Deep Brain Stimulation for Advanced Parkinson's Disease

SEPTEMBER 2000, VOL 72, NO 3

Home Study Program DEEP BRAIN STIMULATION FOR ADVANCED PARKINSON‘S DISEASE

T

he article “Deep brain stimulation for advanced Parkinson’s disease,” is the basis for this AORN Journal independent study. The behavioral objectives and examination for this program were prepared by Helen Starbuck Pashley, RN, MA, CNOR, contributing editor, with consultation from Eileen J. Ullmann, RN, MHS, CNOR, professional education specialist, Center for Penoperative Education. A minimum score of 70% on the multiple-choice examination is necessary to earn 3 contact hours for this independent study. Participants receive feedback on incorrect answers. Each applicant who successfully completes this study will receive a certificate of completion. The deadline for submitting this study is Oct 31, 2001. Send the completed application form, multiple-choice examination, learner evaluation, and appropriate fee to AORN Customer Service c/o Home Study Program 2170 S Parker Rd, Suite 300 Denver, CO 8023 1-5711 Or fax the information with a credit card number to (303) 750-3212

BEHAWOW OBJECTIVES

After reading and studying the article on deep brain stimulation for advanced Parkinson’s disease, the nurse will be able to (1) discuss Parkinson’s disease (PD), (2) describe the treatment of patients with PD, and (3) describe perioperative care of the patient undergoing deep brain stimulation for PD.

This program meets criteria for CNOR and CRNFA recertification, as well as other continuing education requirements.

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Deep Brain Stimulation for Advanced Parkinson’s Disease usually occurs in one of the upper limbs and is reduced by voluntary movement. As the disease progresses, the patient gradually loses automatic movements (eg, eye blinking, crossing the legs, swinging the arms while walking). Complicated movements become slow and difficult to perform, affecting the patient’s ability to perform activities of daily living. Patients begin to have a typical shuffling gait with small steps. In advanced PD, the posture becomes affected. Patients have difficulty rising from a seated position and become unable to make postural adjustments to prevent falling. Parkinson’s disease usually does not affect the intellectual faculties until very late in the course of the disease; however, because the emotional strain of living with such a condition is great, mood disturbances often occur. A variety of pharmacological treatments are initially effective in reducing the symptoms of PD. As the disorder progresses, however, the efficacy of medication diminishes, and medications commonly produce debilitating side effects. Treatment with levodopa, the mainstay of pharmacotherapy, A B S T R A C T Deep brain stimulation (DBS) is a new and promising technique eventually leads to troublesome for the treatment of movement disorders. Medically intractable dyskinesias and motor fluctuaParkinson‘s disease (PD) is one of the most common indications for tions in most patients.‘ For DBS. There are three possible subcortical targets for PD, depending patients with symptoms that are on the symptomatology (ie, the motor subdivision of the thalamus, inadequately controlled by medication or those experiencing unthe globus pallidus internus, the subthalamic nucleus [STN]). Thalamic stimulation has been well established as a safe and effec- acceptable adverse effects from tive treatment for essential tremor and the tremor associated with medication, surgical treatments PD. Globus pallidus internus and STN DBS are being investigated for may reduce symptoms and imthe treatment of all the cardinal signs of PD. This article describes the prove function. arkinson’s disease (PD) was first described in 1817 by James Parkinson, an English physician.’ Parkinson’s disease is an idiopathic, progressive, neurodegenerative disorder involving the loss of cells that produce the neurotransmitter dopamine in a part of the brain stem called the substantia nigra pars compacta.2 It is manifested clinically by rigidity, bradykinesia, tremor, and postural in~tability.~ Parkinson’s disease is common, with an age-dependent prevalence ranging from one case per 1,OOO people in middle-aged adults to 50 cases per 1,000 in the elderly. Table 1 lists a glossary of terms associated with PD. The diagnosis of PD is made by identifying the characteristic manifestations of the disorder. Parkinson’s disease is slowly progressive over a period of decades. Early in the illness, the patient may notice a slight slowing in the ability to perform usual activities. A general feeling of stiffness may be noticed, along with mild diffuse muscular pains. Tremor is a common early symptom of PD. Tremor

pathophysiology of PD, the surgical treatment history of PD, surgical techniques used for DBS implants, and the role the perioperative nurse has in the care of the patients undergoing these procedures. AORN J 72 (Sept 2000) 387-408.

HlSlORY

The surgical treatment of PD has a long history. Beginning in

DEBRA L. BYRD, RN; WILLIAM J. MARKS, JR, MD; PHILIP A. STRARR, MD ---------------------------

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Table 1 GLOSSARY OF TERMS

Brudykinesio: Slowness of movement. Tremor: Involuntary, rhythmic shaking. Rigidily. Muscle stiffness. 0

Dyskinesia Involuntary writhing movements, often induced in Parkinson’s patients by levodopa.

0

Dystonia Sustained muscle contractions leading to twisting, repetitive movements and abnormal postures.

0

Levodopo: A dopamine precursor used in combination with carbidopa as the major anti-parkinsonianmedication

0

Sinemef: A mixture of levodopa and carbidopa, the most widely used anti-parkinsonianmedication.

0

Basal ganglia: A collection of nerve cells at the base of the brain involved in control of movement.

0

Substunfiu nigro: A large nucleus in the upper brain stem that is composed of neurons that contain dopamine. Loss of these cells is associated with Parkinson‘s disease.

0

Globus pollidus internus: A key structure in the basal ganglia that is overactive in Parkinson’s disease

0

Tholomus: A large mass of gray matter above the midbrain that is composed of several different cell groups. One of its nuclei receives input from the globus pallidus and sends fibers to the motor cortex.

0

Subthulumic nucleus: A key structure in the basal ganglia that is overactive in Parkinson’s disease.

0

Pallidotomy:Surgical destruction of part of the globus pallidus.

0

Tholornotomy:Surgical destruction of part of the thalamus

0

7 -methy/-4-phenyl-1, 2, 3, 6-tetrahydropyrine:A neurotoxin that causes parkinsonism in humans or animals.

0

Deep bruin stimulufion: Use of a chronically implanted electrode, with an implanted pulse generator, to alter brain activity.

0

stereotaxy: An external coordinate system (provided by a frame attached to the skull) used in conjunction with a computed tomography or magnetic resonance image to guide surgery of a deep brain target through a small opening.

0

Microelectrode recording: A method used to precisely locate brain structures by recording bruin cell activity with a fine electrode.

0

Micropositioner: A device used to advance an electrode into the brain in small increments in a controlled manner

0

Microlesion efect: A temporary improvement in parkinsonian motor symptoms due to microelectrode mapping or deep brain stimulation lead insertion.

