Feasibility and Outcome of Endoscopic Ulnar Nerve Release in Cubital Tunnel Syndrome
Ahmed Saleh, MD
Department of Neurosurgery, Faculty of Medicine, Benha University
Abstract
Objectives: To evaluate the surgical short-term outcome of endoscopic ulnar nerve release in patients with
cubital tunnel syndrome (CTS) after at least 6-months postoperative (PO) follow-up.
Patients & Methods: The study included 17 patients; 10 males and 7 females with mean age of 31.9±5;
years. The dominant hand was affected in 9 patients (52.9%) with a mean duration of the complaints of
15±5.5 months and mean duration of preoperative conservative treatment of 8.4±2.7 months. There were 2
patients (11.8%) Dellon's grade 1, 14 patients (82.3%) were Dellon's grade 2 and one patient (5.9%) was
Dellon's grade 3. Preoperative nerve conduction studies, both sensory and motor were conducted to confirm
ulnar nerve compression at elbow level. All patients underwent endoscopic release under general anesthesia
and were followed up daily for one week, weekly for one month and then three monthly. Outcome was
judged using Modified Bishop rating system.
Results: Proximal endoscopic advancement was failed in one case (5.9%) and nerve release was completed
through an open incision. Fourteen patients (82.4%) reported significant improvement of symptoms within
the first PO 24 hours, 2 patients (11.7%) reported similar improvement on the 2nd PO day, while the patient
(5.9%) who had open completion reported improvement on the 6 th PO day. Thirteen patients had full elbow
motion within 72 hours after surgery and 4 patients within a week. After a mean follow-up duration of
12.5±2 months, 15 patients documented better improvement, 10 patients became asymptomatic, 11 patients
regained their grip strength, 14 patients had improved sensibility and 15 patients returned to their
preoperative job. Thus, according to modified Bishop Rating System, 12 patients (70.6%) had excellent
outcome, 4 patients (23.5%) had good result and only one patient (5.9%) had fair result with a total mean
score of 7.8±1.3; range: 4-9. All patients showed PO improvement of nerve conduction velocity compared
to preoperative one. Four patients had PO minor complications that resolved spontaneously. No recurrence
was reported.
Conclusion: Endoscopic cubital tunnel release of entrapped ulnar nerve is feasible, safe and easy procedure
with procedural success rate of 94.1% and high successful outcome. Moreover, it provides small
cosmetically acceptable wound with minimal PO complications and could be managed as one-day surgery.
Keywords: Cubital tunnel syndrome, Endoscopic release
Abbreviations: postoperative (PO), ulnar nerve (UN), flexor carpi ulnaris (FCU), cubital tunnel syndrome (CTS)
Introduction
With the normal motion of the elbow, the ulnar nerve is subjected to frictional injuries
and compression can occur in five anatomic points: the arcade of Struthers, a second site just
proximal to the medial epicondyle, the ulnar groove, the point between the humeral and ulnar
heads of the flexor carpi ulnaris muscle and, finally, where the ulnar nerve leaves the flexor carpi
ulnaris. According to different studies, the ulnar nerve is much more vulnerable to compression
through the previous third and fourth anatomic regions, (1, 2).
Ulnar nerve entrapment at elbow is considered the second most common compression
neuropathy of the upper limb after carpal tunnel syndrome. Neuropathy in CTS is mostly due to
alteration in the volume and the pressure of the cubital canal with flexion and extension. Elbow
flexion causes traction and excursion of the ulnar nerve leading increased intraneural pressure.
Prolong flexion of the elbow may lead to neuropathy and demyelination which is commonly
located in the bulbous swelling proximal to the entry of the nerve into the cubital tunnel. Patients
complain of numbness and/or tingling in the ulnar aspect of the hand, little and ring finger. It may
be accompanied by medial elbow pain, weakness of grip, and when severe, intrinsic muscle
wasting and static numbness, (3, 4, 5).
Non-operative treatment of CTS in selected cases may provide symptomatic relief. In
patients with early symptoms, activities and positions which produce friction from repetitive
1
elbow movements or stretching and compression of the nerve from excessive elbow flexion
should be avoided, (6). For constant pain and parasthesia, a rigid thermoplastic splint positioned in
45° of flexion can be used to decrease pressure on the ulnar nerve. As symptoms subside, patients
can wear the splint just at night, (7).
