A Simple Method to Improve the Safety and Comfort of Anesthesia for Deep Brain Stimulation: Case Report and Literature Review

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A Simple Method to Improve the Safety and Comfort of Anesthesia for Deep Brain Stimulation: Case Report and Literature Review

Yi-Hui Lee, M.D.¹, Kuen-Bao Chen M.D.², Yu-Cheng Kuo, M.D.^3,4,5, Chi-Tsung

Chien, M.D.^1,6, Chia-Wen Chen, M.D.^2,7

1 Department of Anesthesiology, Sijhih Cathay General Hospital, Taipei, Taiwan

2 Department of Anesthesiology, China Medical University Hospital, Taichung, Taiwan

3 Department of Radiation Oncology, China Medical University Hospital, Taichung, Taiwan

4 Department of Biomedical Imaging and Radiological Science, China Medical University, Taichung, Taiwan

5 Department of Biomedical Imaging and Radiological Sciences, National Yang-Ming University, Taipei, Taiwan

6 Institute of Brain Science, National Yang-Ming University, Taipei, Taiwan

7 Graduate Institute of Clinical Medical Science, China Medical University, Taichung, Taiwan

Corresponding Author:

Chia-Wen Chen, MD

Department of Anesthesiology China Medical University Hospital 2 Yuh-Der Road, North District, Taichung 404, Taiwan

Tel: 886-4-22052121#3562 Fax: 886-4-22360795

E-mail: [email protected]

Running head:

Safety Anesthesia for Deep Brain Stimulation

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A Simple Method to Improve the Safety and Comfort of Anesthesia for Deep Brain Stimulation: Case Report and Literature Review

Abstract

Deep brain stimulation (DBS) is widely accepted in the treatment of Parkinson’s

disease and other movement disorder. Local anesthesia or monitored anesthesia with

or without light sedation is the most common method for patients undergoing deep

brain stimulation. Many complications occurred during this procedure while

respiratory complications are the most be feared as the fixed frame may make the

access to the patient’s airway difficult. Hereby we report a simple method using local

anesthetics to enhance tolerance of endotracheal tube with and without sedation. We

believe this modification improves the safety and comfort of anesthesia for deep brain

stimulation.

Key words:

deep brain stimulation (DBS), Parkinson’s disease, anesthesia, local anesthetic,

epidural catheter

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Implantation of deep brain stimulators is now widely accepted for the treatment

of Parkinson’s disease.^1,2,3,4 The most common anesthetic technique used for DBS

procedures was local anesthesia or monitored anesthesia using light sedation because

intraoperative evaluation of clinical signs ensures optimal placement of the

electrodes.⁵ However, airway, respiratory, neurologic, and psychologic/psychiatric

complications have been reported.⁵ In particular, the fixed stereotactic head frame

may cause difficulty in accessing the patient’s airway. DBS is a procedure which

presents many anesthetic challenges.⁵ Surgeons and anesthesiologists might meet the

dilemma between patients’ comfort and optimal surgical conditions including safety

and intraoperative neuromonitoring. Here, we presented a simple method to improve

the safety and comfort of anesthesia for DBS.

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CASE REPORT

A 67-year-old man with Parkinson’s disease was scheduled for DBS. His past

medical history included type II diabetes mellitus and hypertension with regular drug

control. Preoperative evaluation including chest X-ray, electrocardiography, and

laboratory studies revealed grossly normal except mild cardiomegaly and mild anemia

(hematocrit was 30%). In the operative room, standard monitors including

electrocardiography, noninvasive cuff blood pressure, and pulse oximeter were set and

the vital signs revealed normal with blood pressure 136/85 mmHg, heart rate 78 beats

per minute, and O₂ saturation 95% in room air. An arterial line and a large bore

venous catheter were placed for closely blood pressure monitoring and preventing

accident bleeding during the operative period. We modified the 7.5mm ID nasal

endotracheal tube (ETT) with an epidural catheter (B|BRAUN, Perfix^®catheter, 20G)

which tip was fixed above the distal end of the cuff at a distance of 1mm away (Fig.

1). The patient was premedicated with intravenous injection of midazolam 1 mg and

alfentanil 500μg. After adequate preoxygenation, the patient was intubated using this

modified nasal ETT awakely under fiberscopic guidance. 2ml of 2% lidocaine was

infiltrated around the modified ETT cuff intermittently via the epidural catheter

during the procedure to reduce the stimulation of the ETT cuff. We used total

intravenous anesthesia with infusion of alfentanil (0.3-0.5μg/kg/min) and

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dexmedetomidine (0.3-0.5μg/kg/hr) intermittently during the periods without neural

intervention and testing. Additional intravenous bolus of propofol 10-20 mg was

performed only when the patient was more anxiety and restlessness. Total intravenous

anesthesia was stopped before stimulation testing to allow the patient to be awake and

cooperative. The patient’s ventilation was maintained with spontaneous breathing in

FiO₂ 50%and the tidal volume was kept about 350-500 ml._.The whole course was

smoothly completed in this four-hour operation and the patient kept spontaneous

breathing without any bucking or coughing, and remained hemodynamically stable.

No hypoxemia or hypercarbia was noted intraoperatively. At emergence from the

DBS procedure, the patient was waked and smoothly extubated. No further

complications were noted in postoperative follow-up.