0

Unified Parkinson’s Disease /?ofif&! Scale: A standard rating scale of motor function used in the quantitative evaluation of parkinsonian symptoms. 388 AORN JOURNAL

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the 1950s, thalamotomy (ie, surgical destruction of the motor thalamus) and pallidotomy (ie, surgical destruction of the globus pallidus, internal segment) were performed before a solid scientific basis for these procedures was established. The use of levodopa therapy for PD became widely available in the 1960s and was highly successful short term. As a result, surgical therapy fell out of favor in the late 1960s and 1970s. The recent resurgence of interest in surgery for PD is due to recognition that, for many patients, long-term levodopa therapy declines in effectiveness and leads to debilitating side effects; the advent of computed tomography (CT) scans Figure 1 Schematic illustration of a cross-section of and magnetic resonance imaging (MRI) and the brain. (a) globus pallidus, internal portion; (b) advances in image-guided stereotactic surgery globus pallidus, external portion; (c) putamen; (d) make surgery safer and more precise; and caudate nucleus; (e) thalamus; (f) subthalamic nuclea theoretical basis for PD surgery was developed us. (Illustration by Mark Kotnik Denver) based on primate models of PD.5 Although it still is not known what triggers the disease, the physiology of the parkinsonian brain is suppress this hyperactivity in STN or GPi and, therenow much better understood than in the early days of fore, improve the symptoms of PD. Creating surgical neurosurgery for PD. In the 1980s, it was discovered lesions of STN or GPi permanently stops their excesthat a neurotoxin (ie, l-methyl-4-phenyl-l,2,3,6- sive activity. Examples of ablative, or “lesioning,” tetrahydropyrine [=I) can cause a neurological surgery include pallidotomy and thalamotomy. In disorder nearly identical to PD. This neurotoxin was these procedures, an electrode is placed in the target an accidental by-product of illegal drug synthesis, area of the brain (eg, GPi or motor subdivision of the whose effects were discovered when a number of IV thalamus) using stereotactic neurosurgical techdrug abusers developed sudden, severe parkinsonian niques. Lesions are created by heating the exposed symptoms after self-injecting synthetic opiates from a electrode tip with radiofrequency current. The mechsingle improperly synthesized batch. When MPTP anism of this surgery is relatively simple: a surgicalwas injected into subhuman primates, an excellent ly created lesion in a nucleus interrupts excessive or animal model of PD was produced. This primate abnormally patterned neuronal activity in that nuclemodel led to an improved understanding of how us, releasing its afferent targets from abnormal influmotor function is abnormal in PD. This provided the ences and allowing its efferent connections to function more normally.* rationale for current surgical therapy.6 Deep brain stimulation (DBS) is a technique that is rapidly evolving for many disorders, and it may SURGlCALTRENWEWTOF RARKINSON’S DISEASE Parkinson’s disease affects a part of the brain’s supplement or replace ablative the rap^.^ High fremotor system called the basal ganglia. In parkinson- quency stimulation (ie, > 100 Hz) in a target nucleus ism, the loss of dopaminergic neurons of the substan- suppresses abnormal activity and has behavioral tia nigra results in excessive and abnormally pat- motor effects similar to ablation of that target, terned activity in many parts of the basal ganglia, par- although the mechanism involved is uncertain.” Deep ticularly in the subthalamic nucleus (STN) and in its brain stimulation involves implantation of an elecmajor target nucleus, the globus pallidus internus trode into a specific brain region using stereotactic (GPi) (Figure 1). This is thought to be the basis for neurosurgical techniques. The surgeon connects the many of the motor abnormalities in PD.’The GPi nor- lead by an extension wire to a programmable pulse mally inhibits the motor cortex. When the STN and generator implanted below the clavicle (Figure 2). GPi are overactive, motor cortex activity is sup- The stimulation parameters are programmed using non-invasive radio-telemetry to achieve maximal pressed and movement slows down. Several types of neurosurgical interventions can clinical benefit. Unlike surgery that creates lesions, 389 AORN JOURNAL

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DBS for advanced PD currently are investigational procedures in the United States. They are rapidly emerging treatments that appear to provide the maximal symptomatic relief of any surgical therapy currently available for PD. Although the commonly used DBS system has been FDA approved for unilateral electrical stimulation of the thalamus for the treatment of medically refractory essential tremor and the tremor associated with PD, its use at other sites (ie, GPi, STN) for advanced Parkinson’s disease still is under investigation. At the University of California at San Francisco/San Francisco Veterans Affairs Medical Center (UCSF/SFVA), we currently are studying the efficacy and safety of GPi and STN DBS for patients with advanced PD. As it is not known which target is optimal for symptom relief, most of our advanced PD patients enter a research protocol in which the choice of GPi versus STN as the target is made by random assignment. This protocol has been approved by the institutional review board of UCSF/SFVA.

Figure 2 0 Device used for deep brain stimulation therapy at the University of California at San Franciscokian Francisco Veterans Affairs Medical Center. (Photo courtesy of Medtronics, lnc)

DPEP BRAlN SnMUlAlWN PROCEDURE

stimulation does not destroy brain tissue. Instead, it alters the function of the abnormal tissue in the region of the stimulating electrode to produce effects that are similar to those achieved when lesions are created. At present, there are three possible target sites in the brain that may be selected for placement of stimulating electrodes for the treatment of various movement disorders (ie, the GPi, STN, the motor subdivision of the thalamus). Thalamic stimulation has been well established as a safe and effective treatment for essential tremor and the tremor associated with PD.” Thalamic stimulation only treats tremor, however, and is not useful for the other symptoms of PD. Recent reports on GPi stimulation and STN stimulation indicate benefit for all of the major signs and symptoms of PD (ie, bradykinesia, rigidity, tremor, dystonia, gait disorder).” Additionally, GPi stimulation directly suppresses levodopa induced dyskinesias, while chronic STN stimulation allows patients to reduce their levo-dopa intake, leading to a reduction in dyskinesias. Ablative and DBS procedures do not stop the underlying disease process of PD, but they do help ease symptoms. Globus pallidus intemus and STN

Deep brain stimulation surgery for advanced PD requires the precise placement of an electrode in the motor-controlling region of the target nucleus (ie, GPi or STN). At UCSF/SFVA, three methods are used in succession to achieve the most precise placement of the brain electrode-image-guided stereotaxy, microelectrode recording, and test stimulation through the DBS lead. Stereotaxy. This is a technique that allows accurate surgical localization of a tiny area of the brain in three-dimensional space using a preoperative image of the brain. Our stereotactic technique involves placing a stereotactic frame on the patient’s head on the morning of surgery and then obtaining an MRI with the frame in place. The surgeon then can localize the target in the brain based on the MRI of the target structure in reference to the frame. This allows the surgeon to perform surgery through a small burr hole. Microelectrode recording. Intraoperatively, microelectrode recording of individual neuronal cells allows the surgeon to perform a more precise placement of the DBS lead. Test stimulation. After the surgeon implants the DBS lead, intraoperative test stimulation is performed to verify lead placement, determine voltage thresholds, and assess the patient €or adverse effects of stimulation. All of these steps are performed with local anesthesia only. After the lead is implanted and

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Figure 3 Magnetic resonance images following placement of the deep brain stimulation electrode into the globus pallidus internus, contralateral to a previous pallidotomy.

tested, the surgeon closes the incision and general anesthesia is induced for implantation of the pulse generator. After surgery, the patient has an MRI to confirm lead placement and rule out surgical complications (Figure 3).

