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NEWS
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STEREOTACTIC SURGERY
This is an upcoming tool for minimally invasive brain surgeries.Its applications range from treatment and diagnosis of different pathologies. Most common use of this procedure is in successful cure of few most difficult and dangerous brain diseases. These include
Brain biopsy
Stereotactic surgery or stereotaxy is a minimally-invasive form ofintervention 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. "Stereotactic" in Greek (another accepted spelling is "stereotaxic") means "solid ordering".
In theory, any organ system inside the body can be subjected to stereotactic surgery. its applications have been limited mostly to brain surgery.. computed tomography OR mri can be used to guide the procedure.
History
The stereotactic method was first developed by two British scientists in 1908, working at University College London Hospital, Sir Victor Horsley, a physician and neurosurgeon, and Robert H. Clarke, an engineer.
ing the Horsley-Clarke apparatus for human brains was difficult because of the inability to visualize intracranial anatomic detail via radiography. However, contrasted brain radiography (particularly pneumoencephalography and ventriculography) permitted the visualization of intracranial anatomic reference points or landmarks. The first stereotactic devices for humans used the pineal gland and the foramen of Monro as landmarks. Later, other anatomic reference points such as the anterior and posterior commissures were used as intracranial landmarks. These landmarks were used with a brain atlas to estimate the location of intracranial anatomic structures that were not visible in radiographs.
Using this approach between 1947 and 1949, two American neurosurgeons, Ernest A. Spiegel and Henry T. Wycis, and a Swedish neurosurgeon, Lars Leksell, developed the first stereotactic devices that were used for brain surgery in humans. Spiegel and Wycis used the Cartesian coordinate system (also called the translational system) for their device. Leksell's device used the polar coordinate system (also called spherical) that was far easier to use and calibrate in the operating room. The stereotactic localization system was also used by Leksell in his next invention, a device for radiosurgery of the brain. This system is also used by the Gamma Knife device, and by other neurosurgeons, using linear accelerators, proton beam therapy and neutron capture therapy. Lars Leksell went on to commercialize his inventions by founding Elekta.
In 1978, Russell A. Brown, an American physician and computer scientist, invented a simple technique to guide stereotactic surgery using computed tomography.[1] [2] This technique significantly improves surgical precision because computed tomography permits direct visualization of intracranial anatomic detail. The technique uses fiducials to create extracranial landmarks in each tomographic image or section. These landmarks specify the spatial orientation of that section with respect to the stereotactic device. Brown's invention stimulated intense interest in stereotaxy and radiosurgery. It is widely used today in the Brown-Roberts-Wells (BRW) stereotactic system[3] as well as other stereotactic and radiosurgical devices.
The stereotactic method has continued to evolve, and at present uses an elaborate mixture of image-guided surgery using computed tomography, magnetic resonance imaging and stereotactic localization.
How it works
Stereotactic surgery works on the basis of three main components:
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A stereotactic planning system, including atlas, multimodality image matching tools, coordinates calculator, etc.
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A stereotactic device or apparatus
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A stereotactic localization and placement procedure
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Step 1 frame fixation on head under local anaesthesia
Step 2 CT scanning for localization of lesion and target coordinate calculation
Step3 coordinte fixation of final frame
Step 4 small needle hole on skull for introduction of bioplsy needle under local anaesthesia
Step 5 Biopsy taking by biopsy needle or stereotactic biopsy forceps
The stereotactic apparatus uses a set of three coordinates (x, y and z) in an orthogonal frame of reference (cartesian coordinates), or, alternatively, a polar coordinates system, also with three coordinates: angle, depth and antero-posterior location. The mechanical device has head-holding clamps and bars which puts the head in a fixed position in reference to the coordinate system (the so-called zero or origin). In small laboratory animals, these are usually bone landmarks which are known to bear a constant spatial relation to soft tissue. For example, brain atlases often use the external auditory meatus, the inferior orbital ridges, the median point of the maxilla between the incisive teeth. or the bregma (confluence of sutures of frontal and parietal bones), as such landmarks. In humans, the reference points, as described above, are intracerebral structures which are clearly discernible in a radiograph or tomogram.
Guide bars in the x, y and z directions (or alternatively, in the polar coordinate holder), fitted with high precision vernier scales allow the neurosurgeon to position the point of a probe (an electrode, a cannula, etc.) inside the brain, at the calculated coordinates for the desired structure, through a small trephined hole in the skull.
