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Deep Brain Stimulation: A paradigm to Treat Parkinsons Disease

Deep Brain Stimulation surgery

What is Deep brain Stimulation Treatment ? 

Movement and behavioral disorders have been an enigma for the medical field as any type of treatment has not been able to completely cure the patient and most of the times they have to live with the symptoms for the rest of their lives. Deep brain stimulation (DBS) is arevolutionary and welcoming treatment protocol for patients suffering from Parkinson’s disease, Idiopathic dystonia, severe obsessive-compulsive disorder (OCD), multiple sclerosis andfor medically intractable essential tremor (ET). Itinvolves placement of a pacemaker-like device aimed at sending constant electrical stimulating signals to various regions in the brain. The US Food and Drug Administration (FDA) granted approval to DBS in 1997and since then it has successfully treated more than 40000 patients worldwide by 2012. It is based on the concept of neuroplasticity that incorporates chronic high frequency inductions to perform a number of functional changes ranging from slow metabolic to fast physiologic alterations and consequent structural re-organization of the brain.  

Types of Diseases treated by Deep brain stimulation (DBS):

The US Food and Drug Administration (FDA) approved Deep brain stimulation (DBS) treatment for: 

  • Essential tremor (ET) in 1997: ET is a movement disorder where opposing muscles undergo smooth contractions in an oscillating manner leading to an involuntary action tremor. The ventral intermediate nucleus of the thalamus is treated via thalamic DBS. It results in stable and sustained reduction in tremors that might persist for years. 
  • Parkinson’s disease (PD) in 2002: The pathophysiology is traced to the degeneration of neurons in the substantianigra in the mesencephalon or mid brain. Neuronal deterioration in the pars compacta of the midbrain results in decreased levels of dopamine in the various regions of the brain including the basal ganglia. Within standard levels and under normal physiologic conditions, dopamine is an excitatory neurotransmitter of the direct pathway and neuroinhibitor of the indirect pathway. Neuronal degeneration in the striatum results indopamine deficiency that leads to uncoordinated activity of the indirect pathway and consequentdecreased thalamic excitatory input to thecortex, which is responsible for the symptoms. Pharmacological therapy is the first line of management but it can be complicated by the end-dose dyskinesia induced by levodopa. Cases that have shown a good response to L-dopa preoperatively; are best suited for Deep brain stimulation therapy. 
  • Dystonia in 2003: Dystonia is a characterized as a heterogeneous group of disorders of unknown etiology, causing sustained or intermittent muscle contractionresulting in abnormal postures and/or repetitive movements. Primary treatment option includes anticholinergic drugs for the management of generalized dystonia and intramuscular botulinum neurotoxin (BoNT) for the treatment of focal dystonia.Deep brain stimulation is employed as a second line of treatment in patients with medically refractory dystonia wherein the debilitating symptoms lead to decreased quality of life. High frequency DBS is used to target the globuspallidusinterna bilaterally.
  • Severe obsessive-compulsive disorder (OCD) in 2009: Oral pharmacological therapy is the first line of treatment but the patients suffering from severe forms of obsessive-compulsive disorder become unresponsive to serotonin reuptake inhibitors and later on even to specialized cognitivebehavioral therapy. In these patients, DBS of the anterior limb of theinternal capsule is indicated that leads to significant improvement in OCD symptoms with limited adverse effects. 
  • Refractory epilepsy in 2010: DBS treatment for epilepsy involves the disruption or modulation of the classical memory circuit of Papez beginning from the hippocampus to the thalamus. A sustained increase in the expression of adenosine which is a neuromodulator in the hippocampus; is proposed to be responsible for the antiepileptic effect of DBS treatment. It is primarily beneficial in complex cases of partial epilepsy. 