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p A T m I

Patients with Parkinson’s disease who are referred to UCSF/SFTA for GPi or STN stimulation receive an extensive evaluation to determine whether they are appropriate candidates for surgical treatment. The best results are seen with patients who are less than 70 years old and still responding to levodopa. Some patients experience “on/off’ cycles during which there are musculoskeletal fluctuations in response to levodopa. During off phases, patients literally may be frozen and unable to move. This may last for a few minutes to a few hours and is followed by an “on” cycle where movement is possible. Patients with severe “odoff’ cycles that result in muscle rigidity, bradykinesia, and levodopa-induced dyskinesias are considered for DBS surgery. Patients whose symptoms are still well controlled with medications are not candidates. Candidates for DBS must be well motivated and have a clear understanding of the surgery to undergo this lengthy surgical procedure while conscious. Some patients cannot tolerate lying supine for several hours due to chronic low back pain or other ailments. There are several important contraindications to DBS, including dementia, extensive brain atrophy, or

any associated medical problem (eg, coagulopathy, untreated chronic hypertension), that greatly increase surgical risk. A stimulator should not be placed in a patient who is unwilling or unable to comply with regular follow-up examinations because stimulation parameters may require adjustment. The DBS stimulator is an indwelling device; therefore, a stimulator should not be placed in any patient with a concurrent infection. The final decision to proceed with DBS surgery is made by the surgeon based on in-depth patient and family member interviews before he or she obtains informed consent. The surgeon discusses realistic expectations of surgery with the patient and family members, emphasizing that the patient’s mobility during DBS therapy will be no better than his or her condition during his or her best “on medication” state. The surgeon also discusses potential postoperative side effects (eg, temporary personality changes, depression). Possible complications of DBS surgery, especially infection and stroke resulting from hemorrhage, also are addressed. All patients deemed to be candidates for DBS surgery undergo systematic neurological testing that includes assessment of motor function using standard rating scales (eg, the Unified Parkinson’s Disease Rating Scale [UPDRS]; a speech and swallowing evaluation; a video gait assessment; a motor fluctuation diary; a sickness impact profile, which is a written evaluation used to assess how PD affects the patient’s quality of life). Many of these evaluations

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are performed with the patient on and off anti-parkinsonian medication (Figure 4). The patient is instructed not to take any aspirin or nonsteroidal anti-inflammatory drugs for 10 days before surgery. A preoperative anesthesia assessment is scheduled, and the anesthesia care provider discusses the patient’s anesthesia and pain control options. The patient’s hemoglobin and hematocrit levels and blood clotting factors are tested, and a chest x-ray and a 12-lead electrocardiogram (ECG) are performed.

The perioperative nurse has an important role in DBS surgery. The following are some examples of potential problems with which the perioperative nurse must be concerned. Many PD patients have impaired physical mobility, and there is a risk of injury during their transfer from wheelchair to gurney or to the OR bed. Careful positioning and padding also are important. As the procedure usually lasts for several hours, the patient is at risk for positioning injuries. The DBS patient is required to be fully conscious for most of the procedure; therefore, the perioperative nurse must frequently assess the patient for alterations in comfort. The DBS procedure involves use of an indwelling device, so the perioperative nurse must be concerned with the risk of infection. The patient should receive IV antibiotics before the surgeon initiates the skin incision. Strict aseptic technique, antibiotic irrigation, and the use of a second set of sterile instruments and supplies for the second part of the procedure (ie, insertion of the pulse generator) are all important perioperative interventions. It also is important for the nurse to be familiar with the technical aspects of the surgery and the complex equipment used. This prevents the patient from experiencing additional anxiety due to a perceived lack of competence on the part of health care team members. Emotional care is an important perioperative intervention. With a basic knowledge of the procedure and careful planning, the perioperative nurse can help minimize the length of the surgery and make it a less stressful experience for the patient. Admission. The patient usually is admitted to the hospital at least one day before surgery. The neurosurgical clinical nurse specialist (CNS) discusses what to expect on the day of surgery (eg, frame placement, MRI scans, length of surgery) with the patient. He or she prepares the patient for potential postoper-

ative side effects (eg, periorbital edema secondary to frame placement, mood changes) and provides support to the patient and family members. The neurosurgical ward nurse discusses mandatory preoperative preparation procedures (eg, shower and shampoo before surgery, NPO after midnight), The nurse obtains IV access in the arm ipsilateral to the side of the surgery so that the arm contralateral to the side of the surgery is free for intraoperative testing. All antiparkinsonian medications are stopped the night before surgery and resumed postoperatively. This minimizes medication-induced dyskinesias and makes physiological identification of the target easier because the brain is in its most parkinsonian state. Preoperative preparation. On the morning of surgery, the patient is transported by wheelchair from the neurosurgical ward to the preoperative area for placement of the stereotactic frame. The supplies for frame placement are gathered before the patient’s amval. The surgeon assembles the frame using the Leksell frame kit. This kit containb pins of various lengths to allow for variability in head size. It is useful to have a supply of pins ranging in length from 30 mm to 60 mm in 5 mm increments. Selection of the proper pin size is important. Pins that are too short may result in frame slippage. Pins that are too long may not allow the frame to fit into the MRI head coil. Other supplies needed for frame placement are 1% lidocaine hydrochloride with epinephrine 1:1OO,OOO combined with 7.5% sodium bicarbonate (1 mL of sodium bicarbonate per 10 mL of local analgesic to reduce the discomfort felt with the injection), a razor, povidone-iodine swabs, syringes, needles, and a 2 mg vial of midazolam hydrochloride for patient sedation. Frame placement may be challenging because of the involuntary movements or the twisted postures often experienced by patients with advanced PD. The anesthesia care provider or assistant surgeon often help with frame placement. Patients often report that frame placement is one of the most uncomfortable aspects of the surgery; therefore, the surgeon and assistant prepare the patient for the temporary discomfort by administering 0.5 mg to 2.0 mg midazolam hydrochloride. The patient’s vital signs are monitored by the anesthesia care provider. The surgeon shaves the four pin sites, preps with

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Figure 4 SCHEDULE OF PREOPERATIVE AND POSTOPERATIVE EVALUATIONS AND TESTING FOR PATIENTS UNDERGOING DEEP BRAIN STIMULATION

Deep brain stimulation (DBS) protocol for advanced Parkinson‘s disease

refractory Parkinson’s disease (PD)

Patient meets entrance criteria and is interested in DBS treatment under the protocol. Signed consent is obtained.

Preoperative Evaluation Neurologic evaluation on and off medication (physical examination, Unified Parkinson’s Disease Rating Scale, timed tests, 3-D video gait assessment) Neurocognitive testing Speech and swallowing evaluation Sickness impact profile Motor fluctuation diary J

I

/ Unilateral globus pallidus internus DBS I

Unilateral subthalamic nucleus DBS

/

\

I

Three-month postoperativeevaluation Neurologic evaluation on and off medication with DBS on and off 3-D video gait assessment on and off medication with DBS an and off Neurocognitive testing Speech and swallowing evaluation Sickness impact profile Motor fluctuation diary If indicated and desired by patient

as the first procedure).