It is very important for the patient who is facing a stereotactic needle biopsy procedure to know that there is the possibility of needing a repeat biopsy procedure. A repeat biopsy is necessary if there is a discrepancy between the radiology reports and the pathologist's findings from laboratory analysis of the sample (concordance). As with any procedure, there is a slight risk of allergic reaction to anesthesia. To be well informed, patients should consult with their physician about the risks prior to undergoing SNB.
Results
Stereotactic needle biopsy is a diagnostic tool used to determine the presence of cancer cells. It is not a therapy used to obliterate an area of abnormal tissue. The results of the biopsy help the physician to determine the best medical or surgical options available to the patient. The biopsy results are reviewed by the physician performing the biopsy and by the pathologist who analizes the sample. Results are reviewed and discussed with the patient and options for further treatment or follow up are presented. The patient, with the guidance and expertise of the physician, selects a course of therapy.
Brain haemorrhage
Hypertension is considered to be the main cause of intracranial spontaneous bleeding. Most of the patients are having multiple problems. Besides hypertension they usually have diabetes and cardiac diseases. Brain haemorrhage in such patients poses significant life risk by pressure on the surrounding brain and by itself damaging the brain tissue. If indicated removal of the haematoma is important in saving patients life and improving the overall outcome of the disease. Now a days newer less invasive methods are being evolved to effectively remove the blood clot without significant surgical risks.
Stereotactic removal is a such new technique.
Advantages
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Procedure can be done without general anaesthesia and hence it can be done in persons with many medical diseases which contraindicate GA.
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This is a CT Scan assisted procedure and immediate post op scan can help in evaluating success of procedure. In residual cases procedure can be repeated without and further risk.
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minimally invasive surgery and requires only 5 mm hole to complete the procedure.
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this procedure can remove clots from the deepest parts of the brain where open surgery is likely to be very traumatizing
Step 1 frame fixation under local anaesthesia in ICU
Step 2 CT Scan with frame
Step 3 coordinate (x,y & z) calculation
Final step haematoma removal under local anaesthesia in OT
Quantitative measurement of removed haematoma is possible
Post operative CT Scan shows good evacuation of blood clot.
Functional Neurosurgery |
Parkinson disease is a brain disorder. It occurs when certain nerve cells (neurons) in a part of the brain called the substantia nigra die or become impaired. Normally, these cells produce a vital chemical known as dopamine. Dopamine allows smooth, coordinated function of the body's muscles and movement. When approximately 80% of the dopamine-producing cells are damaged, the symptoms of Parkinson disease appear.
Signs and symptoms of Parkinson disease
The loss of dopamine production in the brain causes the primary symptoms of Parkinson disease. The key signs of Parkinson disease are:
- Tremor (shaking)
- Slowness of movement
- Rigidity (stiffness)
- Difficulty with balance
Other signs of Parkinson disease may include:
- Small, cramped handwriting
- Stiff facial expression
- Shuffling walk
- Muffled speech
- Depression
Parkinson disease affects both men and women in almost equal numbers. It shows no social, ethnic, economic or geographic boundaries. In the United States, it is estimated that 60,000 new cases are diagnosed each year. While the condition usually develops after the age of 65, 15% of those diagnosed are under 50.
The process of making a Parkinson disease diagnosis can be difficult. There is no X-ray or blood test that can confirm Parkinson disease. A physician arrives at the diagnosis only after a thorough examination. Blood tests and brain scans known as magnetic resonance imaging (MRI) may be performed to rule out other conditions that have similar symptoms. People suspected of having Parkinson disease should consider seeking the care of a neurosurgeon /neurologist who specializes in Parkinson disease
Indications for treatment :
• Prevention of disease progression
• Symptomatic control of parkinsonism
• Prevention of motor complications
• Control of motor complications
• Control of non-motor complications
Type of intervention
Drug treatment
Levodopa ,Amantadine , Anticholinergics , MAO-B inhibitors , COMT inhibitors , DA agonists
Ergot compounds :Bromocriptine , Cabergoline , Lisuride ,Pergolide
Non-Ergot Compounds: Apomorphine , Piripedil , Pramipexole ,Ropinirole
Surgical treatment
• Deep brain surgery
• Neural transplantation
The purpose of drug therapy is to relieve symptoms and improve your quality of life . Drugs will not stop the progression of the disease . Drugs will help you function better but they are not perfect and may cause side effects . You may have to take your medication several times a day . these drugs work on the brain’s complex chemistry – use them only as prescribed and never alter dosages without first consulting your doctor .
