Patients selection for awake neurosurgery.

2009·0.36 MB·English

by  Dreier, J D

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ORIGINAL ARTICLE
Endorsed by
19
Patients selection
for awake neurosurgery
J.D. Dreier1, B. Williams2, D. Mangar2,3, E.M. Camporesi2
¹Critical Care Fellow, Department of Anesthesiology and Critical Care Medicine, University of South Florida, Tampa, Florida;
2Professor of Surgery / Anesthesiology Professor of  Molecular Pharmacology & Physiology
University of South Florida College of Medicine Tampa General Hospital;
3Chief of Anesthesiology Services; Chief of Staff, Tampa General Hospital, Tampa, Florida
ABSTRACT
Background: Based upon the surgical location and indication, including redundant regions, eloquent areas,
deep brain stimulation, and epilepsy foci, some patients will benefit from an awake craniotomy, which allows
completion of neurocognitive testing during the intra-operative period. This paper suggests patient selection
criteria through a new decision algorithm.
Methods: We completed a retrospective chart review at Tampa General Hospital after IRB approval; data were
obtained concerning total number of craniotomies, indications, and problems experienced for selection of
awake vs. general anesthetic techniques.
Results: A total of 397 craniotomies were performed during the two years 2005 and 2006: among those 79
patients received an awake craniotomy (20%). We have utilized a sedation sequence which includes dexme-
detomidine, propofol and LMA placement. A skull block is then performed to anesthetize pin placement, and
desflurane and remifentanil are used for maintenance until the dural incision. At this time the inhalation agent
is stopped and the LMA is removed while breathing spontaneously: the patient remains sedated on dexmedeto-
midine and remifentanil for the duration of the operation and can communicate effectively if closely coached.
Analysis of all patient data led us to a decision tree to guide the surgeon and anesthesiologist in selecting the
awake patients.
Discussion: We describe the sequence of steps and anesthetic agents which has proved successful for our
group. Finally, the use of the proposed decision algorithm simplifies preoperative anesthetic selection and pre-
vents erroneous assignment of inappropriate patients to an awake technique.
Keywords: awake craniotomy, anesthesia for neurosurgery, patient selection.
INTRODUCTION control of ventilatory level, and rapid emer-
gence for rapid neurological evaluation.
There is a paucity or absence of studies re- Current practices vary, and include the use
porting data on patient outcome, following of general anesthesia involving volatile or
awake or asleep craniotomies. The ideal intravenous anesthetics, or a combination
anesthetic for neurosurgical procedures of both, as well as awake techniques (1),
should provide optimal surgical conditions, each of which has benefits and drawbacks.
stable hemodynamics, appropriate cerebral The awake anesthetic technique for elec-
oxygen supply and demand, a secure airway, tive craniotomy is usually selected based on
surgical indications, such as supratentorial
Corresponding author: cortical tumors, thalamic and brainstem tu-
Enrico Camporesi, MD mors or removal of epileptic foci.
Professor of Surgery/Anesthesiology
Professor of Molecular Pharmacology & Physiology; The precise location of different tumors
University of South Florida College of Medicine
causes significant consequences in regards
Tampa General Hospital
1, Tampa General Circle Drive - Suite G 214 to the anesthetic choice. Amongst all pa-
Tampa, Florida 33606
e.mail: [email protected] tients, approximately 65-70% of tumors
J.D. Dreier, et al.
20 are located in the redundant cortex, 10- choose the anesthetic technique based on
15% in eloquent regions such as the mo- surgical indication and few additional cri-
tor/sensory strip and speech/language cen- teria. In this paper we describe an awake
ters and a final 10-15% in the thalamic re- craniotomy technique that is commonly
gion (2, 3). Because of tumor location, the used in our practice.
first group of interventions can be usually
completed with general anesthesia, while
the remaining 30% would most likely re- METHODS
quire an awake craniotomy, in order to
map eloquent regions and permit evaluat- We completed a retrospective chart review
ing responses to deep brain stimulation of all craniotomies performed at our Insti-
and/or recognize onset of seizures. Patients tution in 2005 and 2006. Tampa General
undergoing resection of seizure foci might Hospital is a large, tertiary-referral center in
also require awake craniotomy, as these Tampa, along the western coast of Florida.
