We often associate the passing of life with the onset of numerous pathologies.
Although getting older increases the risk, it does not necessarily imply suffering from a disease such as essential tremor. In other words, a person ends up suffering from a tremor because he or she develops this problem, not because he or she is older.
Essential tremor, the most frequent ailment in movement disorders, affects 6% of people over 60 years of age, although it can occur, as we have said, from an early age.
In fact, it is common for patients to state that they have been living with it for many years and that it has increased with age, affecting their daily activities.
It is not a neurodegenerative disease, but is caused by a dysfunction of neuronal circuits involved in movement.
It frequently occurs in several family members, so there is a hereditary factor, but specific genes have not yet been detected in most cases.
It manifests in both hands when performing an action, although it may be more severe in one hand.
If the tremor is sufficiently intense, the patient may have difficulty performing everyday tasks such as writing, holding a glass of water without spilling it, using cutlery when eating, brushing teeth, applying makeup, shaving, tying buttons or zippers, putting on earrings, etc. Some people may also experience tremor in the voice or head.
It is, therefore, a pathology that can greatly impact the quality of life if it reaches a considerable intensity. It is therefore important to seek a personalized solution to this problem.
Trigger unknown
Tremor is caused by the malfunction of neurons in a brain nucleus (the ventral intermediate nucleus of the thalamus) involved in movement.
In these neurons, the discharge pattern necessary for correct movement is replaced by an oscillatory activity that is imposed on the entire motor circuit. This causes the hands to shake at the same frequency as the oscillatory activity of these neurons when going to perform an action.
Although it is not known for certain what triggers it, the available data indicate that there is a dysfunction of the cerebellum with regard to the neuronal activity of the ventral intermediate nucleus of the thalamus.
It is a situation, therefore, different from that of other pathologies that produce tremors, such as degenerative diseases like Parkinson’s disease. In this disease, the tremor -which usually occurs at rest- arises from the progressive death of neurons that produce dopamine, a neurotransmitter responsible for modulating the motor circuitry and normal movement.
In addition to tremor, Parkinson’s patients suffer from other disorders such as clumsiness, rigidity, etc.
HIFU, a treatment that helps to control tremor
When a patient has essential tremor, the goal is to get his or her motor circuitry back to function normally. Consequently, treatments are aimed at restoring the pattern of activity of the neurons so that the execution of the movement is correct.
The main therapies that have been used for this pathology are beta-blockers and antiepileptic drugs.
However, their use is generally not sufficient to improve the patient’s quality of life.
Fortunately, we can now resort to the HIFU system, a high-intensity focused ultrasound equipment that makes it possible to lesion the affected neurons in the ventral intermediate nucleus of the thalamus, which is a deep structure of the brain, without open cranial surgery and in a controlled manner.
This method allows access to many patients, as it is minimally invasive.
To carry out the process, the first step is to shave the patient’s hair and attach a frame to his head that will anchor him to the MRI where the treatment is performed. Once the patient is lying on the MRI table, a membrane through which very cold water circulates is also placed on the head to cool the scalp and prevent the ultrasound from heating the skin too much.
The patient is awake at all times, collaborating with the professionals during the procedure.
The ultrasounds are focused on the point of the brain where the neurons we want to eliminate are located. By emitting an increasing amount of energy, this is transformed into heat to warm the tissue in the selected area and perform the lesion. As the temperature increases, the tremor progressively disappears, confirming that we are targeting the correct site.
Once this result is obtained, the power of the energy is increased to achieve a temperature that causes the irreversible lesion in the neurons and the definitive improvement of the tremor.
Immediate benefit
One of the major advantages of this procedure is that the improvement of the tremor usually occurs immediately.
Since the patient does not require prior hospitalization, he or she can be discharged within 24 hours of undergoing HIFU.
It is true that, as with any treatment, some side effects may occur. But they are generally related to the appearance of edema around the injured area, which resolves itself after a short time.
For this reason, the patient usually shows a high degree of satisfaction after the intervention. It is not necessary to resign oneself to living with essential tremor.
*María Cruz Rodríguez Oroz is Director of the Department of Neurology, University of Navarra, Spain.
*This article was published in The Conversation and reproduced here under Creative Commons license. Click here to read the original version.