Stereotaxy or Stereotactic Surgery is a minimally-invasive surgical procedure which uses 3D co-ordinate system to locate small goals inside the body and perform on them procedures such as injection, biopsy, ablation (removal), lesioning, implantation, stimulation, radiosurgery (SRS) etc.
Any organ system inside the body can be subjected to stereotactic procedures. Complications in fixing up a dependable frame of reference ( as bone landmarks which bear a constant spatial relation to soft tissues) however, makes its applications been limited to brain surgery.
Functional and stereotactic surgeries were first introduced in 1940’s and 50’s, but did not much flourished as expected due to high mortality and morbidity rates in the procedures. Neurosurgery was developed in India after the II world war.
In 1940, pioneers like Chintan Nambiar had performed 74 cases of chemopallidotomy using the free hand stereotactic technique. In 1949, Jacob Chandy and Baldev Singh were established the first neurosurgical centre at Christian Medical College (CMC), Vellore in Tamilnadu. In 1950’s, V. Balasubramaniam and B. Ramamurthi performed the pallidal lesioning with inflatable balloon and alcohol.
Dr H M Dastur has started the stereotactic surgery at King Edward Memorial (KEM) Hospital Mumbai in year 1959. Initially he used Oliver’s guide and later Narabayashi frame along with Dr. Gajendra Singh (Jaslok hospital, Mumbai) to perform stereotactic surgery.
Dr S N Bhagwati (Mumbai) in 1964, used Mckinneys apparatus and Leksell’s frame .
In 1970, Dr S. Kalyanaraman (Madras Medical College) has performed stereotactic surgeries using a combination of Leksell and Sehgal stereotactic equipments to perform the simultaneous targeting of many intracranial structures.
Dr R M Verma who was trained in Bristol has started neurosurgical units in AIIMS and was instrumental in establishing National Institute of Mental Health and Neurosciences (NIMHANS).
The Indian Society of Stereotactic and Functional Neurosurgery was formed in year 1997 with Dr V. Balasubramaniam, as its first President.
The Stereotactic Radiosurgery was first introduced in India at the Apollo Hospital, Chennai using the Linac X-knife system. Gamma knife was first introduced at Hinduja Hospital, Mumbai in 1997.
In Mumbai, Dr Paresh Doshi (Jaslok Hospital, Mumbai) has performed surgery for Parkinson’s disease. Initially he started with GPi lesioning and later switched to STN-DBS surgery.
The word ‘‘stereotactic’’ was derived from the Greek word ‘‘stereos’’ means ‘three dimensions,’’ and the Latin word ‘‘tactus’’ means ‘‘to touch’’.
Stereotactic biopsy is a neurosurgical procedure which involves the mapping of the brain in a three dimensional coordinate system, with the help of CT and MRI scans and a 3D computer workstations and by this any area of the brain can be accurately targeted in stereotactic space (3D coordinate system).
Stereotactic brain biopsy is a minimally invasive neurosurgical procedure that uses this technology to obtain tissue samples of the brain for diagnostic purposes or excision of tumors.
The biopsy will help to provide information on the types of abnormal cells present in the lesion. The purpose of any biopsy is to discover the type and grading of the lesion as well as its molecular biology and growth pattern.
With the help of MRI, CT scans and 3D computer workstations, the neurosurgeons are now able to accurately target any area of the brain in the stereotactic space (3D coordinate system). The Stereotactic biopsy surgery is now the most accurate method of reaching a diagnosis.
Once the sample is obtained, a pathologist examines the tissue under microscope and gives a pathology report depending upon the analysis of the brain tissue.
This procedure is done by neurosurgeons to obtain tissue samples of suspected areas of the brain that are suspicious for tumors or infections.
We commonly perform Stereotactic brain Biopsies under local anesthesia with or without any intravenous sedation. Most of the biopsies are performed with the help of CT localization, however, in cases where the lesion cannot be seen on CT, MRI guided biopsies can be done.
The procedure usally takes about 3 hours.
It begins with a stereotactic frame attached to the patient’s head using local anesthesia at the pin insertion points.
This works as a reference point for all the scans (CT, MRI and PET) which are used for target localization. The system allows computerized planning of the surgical approach of the lesion with sub-millimeter precision. A CT/MRI scan is then performed to obtain the co-ordinates to the target.
In the operating room, the patient’s head is to be rested on a clamp system in a comfortable position. A small linear incision is then made on the scalp and a small burhole is drilled into the skull.
A reedy biopsy needle is then put into the brain using the coordinates obtained by the computer workstation to the target lesion. This is a very less invasive and much more precise than an open biopsy procedure that requires a craniotomy which involves removing of a piece of the skull in order to get access to the brain lesion.
The specimen is then sent to the pathologist for histopathologic evaluation who will give opinion, if the tissue is representative of the lesion targetted and adequate for the final diagnosis.
Post-operatively, a CT scan is done to rule out any haemorrhage and also to confirm the site of biopsy taken.
The patient is then kept under observation following the procedure and usually goes to home within 1-2 days.
The incidence of morbidity due to stereotactic biopsy ranges from 1.0–6.5%, and mortality rates range from 0 to1.7%
the risks associated with stereotactic brain biopsy are minimal. The complication rate of a stereotactic brain tumor biopsy is 2.3%, predominately caused by hemorrhages (0.7%), and edema or infection (< 2%).
From time to time the sample of tissue acquired may be non-diagnostic, which may warrant a repeat biopsy.
The diagnostic accuracy is 97%.