regions are often located in proximity of After obtaining approval for the retrospec-
speech and language centers. Piccioni and tive review from the University of South
Fanzio have recently described a variety Florida IRB, charts were abridged and data
of techniques in the current literature (4). obtained concerning description of the type
Advances in neurosurgical technique have of craniotomies, indications, and anesthet-
utilized automated stereo-tactic navigation ic technique. During the two years study
equipment to aid in the complete removal period (2005 and 2006), 397 craniotomies
of supratentorial pathology. Crucial to this [64% were male (N=254) and 36% female
system, however, is the maintenance of (N=143)] were completed at Tampa Gen-
proper alignment between the patient and eral Hospital by the faculty from the depart-
the navigation system, which is challeng- ment of Neurosurgery at the University of
ing for the awake participant. Regardless of South Florida. Amongst these patients, 79
the technique used, an established method (20%) received an awake anesthetic tech-
of firmly stabilizing the head is necessary nique: 64 of the awake patients (81%) re-
when performing intracranial microsurgi- ceived awake craniotomy for epileptic foci
cal procedures. Utilization of regional an- while 15 patients (19%) received awake
esthesia (skull blocks) with a combination craniotomy for eloquent regions. A further
of short and long-acting local anesthetic breakdown revealed that craniotomies were
offers benefits for both general and awake performed for supratentorial and brain
craniotomy, allowing for intra- and post- stem tumors, epileptic foci resection, or re-
operative pain control as well as decreased section for vascular abnormalities (Table
needs for sedation during pin placement, 1). Amongst the 110 supratentorial tumors
skin incision and craniectomy (5).
There has been no consensus on indica- Table 1 - Indications for craniotomy performed at
tions, inclusion and exclusion criteria in Tampa General Hospital in 2005 and 2006.
the literature: in order to determine the best Number
Surgical Indication Percentage
fit between a patient and the indication for of Patients
awake supratentorial craniotomy the data- Supratentorial Tumor 110 27%
base of all craniotomies performed at our
Brain Stem Tumor 26 6%
institution during 2005 and 2006 were
Vascular Abnormality 186 46%
retrospectively reviewed, in order to iden-
Epileptic Foci 75 21%
tify selection criteria to aid the clinician to
Patients selection for awake neurosurgery
resected, 77 (70%) were in redundant re- a skull block is performed with 30 ml of 21
gions, 17 (15%) in eloquent regions, and 0.5% bupivacaine and the placement of an
16 (15%) in the thalamus. arterial line.
This review also revealed that the patients
selected for the “awake” technique needed Skull Block Technique
to provide enthusiastic cooperation. This Appropriate doses of different local an-
section required excellent communication esthetic agents used are listed in Table 2,
between the surgeon and the anesthesiolo- while an anatomical drawing of injection
gist, as well as accepting of a prolongation sites is illustrated in Figure 1. Injected vol-
of the surgical time required for the need umes may need adjustment to ensure that
of awake testing and for the additional re- less than toxic levels of local anesthetic are
quirement at an early stage to initiate skull used, although the volumes of these injec-
blocks for the insertion of pins. tions are kept relatively small (6-8). The first
nerve block starts with the supraorbital and
Common Sequence for “Awake” supratrochlear nerve and then progresses to
Craniotomy involve the auriculotemporal, postauricu-
The common sequence of steps executed lar, greater, lesser and third occipital nerves.
at our institution when providing anesthe-
sia for awake craniotomy comprise first, a Table 2 - Anesthetic technique; awake versus general in
loading dose of dexmedetomidine 0.5 mcg/ supratentorial craniotomy subgroups.
kg over 20 minutes in the pre-operative Local Anesthetic Volume
holding area, followed by an intra-operative
0.5% Bupivacaine 30 ml
infusion rate of 0.4 to 1.0 mcg/kg/h. Induc-
0.75% Ropivacaine 20 ml
tion of anesthesia is accomplished with
propofol (3 mg/kg), followed by laryngeal 0.5% Bupivacaine + 1%
15 ml + 15 ml
mask airway (LMA) placement. Finally, Lidocaine
Supratrochlear nerve
Supra-orbital nerve
Zygomatico-temporal
Auriculo- Supra-orbital n. nerve
temporal n.