There is no standard for surgical treatment for ulnar entrapment syndrome, but there were
multiple procedures for its management including in situ decompression of the nerve, often
described as ‘‘simple decompression’’ and subcutaneous, or submuscular, anterior transposition
of the nerve, (8, 9). Minimally invasive procedures are becoming increasingly popular. Endoscopic
release is the newest of the surgical options for cubital tunnel syndrome providing multiple
advantages over the standard open techniques; namely, it can be performed through a smaller
incision and is less invasive than anterior transposition resulting in less recuperation time. It can
be performed quicker and has reported results as effective as more invasive procedures. It
provides for a limited soft tissue dissection, thereby, allowing a more rapid recovery with
minimal scarring, (10, 11, 12, 13).
The objective of the present study was to evaluate the surgical short-term outcome of
endoscopic ulnar nerve release in patients with cubital tunnel syndrome after at least 6-months
postoperative follow-up.
Patients & Methods
This prospective study was conducted at Neurosurgery Department, Military Hospital,
Riyadh, KSA since May 2009 till end of follow-up at Nov 2010. After approval of the study
protocol and obtaining fully informed patients' consent, 17 patients; 10 males and 7 females with
mean age of 31.9±5; range: 24-47 years were enrolled in the study. All patients must have a
history of failure of conservative treatment for at least six months.
All patients underwent complete history taking and clinical examination including mode
of presentation with numbness, tingling, and/or related muscle weakness. Clinical evaluation
included evaluation of 2-point discrimination, Tinel's sign, chuck and key pinch, Warternburg
sign, determination of range of elbow motion, elbow flexion test, presence of atrophy and
clawing and five-stage grip test. Preoperative nerve conduction studies, both sensory and motor
were conducted to confirm ulnar nerve compression at elbow level. Patients were categorized
according to severity of symptoms using Dellon’s grading system (14) into mild (intermittent
parasthesia and subjective weakness), moderate (intermittent parasthesia and measurable
weakness) and severe (permanent parasthesia and palsy). Patients with cervical radiculopathy,
Pancoast’s tumors and lesions of brachial plexus as well as ulnar nerve compression at other sites
e.g. Guyon’s canal or had senile intrinsic hand atrophy and dysfunction were excluded of the
study.
Surgical Procedure
All surgeries were conducted under general enodotracheal inhalational anesthesia. After
induction of anesthesia, tourniquet was applied to the upper arm. Broad-spectrum antibiotic was
injected in the other arm and was continued orally postoperatively.
Patient was placed supine on the operating table with the arm abducted 90o and the
forearm supinated and flexed. A transverse 2-3 cm long incision was made in one of the skin
creases over the humoral retrocondylar groove, and then blunt dissection was performed down to
the retrocondylar tunnel roof which was opened so as to identify the ulnar nerve which is
recognized by the vasa nervorum. The cubital tunnel was sufficiently opened and dissected
bluntly so as to allow trocar placement within the cubital tunnel without binding. A spatula was
placed between the ulnar nerve and the roof of the cubital tunnel proximally and distally
developing a space between the nerve and the roof of the tunnel to allow orientation of the ulnar
nerve course prior to placement of the trocar.
2
A 4-mm endoscope with a blunt dissector was then placed within the trocar. The fascia
was divided under vision to allow clear visualization of the ulnar nerve up to a point 12-14 cm
distally from the midpoint of the retrocondylar groove. Cutaneous nerve branches which cross the
fascia in the deeper fat were carefuuly preserved. The fibrous raphe between the two muscular
heads of the flexor carpi ulnaris was cut with release of fibrous bands crossing the nerve distally.
All constricting elements up to a distance of 8 to 12 cm measured from the mid-point of the
retrocondylar groove were divided carefully to protect all motor branches of the nerve to the
flexor carpi ulnaris, (Fig. 1). The endoscope was carefully pulled back to confirm complete
release. Proximally, the fascia was divided up to 8 to 10 cm from the midpoint of the
retrocondylar groove in the same fashion. The intermuscular septum was not injuried, but if the
Struther’s arcade was present it was divided. Then, tourniquet was released and hemostasis was
achieved by using pressure for a several minutes. Bipolar cautery was used when necessary under
direct visualization with the use of the endoscope. The skin was closed with absorbable
subcuticular sutures without drain and soft compressive dressing was applied.
