Cubital.html
Cubital tunnel syndrome: A report of two cases
F E Suleman, MB ChB, FCRad(D)(SA), MMedRad(D)
Department of Radiology, University of Pretoria
M Velleman, MB ChB, FCRad(D)(SA), MMedRad(D)
Radiology Department, Little Company of Mary Medical Centre, Pretoria
Corresponding author: F Suleman (fesuleman@gmail.com)
Cubital tunnel syndrome is the
second most common peripheral neuropathy of the upper limb. This is due
to the anatomy of the tunnel, the physiological changes that the nerve
undergoes during elbow flexion, as well as pathological conditions that
occur within the tunnel. We present two cases of ulnar neuropathy
occurring at the level of the cubital tunnel, demonstrating that this
entity may occur owing to an identifiable cause or may show only signal
alteration without a visible cause on MRI.
S Afr J Rad 2012;16(2):77-78.
Introduction
Cubital tunnel syndrome occurs as a result of compression of the
ulnar nerve between the medial epicondyle, the olecranon and the roof
of the tunnel that is formed by the retinaculum which is also known as
Osborne’s band or the arcuate ligament.1
,
2
Physiological compression occurs during elbow flexion, but compression
may also be the result of masses in the tunnel, including ganglions and
bursae or synovitis or osteophytes.3 Rarely, compression has been attributed to the presence of an accessory muscle – the anconeus epitrochlearis.2
,
3
The ulnar nerve is also the most commonly injured nerve, owing to the
relatively unprotected location of the nerve within the tunnel at the
elbow.3
Case report
Two unrelated men aged 40 and 42 years, respectively, were referred
for magnetic resonance imaging (MRI) on separate occasions, with elbow
pain and suspected cubital tunnel syndrome. There was no history of
work-related causality or injury in either case. MRI was requested to
rule out any underlying mass lesion or anatomic variants that might
have contributed to the development of an ulnar neuropathy at the level
of the cubital tunnel.
Patient 1
A 40-year-old man revealed high signal on T2W (T2 weighted) MRI in a
thickened ulnar nerve with no evidence of mass lesions or
osteodegenerative changes. A normal cubital tunnel retinaculum was seen
and no anatomic variants were noted. The rest of the joint was within
normal limits (Fig. 1). A diagnosis of cubital tunnel syndrome of
unknown aetiology was made.
Patient 2
A 42-year-old man demonstrated the presence of an olecranon spur as
well as an anconeus epitrochlearis muscle on MRI scanning. Tendinosis
of the triceps muscle was also present. T2WI also demonstrated high
signal in the thickened ulnar nerve (Fig. 2). A diagnosis of cubital
tunnel syndrome was made, with both the olecranon spur and the anconeus
epitrochlearis muscle being implicated in the aetiology.
Discussion
Physiological compression of the ulnar nerve within the cubital
tunnel occurs without neuropathy. Pathological compression gives rise
to cubital tunnel syndrome. Possible causes include overuse,
subluxation of the nerve, trauma including fractures around the elbow
joint, osteophyte formation, soft-tissue masses and a thickened
retinaculum. The presence of the anconeus epitrochlearis muscle is
rarely implicated. The incidence is also reported to be higher in
certain occupations especially those involving repetitive actions,
prolonged flexion of the elbow and the use of vibrating tools. Diabetes
and obesity are also predisposing factors.4
Patients may present with pain in the medial elbow but more commonly
complain of sensory loss in the ulnar nerve distribution. Clinically,
in long-standing cases, marked wasting of the small muscles of the hand
on the ulnar side may be seen.4
The diagnosis is usually based
on clinical findings and nerve conduction tests. Imaging is indicated
only to exclude possible underlying causes of nerve entrapment.
Radiographs of the elbow joint may show evidence of osteoarthritis or
previous trauma, and ultrasound can be used to image the nerve itself
but MRI is excellent for visualising changes in the signal of the nerve
as well as changes in the nerve diameter while excluding any underlying
masses or anatomical variants that may result in ulnar neuropathy. In a
study of cadavers, O’Driscoll et al.5 classified the variants of the retinaculum into the following types:
Type 0: absence of the retinaculum that predisposed to subluxation of the ulnar nerve
Type 1a: normal thin retinaculum that did not compress the nerve even in flexion
Type 1b: thickened retinaculum that was thought to predispose to chronic nerve compression
Type 3: replacement of the retinaculum by the anconeus epitrochealaris muscle.