Supratrochlear n.
Zygomatico- Auriculo-temporal
temporal n. nerve
Lesser
occipital nerve
Third
occipital nerve
Figure 1
Skull block diagram for cranial vault analgesia. Full circles are indicating major insertion points for nee-
dle placement, • = injection sites. Adapted from Pinosky PL, Fishman RL, Reeves ST, Harvey SC, Patel
S, Palesch Y, Dorman H. The Effect of Bupivacaine Skull Block on the Hemodynamic Response to Crani-
otomy. Anesth Analg, 1996; 83: 1256-61.
J.D. Dreier, et al.
22 The supraorbital and supratrochlear nerves General Anesthetic Technique
are blocked with 2 mL of solution injected Induction is with fentanyl 2-4 mcg/kg,
just superior to the supraorbital foramen at propofol 3 mg/kg, lidocaine 1-2 mg/kg, and
the supraorbital ridge. The auriculotempo- rocuronium 0.6 mg/kg, followed by endo-
ral nerves, branches of the trigeminal (V3) tracheal intubation.
are blocked next with 5 mL of solution in- A skull block as previously described is
jected 1.5 cm anterior to the tragus of the then also performed. Maintenance of anes-
ear. Care should be taken while infiltrating thesia includes remifentanil 0.05-0.1 mcg/
these nerves, as there is potential to block kg, isoflurane up to 0.5 MAC, and intermit-
the facial nerve as well at this location. tent boluses of rocuronium to maintain 1 of
Therefore, the injection is performed just 4 Train-of-Four twitch.
deep to the subcutaneous tissues. Next, the
postauricular branches of the greater auric-
ular nerves are injected with 2 mL of solu- RESULTS
tion 1.5 cm posterior to the antitragus. The
greater, lesser, and third occipital nerves are Distribution of anesthetic techniques can
injected last with 5 mL of solution. This is be found in Table 3. This table illustrates
accomplished by inserting a 22 gauge spinal that most of the patients having neurosur-
needle at the mastoid process and injecting geries for eloquent regions and epileptic
along the nuchal ridge until the midline is foci were predominantly selected for an
reached (6). The concentrations of local an- awake craniotomy technique, denoting the
esthetic can be manipulated based on the preference of our surgery/anesthesia team
anesthetic goals of intra-operative or post- for this technique in both these groups. Of
operative pain control. the patients with a lesion in the eloquent
Scalp incision, craniectomy, and dural re- region, two were unable to undergo awake
section proceed, while the patient is spon- anesthesia.
taneously breathing 0.5 MAC of desflurane. The first patient was 14 years old, unable to
At this time a remifentanyl infusion (0.1- cooperate, while the second patient spoke
0.2 mcg/kg/min) is usually started, the des- only Korean and an appropriate interpret-
flurane is discontinued and the LMA can be er was not available. In the epileptic foci
removed. Patients are then able to converse group, 11 patients were unable to receive
with the surgical team and neurocognitive awake anesthesia. Four patients refused, 6
testing is accomplished, followed by tumor were less than 10 years old and unable to
or epileptic foci resection. At the conclu- cooperate, and 1 had altered mental status.
sion of the procedure the dural closure and The criteria for the selection of patients for
craniectomy closure proceed while the pa- awake craniotomy group was based on two
tient is still awake, although at times pa- major principles, the first being patients
tients need to be anesthetized at this stage who needed surgery within an eloquent ar-
for the completion of the procedure. eas or patients with epileptic foci and sec-
Table 3 - Three common local anesthesthetic concentrations and total volumes necessary for skull block.
