Initial assessment of efficacy and safety of spinal anesthesia combined with obturator nerve block for transurethral resection of bladder tumor

JOURNAL OF MILITARY PHARMACO-MEDICINE N07-2016

INITIAL ASSESSMENT OF EFFICACY AND SAFETY OF SPINAL
ANESTHESIA COMBINED WITH OBTURATOR NERVE BLOCK
FOR TRANSURETHRAL RESECTION OF BLADDER TUMOR
Nguyen Trung Kien*; Hoang Van Chuong*; Tran Van Hinh*
Nguyen Phu Viet*; Pham Quang Vinh*
SUMMARY
Objectives: To assess the efficacy and safety of spinal anesthesia combined with obturator
nerve block (ONB) for transurethral resection of bladder tumor. Subjects and methods: A
prospective study was carried out on 10 patients who underwent spinal anesthesia combined
with ONB using nerve stimulation for transurethral resection of bladder tumor. Quality of
anesthesia, violent adductor contraction and inadvertent bladder perforation as well as side
effects were monitored. Results: All patients had an excellent quality of anesthesia, distance
from skin to obturator nerve was 2.6 ± 1.4 cm on everage, 9 patients were absent of leg jerking.
Side effects included shiving in 2 cases, hypotension in 1 case and bradycardia in 1 case.
Conclusion: Combination of spinal anesthesia and ONB provided good effective anesthesia for
transurethral resection of bladder tumor: adductors muscle spasms were absent in 90%, side
effects were transient and mild.
* Key words: Bladder tumor; Spinal anesthesia; Obturator nerve block; Transurethral resection
of bladder tumor.

INTRODUCTION
Bladder cancer is the fourth most
common cancer in men in the world. The
obturator nerve may be accidentally
stimulated during transurethral resection
of lateral bladder wall tumors, causing
adductor contraction. Spinal anesthesia is
a favoured anaesthetic technique but the
rate of adductor spasm can get as high as

40% [3]. That is also the main reason
leading to bladder wall perforation and
increase
morbidity.
Methods
of
preventing the stimulation of the obturator
nerve include: reduction of the
electrocautery power, bipolar resection,
general anesthesia, or ONB following
spinal anesthesia [8]. The objective of this
study is: To assess the efficacy and
safety of combination of spinal anesthesia

and ONB for transurethral resection bladder
tumor.
SUBJECTS AND METHODS
1. Methods.
A prospective study was conducted
from 6 - 2015 to 6 - 2016 to assess the
efficacy and safety of combination of
spinal aneshthesia and ONB using nerve
stimulator in 10 patients who underwent
transurethral resection bladder tumor.
- The patients were admitted into
operating room, and established intravenous
access for 0.9% of NaCl infusion. Constant
monitoring was ensured of ECG, heart
rate, pulse oxymetry (SpO2); non-invasive
blood pressure measurements were taken

every 2.5 minutes; oxygen was delivered
3l/mins via facemask.

* 103 Hospital
Corresponding: Nguyen Trung Kien ()

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JOURNAL OF MILITARY PHARMACO-MEDICINE N07-2016

- Spinal anesthesia was performed in
the sitting position, most frequently in the
L3-L4 or L2-L3 space with the dose of 8 10 mg of hyperbaric bupivacaine 0.5%
depending on the patient’s status and 20
mcg of fentanyl. Betadine was used for
skin antisepsis before inserting the spinal
needle.
- 25G spinal needle was inserted,
when cerebral spinal fluid was free, the
mixture of bupivacaine - fentanyl was
slowly injected into intrathecal space and
then placed in the supine position.
- Bilateral ONB was then performed: a
100 mm long stimuplex needle (B. Braun,
Melsungen, Germany) that was connected
to a stimulating current at 2 mA was inserted
2 cm caudally and laterally to the pubic
tubercle. The needle was then slowly
introduced below the horizontal remus of

the pubis and inserted deeper until its tip
laid in the obturator canal. The optimal
needle position was reached when the
minimal stimulating current (< 0.5 mA)
induced adductor spasm. Once this position
was reached, 10 mL of 2% lidocaine were
injected. The whole procedure was repeated
on the other side.

blocked conduction in the sensory nerve
fibers of the bladder, the patient was
placed in the obstetric position.
- The quality of anesthesia was judged
on a 4 point scales as:
+ Excellent: no pain or sensation.
+ Good: mild pain or discomfort.
+ Fair: mild discomfort that required
analgesia.
+ Poor: patient in moderate or severe
pain that required general anaesthesia.
- The duration of spinal anaesthesia
was defined as the period from spinal
injection to the first time when the patient
requested for analgesia in the postoperative
period.
- Monitor degree of motor block by
Bromage scale:
+ Grade 0: no motor block.
+ Grade 1: inability to raise extended
leg; able to move knees and feet.