Postoperative evaluation 12 months after first DBS; same as three-month evaluation. I

after first DBS; same as 12-month evaluation. I

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burr hole instruments, Mayfield table attachment, a high-speed drill, a stereotactic arc, a microelectrode, a recording apparatus, a hydraulic drive, a test stimulator, a micropositioner, a cement fume evacuator system, a fibrin glue, a cranial plating system, a a supply of extra gowns and gloves, a flashlight, a brain atlases, a graph paper, and a drawing supplies. It is important to verify the correct side of the DBS proced&e so that the OR can be prepared properly. The room is set up so that the surgeon or neurologist can easily perform intraoperative testing of limb function on the side contralateral to the brain implant. The anesthesia equipment is positioned at the patient’s side on the same side as the surgery. The scrub person sets up at the head of the OR table on the opposite side of the surgery (eg, on the right side of the patient’s head if the DBS will be placed in the left side of the brain). He or she places a a

Figure 5 Application of the Leksell stereotactic frame. Note that the frame must align with the ear canal and the nose. (/lustrution by Kurt Jones, Denver)

povidone-iodine, and infiltrates the area with local anesthetic. During placement of the frame, the surgeon temporarily places ear bars in the patient’s external auditory canals to help stabilize the frame and to keep the x-axis (ie, right-left axis) of the frame perpendicular to the midsagittal plane of the brain. The surgeon angles the y-axis (ie, anterior-posterior axis) of the frame by visually aligning it with an imaginary line connecting the patient’s external auditory canals with the inferior orbital walls. The assistant helps hold the frame in the correct position while the surgeon fixes the frame to the patient’s skull with pins. Care is taken to ensure that the frame does not create pressure on the patient’s nose or the back of the neck. The pins are securely tightened to guard against any movement of the frame (Figure 5). After placement of the frame, the surgeon accompanies the patient to the MRI scanning area. The MRI scanning procedure takes about 30 minutes. The surgeon then chooses the surgical target and calculates the stereotactic coordinates based on the MRI scans. During this time, the perioperative nurses ensure that the OR has been set up correctly (Figure 6). The supplies and equipment needed for DBS surgery include

Figure 6 Layout of OR for patient undergoing left deep brain stimulation. The scrub person and instruments are at the head of the OR bed on the side opposite surgery. Recording equipment is placed on the side opposite surgery. Anesthesia equipment is on the same side as surgery.

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the surgical instruments and equipment on two back tables and a Mayo stand. One Mayo stand is positioned next to the patient’s head to hold the bipolar electrosurgical forceps, drill, and suction. The scrub person positions the second Mayo stand on the other side of the patient’s head to hold the micropositioner (used to advance the microelectrode and the DBS lead into the brain). The hydraulic drive for the micropositioner is placed on a prep table next to this Mayo stand. An electronic rack for microelectrode recording is placed near the foot of the bed on the side opposite the procedure. At our institution, we use a commercial electronics rack, equipped with an adaptive filter, that reduces 60 Hz electrical interference during microelectrode recording. No special efforts need to be made to ensure electrical isolation of the environment. The perioperative nurses test equipment (eg, drill, suctions, electrosurgical units), resolve any problems associated with this, and ensure that the room temperature is comfortable. Zntraoperative care. The patient is returned to the preoperative area immediately after the MRI scan is completed. At this time, the circulating nurse checks the name band and interviews the patient, verifying pertinent medical history, allergies, NPO status, laboratory studies, and surgical consent. The nurse contacts the blood bank to order fibrin adhesive, a blood product that contains concentrated fibrinogen and is used topically with bovine thrombin. The circulating nurse assesses the patient’s baseline symptoms (eg, presence of tremor, rigidity, bradykinesia). This is an important assessment because the patient may experience improvements in these symptoms during the procedure. The circulating nurse evaluates the patient’s understanding of the procedure. He or she can help allay anxiety by allowing the patient to express concerns, answering questions, and explaining what to expect in the OR and immediately postoperatively. This procedure is lengthy; therefore, the circulating nurse assesses the patient’s skin condition and the need for additional positioning devices or padding. If the patient is very uncomfortable with the frame in place, he or she is placed on a gurney at this point. We have found that elderly, frail patients who are unable to tolerate sitting upright in a wheelchair with the heavy frame in place appreciate this. If the patient has greatly impaired mobility, the perioperative nurse has another person help with the transfer from the wheelchair. The anesthesia care provider also assesses the patient at this time.

After these assessments, the patient is taken to the OR and prepared for surgery. The patient will be required to be in the same position and fully conscious for several hours, so he or she must be made as comfortable as possible. The perioperative nurse pads the OR bed, and a warm blanket is placed on the table just before transferring the patient. The patient is helped into a comfortable, semireclining position with a pillow under the knees and head. The circulating nurse assesses the fit of the frame on the patient’s head and places padding between the frame and the back of the neck, if needed. The anesthesia care provider places ECG electrodes, a blood pressure cuff, a pulse oximeter, and a nasal oxygen cannula. He or she administers hypotensive agents, if needed, to maintain a normal systolic blood pressure and reduce the risk of intracranial hemorrhage during surgery. Preoperative antibiotics also are administered. As the duration of surgery usually is greater than three hours, a Foley catheter is placed. The perioperative nurse uses 2% topical lidocaine jelly to make this part of the procedure less painful. The anesthesia care provider starts an infusion of 1% propofol (ie, Diprivan) just before the circulating nurse inserts the urinary catheter. This infusion is not stopped until the burr hole is drilled and the surgeon is ready to begin microelectrode recording. It is important that no sedation is used during microelectrode recording because it would alter the characteristic neuronal activity in the target structures. Additionally, the patient must be fully conscious and able to cooperate when the DBS lead is tested. The surgeon and circulating nurse secure the patient’s head frame to the OR bed with the Mayfield adapter. They then assist the patient into a comfortable semi-sitting position. Care is taken to keep the head straight while allowing the patient to choose a position of relative comfort. A pillow is placed under the knees to reduce low back strain. The patient is kept warm with either cotton blankets or a temperature regulating blanket system. A safety strap and arm boards are used for positioning. The surgeon shaves the frontal area of the patient’s scalp on the surgical side only. The circulator preps with povidone-iodine scrub and 2% iodine paint. The surgeon gowns, double gloves, attaches the Leksell axis rings to the frame, and sets the previously determined coordinates. The assistant surgeon verifies the coordinates. As the frame is not sterile, the surgeon must be very careful not to contaminate his gloves while attaching the rings to the frame and

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Figure 7 The stereotactic arc attached to the Leksell frame. (Photo couflesy of EIektO Instruments, Inc)

draping the surgical field. He or she drapes the patient’s head with two folded towels, an iodineimpregnated adhesive drape (with slots cut for the rings), a split sheet (with the split end down), and a medium sheet. A pouch drape is attached under the head and connected to suction to collect the excess irrigation. The surgeon attaches the drapes to two IV poles on either side of the patient’s head. They are carefully folded and secured to the poles to keep the excess drapes off the patient’s face, as the patient’s eyes must be visible for examination of visual fields and ocular motility. After the patient is prepped and draped, the surgeon injects a mixture of 2% lidocaine hydrochloride and 0.5%bupivacaine hydrochloride with epinephrine 1:200,000. This is usually sufficient for the entire procedure, although occasionally, additional local anesthetic is needed for closure. The surgeon then attaches the stereotactic arc to the axis rings (Figure 7). The surgeon makes a 6-cm incision and uses a 5.0 mm round cutting burr to drill the burr hole. The dura is opened widely. The surgeon then fills the burr hole with fibrin glue to prevent air embolus; to prevent continued cerebrospinal fluid loss, which would lead to progressive brain shift; and to dampen electrical artifact from brain pulsations, which improves the quality of the microelectrode signal. He or she attaches the micropositioner to the arc to advance instruments into the brain in precise increments (Figure 8). A micro-

electrode and guide tube are attached to the micropositioner. Using a hand-operated hydraulic drive, the surgeon slowly lowers the microelectrode through the guide tube to the target area in the brain. The surgeon identifies individual neuronal cells as the microelectrode is lowered through the burr hole to the target area (ie, GPi, STN). The circulating nurse contacts the neurologist so he or she can be present for microelectrode recording and insertion of the DBS lead, Microelectrode recording allows the surgeon to physiologically explore the target region. A series of three or four parallel microelectrode penetrations usually are performed. The initial target point is selected to provide maximal localizing information from the initial microelectrode penetration. Subsequent tracks are made to localize nuclear boundaries not identified on the f i t track. The patient is conscious at this point and is repeatedly examined by the surgeon or neurologist. The examination consists of passive movements of the shoulder, arm,wrist, hip, knee, and foot to determine the effect, if any, on the neuronal firing rates. A change in neuronal discharge with joint movement indicates

Figure 8 Patient‘s head with microelectric drive appamtus (ie, micropositioner) attached to the stereotactic arc.