3
UN
FCU
UN
Fig. (1): showed endoscopic release of the ulnar nerve (UN)
Postoperative care and follow-up
All patients were managed as one-day surgical case and were discharged 24-hrs after
surgery for evaluation of improvement. Active and passive gentle motion exercises were started
on the 1st PO day avoiding resting the arm in flexion position for 4 weeks to prevent secondary
nerve subluxation during the healing period. Patients were followed-up at the outpatient clinic
daily for one week, weekly for one month and then three monthly. Outcome was judged using
Modified Bishop rating system, (Table 1) with a total score of 8-9 indicated excellent, 5-7
indicated good, 3-4 fair and 0-2 poor outcome (16). Nerve conduction studies were repeated 6
months after surgery.
4
Table (1): Modified Bishop rating system
Severity of residual
symptoms
Extent
Score
asymptomatic
3
Improvement
Extent
Better
Mild
2
Unchanged
1
Moderate
1
Worse
0
Severe
0
Score
2
Work status
Extent
Previous
job
Changed
job
Not
working
Grip strength
Score
2
Extent
≥80%
score
1
1
<80%
0
Sensibility (2-point
discrimination)
Extent
score
≤6
1
mm
>6
0
mm
0
Statistical Analysis
All data were presented as number, percentages, mean±SD, ranges and were analyzed by
t-test using SPSS program, version 10, 2002.
Results
The study included 17 patients; 10 males and 7 females with mean age of 31.9±5; range:
24-47 years. The dominant hand was affected in 9 patients (52.9%); 13 patients (76.5%) had
affection of the right and 4 patients (23.5%) had affection of the left ulnar nerve. The mean
duration of the complaints was 15±5.5; range: 8-30 months. Mean duration of preoperative
conservative treatment was 8.4±2.7; range: 6-13 months and included activity modification, night
splint and non-steroid anti-inflammatory medications; however none had beneficial effect.
All patients had pain in the forearm distal, wrist and ulnar part of the hand, and loss of
sensitivity at the fourth and fifth fingers. During the physical examination, a mild numbness in
mostly ulnar side of the fourth and fifth fingers and was increased when the arm was maintained
at full flexion at the elbow level for about 30 seconds with a positive Tinel sign at the elbow
level. Ten patients had various degrees of weakness in the muscles of affected site, and one had
muscle atrophy, but no patient had claw hand deformity. According to Dellon's classification;
there were 2 patients (11.8%) Dellon's grade 1, 14 patients (82.3%) were Dellon's grade 2 and
only 1 patients (5.9%) was Dellon's grade 3, (Table 2).
Table (2): Preoperative clinical data
Data
Number
Age (years)
Gender
Affected dominant hand
Affected hand side
Males
Females
Right
Left
Duration of complaints (months)
Duration of preoperative conservative treatment (months)
Clinical examination findings
Pain
Loss of sensation at 4th and 5th fingers
Muscle power affection
Weakness
Atrophy
Claw hand
Dellon's grading
Grade 1
Grade 2
Grade 3
Data are presented as numbers and mean±SD; percentages & ranges are in parenthesis
5
Findings
17
31.9±5 (24-47)
10 (58.8%)
7 (41.2%)
9 (52.9%)
13 (76.5%)
4 (23.5%)
15±5.5 (8-30)
8.4±2.7 (6-13)
17 (100%)
17 (100%)
16 (94.1%)
1 (5.9%)
0
2 (11.8%)
14 (82.3%)
1 (5.9%)
All surgeries were conducted smoothly apart from one case (5.9%) in which tunnel
dilatation could not allow sufficient proximal endoscopic advancement for completion of nerve
release and this case was considered as procedural failure and nerve release was completed
through an open incision along the medial border of the tricepis muscle. For the completed 16
cases, the mean wound length was 28.4±4.7; range: 20-35 mm and the mean length of ulnar nerve
decompression was 20±2.4; 14-22 cm with a mean duration of surgery was 118.7±12.2; range:
90-135 minutes, (Table 3).
