What it Parkinson's Disease?
Parkinson's disease, which results from the death of nerve cells in the brain, is a chronic, degenerative neurological disorder that affects at least one million people in the United States and more than five million worldwide. It affects adults of all races, and the risk of developing the disease increases with age. Recent research indicates that one in 100 people over the age of 60suffer from this debilitating and progressive disease (symptoms continue to worsen over time).
Motor impairments (also called cardinal symptoms because they are the hallmark of the disease) include resting tremor, slowness of movement (bradykinesia), rigidity, and postural instability. Non-motor symptoms include sleep difficulties, loss of sense of smell, constipation, speech and swallowing problems, and low blood pressure when standing. There could be also mood disorders and cognitive impairment ranging from mild memory difficulties to dementia.
The area of the brain that is most affected by Parkinson’s disease is the substantia nigra in the brainstem. Nerve cells lost there are the ones that produce dopamine, a chemical involved in communication to the part of the brain that controls movement and coordination. As the disease progresses, the amount of dopamine produced in the brain decreases, leaving the patient unable to control movement normally.
Current Treatments for Parkinson's Disease
Currently there is no cure for Parkinson’s disease. The therapies listed here (drugs or surgery) provide only symptomatic improvement. Please see belowhere to the left, a lecture given on the 9th Jan, 2013 at the NIH National Institute of Health in the USA, about the different current treatments.
ExAblate Neuro MR guided Focused Ultrasound (MRgFUS) Treatment for Parkinsons’s Disease
Focused ultrasound is a completely noninvasive way to perform the lesioning procedure described above. Using this treatment modality in conjunction with image guidance, the physician directs a focused beam of acoustic energy through the patient’s scalp, skull, and brain to thermally coagulate of small area of the brain, thereby destroying targeted tissue without damaging nearby tissue or the tissues through which the beam passes on its way to the target.
Using magnetic resonance imaging (MRI) thermometry to monitor and control the focused ultrasound energy delivery, the treating physician is able to identify the region of energy deposition at the ultrasound focus point before generating ablative temperatures. This use of thermometry allows closed loop control on the location and extent of the thermal tissue necrosis.
Benefits of ExAblate Treatment for Parkinson's Disease
- Focused Ultrasound treatment is non-invasive just like radio-surgery, however it therapeutic effects are immediate and it does not use ionizing radiation and thereby does not have the adverse effect and limitation associated with it.
- Compared to radio-frequency ablation, focused ultrasound is non-invasive and therefore has significant reduced risk for infection. Also as focused ultrasound is done under closed loop thermal feedback, it is more likely to damage only targeted tissue and spare non-targeted healthy brain.
- Compared to implantation of deep brain stimulation device, focused ultrasound is a onetime procedure, and does not require subsequent procedure to replace batteries. Focused Ultrasound also does not involve implantation of a foreign body, and thereby carries a reduced risk of blood clots creation.
- Since there is no need to insert electrodes or needles the collateral damage to the brain is reduced
Drug Therapy for Parkinson’s
Drug therapy involves stimulating communication to the motor part of the brain. Different classes of drugs can provide more dopamine to the brain (levodopa therapy), reduce dopamine breakdown (MAO-inhibitors or COMT-inhibitors), or mimic the effects of dopamine (dopamine agonists). In the course of the disease, as it progresses, there is a need to move to a more potent class of medication like levodopa therapy. However, within a few years of initiating levodopa therapy, patients develop refractory Parkinson's disease symptoms, motor fluctuations (on off periods), and dyskinesia. Even with optimal intervals and dosages of medication, the amount of time spent with good motor control declines in late-stage Parkinson's disease, and it is at this point that patients consider surgical options to improve their quality of life.
Surgery for Parkinson’s Disease
Surgical options to improve motor symptoms include implantation of deep brain stimulation (DBS) device or surgical lesioning of a specific area in the brain.
Deep Brain Stimulation Device
Implantation of a DBS device or “Pacemaker” takes two steps. First, the surgeon creates an opening in the patient’s skull and implants electrodes into a specific area in the brain (the globus pallidus or subthalamic nucleus). Then the surgeon implants the stimulator under the skin of the patient’s collar bone and tunnels the electrodes under the skin of the neck to connect them to those implanted in the brain. Small electrical pulses emitted from the DBS device block some of the Parkinson's symptoms and reduce the adverse effects associated with prolonged use of drugs. DBS is the most common surgical intervention used to treat Parkinson’s disease.
Lesioning is a procedure whereby a small volume of tissue is being destroyed. In a lesioning procedure done for treatment of Parkinson’s disease the targeted volume cells inhibit motor function, and destroying these cells can improves the patient’s residual motor capacity, (pallidotomy or thalatomy). This procedure can be done by radiosurgery or Radiofrequency ablation.
Using stereotactic radio surgery the radiation oncologist deliver a very high dose of ionizing radiation to a predefined small volume in the brain thereby destroying all living cells in this volume.
In a radiofrequency ablation procedure the surgeon heats a small volume in the brain via a needle inserted into it through a small opening (bore hole) in the skull. This temperature rise cooks and kills the living cells by heat denaturation of the cell proteins, just like cooking an egg.
Patient Advocacy and Online Resources
The Michael J. Fox Foundation is dedicated to finding a cure for Parkinson’s disease through an aggressively funded research agenda and to ensuring the development of improved therapies for those living with Parkinson’s today. http://www.michaeljfox.org
The Parkinson’s Disease Foundation (PDF) is a leading national presence in Parkinson’s disease research, education, and public advocacy. They also have a national help line and answer questions via email. http://www.pdf.org
The Wikipedia entry on Parkinson’s disease is extensive and covers everything from symptoms and pathology to treatment options, research ideas, and notable cases. http://en.wikipedia.org/wiki/Parkinson's_disease