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Figure 9 Different patterns of neuronal activity encountered along a microelectrode track during physiologk itmlization for deep brain stimulation surgery.

Figure 10 Bilateral deep brain stimulation surgery (DBS) with the DBS leads secured by titanium miniplates.

that the microelectrode is in a motor territory, rather than a limbic or cognitive area. Neuronal discharges are vieived on an oscilloscope and played on an audio monitor because discharge patterns often are best appreciated aurally rather than visually. As the surgeon moves between the sterile field and the front of the patient to perform the examinations and operate the hydraulic drive, frequent gown and glove changes are necessary. To avoid contaminating the equipment, the surgeon removes his or her outer gloves each time he or she leaves the sterile field. The surgeon lowers the microelectrode in 50- to 100-micron increments. The circulating nurse or neurologist makes a scaled drawing of the cells encountered at each depth on graph paper. The drawings are shaded according to the identity of the cells encountered at each depth. This information then is superimposed on enlargements of parasagittal sections adapted from a standard human brain atlas. The surgeon makes a visual judgment of the best fit of the tracks to the atlas to determine the electrode’s exact position in the brain (Figure 9). The surrounding anatomy and physiology are different for each target area, and the testing is individualized depending on the target. For targets close to the optic tract (ie, GPi), light-evoked fiber discharges are identified by listening for alterations in neuronal discharges that coincide with a light stimulus. Microstimulation through the microelectrode also can be used at this time. If the patient perceives transient visual phenomena (eg, flashes or sparkles) with low-volt-

age stimulation, this indicates that the microelectrode tip is near or within the optical tract. If the patient’s tongue, face, or hand contracts during microstimulation, this is an indication that the electrode tip is near the corticobulbar or corticospinal tract. It is important to keep the room as calm and quiet as possible during this part of the procedure. The surgeon and neurologist need to be able to identify very subtle changes in the neuronal firing by listening to the audio monitor of the microelectrode signal to accurately localize the microelectrode tip. The patient is instructed to speak only if absolutely necessary, as speech interferes with the microelectrode recording. The patient is conscious and aware of everything that is occumng and may need reassurance that the procedure is going well. The circulator frequently assesses the patient’s level of comfort. Supportive measures (eg, neck massage, application of warm blankets) help to make the patient more comfortable during this long procedure. The surgeon decides where to place the DBS lead based on the physiologically derived brain map. The DBS lead is 1.27 mm in diameter. The intracranial end has four contacts that are each 1.5 mm in length and are spaced 1.5 mm apart. Any one or more of the four stimulating contacts may be used for monopolar stimulation, and any two or more may be used in combination for bipolar stimulation. The surgeon slowly lowers the DBS lead into the brain through a guide tube. Neurological examinations are performed by the neurologist or surgeon

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during this part of the procedure. Testing of the DBS lead is performed during placement. The surgeon decides on the target location and drives the lead close to the target depth. The lead is attached to an external testing device that is used to adjust the desired lead contacts, pulse width, amplitude, and rate of stimulation. Testing is used mainly to determine the voltage thresholds for adverse effects, rather than for beneficial effects. Beneficial effects of stimulation on rigidity, bradykinesia, and gait may require hours or days to become apparent; .thus, intraoperative assessment of these symptoms is impractical. Effects on tremor, if present, usually are immediate. The circulating nurse documents the testing of the DBS lead. This documentation includes depth of DBS lead, contacts used, pulse width, amplitude of stimulation, and patient response. Patients often demonstrate a “microlesion effect” (ie, a temporary improvement in parkinsonian symptoms) even before the DBS lead is tested. This temporary improvement is due to the minor tissue trauma produced during the microelectrode passes or insertion of the DBS lead. This effect lasts only a few hours or days. During this phase of the operation, it is important to reassure the patient that the adverse effects he or she experiences during testing (eg, tingling, dysarthria, visual phenomena) are temporary and should not occur after the DBS lead is programmed and turned on. After the surgeon places the DBS lead in its final position, the anesthesia care provider sedates the patient, Methylmethacrylate cranioplasty is used to fill in the burr hole defect and secure the lead. A cement evacuator system is used to protect the team from the methylmethacrylate fumes. At UCSF/SFVA, the lead then is anchored in place with a 7-hole miniplate and 4 mm screws (Figure 10).The surgeon creates an internal subcutaneous area for the distal end of the DBS lead, lateral to the burr hole defect, so that it can be retrieved easily when the pulse generator is implanted. The wound is irrigated with antibiotic solution and closed with 2-0 subcutaneous polyglycolic (ie, Dexon) sutures. The surgeon closes the skin with 3-0 nylon and applies dressings. He or she removes the stereotactic frame and applies the regular head end table attachment to the table. The pulse generator usually is implanted on the same day, immediately after the head incision is closed. This part of the procedure is performed with general anesthesia due to the discomfort associated with subcutaneous tunneling of the DBS extension wire. The perioperative team turns the OR bed so the

patient’s head is toward the anesthesia equipment. After induction, the head of the bed is turned so that the surgical side is away from the anesthesia equipment. The patient’s head is turned to the side and positioned on towels, and a shoulder roll is placed. The circulating nurse pads the patient’s elbows and places an electrosurgical unit grounding pad on the thigh. He or she shaves the patient from behind the ear to above the nipple line on the operative side. The skin is prepped with povidone-iodine scrub and 2% iodine paint. The previous incision is not included in the surgical field. To reduce the risk of contamination,a second set of sterile instruments, drapes, and supplies is used for this part of the procedure. The surgeon drapes the patient with a medium sheet, towels, an iodineimpregnated adhesive drape, and a split sheet. After making a 6-cm infraclavicular incision, the surgeon uses blunt dissection to create a subcutaneous pocket over the pectoralis fascia for the pulse generator. The distal end of the DBS lead is dissected out and is connected to an extension wire. The surgeon tunnels the extension wire from the patient’s head to the pulse generator pocket. After all the connections are made, he or she irrigates the incisions with antibiotic solution and closes the incisions with 2-0 polyglycolic and 3-0 nylon suture. The incision sites are dressed with nonadherent dressings (ie, Telfa) and transparent adhesive film (ie, Tegaderm). The circulating nurse communicates with members of the postanesthesia care unit (PACU) and the MRI department so that they can plan for the postoperative scans. Postoperative care. Patients are sent to the PACU immediately after surgery, and standard postoperative care is initiated (eg, ECG, pulse oximetry, blood pressure/vital sign monitoring). The PACU nurse also performs frequent neurologic examinations. The patient is observed closely for signs of confusion, hemiparesis, and hemanopsia. Before discharge from the PACU, the patient undergoes an MRI scan to rule out intracranial hemorrhage and to confirm lead placement. The PACU nurse monitors the patient while he or she is in the scanner. On discharge from the PACU, the patient is taken to the neurosurgical unit. The nurse removes the Foley catheter, resumes the patient’s anti-parkinsonian medications, and continues antibiotic therapy for 24 hours. Discharge usually is two days after surgery. The neurosurgical clinical nurse specialist is involved in discharge planning. An appointment is made with the clinical nurse specialist for approximately one week