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DISCUSSION

DBS at high frequency was first used in 1977 to replace thalamotomy in treating

the characteristic tremor of Parkinson’s disease, and has subsequently been applied to

the pallidum and the subthalamic nucleus (STN).⁶ It is increasingly accepted in the

treatment of Parkinson’s disease and other movement disorder, such as cerebellar

outflow tremors, and dystonia.^7,8,9 The common anesthetic aims are to: (1) provide

patient comfort and optimal surgical conditions such as hemodynamic stability and

respiratory sufficiency, (2) facilitate intraoperative monitoring, including

neuromonitoring for target localization, and (3) rapidly diagnose and treat any

complications. Numerous anesthetic techniques have been described including and

“awake” technique with local anesthesia or scalp nerve blockade, monitored

anesthesia with intravenous sedation, and general anesthesia. Among these, local

anesthesia or monitored anesthesia care with or without light sedation is most popular

in DBS procedures.

However, surgeons or anesthesiologists meet the dilemma between patients’

comfort and optimal surgical conditions since these patients frequently are in old age

with complex medical problems^{10, 11} as well as their more severe condition for

movement disorders. Since the patients are unable to alter their position with head

fixed via the head frame to the operation table once the procedure is underway, these

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procedures with long duration might cause patients discomforts and anxiety under

local anesthesia or nerve blockade and thus influence their hemodynamic stability.

Further tremors, agitation, seizures, and even fatigue, might also happen. All of these

increase the risk of perioperative neurologic complications, including intracranial

hemorrhage as well as cardiovascular events. In addition, the DBS procedure using

monitor anesthesia with light sedation might cause patients to be difficulty in

breathing or even complete airway obstruction,¹² which interferes the proceeding and

the safety of the operation.

General anesthesia has also been used for patients underwent DBS, especially for

those unsuitable for a conscious technique, such as those with concurrent psychiatric

problems, discomfort due to off-period dystonia, or severe anxiety with associated

hypertension. However, almost all analytic or anesthetic drugs might have adverse

effects on neurophysiologic monitoring⁴ thus make the intraoperative assessment of

motor disability and dyskinesia being impossible. Although some believes general

anesthesia has no significant impact on clinical surgical results,¹³ there are still

debates of this opinion. A retrospective study on the effect of general anesthesia

showed that the residual motor disability and intensity of stimulation appeared to be

slightly higher in patients under general anesthesia, implying that STN stimulation

was less precise the absence of intraoperative clinical assessment.¹⁴

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In our case, we chose monitored anesthesia with light sedation only during the

period of nonintervention, which provide more comfort and safety for our patient as

well as minimize the disturbance of neuromonitoring. We used alfentanil and

dexmedetomedine because of their short duration. They were only given during the

periods of nonintervention to reduce their mental stress, and the infusions were

stopped before stimulation testing to allow the patient to be awake and cooperative to

participate the physiologic localization and neuromonitoring.⁵ In addition, the use of

dexmedetomedine for sedation during deep brain stimulator insertion was shown to

result in better control of blood pressure and need less antihypertensive medications.¹⁵

Besides, respiratory complications must always be aware because of the fixed

stereotactic head frame could make access to the patient’s airway difficult or even

impossible¹² during emergent condition. This should be taken more concern even in

local anesthesia or if the sedatives or anesthetics have been used, which might

suppress respiratory driving in turns inducing further hypoxemia or hypercarbia.

Although the rate of perioperative risks is around 1.6%,¹⁶ patients’ weaker

cardiopulmonary reserve may arise not only from old age and co-morbidities, but also

from Parkinson’s disease which, itself alone, might cause patients’ pulmonary

function impairment.¹⁷ We used preoperatively nasal ETT intubation for preventing

further pulmonary complications while our patient is awake. Intratracheal local

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anesthetics infiltration through the epidural catheter reduced the discomfort and

stimulation of ETT cuff, while also inhibited cough reflex through the complete

course. It decreases the risks of respiratory suppression by sedatives, which might

cause hypoxemia or hypercapnia, both in turn result in increasing intracranial pressure

and neurological complications.¹⁸

This application is similar to the technique used by Huncke et al.¹⁹ for

awake-asleep-awake techniques in awake craniotomy. Patients could well tolerate the

ETT being awake and cooperative during the periods of nonintervention and

neuromonitoring with suspending intravenous medications. The patient could be

spontaneously breathing,and gentle assisted manual ventilation was only given to

maintain adequate tidal volume. End-tidal carbon dioxide could be monitored for

detecting venous air embolism. Modifications using extraglottic airway devices such

as laryngeal masks are also widely used,²⁰ but ETT intubation still provides more

securing ventilation without needs for emergent airway management as mal-position

of these devices. In addition, the late stages of Parkinson’s disease present high

incidence of aspiration pneumonia.¹⁷ In these cases, ETT provides better manual

assisted ventilation than extraglottic airway devices for decreasing the risks of gastric

aspiration²¹ and hypercapnia.

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CONCLUSION

At present, there are still no studies comparing different anesthetic techniques

and perioperative risks for DBS procedures. The balance between patient’s comfort

and surgical consideration for anesthesiologists is challenging and, thus, might be also

considered case by case. In our opinion, a good ventilation support as we use provides

benefits for reducing not only respiratory but also possible neurological complications,

especially in patients with more severe condition. Further risk-to-benefit assessment

needs more prospective studies.

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Figure Legend

FIGURE 1. The modified nasal ETT to facilitate tolerance of intubation during

DBS procedure. The modified ETT is a regular tracheal tube with an epidural

catheter (B|BRAUN, Perfix^®catheter, 20G) fixed along the wall of the lesser curvature

of the ETT by a 3M^TMTrgaderm^TM under aseptic technique. The tip of epidural

catheter was fixed above the distal end of the cuff at a distance of 1 mm away (black

arrow). Local anesthetics was infiltrated around the ETT cuff via the epidural catheter.

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Figure 1.