Table (3): Operative data
Data
Procedural outcome
Findings
16 (94.1%)
1 (5.9%)
28.4±4.7 (20-35)
20±2.4 (14-22)
118.7±12.2 (90-135)
Success
Failure
Wound length (mm)
Ulnar decompression length (cm)
Duration of surgery (min)
Data are presented as numbers and mean±SD; percentages & ranges are in parenthesis
On the first PO day, 14 patients (82.4%) reported significant improvement of symptoms
within the first 24 hours after surgery, on the second PO day, 2 patients (11.7%) reported similar
improvement, while the last patient (5.9%) who had open surgical completion showed delay
improvement that was reported on the 6th PO day but to a lesser extent compared to other patients.
As regards elbow motion, 13 patients had full elbow motion within 72 hours after surgery and the
reminder had achieved such improvement within a week.
At end of follow-up, 12 patients were rated as excellent on modified Bishop rating
system; 5 patients documented better improvement and were asymptomatic with regained normal
grip strength and sensibility and were scored 9. Four patients documented better improvement
without residual symptoms apart from the grip strength that was <80% and ranged between 7080% despite being significantly improved compared to preoperative strength. Two patients
documented better improvement despite mild residual symptoms but all other parameters of
Bishop rating system were normalized and were scored 8. The 12th patient showed longer
distance during 2-point discrimination test and was scored 8. Four patients were rated as good on
modified Bishop rating system; 3 patients reported mild residual symptoms, two had grip strength
<80% and one denied improvement and scored his symptoms as unchanged; the three patients
were scored 7. One patient changed his carrier despite the reported better improvement but for
fear of recurrence due to the presence of mild residual symptoms and decreased sensibility and
was scored 6. The patient who had open completion of surgery, also changed his carrier to light
work because of mild residual symptoms with still weak grip strength and his believe of no
improvement despite the mild residual symptoms and improved sensibility on the 2-point
discrimination test and was rated as fair result with score of 4, despite being Dellon grade 3
preoperatively.
Collectively, 15 patients documented better improvement, 10 patients became
asymptomatic, 11 patients regained their grip strength, 14 patients had improved sensibility and
15 patients returned to their preoperative job. Thus, postoperative evaluation according to
modified Bishop Rating System, 12 patients (70.6%) had excellent outcome, 4 patients (23.5%)
had good result and only one patient (5.9%) had fair result with a total mean score of 7.8±1.3;
range: 4-9, (Table 4, Fig. 1). All patients showed improvement of nerve conduction velocity
evaluated after surgery compared to preoperative one.
Two patients developed superficial hematoma that was resolved spontaneously; another 2
patients developed hypoaesthesia in the ulnar forearm skin area innervated by the ulnar
antecubital cutaneous nerve but was resolved spontaneously within three and four months,
6
respectively. Throughout a mean follow period of 12.5±2; 8-15 months, no recurrence was
reported.
Table (4): Outcome judged by modified Bishop rating system
Data
Severity of residual symptoms
Improvement
Work status
Grip strength
Sensibility (2-point discrimination)
Outcome rating
Findings
10 (58.8%)
7 (41.2%)
0
0
15 (88.2%)
2 (11.8%)
0
15 (88.2%)
2 (11.8%)
0
11 (64.7%)
6 (35.3%)
14 (82.4%)
3 (17.6%)
5 (29.3%)
7 (41.2%)
3 (17.7%)
1 (5.9%)
0
1 (5.9%)
7.8±1.3 (4-9)
Asymptomatic
Mild
Moderate
Severe
Better
Unchanged
Worse
Previous job
Changed job
Not working
≥80%
<80%
≤6 mm
>6 mm
Excellent
9
8
Good
7
6
5
Fair
4
Total score
Data are presented as numbers and mean±SD; percentages & ranges are in parenthesis
8
7
Number of patients
6
5
4
3
2
1
0
Score=4
Score=5
Score=6
Score=7
Score=8
Fig. (2): Patients' distribution according to modified Bishop
rating system
7
Score=9
Discussion
Cubital tunnel syndrome is the second most common compression neuropathy in the
upper extremity. Patients complain of numbness in the ring and small fingers, as well as hand
weakness, but advanced disease is complicated by irreversible muscle atrophy and hand
contractures, so ulnar nerve decompression can help to alleviate symptoms and prevent more
advanced stages of dysfunction. Many surgical treatments exist and comparative studies have
shown some short-term advantages to one or another technique, but overall results between the
treatments have essentially been equivocal, thus careful consideration of the potential sites of
nerve compression and the etiologies for these local irritations could aid for appropriate surgical
technique selection and so a good outcome could be anticipated in most patients, (16, 17).