Awake Anesthetic General Anesthetic
Procedure
(Number of Patients/Percent) (Number of Patients/Percent)
Eloquent Regions 15/88% 2/12%
Epilepsy Surgery 64/85% 11/15%
Patients selection for awake neurosurgery
ondly, the patients’ willingness to partici- of a decision-tree algorithm to assist the team 23
pate in awake craniotomies. in choosing appropriate patients (Figure 2).
Results drawn from our retrospective study This algorithm fits all individual cases ob-
illustrated that patients selected for the served in these two years and would have
awake craniotomy did not experience any excluded all patients who were not appro-
major complications from airway obstruc- priate candidates. Presently this algorithm
tion, local anesthetic toxicity, and did not continues to be used for forward selection
require re-intubations during the proce- of patients who will require an “awake”
dure or post-operatively, nor complained craniotomy.
of severe pain from rigid head pin fixation.
However, these patients experienced ex-
tended surgery duration, compared to pa- DISCUSSION
tients in the general anesthesia group.
In conclusion, our surgeons demonstrat- Utility of the “awake” technique
ed a preference for the awake craniotomy Patients undergoing craniotomy for resec-
technique for patients with supratentorial tion of tumors and epileptic foci in many
tumors, epileptic foci, and other lesions in circumstances benefit from techniques in-
the eloquent areas, with the aim to mini- volving at least some wakeful period with
mize complications, maximally resect the opportunity for intraoperative communi-
lesions as well as sparing motor, sensory cations. Patients can be selected for awake
and language areas. craniotomy when the planned procedure
Based on these data we can propose the use involves eloquent areas of the brain, and
Figure 2
Decision tree.
Supratentorial
craniotomy
Yes Eloquent region No
deep brain stimulation
epilepsy surgery
Child
altered mental status Yes General Anesthesia
language barrier for craniotomy
patient refusal
No
Awake craniotomy
J.D. Dreier, et al.
24 an awake cooperative patient is capable to midine infusion, respiratory depression has
undergo neurocognitive and sensory-motor been shown to cause complications. Awake
testing in order to minimize postoperative and asleep-awake-asleep sequences can be
neurological dysfunction. The patient must accomplished utilizing several total intrave-
be comfortable during the procedure, which nous anesthetic (TIVA) techniques. Drugs
can be very lengthy, yet still be alert enough such as propofol, remifentanyl and dexme-
to cooperate and participate in complex detomidine have been described as combi-
neurological and cognitive testing. nations in the literature.
Localization of the motor and sensory cor- As an example, one of such techniques in
tex is important to minimize the risk of con- the literature (12) utilizes both intra-ve-
tralateral motor and sensory deficits result- nous and regional anesthesia: In this case,
ing from surgical procedures in its vicinity. general anesthesia was induced at the onset
The location of primary motor cortex var- of the procedure with a combination of IV
ies to a high degree. Direct cortical stimula- infusions of propofol 75 mcg/kg/min and
tion of the brain surface is one technique of remifentanil 0.1 mcg/kg/min along with
localization that allows patients to respond intermittent boluses of propofol (10-20 mg)
when motor regions are stimulated. as needed, until loss of lid reflex. Sponta-
The opportunity to perform intraoperative neous ventilation was maintained through-
neurocognitive and language testing de- out the procedure. The Mayfield pin head
creases the chance of permanent disability holder was applied after anesthetizing the
(3) leads to decreased incidence of postop- pin sites with a local anesthetic consisting
erative seizure (3, 9) reduces hospital stay of equal volumes of 1% lidocaine with epi-
(3, 9) and necessitates fewer invasive mon- nephrine 1:100000 and 0.25% bupivacaine
itors (9). with epinephrine 1:200000.