+ Grade 2: inability to raise extended
leg and move knee; able to move feet.
+ Grade 3: complete block of motor limb.
- Monitor the distance from skin to the
abturator nerve; quality of ONB.

- Transurethral resection bladder tumor
procedure was performed.

+ Good: no reflexes from the obturator
nerve during procedure.

- Materials and devices: stimulex HNS
12, B.Braun; 100 mm long stimulex needle;
monitor Nihon Kohden (Japan).

+ Bad: had any reflexes from the
obturator nerve during procedure, bladder
perforation during electroresection and
other complications.

2. Some terms were used in the
study.
- Sensory block level on the skin was
assessed by Pin-prick test. Upon reaching
the appropriate anesthesia level T10, which

- Hypotension is difined as a fall in
blood pressure of more than 20% below
the preoperative blood pressure or a mean

arterial pressure of less than 60 mmHg.
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JOURNAL OF MILITARY PHARMACO-MEDICINE N07-2016

RESULTS
1. Patient and surgical demographics.
Table 1: Patient and surgical demographics.
Result (n = 10)
Gender: male/female
Age (mean ± SD)
2

BMI (kg/m ) (mean ± SD)
ASA grade: 1/2/3/4/5/6

8/2
48.5 ± 17.6 [42 - 69]
21.3 ± 3.4 [18.2 - 24.8]
4/3/2/0/0

Duration of taking ONB (minutes) (mean ± SD)

5.4 ± 3.7 [2.5 - 8.3]

Distance from skin to obturator nerve (cm, mean ± SD)

2.6 ± 1.4 [2.3 - 4.2]

Bilateral ONB/unilateral ONB block

10/0

Bromage score 0/1/2/3 ten minutes after spinal block

0/0/0/9

Quality of spinal anesthesia (n)
Excelent/good/mild/fair

10/0/0/0

Duration of spinal anesthesia (minutes) (mean ± SD)

226.8 ± 37.5

2. Other perioperative characteristics.
Table 2:
Result
Adductor muscle contraction n (%)
No

9 (90%)

Moderate

1 (10%)

Severe

Operation time (minutes, mean ± SD)

0
22.7 ± 9.3 [18 - 32]

Tumor size (mm) (mean ± SD)

5.2 ± 4.9 [2 - 12]

Tumor number (n) (mean ± SD)

2.1 ± 1.7 [1 - 4]

Bladder perforation (n) (%)

0

Complete resection (n) (%)
Yes

9 (90%)

No

1 (10%)

3. Vital signs.
Respiratory rate, pulse oxymetry (SpO2,), pulse rate, blood pressure were stable
and ranged in normal limitation.
* Complications and side effects (n = 4):

Shivering: 2 patients (20%); hypotension: 1 patients (10%); bradycardia: 1 patients
(10%); nausea: 0 patients (0%); anesthetic toxicity: 0 patients (0%).
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DISCUSSION
An advantage of spinal anesthesia is
that profound nerve block can be produced
in a large part of the body by the relatively
simple injection of a small amount of local
anesthesia. This technique is commonly
used for transurethral resection of the bladder
tumor. Also it has an adequate quality of
anesthesia for most kinds of intervention
in urology, but it can not prevent bladder
perforation from contracting adductor due
to stimulating during transurethral resection
of lateral bladder wall tumors. Transurethral
resection of bladder tumors which are
close to these areas may stimulate the
obturator nerve, causing violent adductor
contraction and possible inadvertent bladder
perforation. To avoid this reaction, local
anesthetic blockade of the obturator nerve
as it passes through the obturator canal is
effective in stopping adductor spasm during
spinal anesthesia [4]. Thus, we had an initial
assessment efficacy of spinal anesthesia

combined with ONB for this kind of surgery
at 103 Hospital.
In our study, mean age was in labour
age and male had a higher rate than
female. The distance from skin to
obturator nerve was 2.6 ± 1.4 cm on the
sagittal plane and the pubic tubercle
(Table 1). This result is similar to Locher’s
results when he studied in ten cadavers
(ranged from 1 to 3.8 cm) [6]. There were
10 patients who needed bilateral ONB
because two sides wall bladder of the
tumor located; of which 9 patients had not
seen adductor muscle contraction, but 1
case still had slight contraction of adductor
muscle although the quality of anesthesia
was excellent in all patients (table 2).
According to Bolat (2015) [3], adductor