After three to six years of drug treatment, many patients begin to lose sustained treatment
benefit. The result is increasing time spent "off," or without relief from symptoms. Increasing the amount of medication can usually minimize off time to acceptable levels for several years. After three to six years, patients often also develop uncontrolled movements called dyskinesias that occur when their drug treatment is working. For patients on levodopa, a COMT inhibitor may be added to help increase the effectiveness of levodopa. These include tolcapone and entacapone . A special combination pill contains levodopa and entacapone . In addition, a medication such as apomorphine injectable may then be used as a rescue therapy, with a rapid return to the on state.
Brain surgery is an option for advanced PD patients whose symptoms can no longer be adequately managed with medications. The best surgical candidate is someone who:
- Responds well to dopaminergic therapy
- Has motor complications (off periods and dyskinesias) that are limiting factors
- Is otherwise healthy and a good surgical risk
Advanced age is not necessarily a barrier to surgery, but impaired cognition, including forgetfulness, diminished decision-making ability, and language difficulties, along with gradual loss of brain matter (brain atrophy or shrinkage), make the surgery more risky and decreases the likelihood of an optimal outcome.
Depending on the patient, procedure, and skill of the operating team, cognition may be mildly impaired or largely unaffected by the surgery itself. The most commonly reported adverse cognitive effects are reduced decision-making abilities and language impairments.
It is impossible to predict the benefit any individual patient can expect from surgery. The general rule of thumb is that the maximum benefit is equal to the best response from a dose of levodopa (minus the effect on dyskinesias). Therefore, if a patient's symptoms are 50% better at the peak of a levodopa dose, the surgery is not likely to improve the patient's symptoms more than that amount. Importantly though, improvements from surgery are most dramatic during the times the patient is not experiencing the effects of medications ("off" time). Therefore, surgery may greatly improve the amount of the day during which symptoms are reduced.
Types of Surgery
There are two surgical procedures—lesioning and deep brain stimulation—and three target locations in PD surgery: thalamus, Globus pallidum internus (GPi), and subthalamic nucleus (STN). Other surgery-based procedures—cell transplants, gene therapy, and neurotrophic factor delivery—remain experimental procedures for the treatment of PD.
Lesion procedures (i.e., pallidotomy, thalamotomy) deliver radio-frequency energy to heat and ablate (destroy) a pea-sized region within the target, where there is abnormal activity related to the movement problems.
Deep brain stimulation (DBS) uses implanted electrodes to stimulate one or another of these same regions. The electrical stimulation interferes with the abnormal activity, creating the same effect as a lesion. The effect lasts as long as the stimulation continues, but ceases when it is shut off.
During needle-guided (stereotaxic) brain surgery, the patient remains awake. This is for two reasons. The first is that the brain itself has no pain sensors, and once the initial incision is made (using a local anesthetic like Novocain), there is no pain. The second is that patients must be able to respond to the surgical team's questions about what they are experiencing during the surgical procedure. The pathway to the target lies close to several other important structures in the brain that may be inadvertently stimulated during the procedure. This may cause unusual sensations such as flashing lights, tingling, or experience of emotions. Patients then report these sensations to the surgeon during the procedure. Avoiding these areas is crucial for successful surgery.
Because surgery requires very precise placement of surgical instruments, a three-dimensional frame is attached to the patient's head to guide the surgeon. The frame may be uncomfortable and local anesthetic is used to ease the discomfort. Before surgery, patients will also undergo several imaging procedures, in order to identify the target and other landmarks within the brain. Depending on the center, the procedures may include magnetic resonance imaging (MRI) scans, computerized tomography (CT), or ventriculography.
Neurostimulators:
A pacemaker-like device that contains a battery and microelectronic circuitry for controlled electrical pulse generation. The neurostimulator is implanted subcutaneously near the clavicle, and generates electrical signals that are delivered by the extension and lead(s) to the targeted structures deep within the brain.
Kinetra Dual channel Neurostimulator
The Kinetra® dual-channel neurostimulator accommodates two extensions/leads, and thus provides bilateral neurostimulation from a single neurostimulator. The Kinetra neurostimulator is 61 mm x 76 mm x 13 mm and weighs 83 grams.
DBS Lead: Four thin, insulated, coiled wires bundled within polyurethane insulation. Each wire ends in a 1.5 mm electrode, resulting in four electrodes at the tip of the lead. The DBS Lead delivers stimulation using either one electrode or a combination of electrodes.
Therapy Controllers:
A patient places the compact, handheld therapy controller over the neurostimulator and presses buttons to turn one or both of the neurostimulators ON and OFF, to view the system's ON/OFF status, and to check the system's battery status.
Patients with a Kinetra® neurostimulator may use the Access® Therapy Controller, which allows them limited control of stimulation parameters within a physician’s prescribed limits |
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