Transsylvian-transinsular evacuation of hypertensive basal ganglia hematomas, maximizing hematoma evacuation, with a minimal operative footprint

INTRODUCTION

Spontaneous intracerebral hematomas (ICHs) remain a significant cause of mortality and morbidity, accounting for 10–20% of all strokes.^[1] Of these, the basal ganglia (BG) (and the overlying insular cortex) remains the most common site of the bleed, in nearly 51–71.3% of cases.^[2] The optimal management of these patients remains largely controversial as outcomes are considered dismal, despite the modality of treatment chosen.

Current evidence does not support specific, over-arching recommendations for surgery, the treatment paradigm stems from balancing hematoma evacuation with minimal collateral cortical damage.^[3] Of the various surgical approaches available, the transsylvian–transinsular (TSTI) route offers a surgical corridor that allows for a direct path to the hematoma with adequate cortical preservation. With available research advocating for more minimally invasive (MI) approaches to this pathology,^[4,5] a significant constraint is the availability of infrastructure such as neuronavigation and endoscopic equipment and instruments, in centers to effectively carry out such procedures. The TSTI approach addresses this by reducing cortical transgression, white matter injury, and associated retraction injury, while effectively allowing for hematoma removal, thereby allowing for a conventional approach with a “minimal footprint.”

This article aims to refocus attention on this surgical strategy by demonstrating its effectiveness in a series of ten consecutive patients.

MATERIALS AND METHODS

Patients operated by the TSTI route over a period of 1 year (from November 2022 to October 2023) at J.S.S Hospital Mysore were retrospectively analyzed and included in this retrospective study. The criteria for patient selection were the presence of hematoma within the BG, with a volume of >30 cc and a midline shift of more than 5 mm on a plain computed tomography (CT) brain, with CT angiography showing no underlying vascular pathology, with a baseline Glasgow coma scale (GCS) score of more than 5 at presentation, irrespective of the age of the patient. Patients who were managed conservatively, denied surgery, had a presentation GCS score of <5 or were found to have an underlying vascular or secondary cause of hematoma were excluded from the study. The decision to perform surgery on these patients was protocol-dependent (as per the abovementioned criteria).

The hematoma volume was calculated using the formula: Height × width × length × 0.5, while midline shift was calculated at the level of the foramen of Monro.

Data that were collected included basic demographic details of the patient, antecedent comorbidities, pre- and postoperative hematoma volumes, duration of hospitalization, duration of intensive care unit (ICU) stay, and patient outcomes.

Primary outcomes were defined as the changes in hematoma volume in the pre- and post-operative period as per imaging, change in midline shift between pre- and post-operative imaging and outcome at discharge. Secondary outcomes were defined as the duration of intensive care stay and overall hospitalization as well as condition at follow-up.

Statistical analysis was performed using the Statistical Package for the Social Sciences software (IBM). Parameters such as midline shift and hematoma volume were initially tabulated using descriptive statistics such as mean, median and mode, and compared pre- and post-operatively using the Wilcoxon signed-rank test. The remainder of the observed parameters were tabulated with descriptive statistical tools.

Surgical technique

The patients were placed in the supine position with their heads turned toward the normal side 30° with 15° of extension. Standard decompressive craniectomy was performed in all patients. The sylvian fissure was sharply separated under a microscope from the lateral to medial direction near the frontal side. Identification of the M3 branches within the fissure provided a reference for further proximal dissection to M2 divisions and the insular cortex. A small 1.5-cm corticectomy site was created in the insula cortex, and the hematoma cavity was entered. This corticotomy was the limit of cortical transgression during the procedure, the hematoma cavity was usually found at a depth of 2 mm to 1 cm from the point of cortical incision. The operative corridor following a transsylvian split is depicted in Figure 1. Hematoma evacuation was performed using suction and bipolar cautery. The lenticulostriate artery (LA) can be exposed well, and its bleeding can be stopped. Papaverine instillation was performed at the conclusion of surgery to prevent vasospasm. Lax duroplasty was performed, and as per institute protocol, the bone flap was not replaced.

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Figure 1:

Schematic diagram depicting the transinsular corticotomy after a sylvian fissure split (Green hashed region). This image shows a generous split, while in patients, the degree of the split can be tailored to allow the operator to comfortably evacuate the hematoma. ICA: Internal carotid artery; MCA: Middle cerebral artery; M1, M2: Segments of middle cerebral artery; ACA: Anterior cerebral artery; A1: Segment of anterior cerebral artery.

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RESULTS

Ten patients were enrolled in the study period, fulfilling the criteria mentioned earlier, of which nine patients were male and one was female. All the patients were known to have antecedent hypertensive disease. Six patients had right-sided BG bleeds, with the rest being left-sided [Table 1].

Hematoma volume

• Pre-operative period: The mean hematoma volume among patients before the operation was 100.00 mL (SD = 42.37), with a median value of 108 mL. The hematoma volume ranged from 40 mL to 170 mL.

• Post-operative period: Following the operation, the mean hematoma volume significantly decreased to 9.60 mL (SD = 5.60), with a median value of 9 mL. The minimum and maximum volumes observed postoperatively were 2 mL and 20 mL, respectively.

