What is Parkinson’s disease?

Idiopathic Parkinson's Disease (PD) is a complex disease of the nervous system, that is degenerative and progressive in nature. It is characterized by the loss of dopaminergic nerve cells of the substancia nigra (SNc) of the midbrain, which are the main producers of a chemical compound called dopamine in the brain. The baseline clinical signs of the disease are: resting tremor, rigidity, bradykinesia, and postural instability.

It is the second most frequently diagnosed neurodegenerative disease after Alzheimer's dementia, and it generally begins in mid to late stages of life, so age is the main risk factor.

Causes of Parkinson’s disease

As of today, the ultimate cause of Parkinson's disease is not known. However, it is thought to be due to a combination of environmental and genetic factors and factors related to the body's own aging.

There are three factors involved in the risk of developing the disease:


Age has shown itself to be a clear risk factor, with the median age of diagnosis being between 55-60 years. The prevalence increases exponentially from the sixth decade of life onwards. When Parkinson's disease appears before age 50, it is called early-onset Parkinson's.

Genetic predisposition

90% of Parkinson's cases are sporadic forms, that is, they are not due to a specific genetic alteration. However, it does run in families and it is estimated that between 15% and 25% of people who develop Parkinsons have a relative who also has it.

Environmental factors

Some studies cite the continued consumption of well water over the years, or having been exposed to pesticides and herbicides as risk factors.


The clinical expression of the disease is noted in the gradual development of the following symptoms: 

  • Bradykinesia (slowed movement): defined as a loss of speed, slowness in the ability to begin and execute movements, and a gradual reduction of the range of movement.
  • Stiffness: muscles become stiffer and do not stretch or relax as they should
  • Tremor: Parkinsonian tremor is distinguished by an activity at rest in the frequency of 3-5 Hz, with distal predominance and which is usually asymmetric. 
  • Postural instability and gait disorder: difficulty walking, especially at the beginning or making turns, and a tendency to lean unnaturally forwards when walking.
  • Other clinical indications of the disease: symptoms include scarcity of automatic movements such as blinking or swinging arms when walking, lack of facial expressivity, speech disorders, depression or apathy, urgent urination and incontinence, constipation, dizziness when getting out of bed, sleep problems such as insomnia and nightmares, anosmia (loss of smell), alteration of the reflexes with frequent falls and others.


To diagnose Parkinson's, the neurologist gathers a detailed medical history of the patient with data provided by the patient and the patient’s family, and performs a physical examination. 

When necessary, this information will be complemented with laboratory tests. A blood test, and an MRI of the brain or a PET with F-dopa, which can help increase diagnostic certainty by differentiating it from other processes that share clinical characteristics (atypical and secondary parkinsonisms, etc.).

The criteria for the diagnosis of idiopathic PD are based on the presence of at least two of the four symptoms or signs mentioned in the previous section, in addition to proof of a good response to L-Dopa.

Treatment of Parkinson’s disease

Conventional Parkinson's treatment is based on the use of drugs that try to compensate for the deficiency of nigrostriatal dopamine. However, nowadays we know that pharmacological treatment does not control the clinical manifestations of the disease indefinitely. In fact, at least 50% of conventionally treated patients experience major complications, such as fluctuations in mobility, dyskinesias, psychic disturbances, and autonomic control, which seriously disrupt therapeutic control and lead to functional disability. The clinical picture is aggravated by the deterioration in the pharmacological response: posture, language changes, impeded gait, freezing and falls.


Because of the limited pharmacological perspectives for successful treatment or prevention of these complications in the mid-term, and thanks to advances such as better pathophysiological knowledge of the structures involved in the origin of Parkinsonian syndrome, the notable technological advances in neuroimaging techniques, the development of new surgical software, the possibility of intraoperative monitoring and the improvement in some surgical techniques, interest has been maintained in surgical treatment options for Parkinson's disease.


Surgery would be indicated when pharmacological treatment fails to control the patient's symptoms throughout the day, significantly reducing their quality of life. As Parkinson's disease currently has no cure, the benefits of surgery are truly important. Very significant improvements in movement can be achieved, as well as a decrease in rigidity and tremors. In addition, it makes it possible to reduce the medication, which is beneficial for reducing the side-effects associated with their long-term use.

There are different types of surgical treatment. Here we will describe the techniques that are currently most frequently used. 

Surgical ablation

This type of surgery consists of producing an ablation or controlled injury in a selected small part of the brain. This treatment modality can be carried out interchangeably by three different methods and each of them constitutes a treatment technique in itself: radiofrequency thermal ablation, ionizing radiation injury (radiosurgery), and thermal ablation when administering a high dose of Ultrasonic energy using magnetic resonance-guided focal ultrasound.  

Deep brain stimulation (DBS)

This is the most widely used treatment modality worldwide today. It consists of high frequency stimulation in a small part of the brain. Through electrical impulses, the part of the brain that is abnormally overactive is inhibited or modulated – the part responsible for the symptoms of the disease. To do this requires implanting brain electrodes and a small neurostimulator similar to a cardiac pacemaker in the body. Once implanted, your doctor can adjust device settings and stimulation levels using an external programming device.

Three nuclear structures have been defined as surgical targets of choice for these modalities: 

  • The motor thalamus, at the level of the nucleus ventralis intemedialis (Vim)
  • The posteroventral region of the internal globus pallidus (GPi)
  • The sensory motor region of the subthalamic nucleus (STN)

In recent years, the continuously growing knowledge about the function of the basal ganglia and the pathophysiology of the motor disorders of Parkinson's disease have led physicians to focus on the subthalamic nucleus, considering its role as a nodal modulating structure of efferent nerve activity, the motor of the basal ganglia. It has been widely used since its introduction, and is considered the preferred target in the treatment of the motor signs of this disease.

This surgery is carried out following the methodology that we describe here. A stereotactic guide or crown is first placed on the patient's head. The radiological location of the surgical target is determined with neuroimaging fusion (CT/MRI), combining anatomical images and diffusion tensors (DTI tractography). Once this is done, the intracerebral trajectories are simulated by the computer with the support of very powerful surgical programs or software. 

The patient receives local anesthesia/sedation, and the highly accurate image-guided surgical technique is performed using the help of various neural electrical records and micro-stimulation to identify the electrophysiological location of the surgical target. The electrodes are immediately implanted in the selected structure. A small, rechargeable neurostimulator is also implanted in another part of the body (infraclavicular region or abdomen), which is connected to the electrodes to stimulate these brain structures. This system implanted in the patient is controlled by the doctor in each hospital visit in a non-invasive way, through a programming device that uses 3D graphics to allow the stimulation parameters to be easily adjusted, including the directional stimulation that helps increase the efficiency and safety.

Who are the doctors who treat idiopathtic Parkinson’s disease at Instituto Clavel?


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