DBS is being investigated for the treatment of:

  • Chronic pain: DBS treatment of the periventricular gray region and somatosensory area of the thalamus are targeted for treatingnociceptive pain and neuropathic pain respectively. It has been reported that DBS is effective in treating patients with chronic neuropathic paincaused due to amputation and stroke resulting in sustainable and stable results. 
  • Alzheimer’s disease: It has been recently reported through functional imaging that DBS can be utilized to modulate neuronal activity in memory circuits and alter pathological cortical physiology. This has opened new avenues for the treatment of dementia seen in patients suffering from Alzheimer’s disease. 
  • Psychiatric disorders, such as treatment-resistant depression: The beneficial results obtained in DBS clinical trials have prompted its use for the management of depression induced by a known psychiatric disease. 
  • Tourette syndrome: The success tales of DBStherapy for OCD patients has widened the horizonfor the management of other related psychiatric disorders suchas Tourette syndrome.

Signs & Symptoms of Movement and behavioral disorders:

  • Uncontrollable, involuntary and rhythmic shaking of extremities; especially the hands, and lasting for a brief period of time. In patients of essential tremors these occur as a solitary phenomenon while in patients of Parkinson’s disease and Alzheimer’s disease, associated neurological symptoms are also present. 
  • Tremors can exacerbateduring periods of stress either physical or emotional and might be relieved with rest.
  • Balance and movement problems leading to impaired postures and loss of autonomic functions. This interferes with the execution of the daily activities such as brushing, walking, applying makeup, etc.
  • A classical triad of tremor, rigidity, and bradykinesia is seen in Parkinson’s disease. Tremors may affect any of the limbs and subsequently the fingers and toes are also affected. Bradykinesia is the term given to the slow and sluggish movements demonstrated by these patients. 
  • Involuntary muscle contraction leads to cramps which range from mild to severe depending on the stage of dystonia. Repetitive slow muscle movements and abnormal posture leads to pain and exhaustion. 
  • Repetitive, unusual and involuntary movements are seen in epilepsy such as jackknife movements, grabbing movements, head nodding, etc. 

Diagnostic assessment prior to Deep brain stimulation (DBS)

  • Stimulus tool: For patients with Parkinson’s disease, cases that have shown a good response to L-dopa preoperatively; are best suited for Deep brain stimulation therapy. It is to predetermine whether the patient is positively responsive to levodopa and which symptoms are relieved with it. Thus the patient is evaluated before and after taking the drug and the responses are duly noted. 
  • Cognitive assessment: It is done to establish the patients’ suitability for the surgical procedure. It is performed as a neurostimulator evaluation to anticipate risks of cognitive problems that may present at the time of DBS treatment. 
  • Occupational therapy: Sometimes an evaluation of speech, language and swallowing pattern of the patient may be assessed to confirm if the patient can sustain DBS treatment. 
  • Magnetic resonance imaging (MRI): MRI is the best suited diagnostic tool for brain evaluation as it provides a clear, contrast and detailed image. When a deeper area of the brain has to be assessed then an MRI is preferred. It helps in guided through the exact areas in the brain where the electrodes are to be precisely placed. It is contraindicated in patients with pacemaker, and in these patients CT is advised.
  • Computed Tomography (CT): CT is advised for small and superficial brain lesions as CT images are not as clear as the MRI images. It can be used in cases of essential tremors which require ventralisintermedius (VIM) nucleus placement.

Components of Deep brain stimulation (DBS)

  • Lead: The lead or the electrode is a thin, insulated wire that is implanted into the target tissue in the brain. A small opening is made in the skull and the tip of the electrode is placed carefully within the targeted brain region.
  • Extension: The lead extensor is an insulated wire that connects each lead to the neurostimulator. It is passed under the skin of the head, neck, and shoulder to reach the Implantable pulse generator. 
  • Implantable Pulse Generator (IPG) or Neurostimulator: It is the pacemaker device andalso termed as the ‘battery pack.’It is implanted under the skin near the collarbone or in some cases it can be implanted in the chest or under the abdominal skin.Its function is to constantly deliver fast frequency stimulus to the tip of the electrode that is implanted in the brain. Under diseased conditions the brain undergoes uncoordinated and overactive firing of neurons, which is interrupted by the stimulus generated by the IPG consequently causing resolution of the symptoms. 

