defect is filled with bone powder, and the wound is closed in one or two layers, depending on the depth, typically involving cutaneous and/or subcutaneous tissue closure.

DISCUSSION

The management of cerebellar infarction remains a neurosurgical challenge, particularly in patients presenting with life-threatening complications such as brainstem compression, severe edema, and obstructive hydrocephalus.[ 5 , 10 ] Traditional approaches include suboccipital decompressive craniectomy (SDC), external ventricular drainage (EVD), or a combination of both. SDC, especially when combined with duraplasty or necrotic tissue removal, has demonstrated substantial survival benefits, reducing mortality rates from approximately 70–80% to 20– 40% in appropriately selected patients.[ 6 , 15 ] When performed early, SDC also contributes to favorable functional outcomes, with 40–60% of patients achieving independence.[ 6 ] However, EVD alone is insufficient in cases with significant mass effect, as it does not address the underlying pathology and may even precipitate upward herniation. Its use is, therefore, typically reserved as an adjunct to SDC.[ 1 , 12 ] Combined SDC and EVD approaches yield better results in patients with both hydrocephalus and swelling, including those presenting in coma. In addition, data suggest that patients with large infarct volumes (≥35 mL) derive significant benefit from surgical intervention, whereas those with smaller infarcts (<25 mL) may be better managed conservatively. Prognosis, however, is influenced by age, initial neurological status, and presence of brainstem involvement.[ 2 , 12 , 20 ]

In response to the limitations of traditional craniectomy, we have developed and employed the MENT technique since 2014.[ 14 ] A recent comparative analysis of MENT and conventional craniotomy for cerebellar infarcts revealed that both methods yield similar neurological outcomes as assessed by the SARA and Glasgow Coma Scale scores. However, MENT offers several key advantages: it is less invasive, has a shorter average operative time (approximately 69 min vs. 91 min for traditional craniotomy), and is associated with smaller incisions, which contribute to reduced infection risk, minimized postoperative pain, and faster recovery. This is particularly important in elderly patients with multiple comorbidities, for whom extensive surgical interventions carry increased risk.[ 15 , 20 ]

Surgical precision is another critical factor influencing outcomes in posterior fossa procedures. Several studies highlight the importance of ergonomic factors such as hand support, caffeine intake, and instrument length on spatial accuracy in microsurgery.[ 4 ] Full hand support has been shown to significantly reduce tremor compared to unsupported positions or partial support, with no additional benefit from combining elbow and wrist supports. MENT capitalizes on this by enabling shorter, more stable procedures with ergonomic hand positioning, further enhancing control and accuracy.[ 3 ]

Technological advances also play a pivotal role in refining surgical outcomes. Devices like the Mari system, which attach to the eyepieces of counterweight-balanced microscopes, provide head-mounted stabilization through supportive metallic plates. These innovations enhance the surgeon’s precision and reduce fatigue by facilitating stable interaction between the surgeon and the microscope.[ 17 ] The integration of such devices with the MENT technique can further improve operative efficiency and safety.[ 14 ]

In addition, the use of keyhole access and endoscopic visualization in MENT focuses the surgical field and enhances anatomical orientation, mitigating the effects of tremor and minimizing tissue disruption. While trajectory planning may add a few minutes to the procedure, this time is negligible compared to the extended duration required for midline exposure and dural opening in standard craniotomy.[ 6 , 13 , 19 ]

CONCLUSION

The MENT technique offers a safe and effective alternative to traditional craniotomy for managing large cerebellar infarcts. By combining keyhole access, endoscopic visualization, and ergonomic advantages, MENT minimizes surgical trauma, reduces operative time, and promotes faster recovery, especially in elderly or high-risk patients. When integrated with modern supportive technologies, this approach holds a strong potential to improve both surgical precision and overall patient outcomes.

Ethical approval:

Institutional Review Board approval is not required.

Declaration of patient consent:

Patient’s consent not required as there are no patients in this study.

Financial support and sponsorship:

Nil.

Conflicts of interest:

There are no conflicts of interest.

Use of artificial intelligence (AI)-assisted technology for manuscript preparation:

The authors confirm that there was no use of artificial intelligence (AI)-assisted technology for assisting in the writing or editing of the manuscript, and no images were manipulated using AI.

Disclaimer

The views and opinions expressed in this article are those of the authors and do not necessarily reflect the official policy or position of the Journal or its management. The information contained in this article should not be considered to be medical advice; patients should consult their own physicians for advice as to their specific medical needs.

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