The present study tried to present the short-term outcome for a follow-up period of at
least 6 months of endoscopic release of entrapped ulnar nerve at the cubital tunnel and included
17 patients fulfilled the inclusion criteria, procedural success rate was 94.1% as in one patient
proximal endoscopic advancement could not be achieved and the release was completed through
an open incision. The reported success rate was in line with that recorded in literature; Ahcan &
Zorman (10) reported one case (2.8%) in their series of endoscopic management that was
converted to open because of a ganglion that surrounded the nerve in the forearm. Cobb et al., (18)
reported two failures requiring open release in their series. However, the reported figure of
procedural failure in the current study (5.9%) was superior to that reported by Ward & Siffri, (19)
who recorded that in four patients, (16%) who were treated with medial epicondylectomy and
failed to experience relief of symptoms, intraoperative ulnar nerve subluxation during endoscopic
second setting and were successfully treated with anterior submuscular transposition, such
intraoperative complication was avoided in our series because of inclusion of only fresh cases
never operated up on previously.
Sixteen patients documented sensory improvement within few days after surgery with
significant regain of muscle power manifested as improved hand grip to non-significant
difference in comparison to the non-operated hand. The obtained improvement was documented
by improvement in nerve conduction velocity in all these patients. Moreover, modified Bishop
Rating System, defined 12 patients (70.6%) had excellent outcome, 4 patients (23.5%) had good
result and only one patient (5.9%) had fair result and 15 patients resumed their usual daily
activities and returned to their preoperative work, one patient changed his carrier for fear of
recurrence despite the excellent result and the remaining patient who had open completion of
surgery, also changed his carrier to light work because of residual muscle weakness and sense of
parathesia.
These results go in hand with multiple previous studies evaluated the outcome of
endoscopic ulnar nerve release. Yoshida et al., (20) reported that preoperative tingling sensations
disappeared postoperatively in 63% of cases, pain and sensory disturbance recovered to normal in
92% and 89% of cases, respectively and abnormal motor nerve conduction velocities improved in
77%. Bultmann & Hoffmann (21) reported immediate improvement right after surgery in 53% of
patients and according to the modified Bishop Rating System, results were excellent in 66%,
good in 32%, and fair in 2% with no poor results. In another series of patients, Bultmann (22)
(2009) recorded normalized sensibility in 94% of patients, improved grip strength improved from
75% of the contralateral side to 94% with significantly improved proximal nerve conduction
velocity and according to the modified Bishop rating system 31 patients (66%) had an excellent,
15 patients (32%) a good and 1 patient (2%) a fair result. Flores, (22) reported that after
endoscopic ulnar nerve release, 76.9% of the cases were completely free of signs and symptoms
(8 and 9 points on the Bishop scale), 15.3% presented with light complaints (7 points), and only
one subject (7.6%) reached 5 points on the outcome scale with an average total score of 7.7 points
on the Bishop scale, a figure consistent with that reported through the current study; 7.8 points.
Only minor postoperative complications were reported in form of hematoma in 2 patients
(11.8%) and mild residual parasthesia in another 2 patients (11.8%) and all recovered
8
spontaneously, a finding agreed with Bultmann (23) who reported subcutaneous harmless
haematomas in 4% of all cases, but recorded a laceration of a single motor branch of the ulnar
nerve innervating the flexor carpi ulnaris in two patients with restitutio ad integrum; a
complication that fortunately did not face us.
It could be concluded that endoscopic cubital tunnel release of entrapped ulnar nerve is
feasible, safe and easy procedure with procedural success rate of 94.1% and high successful
outcome. Moreover, it provides small cosmetically acceptable wound with minimal postoperative
complications and could be managed as one-day surgery for such cases. However, wider scale
study was recommended for establishment of reported results
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