muscle contraction was detected in 40%
of patients in group with spinal anesthesia
but just only 11.4% in group combined
spinal anesthesia with ONB.
The mechanism of adductors’ contraction
during this procedure have been studied.
The sensorimotor nerve arises from the
lumbar plexus at L2-L4 and in the lesser
pelvis, it is adjacent to the obturator fascia,
which covers the outer part of the internal
obturator muscle. It innervates the muscles

responsible for adducting the thigh and
the skin on the surface of the paramedian
segment of the thigh. During transurethral
resection of the bladder tumor, when the
bladder has been filled with irrigation fluid,
the obturator nerve is directly adjacent to the
lateral wall of the bladder. Any unintentional
stimulation during electroresection results
in the adductors’ contraction and resultant
sudden leg movement, which may in turn
lead to extraperitoneal perforation of the
bladder wall with the resectoscope loop.
Adductors’ contraction during transurethral
resection can cause major complications
such as bladder perforation, obturator artery
injury. We did not have any complications
due to small size of study (n = 10)... Akata
T had a case report with life-threatening
haemorrhage following obturator artery
injury during transurethral bladder surgery
as a sequel of an unsuccessful ONB.
According to this result, in spite of prior
blockade of the obturator nerve with 1%
mepivacaine (8 mL) utilizing a nerve
stimulator, violent leg jerking was evoked
during transurethral electroresection of a
bladder tumor approximately 1 hour after
the blockade. He noticed that the patient
became severely hypotensive right after
following the jerking, and a large lower

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JOURNAL OF MILITARY PHARMACO-MEDICINE N07-2016

abdominal swelling concurrently developed.
The urgent laparotomy indicated that the
left obturator artery was severely injured
by the resectoscope associated with the
bladder perforation, causing acute massive
haemorrhage [1]. Thus, combining spinal
anesthesia with ONB brought much benefit
for this procedure.
Volume and concentration of anesthetic
solution are important factors for getting
success in prevention of the obturator
nerve stimulation during the transurethral
procedures. We had an unsucessfull
case because in this patient we injected
two sites and this was not enough
anesthetic solution to cover obturator
nerve. Akata T [1] found that, in order to
attain profound blockade of the motor
neuron fibres of the obturator nerve and
thereby prevent the thigh-adductor
muscle contraction which could lead to
life-threatening situations, larger volume
of a higher concentration of local
anaesthetic with a longer duration should
be used, even with a nerve stimulator, in the

ONB for the transurethral procedures. But
failure in ONB was sometimes due to
accessory obturator nerve that was
presented in 10 - 30% of patients. Thus,
it was clinically important that it was also
considered during ONB. According to
Akkaya [2], the mean accessory obturator
nerve-pubic tubercle distance was 4 cm.
When the needle was classically penetrated
into the obturator nerve to gain access to
the accessory obturator nerve.
Obturator nerve could be blocked
through inguinal approach or intravesical
approach which had a different result
in block. We assessed this nerve via
70

inguinal approach and the rate of success
was 90%. In Tatlisen. A’s study [7], muscle
spasms were absent in 97% (n = 61) with
nerve stimulation guided for ONB.
Another study by Hizli F [4] was carried
out on 41 patients who underwent
transurethral resection of bladder tumor
with spinal anesthesia combined with
ONB. After spinal anesthesia, ONB was
performed with an inguinal approach
(n = 21) or an intravesical approach
(n = 20). In this study, 10 ml of 2%
lidocaine was used to perform the ONB.

The efficacy of ONB was significantly
higher in inguinal approach group compared
to intravesical approach group. The study
by Khorrami M [5] has shown that ONB
using stimulation guided took 5.2 to 6.7
minutes on everage. This time in my
study was 5.4 ± 3.7 minutes. In general,
it’s more accurate to determine the obturator
nerve with nerve stimulation rather than
blind technique.
Complications were not seen in the
study. Side effects were transient and mild
included shiving 20%, hypotension 10%,
bradycardia 10%.
CONCLUSION
Combination of spinal anesthesia and
ONB provided good effective anesthesia
for transurethral bladder tumor surgery:
adductors muscle spasms were absent in
90%, side effects were transient and mild.
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