Shahzad Shams  ( Department of Neurosurgery Unit 1, Lahore General Hospital, Lahore. )
Rizwan Masood Butt  ( Department of Neurosurgery Unit 1, Lahore General Hospital, Lahore. )
Afaq Sarwar  ( Department of Neurosurgery Unit 1, Lahore General Hospital, Lahore. )

Computerized tomography assisted Stereotactic biopsy technique using Leksell stereotactic frame was performed on 27 patients with small, multiple and deep seated brain turnout’s. There were 19 men and 8 women with an age range from 17 to 65 years. Histological diagnosis of 18 glial tumours, 9 non-glial turnout’s (5 colloid cysts, 4 metastatic lesions) was obtained. There was no mortality and minimal morbidity of 3.7%, histological diagnosis provided the information regarding differentiation from infec­tious and vascular lesions and grading of malignancy leading to logical guidance for therapeutic manage­ment of each lesion, confirming the value of stereotactic biopsy in brain tumours (JPMA 46:176, 1996).

Stereotactic brain biopsy using computerized tomogra­phy (CT) assisted imaging technique provides a method of obtaining tissue for pathological diagnosis under local anaes­thesia without an open craniotomy. Modem stereotactic surgery has reduced the high mortality rate formerly associ­ated with open or free hand needle biopsy technique^1,2. Stereotactic biopsy has a high accuracy rate and decides the course of clinical management³. In this study, we retrospec­tively review the location, histological findings, mortality and morbidity associated with stereotactic biopsy ofbrain tumours and its clinical implications in management.

Twenty-seven patients underwent stereotactic biopsy procedures between November, 1994 to February, 1996 for 177brain tumours diagnosed on computed tomography (CT) and then confirmed on histological report. Leksell stereotactic system compatible with Siemens Somatom DR CT scanner was used. Indications for application of technique were small, deep or multiple intrinsic intracranial lesions. There were 19 men and 8 women between 17 and 65 years of age (mean 37.5 years). Histological diagnosis for glial tumours was made according to Kernohan’s grading system. In order to take stereotactic biopsy, coordinate base of Leksell frame was placed on all patients under local anaesthesia in the operation theatre. Then patients were shifted to CT scan room where contrastenhanced CT scanwas obtained. A targetpointwithin the lesion was selected by computer of CT scanner calculatedvalues of X, Y and Z coordinate (Figure 1).

The patients were then brought back to operating room where a semicircular arc was mounted on the coordinate base of Leksell frame and coordinates were fixed according to the values. A burr hole was placed at the entry point under local anaesthesia such that probe trajectory avoided eloquent areas and vascular struc­tures. Biopsy was taken from two Sites, centre and peripheral edge of the lesion, using a 2mm biopsy forceps (Figure 2).

Twenty-seven patients underwent stereotactic biopsy for brain tumours. Location of lesions are shown in Table I.

Twenty-two biopsies were from supratentorial region and 5 infratentorial. Histological diagnosis of the 18 glial tumours and 9 non-glial tumours was obtained as shown in Table II.

High grade (III and IV) astrocytorna was the commonest lesion diagnosed.There was no mortality and minimal morbidity in 1 patient (3.7%) of right thalamic glioma with deterioration of left sided weakness which improved after 72 hours. On the basis of histological diagnosis, these tumours were differenti­ated from infectious (tuberculoma, abscess) and vascular lesions (infarction) benign from malignant tumours. Categori­zation and grading of glial tumours was known. All this information lead to a correct and definite course of therapeutic management of each lesion safely and accurately.

Stereotactic brain biopsy has greatly improved the neurosurgeon’s ability to obtain tissue from lesions with little risk to patient even when the lesion is located deep in cerebral hemispheres orposteriorfossa. The calculation of coordinates is accurate to 1 mm margin. In studies of Apuzzo et al, pathological diagnosis is in excess of 90% which compares with our study⁴. In stereotactic biopsy specimen despite, its small size, provides more representative material from a lesion than open biopsy specimen in which tissue is obtained without radiological guidance⁵. The enhancing periphery of a lesion has the 91% diagnostic yield as compared to 67% in central necrotic areas⁶.
Neurosurgeons continue to refer patients with deeply seated intracranial lesions for radiation and chemotherapy where diagnosis is inferred from CT scanning. With CT compatible stereotactic system histological nature of suspi­cious lesion can be determined safely and accurately. Biopsy procedures are associated with few complications including haemorrhage, seizure, local infections and traumatic aneu­rysms⁷.
Mortality and morbidity for stereotactic procedure is low and reported 1-4%^8,9. In our study we had no mortality and morbidity of 3.7%. In conclusion, this study confirms the value of stereotactic biopsy in diagnosis and rational decision making in management of small multiple and deep seated brain tumours.

1. Heilbrun, M.P., Roberts, T.S.. Apuzzo. M.L.J. Preliminary experience with Brown Roberts Wells computerized tomography stereotactic guidance system J. Neurosurg., 1983;59:217-22.
2. Lunsford, L.D.. Martinez, A.J. Stereotactic exploration of the brain in the era of computed tomography. Surg. Neurol., 1984;22 :222-30.
3. Apuzzo, M.L.J.. Sabshin. J.S. Computed tomography guidance stcrcotaxis in the management of intracranial mass lcsions. Neurosurgery, 1983;12:277-85.
4. Apuzzo, M.L.J,, Chandrasoma, PT., Zelman, V. et al. Computed tomographic guidance stereotaxis in the management of lesions of third ventricular redion. Ncurosurgery, 1984;1 5:502-8.
5. Apuzzo, M.L.J., Chandrasoma, PT.. Cohen, D. et al. Computed imaging sterootaxy: experience and pcrspcctivcrclated to 500 procedures applied to brain masses. Neurosurgery, 1987;20:930-37.
6. Greena, G.M., Hitchon, P.W.. Schelper, R.L. et al. Diagnostic yield in CTguided stcreotactic biopsy ofglioma. 3. Neurosurg., 1989;71:494-97.
7. Shahrakar, K., Boggan, J.E., Salamat, M. S. Traumatic aneurysm: a complication of stereotactic brain biopsy. Neurosurgery, 1995;36:842-46.
8. Bernstein, M., Parrent, AG. Complications ofCT guided stereotactic biopsy of intracranial brain lesions. 3. Neurosurg., 1994;81:165-68.
9. Goldstein, S.. Caumerlock, M.K., Ncuwelt, E.A. Comparison of CT guided and stereotratic cranial diagnostic needle biopsies. J. Neurosurg., 1987;67:34 1-48.