Treatment Procedure

  • Administration of anesthesia: First a stereotactic head frame is fixed on the patients’ head which holds the head in a fixed and suitable position.  Following administration of local anesthesia a minor opening is made in the skull. The procedure is performed under local anesthesia so that the patient is numb in the operative region yet awake which allows the surgical team to evaluate his or her brain functions for the optimal placement of electrodes. 
  • Placement of the lead or electrode: Images are obtained via computerized brain-mapping techniques which guide in identifying the precise location in the brain responsible for altering the nerve signals consequently leading to the development of the signs and symptoms. These highly sophisticated imaging and recording equipment are effective in evaluation of the physical structure of the brain and also provide additional information regarding the functional changes in the brain. 
  • Placement of the internal pulse generator (IPG) or Neurostimulator: This surgery is commonly done a day after the primary surgery. Following the administration of general anesthesia, a small opening is created through which the IPG is implanted in the chest wall.A magnet is used along with the IPG which helps to adjust the stimulation parameters so as to reach the appropriate level of stimulation at the electrode tip.
  • Placement of the extensors: After administration of local anesthesia, a small incision is made behind the ear. The extension wire is passed under the skin and connects the electrodes to the IPG in the chest wall.  

Complications/Risk factors associated with Deep brain stimulation (DBS) treatment 

  • Hardware infection: It is one of the most commonly reported complications of DBS despite standard administration of perioperative antibiotics. There is 15% percent risk of developing minor infections or a temporary implantation problem. Hardware infection can be manifested as migration, lead fractures, and local infection, a 2-3% risk of brain hemorrhage that might predispose to stroke, paralysis or cognitive impairment. 
  • Neural tissue damage: As DBS is an interventional surgical procedure it has an attributable risk of tissue damage. Neuronal degeneration can induce an inflammatory and astrocytic response which causes a glial scar that tends to increase the electrode impedance. It can adversely affect the cognitive abilities leading to a declinein verbal fluency. However there has been a decline in such reports over the years. 

Am I a Good Candidate for treatment/surgery? 

Patients suffering from Parkinson’s disease in whom the tremors and motor fluctuations are not relieved by medications or on changing the type of drug and increase in drug dosage predispose to an increased risk of complications; can benefit from DBS treatment. Similarly in patients with essential tremors if the cognitive decline interferes with the quality of life and pharmacological therapy is ineffective then DBS can be considered as a treatment option. Other essential factors to be considered to be eligible for DBS treatment are: age in combination with general health as risk of surgical complication increase with 70 or more years of age, having a solid support system of family and friends, absence of concurrent neurological symptoms such as dementia or health conditions such as high blood pressure and a cardiovascular disease, absence of an active psychiatric illness such as severe depression, and have realistic expectations from the treatment procedure.

Recovery time

Deep brain stimulation (DBS) treatment may require a day or two of hospitalization. It may take a few months to a year for the doctors to adjust the device settings to be customized according to the patient’s requirement. Four to six weeks post-surgery the patient should visit the doctor to program the deep brain stimulation device. The device is tuned to match with the amount of stimulation needed concurrent with minimizing the symptoms. Typically, patients will establish their optimal stimulation settings in two to three months following surgery but it may vary from patient to patient.The patient can resume their routine life activities within a few days.

Aftercare:

The neurostimulator is controlled by a magnet and the patient is provided with an access control device or handheld magnet which controls the switching on and off of the IPG. Variably depending on the application, the battery has shelf-life of three to five years. When the battery needs to be replaced, it is managed along with the replacement of the IPG, and is usually performed as an outpatient procedure. In most of the patients the stimulator needs to be kept on unless undergoing a medical procedure. Many people turn the stimulator on in the morning upon waking and off at bedtime or accordingly as and when needed to control the tremor.

Success Rate of Deep brain stimulation (DBS) treatment:

It has been estimated that approximately 60% of Obsessive-compulsive disorder (OCD) patients undergoing Deep brain stimulation (DBS) therapy have responded with significant, sustained reductions in both obsessions and compulsive behavior. In complex epileptic patients DBS has shown promising results with a 50% reduction of interictal spikes. A long term reduction in seizure frequency was observed when DBS was used to manage the medial temporal lobe. Treatment of the anterior thalamic nucleus has also shown statistically significant response such as a 40% decrease in seizure activity at 1-2 years following DBS implantation.It has been reported to provide consistent clinical benefits and reduction in dopamine replacement therapy by 50 to 70 percent.

