Clinical Experience with Frame Based Stereotactic Biopsy for Intracranial Space Occupying Lesion

ABSTRACT Introduction Preoperative diagnosis of intracranial space occupying lesion based solely on clinical and neuroimaging evaluation may not be sufficient to institute treatment plan without histopathological certainty. Frame based stereotactic biopsy is a technique of retrieving biopsy specimen to determine the histopathology. The aim of this study is to assess the efficacy and accuracy of frame based technique. Methods This is a cross-sectional study conducted among 80 patients who underwent computed tomography guided frame based stereotactic biopsy during a period of 6 years. All operations were performed under local anesthesia. Histopathology reports were retrieved and accuracy of biopsy technique analyzed. Results Out of 80 patients, 58 were male with male to female ratio of 2.6:1. Median age of patients were 50 years with range from 16 to 75 years. Most lesions were in deeper location 49 (61.3%). Most common location was Parietal, 15 (18.8%) followed by Thalamic, 12 (15%). Mean size of lesion was 2.88±0.71cms ranged from 2 to 5cms. Biopsy was accurate to retrieve target in 74 (92.5%) patients. Histopathology revealed glial tumor in 41 (51.2%) of cases. Overall morbidity was observed in 3 (5.5%) patients. There is no procedure related mortality in this study during study period. Conclusions Frame based biopsy of intracranial space occupying lesion is safe and efficacious procedure with high diagnostic yield.


INTRODUCTION
Preoperative diagnosis of intracranial space occupying lesion based solely on clinical and neuroimaging evaluation may not be sufficient to institute treatment plan without histopathological certainty.Histopathological diagnosis is always necessary to make an effective treatment plan for intracranial mass lesions.
Computed Tomography (CT) guided frame based stereotactic biopsy is a minimally invasive procedure that uses three dimensional (3D) coordinated system for precisely locating lesion to obtain tissue sample for histopathological examination.It is an extremely safe and effective procedure for determining the histopathological diagnosis of intracranial lesions. 1 The aim of this study is to assess the efficacy and accuracy of frame based stereotactic biopsy technique.

METHOD
This is a descriptive cross-sectional study conducted in Upendra Devkota Memorial National Institute of Neurological and Allied Sciences (UPMNINAS), Kathmandu, Nepal among 80 patients, who underwent frame based stereotactic biopsy during six years period from March 2012 to Jan 2017.All operations were performed under local anesthesia.Ethical approval was taken from UDMNINAS, IRC.Deeper lesion and those patients with superficial location who cannot withstand major surgical procedure were included.Superficial lesion with good KPS score who underwent direct surgical excision were excluded.Convenience (nonprobability) sampling method was used and sample size of 80 was calculated using following formula.
Statistical package for social science (SPSS) version 20.0 was used for the data entry and analysis.The data were presented and the outcomes were analyzed using Chi-square test.Proportion and mean were deduced for categorical data and continuous variables respectively.P<0.05 was considered significant.
Technique of frame-based biopsy: Preoperatively patients were assessed clinically and available records such as CT scan, chest x-ray evaluated.Coagulation profile is checked.Head of the patient was shaved or washed with antiseptics and base ring of Brown-Roberts-Wells (BRW) system was secured in to the outer table of the skull with four screws after infiltrating the required points with 2% lignocaine.Patient was shifted to CT scanner.Localizing ring was attached to base ring before CT scanning.Contrast enhanced computed tomography was done in each patient.Areas with contrast enhancement was selected while areas of most suspicion were selected for non-enhancing lesion.Pixel coordinates of nine localizer rods were derived and recorded.X and Y coordinates was calculated with Radionic Stereocalc application in Windows Microsoft software and three scales (Antero-posterior, lateral and vertical) were calculated.Patient shifted to OT. Calculation were calibrated to phantom target.Patient head is prepped and draped.Entry point was infiltrated with 2% lignocaine, incised and small burr hole made with Hudson or Manman perforator.Durotomy was made with electrocautery.Cosman-Roberts-Wells (CRW) frame was mounted on the head.A side cutting biopsy needle was used and an average of 4 specimens were obtained through single trajectory and sent for histopathological analysis.Wound closed with one or two stitches and base ring removed and patient observed in post-operative unit.

RESULTS
Out of 80 patients who underwent frame based biopsy of intracranial space occupying lesion, most of them were male (58 patients) with male to female ratio of 2.6:1.Median age of patients was 50 years with range from 16 to 75 years.Most lesions were observed in right side 42 (52.5%)while 38 (47.5%) lesions were in left side.
Two patients developed seizure and one patient had tract hematoma which was managed conservatively (Table 4).There is no procedure related mortality in our study.

DISCUSSION
With the advent of computed tomography (CT) in the 1970s-precise visualization of the location of lesions affecting the central nervous system (CNS) was Free Full Text Articles are Available at www.jnma.com.nppossible.CT-guided freehand techniques were used to obtain tissue from intracranial lesions until rigidly fixed stereotactic headframes were developed in the early 1980s. 2 Literature comparing diagnostic yield of stereotactic technique is sparse.Hence this study was undertaken to evaluate diagnostic yield of frame based stereotactic technique.
The diagnostic accuracy of frame based stereotactic technique were reported from 84.21% to 97.5% The overall morbidity of needle biopsy is reported from 0.9% to 15% in different literature. 5,9,10In our study, overall morbidity was observed in 3 (5.5%)patients.Kreth et al. highlighted hematoma related complication as a common. 10One patient in our study (1.25%) had tract hematoma which was managed conservatively.Two patients (2.5%) developed seizure.

CONCLUSIONS
Frame based biopsy of intracranial space occupying lesion is safe and efficacious procedure with high diagnostic yield.We recommend future prospective study to compared frame based technique with other needle biopsy technique to ascertain and compare its accuracy, efficacy and safety.

Table 4 . Morbidity related to frame based stereotactic biopsy.
3mong 6 inconclusive reports, 3 were gliosis, 2 were normal brain and a chronic inflammatory neuroparenchyma.Reason for negative report were due to missed target acquiring normal brain for histology or retrieval of glial tissue/nonspecific chronic inflammatory tissue from target.Study done by Jain D et al.3had overall negative result in 15 (15.79%) out of 95 patients.In their study, histology revealed normal brain in 10 (10.5%)out of 95 patients, gliosis in 4.2% cases and inadequate tissue in 1.05% cases.3