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Frame-based stereotactic brain biopsy under local anesthesia: A 10-year retrospective experience with 94 cases in a resource-limited setting
*Corresponding author: Sumit Sahebrao Awasarmol, Department of Neurosurgery, Bansal Hospital, Bhopal-462016, Madhya Pradesh, India. dr_sumit_87@yahoo.co.in
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Received: ,
Accepted: ,
How to cite this article: Garg N, Awasarmol SS, Agrawal S, Sharma S. Frame-based stereotactic brain biopsy under local anesthesia: A 10-year retrospective experience with 94 cases in a resource-limited setting. J Neurosci Rural Pract. 2026;17:455-60. doi: 10.25259/JNRP_146_2026
Abstract
Objectives:
Stereotactic brain biopsy is a safe, minimally invasive procedure for obtaining tissue diagnosis from deep-seated, eloquent, or radiologically indeterminate intracranial lesions. This study reports our institutional experience with frame-based stereotactic biopsy over a decade, analyzing diagnostic yield, safety profile, and technical outcomes.
Materials and methods:
All patients underwent frame-based stereotactic biopsy (Cosman-Roberts-Wells [CRW] system) under local anesthesia. Procedures were performed using selective computed tomography magnetic resonance imaging (CT-MRI) fusion in 48 cases (51%) and CT-based targeting alone in 46 cases (49%). Intraoperative frozen section examination was performed in 51 cases (54.3%). Statistical analysis of diagnostic yield between groups was performed using Fisher’s exact test. Routine postoperative non-contrast computed tomography (CT) was obtained in all patients within 2 hours of biopsy.
Results:
Overall diagnostic yield was 91.5% (86/94 cases). When frozen section was employed, diagnostic yield increased to 96.1% (49/51 cases), compared to 90.7% (39/43 cases) without frozen section. However, this difference was not statistically significant (p = 0.49). CT-MRI fusion achieved a diagnostic yield of 93.8% (45/48), compared with 89.1% (41/46) for CT-based targeting alone, which was also not statistically significant (p = 0.56). Mean patient age was 58.87 years (range 18-91 years), with gender distribution of 54 males and 40 females. Lesion locations included the frontal lobe (31.9%), corpus callosum (20.2%), thalamus (12.8%), parietal (6.4%), and other sites. Pathological diagnoses included high-grade glioma (36.2%), lymphoma (19.1%), low-grade glioma (4.3%), metastasis (7.4%), infection (4.3%), and other lesions (9.6%). Eight cases (8.5%) yielded negative biopsies. Six lesions (6.4%) were non-enhancing on contrast MRI; in these cases, targeting was based on T2/FLAIR abnormality and multi-quadrant sampling. Complications were minimal: one seizure, two cases of target miss from needle deviation, two cases of asymptomatic target site hemorrhages, and zero procedure-related mortality. No permanent neurological deficits were documented.
Conclusion:
Frame-based stereotactic brain biopsy provides high diagnostic yield with minimal morbidity for deep-seated and eloquent-area lesions. Intraoperative frozen section significantly improves diagnostic accuracy and guides real-time therapeutic decisions. This technique is particularly valuable in resource-limited settings, offering reliable tissue diagnosis under local anesthesia without general anesthesia requirements.
Keywords
Deep-seated lesions
Diagnostic yield
Frame-based
Frozen section
Minimally invasive biopsy
Stereotactic brain biopsy
INTRODUCTION
Stereotactic brain biopsy has emerged as a cornerstone minimally invasive procedure for obtaining definitive tissue diagnosis from intracranial lesions that are deep-seated, small, multifocal, or located in eloquent brain regions where open resection is contraindicated or associated with significant morbidity.[1,2]
The clinical challenge of indeterminate intracranial lesions on conventional imaging—whether radiologically benign, inflammatory, neoplastic, or infectious—directly impacts patient management and prognosis. Stereotactic biopsy transforms radiologically uncertain lesions into definitive histopathological diagnoses, enabling precise therapeutic planning, prognostication, and initiation of targeted adjuvant therapy.[3,4]
Frame-based stereotactic systems, such as the Cosman-Roberts-Wells (CRW) frame, offer superior spatial accuracy through rigid skull fixation with fiducial-based coordinate systems, and they continue to provide excellent diagnostic yield and cost-effectiveness in resource-limited settings.[5,6]
The use of intraoperative frozen section examination during stereotactic biopsy can enhance diagnostic accuracy by confirming tissue adequacy in real time and allowing immediate re-sampling when initial specimens are nondiagnostic.[7,8]
Our institution has maintained a prospective registry of all frame-based stereotactic brain biopsies performed over the past decade, providing an opportunity to analyze outcomes in a large cohort and contribute to the growing body of evidence supporting this technique in Indian neurosurgical practice.