MRI changes should be
interpreted with caution, however, and the clinical picture should
always be taken into consideration during the interpretation of images.
In a study of the elbows of 60 asymptomatic patients, Husarik et al.3
found that 60% of subjects had increased signal in the ulnar nerve on
fluid-sensitive MR images, and 23% of patients had the presence of an
anconeus epitrochlearis muscle. The retinaculum was also found to be
thickened in 8% of asymptomatic subjects. The increasing use of
technology is also being implicated in the development of entrapment
neuropathies of the upper limb. Ruess et al.1
reported on a study within their radiology department where a third of
their radiologists sought medical attention during a 3-month period for
symptoms in the upper limbs. All were found to be suffering from
cubital tunnel syndrome, with one having carpal tunnel syndrome in
addition. This implicated prolonged periods spent at the computer with
widespread implementation of PACS, as well as administrative and
teaching duties that involved computer use, as increasing the risk of
development of entrapment syndromes. Prolonged elbow flexion involved
in the use of hand-held dictation microphones and telephone receivers
or mobile phones could also be contributing factors. Poor ergonomics of
workstations were also thought to be a problem. They strongly
recommended that radiology departments obtain professional advice from
ergonomic experts and implement their recommendations for workstation
designs.
Conclusion
MRI is well suited for demonstrating signal abnormality of the ulnar
nerve in patients with cubital tunnel syndrome and also has the
advantage of demonstrating causes such as osteophytes, soft-tissue
masses, a thickened retinaculum and presence of an anconeus
epitrochlearis muscle. Many factors relating to modern living, such as
prolonged use of a computer mouse, telephone and, in certain
occupations, dictation devices, could cause this syndrome, resulting in
signal abnormality in the nerve without an obvious cause on MRI.
1. Ruess L, O’Connor SC, Cho KH, Hussein FH, Slaughter RC, Hedge
A. Carpal tunnel syndrome and cubital tunnel syndrome: Work-related
musculoskeletal disorders in four symptomatic radiologists. AJR
2003;181:37-41.
1. Ruess L, O’Connor SC, Cho KH, Hussein FH, Slaughter RC, Hedge
A. Carpal tunnel syndrome and cubital tunnel syndrome: Work-related
musculoskeletal disorders in four symptomatic radiologists. AJR
2003;181:37-41.
2. Andreisek G, Crook DW, Burg D, Marincek B, Weishaupt D. Peripheral
neuropathies of the median, radial and ulnar nerves: MR imaging
features. Radiographics 2006;26:1267-1287.
2. Andreisek G, Crook DW, Burg D, Marincek B, Weishaupt D. Peripheral
neuropathies of the median, radial and ulnar nerves: MR imaging
features. Radiographics 2006;26:1267-1287.
3. Husarik DB, Saupe N, Pfirmann CWA, Jost B, Hodler J, Zanetti M.
Elbow nerves: MR findings in 60 asymptomatic subjects – normal
anatomy, variants and pitfalls. Radiology 2009;252:148-156.
3. Husarik DB, Saupe N, Pfirmann CWA, Jost B, Hodler J, Zanetti M.
Elbow nerves: MR findings in 60 asymptomatic subjects – normal
anatomy, variants and pitfalls. Radiology 2009;252:148-156.
4. Cutts S. Cubital tunnel syndrome. Postgrad Med Journal 2007;83:28-31.
4. Cutts S. Cubital tunnel syndrome. Postgrad Med Journal 2007;83:28-31.
5. O Driscoll SW, Horii E, Carmichael SW, Morrey BF. The cubital tunnel
and ulnar neuropathy. J Bone Joint Surg Br 1991;73:613-617.
5. O Driscoll SW, Horii E, Carmichael SW, Morrey BF. The cubital tunnel
and ulnar neuropathy. J Bone Joint Surg Br 1991;73:613-617.
Fig. 1. Axial and coronal
fat-suppressed MR images of the left elbow demonstrating increased
signal in the thickened ulnar nerve (arrows). Note the normal
retinaculum (arrowhead).
Fig. 2. Axial fat-suppressed MR
image of the right elbow in patient 2, demonstrating the presence of
the anconeus epitrochlearis muscle (arrowhead) and high signal in the
thickened ulnar nerve (arrow).