What is Stereotaxy
Stereotactic surgery or stereotaxy in India is a minimally-invasive form of surgical intervention which makes use of a three-dimensional coordinates system to locate small targets inside the body and to perform on them some action such as ablation (removal), biopsy, lesion, injection, stimulation, implantation, radiosurgery (SRS) etc.
In theory, any organ system inside the body can be subjected to stereotactic surgery. Difficulties in setting up a reliable frame of reference (such as bone landmarks which bear a constant spatial relation to soft tissues), however, mean that its applications have been limited to brain surgery.
History of stereotactic surgery in India
Functional and stereotactic surgeries were first introduced in 1940’s and 50’s, but did not make progress as expected due to high mortality and morbidity rates. Neurosurgery developed in India after the II world war. In 1940 pioneers like Chintan Nambiar performed 74 cases of chemopallidotomy using free hand stereotactic technique. In 1949 Jacob Chandy and Baldev Singh established the first neurosurgical center at Christian Medical College (CMC), Vellore in Tamilnadu. In 1950’s V. Balasubramaniam and B. Ramamurthi performed pallidal lesioning with inflatable balloon and alcohol. H M Dastur started stereotactic surgery at King Edward Memorial (KEM) Hospital Mumbai in 1959. Initially he used Oliver’s guide and latter used Narabayashi frame along with Dr. Gajendra Sinh (Jaslok hospital, Mumbai) to perform stereotactic surgery. Dr S N Bhagwati (Mumbai) used Mckinneys apparatus and Leksell’s frame in 1964. In 1970, S. Kalyanaraman (Madras Medical College) performed stereotactic surgeries using a combination of Leksell and Sehgal stereotactic equipment to perform simultaneous targeting of intracranial structures. R M Verma who was trained in Bristol 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 1997 with V. Balasubramaniam, as its first President. Stereotactic Radiosurgery was first introduced in India at the Apollo Hospital, Chennai using Linac X-knife system. Gamma knife was introduced at Hinduja Hospital, Mumbai in 1997. In Mumbai Dr. Paresh Doshi (Jaslok Hospital, Mumbai) performed surgery for Parkinson’s disease. Initially he started with GPi lesioning and later switched to STN-DBS surgery. In 2009 he was instrumental in performing neural transplant surgery using Mesenchymal Stem cell therapy in collaboration with Reliance Life sciences for Parkinson’s disease. The results of which are awaited.
About Stereotactic Brain Biopsy
A Stereotactic Brain Tumor Biopsy is a neurosurgical procedure in which samples of tissue are taken from the tumor site. The biopsy will provide information on types of abnormal cells present in the tumor. The purpose of a biopsy is to discover the type and grade of a tumor as well as its molecular biology and its growth pattern. With the help of MRI and CT scans and 3D computer workstations, neurosurgeons are able to accurately target any area of the brain in stereo tactic space (3D coordinate system). A stereotactic biopsy surgery is the most accurate method of obtaining a diagnosis. Once a sample is obtained, a pathologist examines the tissue under a microscope and writes a pathology report containing an analysis of the brain tissue.
This procedure is used by neurosurgeons to obtain tissue samples of areas within the brain that are suspicious for tumors or infections. The main indications for stereotactic biopsy are deep-seated lesions, multiple lesions, or lesions in a surgically poor candidate who cannot tolerate anesthesia.
We perform stereotactic biopsies under local anesthesia, with or without intravenous sedation. Most of the biopsies are performed with CT localization, however, in cases where the lesion can only be seen on MRI we have facilities to do MRI guided biopsies. The procedure takes about 3 hours. To begin with a stereotactic frame is attached to the patient’s head using local anaesthesia at the pin insertion site. (Fig.1) This works as a reference for all scans (CT, MRI, PET) which are used for target localisation. This system allows computerized planning of the surgical approach with sub-millimeter precision. A CT/MRI scan is then performed to obtain the co-ordinates.
In the operating room, the patient’s head is rested on a clamp system in a comfortable position. An incision of only a few millimeters is made in the scalp and a small hole is drilled into the skull. A thin biopsy needle is inserted into the brain using the coordinates obtained by the computer workstation. This is less invasive and much more precise than an open biopsy that requires a craniotomy which involves removing a piece of the skull in order to get access to the brain. The specimen is then sent to the pathologist for evaluation who will opine if the tissue is representative of the lesion and adequate for him to give final diagnosis. Patients are monitored for several hours following the procedure and usually go home within 1-2 days.
The risks associated with stereotactic brain biopsy are minimal. The complication rate of a stereotactic brain tumor biopsy is 2.3%, predominately caused by hemorrhage (0.7%), and edema or infection (< 2%). The diagnostic accuracy is 97%. Sometimes the sample of tissue obtained may be non-diagnostic, which may warrant a repeat biopsy.