Benefits of DBS Treatment:

  • Deep brain stimulation is acclaimed as a new life for thepatients suffering from neurological and psychological disorders.  
  • DBS does not damage healthy brain tissues. 
  • It can be successfully used in patients with bilaterally advanced lesions.
  • Safe and well-tolerated in psychiatric patients such as those suffering from Alzheimer’s disease.
  • DBS produces reversible changes in the brain which can be tailor made according to the patients’ need.  
  • There have been reported cases of patients who had to be housebound due the debilitating effects of Parkinson’s disease and other related disorders. Deep brain stimulation helps these patients regain independence and confidence. 
  • DBS is superior to classic radiofrequencythalamotomy as it causes less complications and better tumor control. 
  • It provides relief from symptoms round the clock hence its hassle-free. 
  • DBS is viewed as a safe substitute forpallidotomyowing to its reversible nature, lower predisposition for complicationswhen used for bilateral procedures and adjustment possibilities.
  • Patients who have undergone DBS can still opt for other treatment options like stem cell or gene therapy as and when required. DBS stimulation can be switched off and the device can be removed.

Cost :

The cost of deep brain stimulation depends on the medical condition of the patient, experience of the surgeon, days of hospital admission, small or big city and the facility where the patient chooses to get the surgery done. The average cost might range approximately around$20,000. Additional charges may incur based on additional tests required and variable recovery of the patient. 

Why Choose MedcureIndia? 

Movement disorders have the tendency to variably deteriorate the patients’ quality of life. MedcureIndia aims to ameliorate the patients’ functional life by a standard deep brain stimulation therapy. A custom made treatment plan is prepared for each patient and they are individually taken care of. We provide the patient with authentic information regarding the treatment procedure and assist to make an informed consent. With our team of elite neurosurgeons, we assure you a state of art treatment, prompt recovery and a hassle-free stay.  

 

FAQ

• What is the limitation of DBS?

The primary limitation DBS is the need to replace the batteries. The neurostimulator or IPG is battery operated and is expected to function for 3-5 years depending on the application. Over the course of a battery’s lifespan, the output voltage can decrease significantly which warrants an eventual need for surgical exchange of the depleted IPG during clinical visits.

• How does it feel when DBS is switched on?

During the initial stages, as the level adjustments are made, the patient might experience a minor temporary shock felt like a tingling sensation. As the best location and tuning is obtained the sensation subsides gradually. Following final adjustments the patient can carry on with their functional life without any sensation but a few might experience a slight tingling in the arm or leg especially when the device is switched off at bedtimes. 

What if the battery of the neurostimulator runs out suddenly?

The patient is advised to undergo periodic evaluation of the device in order to prevent the development of such mishaps. When the battery dies off the patient might resume the tremors and other symptoms associated with their condition which may vary from few days to weeks depending on the neurologic disease. They need to contact their medical service provider as soon as possible. 

Will the device be visible over my body? 

DBS treatment is performed as minimally invasive as possible. In the head where the incision was placed, hair is shaved off from that region which can be easily managed by a suitable hairstyle. As the healing occurs in the sutural site hair grows back filling up the space. In the region where holes were drilled in the scalp minute elevations might be present but they are hardly noticeable. The extension wires are tunneled in the adipose tissue beneath the skin and are hardly visible in most of the patients while in skinny patients it might appear as a large vein. The stimulator placed beneath the collar bone might leave a minor scar in the region noticeable if the patient is wearing a deep cut dress. 

• I have a cardiac pacemaker; can I still opt for DBS treatment?

Cardiac Pacemakers and DBS stimulators are typically placed in the same chest region. As the cardiac pacemakeris placed on the left side of the chest, the DBS stimulator can be placed on the right side of the chest. Another alternative option is to place the DBS stimulator just under the abdominal skin. This result in longer extension wires to be placed that might increase the risk for lead fracture, nevertheless there is generally more fat tissue in the abdomen, so the neurostimulator does not protrude much.

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