However when awake methods are con- A six-point scalp block was placed using the
traindicated or impossible to continue, same local anesthetic. A total of 20 mL of
evoked potentials may be used even in the local anesthetic mixture was used for both
anesthetized, paralyzed patient (10) and procedures. Incision, bone flap removal,
provide the anesthesiologist and surgeon and dural opening proceeded without in-
some information in regards to the motor cident in all cases. Neurocognitive testing
and sensory cortex. was completed over an average of forty-five
When recording somatosensory evoked po- minutes.
tentials (SSEP), the primary sensory cor- All patients in this series tolerated the pro-
tex and motor cortex generate potentials cedure well and reported high satisfaction
that are mirror images of each other. This postoperatively in regards to incidence of
“phase reversal” across the central sulcus post-op nausea and vomiting (PONV) and
is a highly reproducible characteristic that recall (12). However respiratory depression
can aid in the localization of the primary was noted in over 33% of the subjects. Ke-
motor and sensory cortex (11). ifer et al. (13) reports similar results in re-
gards to respiratory depression (i.e., PaCO
2
Common Pitfalls of “awake” techniques 50 mm Hg, range: 36-69 mm Hg, minimum
Neuroleptic anesthesia, propofol with or respiratory rate 0, range 0-3 breaths/min,
without opioid infusions, and asleep-awake- lowest SaO 95%, range: 92-98%) dur-
2
asleep (AAA) techniques with laryngeal ing awake craniotomy and reaffirms that
mask airways have been used, but in all “some” patients required laryngeal mask
combinations, except solitary dexmedeto- airway or endotracheal tube placement dur-
Patients selection for awake neurosurgery
ing the operation; however, this was usually preserved during the administration of all 25
easily accomplished when necessary. intravenous drugs (15).
Novel agents such as dexmedetomidine Similarly, Petersen et al. (16) compared two
have been recently proposed as sparing re- general anesthetic techniques: all patients
spiratory depression, but this has not been received 0.9% NaCl at a rate of 2 to 3 mL/
extensively documented. In this regard, kg before induction. After obtaining base-
Mack et al. describe a series of 10 patients line values, anesthesia was induced with
that received a dexmedetomidine load of propofol (1.5-2 mg/kg) in both groups. Af-
0.5 to 1.0 mcg/kg over 20 minutes followed ter the induction of anesthesia, patients
by an infusion at rates of 0.1 to 1.0 mcg/ were randomized to a desflurane-remifen-
kg/h. The dexmedetomidine infusion was tanil group (n=30; 50% nitrous oxide in
continued throughout initial evaluation; all oxygen, 1.5%-2% desflurane, and 0.25 mg/
patients underwent motor or neurocogni- kg/min remifentanil continuous infusion)
tive testing, based on the particular areas or or a desflurane (n=30; 50% nitrous oxide
regions of cortical or subcortical resection. in oxygen and up to 6% desflurane-fenta-
Infusion continued throughout the proce- nyl group). Before intubation, fentanyl (2
dure and stopped once the dressings were mcg/kg) was administered in the desflu-
in place (14). rane-fentanyl group and remifentanil (0.5
Multiple reports describe general anesthet- mcg/kg) was administered in the desflu-
ics, including volatile only and volatile- rane-remifentanil group. Muscle paralysis
intravenous combinations. All the volatile was induced with administration of intra-
anesthetics cause dose-dependent cerebral venous vecuronium bromide (0.1 mg/kg).
vasodilation. The net effect on cerebral For the desflurane-fentanyl group, after
blood flow of introducing a volatile an- endotracheal intubation, the concentration
esthetic will depend on the interaction of of desflurane was reduced to 2% to 3%.
several other factors: concentration of the Before application of the head holder and
anesthetic, the extent of previous cerebral performance of the skin incision and cran-
metabolic rate depression, simultaneous iotomy, fentanyl was repeated at the same
blood pressure changes acting in conjunc- dose. All patients received appropriate ste-
tion with previous or anesthetic-induced roid therapy and mannitol infusion (0.2 g/
autoregulation abnormalities, and simulta- kg). No significant differences in outcome
neous changes in PaCO acting in conjunc- were found between the two groups and are
2
tion with any disease-related impairment therefore equally acceptable (17).