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Very strong electrical or magnetic energy can turn the pulse generator on or off unexpectedly.

later to remove sutures. The clinical nurse specialist gives postoperative instructions to the patient and family members before the patient is discharged. The patient is instructed to report any signs of infection (eg, redness, itching, or burning sensations around the implant sites). After discharge. The DBS is activated several days to one month following surgery. The clinical nurse specialist uses an external programming unit to turn on and program the implanted pulse generator. The pulse width, stimulation amplitude, and stimulation frequency, as well as the choice of active contacts and stimulation mode (ie, bipolar or monopolar), are programmed by placing the wand of the programming unit over the chest where the generator is implanted. After the pulse generator is programmed, the patient may turn the stimulator on or off using an external magnet. The patient is given a control magnet and taught how to use it to turn the pulse generator on and off. Possible side effects of DBS therapy include paresthesias in the contralatera1 limbs or face, contralateral facial and limb contraction, dysarthria, dizziness, headache, double vision, depression, pain, or shocking sensations at the pulse generator site. The patient is instructed to report these side effects. In most cases, the pulse generator can be reprogrammed so side effects are eliminated or lessened. The patient also is instructed to contact the physician if the implant sites show signs of infection, if the pulse generator stops working, or if there are any changes in his or her symptoms related or unrelated to stimulation. Patients are warned that their parkinsonian symptoms may worsen as the microlesion effect wears off, in which case they may need to have their pulse generator reprogrammed. Although patients who have DBS for essential

tremor and tremor-dominant PD can turn their pulse generator off at night to save the battery, patients with advanced PD are instructed to leave the device on all the time. Most medical procedures are unlikely to interfere with the pulse generator; however, patients are instructed to inform medical personnel that they have an implanted device and to bring the control magnet to appointments with them. It may be necessary to turn off the pulse generator for ECGs and for surgery in which electrosurgery must be used near the pulse generator site. Typically, the. pulse generator battery will last three to five years. Remaining battery life can be tested with the external programming unit during routine postoperative evaluations. When the battery is depleted, minor surgery is required to replace the pulse generator, but not the extension or DBS lead. Patients are instructed that most electrical items they encounter in an ordinary day (eg, microwave ovens, appliances, cellular phones) are unlikely to interfere with the pulse generator; however, devices with very strong electrical or magnetic energy (eg, theft detectors, airport security screening devices) can unexpectedly turn the pulse generator on or off. The patient is instructed to use care when approaching these devices and to bypass them if possible. Patients are given an identification card after their device is implanted. They are instructed to carry their identification card with them at all times to verify that they have an implanted device. Postoperative evaluations are performed at three and 12 months. These include a neurologic evaluation, a video gait assessment, neurocognitive testing, speech and swallowing evaluation, quality of life assessments, and motor fluctuation diary. These evaluations are performed with the patient on and off anti-parkinsonian medications. On the morning of the evaluation, the patient is instructed not to take any of his or her anti-parkinsonian medications. After the evaluations are completed, the patient resumes his or her normal dosage of medication, and evaluations are performed again. These studies are performed in a “blinded” fashion. The examiner does not know whether the patient’s stimulator is turned on or off, resulting in an objective examination. If indicated and desired by the patient, DBS of the opposite side (with the same target as the first) can be scheduled. For patients with bilateral syrnptoms who can tolerate a long, conscious surgical procedure, simultaneous bilateral implantation may be performed.

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Postoperative motor scores

CASEFNlly

Mr M is a 46-year-old, right-handed, retired attorney with a 16-year history of Parkinson’s disease. He experienced his first manifestation of PD when he was 30 years old, when he noticed while playing baseball that he had difficulty releasing the ball. At this time, he began to experience freezing episodes, with the right side of his body (ie, his dominant side) worse than the left. At the age of 32, he developed micrographia and gait difficulty. Although he did not have significant tremor, he was diagnosed with PD. He was started on levodopa therapy and experienced total relief of his symptoms on medication. Six months into treatment, he began to experience dyskinesias during his medication peaks and dystonias as the medications wore off. In 1993, as his disabilities progressed, he found it necessary to retire. In 1999, Mr M was referred to the UCSF/SFVA. At this time, he was experiencing extreme on/off fluctuations, causing severe dystonias and cramps that woke him up in the middle of the night and severe appendicular, truncal, and neck dyskinesias during his medication peaks. When he was evaluated at the UCSF/SFVA, Mr M was noted to have a brisk, but brief, response to levodopa that necessitated careful titration of his medications. His medication regimen consisted of crushing 10 tablets of carbidopa/levodopa 25/100, two tablets of 1 mg pergolide, and one teaspoon of crystal vitamin C in l L of Kool-Aid. He took small liquid doses every 15 to 60 minutes, for a total of 1 L to 1 1/2 L in a 24-hour period. Both Mr M and his wife expressed anxiety about his deteriorating condition, and Mrs M felt overwhelmed with his care. As his disabilities progressed, she began to explore the option of hiring a care attendant to assist with his activities of daily living. After a thorough discussion of the surgery, including potential risks and benefits, Mr M decided to undergo DBS surgery. His wife was supportive of his decision. Mr M was deemed to be an excellent candidate for DBS surgery due to the presence of a significant, but brief, response to levodopa; his appropriate level of disability; relative youth; lack of comorbidity; and his motivation to improve. He was enrolled in our randomized trial of STN versus GPi stimulation and was assigned to have STN DBS placement. The left brain was selected for the initial implant site. Mr M was admitted to the hospital and prepared for surgery. The usual tests were performed. The surgeon, neurologist, and neurosurgical CNS assessed Mr M’s knowledge of DBS therapy. Mr M had per-

improved on the Unified

Parkinson’s Disease Rating

Scale.

formed a fair amount of research and already was quite knowledgeable about DBS. Appropriate individualized preoperative instruction was provided. The neurosurgical CNS identified caregiver role strain as a problem for the family and provided additional support to Mrs M. A referral for psychiatric assessment also was made. Table 2 lists nursing interventions in more detail. On the morning of surgery, Mr M’s left subthalamic nucleus was targeted, and he was taken to the OR for the procedure. The perioperative nurse greeted Mr M, performed preoperative assessments, and identified potential problems. The nurse assessed his understanding of the procedure and told him what to expect in the OR and immediately postoperatively. Due to the length of the surgery, positioning injury and impaired skin integrity were identified as potential problems and addressed with careful and comfortable positioning and padding. The risk of infection was minimized with strict aseptic technique. The perioperative nurses also minimized the risk of injury from malfunctioning equipment by testing all equipment before surgery. The procedure took approximately five hours. Microelectrode recording provided valuable neurophysiologic data that was used to establish the anatomic boundaries of the target. After this information was correlated with an anatomic atlas, the surgeon implanted the DBS lead. Mr M experienced a microlesion effect, manifested by improvement in his symptoms due to temporary disruption of the STN by edema around the lead. The postoperative MRI scan confiied lead placement within the STN and no hemorrhage. The surgeon tested the pulse generator on the second postoperative day. The stimulation voltage, frequency, and amplitude were adjusted to give Mr M maximal benefit of stimulation with minimal adverse effects. The neurosurgical CNS taught him how to