In addition to reporting procedural outcomes under local anesthesia, the present analysis specifically evaluates the practical contributions of frozen section assessment, selective computed tomography magnetic resonance imaging (CTMRI) fusion, and post-biopsy imaging verification in a resource-constrained tertiary-care setting in a tier 2 city.
MATERIALS AND METHODS
Study design and patient selection
This is a retrospective analysis of 94 consecutive frame-based stereotactic brain biopsies performed at the Department of Neurosurgery, Bansal Hospital, Bhopal, from January 2015 to December 2025. All patients with radiologically indeterminate intracranial lesions unsuitable for open resection or requiring tissue diagnosis for treatment guidance were considered for stereotactic biopsy.
Inclusion criteria
lesions with uncertain radiological diagnosis requiring tissue confirmation, (2) deep-seated or eloquent-area location precluding open resection, (3) lesions >3 mm in diameter accessible via standard stereotactic trajectory, and (4) patient age ≥18 years.
Exclusion criteria
Included uncorrected coagulopathy, patients on dual antiplatelet therapy without prior clearance, active infection at frame fixation sites, and patient refusal.
Preoperative assessment
All patients underwent high-resolution 3D T1-weighted contrast-enhanced MRI for lesion characterization and stereotactic trajectory planning. computed tomography (CT) was performed on the day of biopsy, after CRW frame application. Both modalities were used for trajectory planning and targeting.
In 48 cases (51%), CT-MRI fusion was performed using stereotactic planning software to enhance targeting accuracy. In 46 cases (49%), CT-based targeting alone was employed based on lesion conspicuity and surgeon preference. Among the 94 lesions, 6 (6.4%) were non-enhancing on contrast-enhanced MRI. In these cases, stereotactic targeting was based on the solid component identified on T2-weighted and fluid-attenuated inversion recovery (FLAIR) sequences, while avoiding cystic or necrotic regions whenever feasible.
Surgical technique
All procedures were performed under local anesthesia. Prilocaine cream 10% was applied to the scalp 1 hour before frame application, and local anesthesia with 1% lignocaine was infiltrated at frame fixation sites.
The CRW stereotactic frame was applied and secured with four titanium pins. Stereotactic coordinates were calculated based on CT or CT-MRI fusion images using calibrated planning software. A small burr hole (3-4 mm) was created at the optimal trajectory point, and the biopsy needle was advanced along the stereotactic trajectory. Tissue samples were obtained using the negative-pressure rotation technique, collecting 4 samples per case from 4 quadrants.
Intraoperative frozen section examination was performed in 51 cases (54.3%) with intraoperative pathologist availability. When the frozen section indicated adequate diagnostic tissue, the procedure was terminated. When the frozen section was non-diagnostic or tissue adequacy was uncertain, additional samples were obtained from the same trajectory and, when necessary, after a slight trajectory adjustment (<2 mm) toward a more solid-appearing region. Sampling continued until adequate diagnostic tissue was obtained or needle deviation/target mismatch was suspected.
At the completion of the procedure, a routine postoperative non-contrast CT scan was performed in all patients within 2 hours to assess for hemorrhage, pneumocephalus, and concordance of the biopsy track with the intended target.
Data collection and analysis
Patient demographics, lesion characteristics, operative findings, histopathological diagnoses, operative time, postoperative complications, and discharge status were recorded. Diagnostic yield was defined as the percentage of cases with a definitive histopathological diagnosis. Complications were categorized as hemorrhagic (any postoperative intracranial hemorrhage on imaging), neurological (transient or permanent deficit), infectious, and procedural-related (needle deviation precluding adequate sampling).
Comparisons of diagnostic yield between frozen section versus no frozen section and CT-MRI fusion versus CT-based targeting alone were analyzed using Fisher’s exact test, with p < 0.05 considered statistically significant.
RESULTS
Demographics and lesion characteristics
Ninety-four patients underwent frame-based stereotactic brain biopsy. Mean age was 58.87 years (range: 18-91 years), and gender distribution was 54 males (57.4%) and 40 females (42.6%).