in CO responsiveness. Inhalational agents It has been postulated that emergence time
2
cause vasodilation, leading to increases in may be decreased following an awake cran-
cerebral blood flow and increases in intrac- iotomy procedure and will facilitate early
ranial pressure in the closed cranium. How- evaluation of the patient’s neurological sta-
ever, according to Holmstrom, increases in tus. However, techniques including propo-
cerebral blood flow are agent-dependent, fol/remifentanil, remifentanil/isoflurane,
with Desflurane inducing changes larger sevoflurane/remifentanil, and desflurane/
than Isoflurane, and respectively larger remifentanil all show similar emergence
than Sevoflurane at 1.0 Mac; but at values times and vary between 3 and 10 minutes
less than 0.5 Mac and at low doses the dif- (1,4, 17). All these times are quite reason-
ference between agents becomes negligible. able in regards to evaluation of neurologi-
It also appears that for the most part, au- cal function postoperatively. Awake cran-
toregulation and CO responsiveness are iotomy does not require an “emergence,”
2
J.D. Dreier, et al.
26 however as the emergence time for general and awake craniotomy). IL-8 levels did not
anesthesia is significantly small, no real dif- significantly change with time, nor did for
ference exists. IL-10 values.
These results showed that patients under-
Proposed advantages of Awake Craniotomy going awake function-controlled cranioto-
In a recent study published by Pirjo H et al. my experience less postoperative pain for
(18), the authors explored the clinical im- the first 12 hours than their general anes-
pression that patients who undergo awake thesia counterparts, having a decrease also
craniotomy have less PONV (Nausea and in the immunologic and strees and pain re-
Vomiting) and require fewer analgesic sponses.
drugs for pain control than patients who
have a general anesthetic. They found in
fact that the volatile general anesthetic was CONCLUSIONS
a risk factor for PONV: nausea occurred
less often in the awake craniotomy group, The anesthetic management of patients for
but this difference was short-lived. Patients craniotomy and intraoperative neurocogni-
who had an awake craniotomy for tumor tive testing present the challenges of pro-
surgery had less PONV and received fewer viding analgesia, sedation, patient comfort,
antiemetics when compared with patients avoiding airway obstruction, hypoventila-
having a general anesthetic, but only in the tion, and hypoxemia. The assortment of
first 4 postoperative hours. Another recent techniques, general, neuroleptic anesthesia,
study by Bilotta and Rosa (19), supported propofol infusion with or without remifen-
local anesthesia for awake craniotomy stat- tanil, and asleep-awake-asleep maneuvers
ing that adequate local anesthesia, aimed to with dexmedetomidine all have benefits
block the sensory branches of the trigeminal and disadvantages.
nerve, is sufficient to provide ‘anesthesia’ Based on the review of the cases completed
for awake neurosurgery. Scalp block with in two years at our Institution we generat-
local anesthetic provides reversible regional ed a decision tree algorithm that will assist
loss of sensation, reduces pain perception the anesthesia provider in choosing the ap-
and global energy expenditure. propriate patient for awake supratentorial
Not only was the anesthesia management craniotomy.
better tolerated by the patients but also the A careful approach to the patient will pro-
inflammatory response was less in patients vide optimal surgical conditions, appropri-
with awake craniotomy, as this is considered ate cerebral oxygen supply and demand, sta-
a stressful procedure because being awake ble hemodynamics, a secure airway, control
while a neurosurgeon removes pathological of ventilatory parameters, rapid emergence
brain tissue appears connected to a more and minimization of complications with
intense emotional response than undergo- both awake and/or general techniques.
ing the same procedure under general anes- Careful attention to tumor location, physi-
thesia. However, perhaps good psychologi- ological parameters, anesthetic concentra-
cal support and active coping mechanisms tions and the operative field allow the anes-
may actually make awake craniotomy less thesiologist to administer a safe anesthetic.
stressful for the patient. A recent study by
No conflict of interest acknowledged by the authors. The
Klimek et al. (20), demonstrated that there
study was supported by funds from the Department of
was a significant plasma IL- 6 increase in
Anesthesiology and Critical Care Medicine, University
time for both groups (General anesthesia of South Florida, College of Medicine
Patients selection for awake neurosurgery
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