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Table 2 CARE PLAN FOR PATIENTS UNDERGOING DEEP BRAIN STIMULATION'

Nursing diagnosis

Nursing interventions for intraoperatlve care

Risk for perioperative 1. Identifies physiological Status. Reviews results of neurologic tests, including specific Parkinson's assessments. positioning injury Assesses baseline symptoms; identifies degree of related to intraoperative uncontrolled movements. positioning and 2. Applies safety devices. Assists with frame application disease process assuring safety measures (ie, monitoring, safely strap) are implemented. 3. Transports per individualized need. Uses caution with transfer from wheelchair to gurney to magnetic resonance imaging (MRI) unit, and from MRI table to OR bed. 4. Positions pdent and places padding with attention to placing pads around the frame and neck as needed; evaluates head movements and frame position, considering length of procedure and patient's inability to control movements. 5. Minimizes length of procedure by planning care. Obtains additional padding or positioning equipment for semisitting positions. Monitors pahent's tolerance to maintaining position. 6. Evaluates pahent for signs and symptoms of injury to skin and tissue. Knowledge deficit related to planned diagnostic tests and surgical intervention

Risk for infection related to surgical intervention

Desired patient outcome The patient is free from signs and symptoms of injury related to positioning. The patient is free from signs and symptoms of injury due to extraneous objects.

1. Provides pahent and family member instruction. Explores postoperative mobility expectations and reinforces that it will not improve immediately afler the procedure. 2. Elicits perceptions about surgev. Explains procedures (eg, frame placement, MRI) and sequence of operative events; reviews pahent's expecta-hons.Establishes willingness to comply with follow-up examinations. Describes surgical complications (eg, infection, stroke) and methods of reporting. 3. Evaluates pahent's understandingof postoperative signs and symptoms and reporting. Reinforces this information. 4. Provides instruction about prescribed medications (eg, stop nonsteroidal anti-inflammatory drugs and other medications that affect clotting 10 days before surgety; stop anti-parkinson medications the night before surgery). 5. Provides instruction regarding surgical recovery and postoperative side effects(eg, penorbital edema, mood changes) and methods and timing for reporting. Provides instruction about evaluations, use of implantable pulse generator. Provides instruction based on age and needs.

The patient demonstrotes knowledge of the physiologic responses to the operative or other invasive procedures.

1. Assesses for signs and symptoms of infection. Administers prescribed prophylactic treatments (eg, IV antibiotics). 2. Implementssurgical asepsis. Identifies and prepares for availability of sterile instruments to be used during each stage of the procedure. Verifies preoperative shower and shampoo are completed before surgery. Performs surgical skin prep.

The patient is free from signs and symptoms of infection.

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The patient demonstrates knowledge of the psychological responses to the operative or other invasive procedures.

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Table 2 CARE PLAN FOR PATIENTS UNDERGOING DEEP BRAIN STIMULATION (CONTINUED)

Nursing diagnosis

Nursing interventionsfor lntraoperativecare 3. Provides inshuction about reportable signs of infection, wound care, and wound healing.

Desired patient outcome

Pain related to multiple transfers and invosive procedure requiring patient consciousness

1. Assesses comfort level during the perioperative period (eg, frame placement, MRI, surgical intervention). Implements pain guidelines and alternate methods of pain control (eg, provides comfort measures during procedure, allows patient to choose position of comfort). Evaluates responses to pain management interventions and alternative methods of pain control. 2. Transfers patient according to individual needs.

Patient demonstrates and/or reports adequate pain control throughout the perioperative period.

Risk for altered tissue perfusion

1 . Obtains and administers prescribed medications (eg, hypotensive agents, fibrin glue). 2. Monitors physiological parameters (eg, fluid administration, blood loss, urine output).

The patient has wound/tissue perfusion consistent with or improved from established preoperative baseline levels.

Risk for injury related to surgical intervention

1. Reviews and verifies perioperative interventions. The patient is free from signs Assesses patient's medical history, allergies, NPO sta- and symptoms of physical tus, and laboratory studies and verifies consent is injury. signed for correct procedure. 2. Establishes appropriate IV access for procedure. 3. Uses supplies and equipment within safe parameters. Positions OR bed and equipment for access. Tests equipment, verifies correct implants are available. Documents appropriately. 4. Identifies psychological status. Maintains a quiet environment to facilitate microelectrode recording.

Risk for hypothermia due to procedure length and patient age

1 . Implements therrnoregulation measures. Monitors

patient and room temperature; adjusts room temperature and uses thermoregulating measures as needed. Keeps patient covered. 2. Evaluates responses to thermoregulation measures.

The patient is at or returning to normothermia at the conclusion of the immediate postoperative period.

Compromised or ineffective patient and family coping.

1 . Provides instruction about the disease process, surgical procedure, treatments, and expected outcomes. Assesses coping mechanisms.

The patient and family members participate in the plan of care.

Risk for caregiver role strain

1. Assesses caregiver for role strain and completes a referral as needed. 2. Provides information to family and patient throughout procedure. Reinforces teaching.

The family participates in the patient's plan of care.

Fear related to level of consciousness during surgical procedure

1 . Develops an individualizedplan of care. Provides emotional support during procedure. 2. Provides instructions based on age and needs. Reinforces teaching.

The patient participates in decisions affecting his or her plan of care; anxiety is reduced.

NOTE 1 . S Beyea, Perioperrotive Nursing Data Set The Perioperrotive Nursing Vocabu/uy(Denver: AORN, Inc, 2000). This care plan uses an approved standard vocabulary for perioperative nursing per the ferioprrotiveNursing Dafa Set This consistent use of the standard language assists nurses in validating nursing contributionsto w e n t care. 405 AORN JOURNAL.

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use the magnet to activate and deactivate the pulse generator. He was taught about potential complications, signs to watch for, and when to contact the doctor. On postoperative day six, Mr M’s sutures were removed. His DBS voltage settings were adjusted again one month postoperatively over the telephone, with the help of the therapy consultant from his area. Mr M returned to the UCSF/SFVA three months later for formal neurologic evaluation and contralatera1 DBS implantation. He was tested with the DBS on and off and on and off of his PD medications. He had clearly received significant benefit from his left STN DBS. Postoperative studies showed an improvement (ie, reduction) in motor scores on the UPDRS from 58 to 34 off his medication. He was able to rise from a chair and ambulate relatively quickly off medication with DBS, whereas preoperatively he could not. It was clear that unilateral DBS had provided significant benefit to his right-sided function, gait, and overall mobility. He was able to decrease his dosage of PD medications from a total of 10 to 15 tablets of 25/100 carbidopa/levodopa per day to five to six tablets per day. Mr M’s second surgery proceeded without incident. Postoperative MRI revealed the lead to be in the STN, symmetric to his initial left STN DBS. His formal postoperative studies again showed improvement in UPDRS motor scores from 34 after unilateral DBS implantation to 25 after bilateral DBS (in the off-medication state). He reported dramatic improvement in his symptoms, including enhanced mobility of limbs, improved gait, increased energy, and increased function overall. He now is able to help with household chores, garden, take long walks, and play racquetball. He has regained a great deal of his independence, and Mrs M has abandoned her plans to hire an attendant. Both Mr and his wife have stated that the qualityOf their liveshas improved since oTHERUSESpoRDEEpBRAlNSTlMlHAllON

