Nursing Management of the Patient Undergoing Focused Ultrasound: A New Treatment Option for Essential Tremor.
One patient treated at our institution was a young gentleman who had experienced essential tremor (ET) for 9 years before he was treated with focused ultrasound (FUS). His story began as a young teenager while he was waiting tables at a restaurant; he started to pour coffee for a man who had Parkinson disease (PD) and his wife. The wife noticed the teenager's hand tremor and asked him whether he was okay. He initially told her he was fine but tired. However, he knew at that point that something was not right. His mother told him later at home to "just stop it," which of course he was unable to do.
This young man grew up very active, playing basketball and football and involved in rodeo. He also loved to draw. He relayed how difficult his life was because "most people do not realize the simple things that people take for granted," such as going out to eat at a restaurant. He never ordered steak because someone else would have to cut it for him. He loved fajitas but was unable to "put them together" to eat. He had difficulty when he went for job interviews because he constantly worried about reaching out to shake hands with a new employer and "missing their hand." After failed treatment with first-line medications, propranolol and primidone, his grandfather was determined to help him and began researching online, where he discovered information about FUS.
After clinical evaluation, this gentleman was deemed to be a good candidate for transcranial FUS thalamotomy and was enrolled as the final patient in the clinical trial at our institution. Posttreatment, the tremor in his treated hand was completely obliterated. The first night in the hospital after his FUS treatment, this young man stayed up all night long drawing because he "was afraid that if I went to sleep I might wake up and it would all have been a dream."
Tremor is a common disorder seen across healthcare settings. It can be both physically and psychologically disabling for individuals. Determining the pathology of tremor is crucial when considering treatment strategies. The clinical diagnosis of tremor is based on presenting symptoms, careful history, and neurological examination.
Essential tremor is the most common tremor disorder (1) and second most common movement disorder impacting approximately 7 million individuals in the United States. (1) Precise estimates are difficult to determine because individuals who seek medical attention represent a disproportionate number of individuals with ET. (1) Age of onset of ET is described as bimodal and commonly begins in adolescence and early adulthood and after the age of 60 years.
Parkinson disease, another common movement disorder, impacts more than 1 million individuals in the United States. (3) This disease affects all races but tends to occur in men older than 60 years and nonsmokers. (3) Parkinson disease is progressive and has rare familial tendencies. The classic PD features are resting tremor with frequency measurements ranging from 4 to 7 Hz, bradykinesia, and rigidity. Resting tremor is worse than tremor with movement in PD.
The usual presenting symptom of ET is bilateral postural or kinetic tremor in the hands. (3,4) Tremor can initially occur in the head or voice and less commonly in the legs, trunk, or face. (3,5) Tremor frequency measurements range from 7 to 12 Hz. (3) Essential tremor intensifies with movement such as writing or drinking from a glass and is usually absent at rest. (3) Large, sloppy handwriting is typically seen. (3) General practitioners and neurologists often diagnose ET when all other causes of tremor have been ruled out. (3,5)
The exact cause of ET is unknown. A familial tendency is seen with more than 50% of individuals with ET having affected family members. There are higher rates seen in monozygotic twins than dizygotic twins. (3) Earlier age of onset is typically seen in familial ET as opposed to sporadic ET. (6) Symptom improvement with ethanol and primidone may suggest a possible role of GABAergic transmission, although other GABAergic compounds such as benzodiazepines and phenobarbital are not effective treatment agents. (3) In addition, other non-GABAergic compounds have been effective for treatment of ET, such as [beta]-blockers and anticonvulsants. (3) Various functional imaging studies on cerebral blood flow and metabolism have been conducted to implicate cerebellar involvement. (7)
Treatment of ET Medication Management
Propranolol and primidone are most often used to treat ET. In studies, these drugs have shown a 60% reduction in tremor in 50% of patients. (3,8-10) The recommendation for the use of propranolol and primidone is class I evidence and is a level A recommendation from the American Academy of Neurology Practice Guideline for Treatment of ET. (10) Propranolol is the only drug approved by the Food and Drug Administration (FDA) for the treatment of ET. Unfortunately, 30% of patients do not respond to first-line therapy, and many patients discontinue these medications because of adverse effects. (3)
Other medications used to relieve symptoms of ET include topiramate, atenolol, gabapentin, sotalol, and alprazolam. (9) These medications showed less efficacy and are considered second-line agents. (10) Adverse effects and drug interactions often limit their use. Other medications that are possibly effective and considered level C evidence include nadolol, clonazepam, and nimodipine. (10) Interestingly, in studies on the treatment of ET, levetiracetam and pregabalin were found to have no effect.