The mean difference in hematoma volumes before and following surgery was 90.40 mL, showing a significant reduction.

This is depicted in Table 2. Representative pre- and postoperative CT images showing evacuation of the hematoma and minimal cortical collateral injury (CT image taken 12 h post-index surgery) are depicted in Figures 2 and 3.

Table 2: Descriptive analysis of the midline shift (in mm) and hematoma volume (in mL) at pre-operative and post-operative period among study patients.

Parameter	Time	n	Mean	SD	Median	Min	Max
Midline shift	Pre-operative	10	9.70	3.30	9	5	16
	Post-operative	10	3.10	0.74	3	2	4
Hematoma volume	Pre-operative	10	100.00	42.37	108	40	170
	Post-operative	10	9.60	5.60	9	2	20

SD: Standard deviation.

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Figure 2:

Pre-operative axial computed tomography image of a representative patient depicting a large basal ganglia hematoma with mass effect and midline shift.

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Figure 3:

Post-operative computed tomography of the same patient depicted in Figure 2, taken 12 h after surgery, showing minimal residual hematoma, near total resolution of midline shift and air pockets in the operative corridor, and significant laxity of the brain.

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No complications attributable to the primary surgery (such as rebleeding, surgical site infection, or post-operative vasospasm) were noted.

DISCUSSION

Numerous surgical techniques have been proposed for the management of spontaneous BG ICH, including endoscopic evacuation,^[6] MI puncture and drainage,^[7] conventional craniotomy,^[5] etc. However, no single approach has been shown to be conclusively better, with a general intuitive consensus being that MI approaches tend to favor better outcomes in patients requiring surgery.^[3] This has been further elucidated in the recently concluded minimally invasive surgery plus alteplase for intracerebral hemorrhage evacuation (MISTIE) phase 2 trial, showing possible potential benefits in carefully selected patients with ICH treated with MI techniques.^[8] However, MI procedures may not always be feasible, especially in patients wherein there is significant edema, warranting a decompressive craniectomy to adequately manage the intracranial pressure post-surgery. An equally important point of contention is the availability of equipment for MI procedures such as endoscopes and frameless neuronavigation.

Once the need for a formal craniotomy is established, the operator is then faced with two options, a transcortical (TC) approach through the middle frontal gyrus or the middle temporal gyrus or the TSTI approach.^[9] The TC approach is usually favored amongst most operators due to its relative ease, familiarity with the relevant anatomy, and a general perception that the TSTI approach is technically difficult as it involves splitting the sylvian fissure in an edematous brain and negotiating the hematoma in windows between the M2 branches of the middle cerebral artery.

However, the TSTI approach has numerous advantages. This allows for a shorter distance from the cortex to the primary pathology at hand, with the hematoma being as low as 2 mm from the point of the corticectomy. In addition, the flat working angle allows for wide exposure of the hematoma and exposure along the long axis of the hematoma. This working angle further minimizes brain retraction while allowing for higher hematoma clearance rates, as evinced in our results, where the majority of patients had a significant reduction in hematoma volumes in post-operative imaging. In addition, effective hemostasis can be achieved, as the offending LA can be easily coagulated in this approach. The consistent location of the hematoma just below the insular cortex and the relationship of the insula to the hematoma (inferiorly placed) obviate the need for neuronavigation and allow for superior drainage of the hematoma. Finally, the opening of the cisterns also allows for better brain relaxation and a decrease in intracranial pressure. This study shows that in experienced hands, the hematoma evacuation rates, and post-operative course, including ICU stay and overall outcomes are comparable with other forms of surgical management of BG ICH with better hematoma evacuation rates.^[10,11]

However, while the TSTI approach does have its advantages, it is not a “one size fits all” approach, as potential complications can arise due to the technical difficulty of the approach and the potential for inducing vasospasm secondary to the mechanical manipulation of the vessels within the fissure.^[12,13] In addition, novice neurosurgeons require longer periods to successfully navigate this approach.^[14]

The ideal situation would be in patients wherein surgical evacuation of the hematoma is required, while an MI approach is not feasible due to significant edema or other factors, and a minimally disruptive procedure is preferred. While this approach may be considered in all patients requiring surgery for BG hematomas, the complexity of the procedure may significantly increase based on the degree of brain edema, the type of sylvian fissure, local venous anatomy, and surgeon experience. While all cases selected for the TSTI approach in this study were successfully completed without any deviation from the intraoperative plan, the authors acknowledge that there may be situations where this approach may be abandoned for the more conventional TC approach.

CONCLUSION

The TSTI approach to BG ICH is a technically challenging, versatile treatment option that minimizes brain tissue injury, allows for superior hematoma evacuation, allows for adequate hemostasis by allowing the operator to visualize the offending vessel, and does not require a neuronavigation system. The TSTI approach is a viable option for hypertensive BG hematomas, offering high hematoma evacuation rates while minimizing cortical damage. Larger prospective studies are necessary to further validate its safety and efficacy, particularly in comparison to MI endoscopic techniques.