Lesion locations were distributed as follows
Frontal lobe 30 cases (31.9%), corpus callosum 19 cases (20.2%), thalamus 12 cases (12.8%), parietal lobe 6 cases (6.4%), cerebellum 4 cases (4.3%), brainstem 3 cases (3.2%), basal ganglia 2 cases (2.1%), ventricular/periventricular 5 cases (5.3%), and multifocal/other locations 13 cases (13.8%) [Table 1].
| Lesion location | n | % |
|---|---|---|
| Frontal lobe | 30 | 31.9 |
| Corpus callosum | 19 | 20.2 |
| Thalamus | 12 | 12.8 |
| Parietal lobe | 6 | 6.4 |
| Cerebellum | 4 | 4.3 |
| Brainstem | 3 | 3.2 |
| Basal ganglia | 2 | 2.1 |
| Ventricular/periventricular | 5 | 5.3 |
| Multifocal/other locations | 13 | 13.8 |
| Total | 94 | 100.0 |
Diagnostic yield and pathological findings
Overall diagnostic yield was 91.5% (86/94 cases). Pathological diagnoses included high-grade glioma 34 cases (36.2%), lymphoma 18 cases (19.1%), metastasis 7 cases (7.4%), low-grade glioma 4 cases (4.3%), infection/tuberculosis 4 cases (4.3%), ependymoma 2 cases (2.1%), radiation necrosis 1 case (1.1%), hematoma (organizing) 1 case (1.1%), and negative biopsy 8 cases (8.5%) [Tables 2 and 3].
| Variable | n | % |
|---|---|---|
| Overall diagnostic yield | 86 | 91.5 |
| Negative/nondiagnostic biopsy | 8 | 8.5 |
| High-grade glioma (WHO grade III-IV) | 34 | 36.2 |
| Lymphoma | 18 | 19.1 |
| Metastasis | 7 | 7.4 |
| Low-grade glioma (WHO grade I-II) | 4 | 4.3 |
| Infection/tuberculosis | 4 | 4.3 |
| Ependymoma | 2 | 2.1 |
| Radiation necrosis | 1 | 1.1 |
| Hematoma (organizing) | 1 | 1.1 |
| Total diagnostic biopsies | 86 | 100.0 |
| Location group | Diagnostic / Total | Yield (%) |
|---|---|---|
| Supratentorial lobar/callosal lesions | 68 / 74 | 91.9 |
| Deep midline lesions (thalamus + basal ganglia) | 13 / 14 | 92.9 |
| Infratentorial lesions (cerebellum + brainstem) | 5 / 7 | 71.4 |
| Overall comparison | 86 / 94 | p = 0.72 |
p-value comparison was not statistically significant
Impact of intraoperative frozen section
Frozen section examination was performed in 51 cases (54.3%), largely depending on intraoperative pathologist availability. In 49 of these 51 cases, diagnostic tissue was obtained, corresponding to a yield of 96.1%, whereas 39 of 43 cases without frozen section yielded a diagnosis, corresponding to 90.7%. Although the absolute increase in diagnostic yield was 5.4 percentage points, this difference did not reach statistical significance (Fisher’s exact test, p = 0.49).
Imaging-guided targeting
CT-MRI fusion was used in 48 cases (51%) and achieved a diagnostic yield of 93.8% (45/48), while CT-based targeting alone was used in 46 cases (49%) with a diagnostic yield of 89.1% (41/46). This difference was not statistically significant (Fisher’s exact test, p = 0.56), although the trend favored fusion-based planning [Table 4].
| Variable | Diagnostic / Total | Yield (%) | p value |
|---|---|---|---|
| Frozen section used | 49 / 51 | 96.1 | 0.49 |
| Frozen section not used | 39 / 43 | 90.7 | |
| CT-MRI fusion used | 45 / 48 | 93.8 | 0.56 |
| CT-based targeting alone | 41 / 46 | 89.1 |
CT-MRI: Computed tomography magnetic resonance imaging, p-value comparison was not statistically significant
Surgical outcomes and complications
Mean operative time was 110 minutes (range: 100-130 minutes), including setup, trajectory planning, and biopsy collection, and mean hospital stay was 3 days (range: 2-5 days). Two cases (2.1%) had asymptomatic target site hemorrhages that were managed conservatively, one patient experienced a postoperative seizure (1.1%) that was controlled with antiepileptic medication, and two cases (2.1%) had target miss due to needle deviation from frame fixture loosening or needle deflection.
Routine postoperative CT identified the two asymptomatic hemorrhages and helped confirm biopsy-track deviation in the two target-miss cases. These findings were useful in correlating non-diagnostic sampling with technical factors rather than histopathological processing alone.
There were zero cases of postoperative infection and procedure-related mortality.
DISCUSSION
Frame-based stereotactic brain biopsy remains a high-yield, safe, and cost-effective technique for obtaining tissue diagnosis from deep-seated and eloquent-area intracranial lesions, particularly in resource-limited settings, especially in tier 2 cities where advanced neuronavigational systems may be unavailable or prohibitively expensive.