There are several other movement disorders for which chronic DBS may be indicated. Chronic stimulation of the motor subdivision of the thalamus has been shown to be safe and effective for the treatment NOTES 1. J Parkinson, An Essay on the Shaking Palsy (London: Printed by

Whittingham and Rowland for Sherwood, Neely, and Jones, 1817). 2 . 0 Homykiewicz, S J Kish,

of tremor. In August of 1997, the US Food and Drug Administration approved a tremor control system to treat essential tremor as well as the tremor associated with PD. Cerebellar outflow tremors, (eg, tremor due to multiple sclerosis or following head trauma or stroke) also can be treated with chronic DBS. So far, variable degrees of success have been reported with cerebellar outflow tremors.I3 Chronic DBS therapy also is being studied for patients with dy~tonia.’~ Dystonia is characterized by sustained muscle contractions leading to twisting, repetitive movements and abnormal postures. Dystonia may be either idiopathic or secondary to traumatic, neoplastic, or infectious lesions involving the basal ganglia. Both thalamic and GPi stimulation are under investigation for the treatment of dystonia.

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Chronic DBS is a relatively new and promising technique for the treatment of movement disorders. Thalamic stimulation now may be considered an established procedure for parkinsonian tremor and essential tremor. The use of GPi and STN stimulation are under active investigation as treatments for the cardinal signs of advanced Parkinson’s disease. Deep brain stimulation offers a potential advantage over ablative therapy in that it is reversible, is adjustable, is probably associated with a lower morbidity, and may be safer for bilateral use. The perioperative nurse has a unique and important role in the care of the patient undergoing DBS surgery. A Debra L. Byrd, RN, BSN, is the neurosurgery service charge nurse at the San Francisco Veterans Affairs Medical Center. William J . Marks, Jr, MD, is assistant professor of neuro[onv.Universin, of California, Sari Francisco, and medical director f t h e Center for Parkinson’s Disease & Movement Disorders, San Francisco Veterans Affairs Mpdjrni . . - ...- -. Cpntpr -.

Philip A. Stan, MD, PhD,is assistantprofessor of neurosurgery, Universiry of California, San Francisco.

“Biochemical pathophysiology of Parkinson’s disease,” Advances in Neurology 45 nos 19-34 (1987) 19-34. 3. R D Adams, M Victor, Principles of Neurology, third ed (New York: McGraw-Hill Book Co,

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1985) 874-880. 4. C D Marsden, J D Parkes, “‘On-off’ effects in patients with Parkinson’s disease on chronic levodopa therapy,” Lancet 1 (Feb 7, 1976) 292-296.

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5. M R DeLong, “Primate models of movement disorders of basal ganglia origin,” Trends in Neurosciences 13 (July 1990) 281-285. 6. J W Langston et al, “Chronic parkinsonism in humans due to a product of mependine-analog synthesis,” Science 219 (Feb 25, 1983) 979-980. 7. DeLong, “Primate models of movement disorders of basal ganglia Origin,” 281-285. 8. P A Stan, J L Vitek, R A Bakay, “Ablative surgery and deep brain stimulation for Parkinson’s disease,” Neurosurgery 43 (November 1998) 989-1015. 9. Ibid. 10. Ibid. 11. A L Benabid et al, “Chronic electrical stimulation of the ventralis intermedius nucleus of the thalamus as a treatment of movement disorders,” Journal of Neurosurgery 84 (February 1996) 203-214. 12. R Pahwa et al, “High-frequency stimulation of the globus pallidus for the treatment of Parkinson’s dis-

ease,” Neurology 49 (July 1997) 249-253; C Gross et al, “High-frequency stimulation of the globus pallidus internalis in Parkinson’s disease: A study of seven cases,” Journal of Neurosurgery 87 (October 1997) 491-498; V M Tronnier et al, “Pallidal stimulation: An alternative to pallidotomy?” Journal of Neurosurgery 87 (November 1997) 700-705; P Krack et al, “Subthalamic nucleus or internal pallidal stimulation in young onset Parkinson’s disease,” Brain 121 (March 1998) 451-457; J Volkmann et al, “Bilateral high-frequency stimulation of the internal globus pallidus in advanced Parkinson’s disease,” Annals of Neurology 44 (December 1998) 953961; J Ghika et al, “Efficiency and safety of bilateral contemporaneous pallidal stimulation (deep brain stimulation) in levodopa-responsive patients with Parkinson’s disease with severe motor fluctuations: A 2year follow-up review,” Journal of Neurosurgery 89 (November 1998)

7 13-718; R Kumar et al, “Pallidotomy and deep brain stimulation of the pallidum and subthalamic nucleus in advanced Parkinson’s disease,” Movement Disorders 13 suppl 1 (1998) 73-82; P Limousin et al, “Electrical stimulation of the subthalamic nucleus in adl‘anced Parkinson’s disease,” The New England Journal of Medicine 339 (Oct 15, 1998) 1105-1111;R Kumar et al, “Comparative effects of unilateral and bilateral subthalamic nucleus deep brain stimulation,” Neurology 53 (Aug 11,1999) 561566 E Moro et al, “Chronic subthalamic nucleus stimulation reduces medication requirements in Parkinson’s disease,” Neurology 53 (July 13, 1999) 85-90. 13. E B Montgomery Jr et al, “Chronic thalamic stimulation for the tremor of multiple sclerosis,” Neurology 53 (Aug 11, 1999)625-628. 14. J K Krauss et al, “Bilateral stimulation of globus pallidus internus for treatment of cervical dystonia,” Lancet 354 (Sept 4, 1999) 837-838.

National Blood Shortage Becoming Critical in United States The majority of American Red Cross (ARC) blood service regions are operating with less than one day’s supply of blood, according to a July 12,2000, article. This means catastrophe could possibly follow. “A blood shortage is a disaster, and we need the same level of public support for this disaster as we do for a hurricane, tornado, flood, or fie,” said Bernadine Healy, MD, president and chief executive oficer of the ARC. “Patients who need blood in emergency situations absolutely depend on a readily available supply.” Washington, DC; Philadelphia; Baltimore; Los Angeles; and Detroit have been hit especially hard by the blood shortage. With a limited blood supply, surgical procedures, organ transplantation, and routine medical procedures become more dangerous. Reasons for the blood shortage include increased use of blood for more advanced procedures (eg, autologous bone marrow transplants) and a public misperception that enough blood is available. A survey conducted by the ARC in the spring

of 2000 showed that 76% of Americans expect blood will be available for them if needed, and 72% underestimate the demand for existing blood. Another issue arises during a blood shortagepossible ramifications during a major crisis (eg, hurricane, earthquake). Blood shortages normally occur in areas where disasters strike. All ARC blood service regions need to be fully operational to effectively supply blood during a major crisis, allowing blood to be moved from one part of the country to another. The current shortage is pushing the system to its limits. In 2000, the ARC has seen an increase in blood collections; however, higher demand from hospitals has fueled the shortage. The ARC’S blood distribution to hospitals was up 5.8% in April and 6.1% in May.

B OMnger, ‘Red Cross calls national blood shortage ‘a disaster.‘“ TheAmerican Red Cross. Available from http:/%vww.r&dcross.org/newdinthnews/00n-T 20-00.html. Accessed 19 July 2000. 408

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