As previously stated, some patients with ET have found temporary relief after consuming small amounts of alcohol. Onset is quick, and effect usually lasts 3 to 4 hours. (8) Patients may experience a rebound tremor after temporary relief. There is no evidence that use of alcohol in patients with ET leads to alcoholism. (8)
Surgical Management of ET
Resistance to pharmacological agents can develop, and intolerant adverse effects can lead to discontinuation of medication treatments, resulting in patients seeking neurosurgical intervention. Deep brain stimulation (DBS) was approved for the treatment of ET by the FDA in 1997. Deep brain stimulation uses high-frequency stimulation from an implanted depth electrode usually in the ventrointermedius of the thalamus. The electrode is connected to a pulse generator implanted in the chest wall. Deep brain stimulation allows for stimulation parameters, such as voltage, pulse width, and frequency, to be adjusted to optimize control of the tremor in the opposite side of the body. It can be used to treat bilateral tremors. Studies have shown a 60% to 90% mean improvement in tremor, resulting in the discontinuation of medications. (3,10) Deep brain stimulation is a level C recommendation from the American Academy of Neurology because of the lack of double-blinded trials. Adverse effects include infection, paresthesia, imbalance, dystonia, and weakness. There is also risk of equipment malfunction, such as fractured leads or misplacement of the electrode.
Thalamotomy is another surgical option for patients with ET. This stereotactic surgical procedure creates a lesion in the ventrointermedius of the thalamus. The lesion is permanent. Studies have shown approximately 75% reduction in tremor symptoms. (10) Thalamotomy can be associated with enduring adverse effects such as dysarthria, confusion, weakness, and paralysis. Bilateral thalamotomy has fallen out of favor because of the potential for unfavorable adverse effects. Unilateral thalamotomy remains a viable option.
Focused ultrasound is a less invasive technique of thalamotomy. A good candidate for FUS is diagnosed by a movement disorder neurologist and has moderate to severe postural or intention tremor of their dominant hand ([greater than or equal to] 2 on the Clinical Rating Scale for Tremor [CRST]). Candidates must be medically resistant to at least 2 medications, including primidone or propranolol. The tremor must be severe enough to impair the ability to perform activities of daily living.
In FUS, an ultrasound transducer creates beams of acoustic energy that can be transmitted through the skull and focused to target cells in the thalamus. (11) It combines 2 technologies, FUS to provide the energy and magnetic resonance imagining (MRI) to provide accurate location. (11) The patient's head is fixed in the FUS brain transducer so that movement is minimal. After the transducer is in place, the patient is put into the MRI scanner. The transducer transmits more than 1000 different individual beams of ultrasonic energy through the scalp and the skull. (12) There is no damage to the intervening tissues. In the control room, the neurosurgeon is able to use MRI to focus these sound waves inside the brain to create heat in the thalamus. The heat interrupts the circuits of the brain that are responsible for the tremor. The ultrasound beams receive exponential frictional energy and heat to cause tissue ablation; the average size of the ablation is between 3 and 5 mm. (12)
Nursing Management Preprocedure Nursing Care
Before the initial clinic evaluation, nurses are essential in prescreening patients for inclusion and exclusion criteria for FUS. Prescreening includes a thorough review of medical history, medications, previous surgeries, presence of a pacemaker or internal cardiac defibrillator, ability to tolerate lying on one's back for up to 3 hours, history of claustrophobia, and functional abilities related to the tremor. Patients who are pregnant or have a pacemaker/internal cardiac defibrillator are not candidates for FUS. (13) At the initial visit, patients are evaluated by a neurologist, neurosurgeon, and physical therapist. The nurse completes part C of the CRST to assess baseline functional disability and tremor severity in the following categories: speaking, eating, drinking (liquid to mouth), dressing, hygiene, working (including domestic task), and social activities. (14) The higher the score, the greater the disability. During this visit, the procedure is explained to the patient and family.
Periprocedural Nursing Care
On the day of treatment, compression stockings are applied, and an intravenous catheter is placed. The nurse assists with shaving of the head and placement of the frame and assists the patient to the restroom before the start of the procedure. Once the rubber membrane is placed to promote skin cooling, the nurse positions the patient, promotes comfort, and performs safety checks.