Diagnostic yield and comparison with literature
The overall diagnostic yield of 91.5% aligns closely with the literature cited in the manuscript, where contemporary stereotactic biopsy series report diagnostic yields ranging from 85% to 97%.[9,10] Recent Indian series cited in the manuscript also reported high yields, including a 95% yield in the SGPGI Lucknow series [6], and various smaller Indian cohorts have documented diagnostic accuracies between 93% and 96%.[11,12]
The improvement in diagnostic yield from 90.7% to 96.1% with the addition of intraoperative frozen section (5.4 percentage point increase) is consistent with published evidence. Several studies have documented that frozen section confirmation reduces non-diagnostic biopsies and allows real-time target adjustment: a meta-analysis of frozen section utility in stereotactic biopsy found that its use elevated overall yield from approximately 73% (baseline without FS) to 90-97% depending on technique and lesion type.[13]
In the present study, both frozen section use and CT-MRI fusion were associated with numerically higher diagnostic yield, but neither comparison reached statistical significance. This likely reflects the limited sample size and the retrospective, non-randomized nature of group allocation rather than the absence of clinical utility.
Impact of intraoperative frozen section
Frozen section-guided biopsy offers several practical advantages, including confirmation of tissue adequacy before procedure termination and immediate opportunity for re-sampling when initial tissue is inadequate.[13] In this series, the decision to perform frozen section depended on the pathologist's availability rather than preplanned randomization.
This point has been clarified to avoid overstating causality. The findings support frozen section as a useful adjunct that may improve tissue adequacy in real time, while acknowledging that the current study design cannot establish definitive superiority.
CT-MRI fusion and targeting
CT-MRI fusion improved soft-tissue localization by combining MRI-defined lesion anatomy with CT-based frame coordinates, and the observed yield was numerically higher than CT-only planning. However, because fusion was selectively used according to lesion conspicuity and surgeon preference, the findings should be interpreted as practice-based observational data rather than proof of superiority.
Lesion location and yield
The predominance of frontal and corpus callosal lesions reflects referral patterns and the accessibility of frame-based stereotaxy for eloquent and deep-seated lesions. Lesion location has been integrated with diagnostic-yield presentation in an additional table, allowing readers to better interpret site-specific performance.
Local versus general anesthesia
Although local anesthesia has historically been the standard approach in many centers, it remains clinically relevant because it avoids the risks of general anesthesia, facilitates intraoperative neurological assessment, and reduces procedural cost in elderly or medically comorbid patients. Frameless or navigation-assisted procedures are often performed under general anesthesia in contemporary practice, but the present series demonstrates that frame-based biopsy under local anesthesia continues to provide dependable tissue diagnosis with low morbidity in a modern tertiary-care setting.
Non-enhancing lesions
Non-enhancing lesions remain a recognized challenge in stereotactic biopsy because target selection cannot rely on contrast uptake alone. In the present cohort, these cases were planned using T2/FLAIR-defined abnormality, with emphasis on sampling the solid radiological component and obtaining tissue from multiple quadrants to reduce the risk of acellular or necrotic sampling.
Post-biopsy verification and technical refinement
Routine post-biopsy CT was useful not only for early detection of hemorrhage but also for evaluating target concordance when sampling was nondiagnostic. In combination with frozen section feedback, this helped identify cases in which additional sampling or minor trajectory adjustment might improve yield, and it also highlighted the importance of regular instrument checks to minimize needle deviation.
Cost-effectiveness
Frame-based stereotaxy remains especially attractive in resource-limited settings because the capital cost of a reusable stereotactic frame is substantially lower than that of a navigation platform, while ongoing procedural costs are also reduced by the use of local anesthesia and basic CT-based workflow. For many Indian tertiary centers, this balance of affordability, precision, and reproducibility supports continued use of frame-based biopsy as a cost-effective diagnostic strategy.
CONCLUSION
This 10-year experience with 94 frame-based stereotactic brain biopsies demonstrates that the procedure achieves a diagnostic yield of 91.5%, rising to 96.1% with intraoperative frozen section guidance, with an exceptional safety profile including zero procedure-related mortality and zero permanent neurological deficits.
Frozen section use and CT-MRI fusion were associated with improved numerical yield, although these differences were not statistically significant in the present cohort. Routine postoperative CT provided useful confirmation of hemorrhagic complications and biopsy-track accuracy, particularly in nondiagnostic cases.
Frame-based stereotactic brain biopsy remains an integral technique for obtaining tissue diagnosis from deep-seated, eloquent-area, and radiologically indeterminate intracranial lesions, especially in resource-limited centers where cost-effective precision remains essential.
Acknowledgment:
We acknowledge the contributions of the operating room nursing staff, intraoperative pathology team, and neuroradiology colleagues at Bansal Hospital for their support in achieving excellent patient outcomes.
Ethical approval:
Institutional Review Board approval is not required as it is retrospective study.
Declaration of patient consent:
The authors certify that they have obtained all appropriate patient consent forms. In the form, the patient has given consent for their clinical information to be reported in the journal. The patient understands that the patient’s names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed.
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.
Financial support and sponsorship: Nil.
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