A sixty-seven-year-old right-hand-dominant
retired machinist presented with a one-week history of swelling,
mild tenderness, and intermittent erythema in the left elbow. He
also had an intermittent burning sensation. He reported no previous problems
with the elbow, but he stated that he had lifted a heavy nativity
scene at his church the day before the swelling was noticed.
On presentation, the patient reported no tenderness, erythema,
or paresthesias of the left upper extremity. The review of systems
was otherwise negative.
Initial examination revealed a full range of motion of the upper
extremities. The skin was slightly warmer than normal, with no erythema
at the site of concern. There was a firm, mobile mass measuring 3
5 cm on the ulnar side of the distal aspect of the arm, at the
level of the epicondyles. The ulnar aspect of the mass appeared
to pulsate, although the remainder of the mass did not. Neurovascular examination
revealed a 2+ radial pulse and a 1+ ulnar pulse.
No sensory deficits were noted; motor examination showed a strength
of 5 of 5 throughout, except for flexion and supination of the elbow, which
were rated 4 of 5. Resisted elbow flexion and supination were not
limited by pain. The remainder of the physical examination revealed
normal findings, and no lymphadenopathy was noted.
Plain radiographs of the left elbow revealed no osseous abnormalities,
and the soft-tissue swelling was not well appreciated. A magnetic
resonance image, made without contrast medium, demonstrated a linear
defect (ventral to dorsal) in the distal brachialis muscle with
decreased signal on T1 and T2-weighted images (Fig. 1). A diagnosis
of a distal brachialis muscle tear was made.
Serial clinical examinations and follow-up magnetic
resonance imaging were performed. Over the next four weeks, the
mass became less tender but caused an occasional burning sensation.
The size of the mass was unchanged, and no warmth or erythema was
noted. The findings on motor examination were 5 of 5 throughout.
Six weeks after the injury, repeat magnetic resonance imaging
(with and without contrast medium) revealed increased signal within,
and thickening of, the distal brachialis muscle. The plane of cleavage and
the retracted muscle fibers were consistent with a partial rupture
of the brachialis muscle, suggesting a traumatic injury rather than
a malignant lesion.
Ten months after the initial presentation, the mass was smaller
and nontender and the findings on physical examination were otherwise
normal.
Isolated rupture of the brachialis muscle appears to be a rare
injury that has not been well documented. Our review of the literature
from the 1960s to the present revealed no reported cases. The current
case involved a partial distal brachialis tear that responded to
nonoperative treatment. Muscle injuries are common and can usually
be diagnosed on the basis of the medical history and the physical examination.
On examination, localized tenderness and pain with muscle activation
are usually present. Our patient had a muscle tear just proximal
to the musculotendinous junction that presented as a moderately
painful mass. Magnetic resonance imaging is recommended only when
a diagnosis cannot be made on the basis of the history and the physical examination3. Magnetic resonance imaging can demonstrate both
acute and chronic muscle tears. T1-weighted images may
show disruption of the normal architecture of the muscle belly or
the tendinous junction. T2-weighted images will show the increased signal
related to edema and hemorrhage. These areas of abnormal signal
can have a varied appearance ranging from linear to more mass-like4.
Note: The authors thank Daniel Davis, MD, for the radiographic
review.