During the procedure, the patient's heart rate and oxygen saturation are monitored continuously, and blood pressure measurements are obtained every 15 minutes. Medications may be administered as needed for comfort and to maintain blood pressures within ordered parameters (Supplemental Digital Content 1, available at http://links.lww.com/JNN/A93). At several intervals during the procedure, the physician performs motor testing on the patient while they are in the MRI scanner (Supplemental Digital Contents 2 [http://links. lww.com/JNN/A94] and 3 [http://links.lww.com/JNN/ A95]). During those intervals, the nurse evaluates for discomfort and may provide range of motion to relieve pressure on the back. When the procedure is complete, the nurse removes all monitoring equipment and assists the patient back to the prep room where the frame is removed and pin sites were dressed. After the procedure, patients are admitted overnight to an acute care neurosurgical unit for observation.
Postprocedure Nursing Care
Patients are allowed to eat and drink immediately. Pain is most often experienced at frame placement sites of the anterior and posterior skull and is usually well controlled with acetaminophen. For patients with lower pain tolerance, oxycodone or hydrocodone can be used in the immediate postprocedure period for pin site pain or headache. A thorough neurological assessment postprocedure is important to evaluate for change in neurological status or adverse effects from the procedure such as gait disturbances, weakness, paresthesias, or numbness. Focused ultrasound thalamotomy is an incisionless procedure requiring only minor pin site care to frame placement sites at the anterior and posterior skull. Pin sites are usually dressed with standard Band-Aids and are removed the morning of discharge, unless oozing from pin sites continues. Patients are encouraged to ambulate often to decrease the risk of deep vein thrombosis, and sequential compression devices are used as an additional measure to reduce risk of deep vein thrombosis while in bed. A postprocedure MRI to assess for perilesional edema is obtained the next morning before discharge.
There are few reported adverse effects of FUS. Adverse effects have included unsteadiness or tingling in the face or fingers, although these adverse effects were mild and resolved within a month from the procedure. (12) In addition, patients can experience headache and discomfort at pin sites.
The results of a multicenter randomized clinical trial involving 76 patients with medication-refractory ET treated with FUS thalamotomy revealed clinically significant reduction in hand tremor at 3 and 12 months postprocedure. (13) The clinical trial measured disability outcomes using the CRST part C, which revealed a 62% reduction in total disability score from baseline to 3 months, with sustained improvement at 12 months. (13) Quality of life was measured using the Quality of Life in Essential Tremor Questionnaire and resulted in a 46% reduction in quality of life score from baseline to 3 months (higher Quality of Life in Essential Tremor scores correspond to lower overall quality of life related to tremor). (13)
A retrospective study of 96 patients compared functional outcomes and quality of life in medicationrefractory ET patients treated with either bilateral DBS, unilateral DBS, or unilateral FUS. (14) Results indicated significant improvements in tremor symptoms and quality of life with all 3 treatments, with no difference in degree of improvements between the 3 modalities. (14) Surgical complications reported with DBS include intracerebral hemorrhage, infection, device malfunctions, lead migration, and fracture. Deep brain stimulation also requires periodic replacement of the programmable pulse generator. To date, no patients have required repeat FUS thalamotomy for return of tremor. Focused ultrasound is a less invasive alternative in achieving symptom relief with the potential for less complications.
Focused ultrasound thalamotomy has resulted in significant improvement in tremor severity, disability, and quality of life for patients with ET. This treatment was FDA approved in the summer of 2016 for ET and is currently being tested in clinical trials for treatment of PD. Neuroscience nurses play an important role in assessment, education, and evaluation for this new treatment method that improves the quality of life for patients experiencing ET.
Questions or comments about this article may be directed to Katherine Dale Shaw, DNPACNP CNRN, at email@example.com. She is an Acute Care Nurse Practitioner, Neurosurgery, University of Virginia Health System, Charlottesville, VA.
Amy Sue Johnston, MSN ACCNS-BC CNRN, is Clinical Nurse Specialist, Neuroscience, University of Virginia Health System, Charlottesville, VA.
Shelly Rush-Evans, MSN RN CNRN, is Staff Nurse, Neurosurgery, University of Virginia Health System, Charlottesville, VA.
Susan Prather, MSN RN CNRN, is Nurse Manager, University of Virginia Health System, Charlottesville, VA.
Kathy Maynard, ADN RN CNRN, is Nurse Coordinator, Neurosurgery, University of Virginia Health System, Charlottesville, VA.
The authors declare no conflicts of interest.
Supplemental digital content is available for this article. Direct URL citations appear in the printed text and are provided in the HTML and PDF versions of this article on the journal's Web site (www.jnnonline.com).
DOI: 10.1097/IN N.0000000000000301
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|Title Annotation:||Clinical Nursing Focus|
|Author:||Shaw, Katherine Dale; Johnston, Amy Sue; Rush-Evans, Shelly; Prather, Susan; Maynard, Kathy|
|Publication:||Journal of Neuroscience Nursing|
|Date:||Oct 1, 2017|
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