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n Case Report
Atypical Pectoralis Major Muscle Wasting in
a Recreational Weight Lifter
Nata Parnes, MD; Maryellen I. Blevins, PA-C, MPAS; Paul Carey, MD; Darren J. Friedman, MD
abstract
Pectoralis major injuries are relatively uncommon and can pose a diagnostic challenge. Deformity and weakness of this muscle in weight lifters is
typically due to traumatic tendon rupture and often requires surgical repair.
However, there are other less common etiologies that can mimic the clinical presentation of pectoralis major wasting and weakness that require different treatment approaches. This article describes a case of a 48-year-old
recreational weight lifter who presented with severe pectoralis major wasting
and weakness secondary to isolated mononeuropathy of the lateral pectoral
nerve possibly due to Parsonage Turner syndrome. The patient was treated
nonoperatively and achieved full recovery 18 months after onset. Parsonage
Turner syndrome should be included in the differential diagnosis of patients
with atraumatic weakness and wasting of the pectoralis major muscle and
dysfunction. [Orthopedics. 2016; 39(4):e756-e759.]
T
he pectoralis major is the largest
and most powerful muscle of the
chest. It is composed of 3 distinct
segments: clavicular, sternal, and sternoabdominal. It has an important role in
forward flexion, adduction, and internal
rotation of the shoulder. The most widely described pectoralis major injury in
weight lifters is tendon rupture from the
humeral insertion secondary to eccentric
contraction. Pectoralis major injury can
cause pain, weakness, deformity, and
muscle wasting. This injury usually requires surgical repair to restore strength
and fatigue resistance.1 However, other
e756
less common pathologies can cause similar clinical presentations. These conditions require different modalities of treatment and should be recognized.
This article describes a unique case in
a recreational weight lifter who presented
with pectoralis major wasting secondary
to isolated involvement of the lateral pectoral nerve likely due to Parsonage Turner
syndrome.
Case Report
A 48-year-old male recreational weight
lifter presented with sudden onset of pain
in his right shoulder after routine workout
activities. There was no history of trauma,
malignancy, changes in workout routine,
prior shoulder or neck surgeries, cervical
spine disease, or viral disease. The patient
reported that the pain began after his daily
weight lifting routine and subsided after
3 weeks. A few weeks after resolution of
the pain, severe shoulder weakness developed. The patient presented to the authors’
clinic 3 months after the initial onset of
symptoms.
Physical examination of the right
shoulder girdle revealed wasting of the
pectoralis major muscle with associated
weakness in horizontal adduction and
internal rotation of the shoulder (Figure
1). Horizontal adduction pectoralis major
muscle strength was rated as 3+ out of 5
The authors are from the Department of Orthopaedic Surgery (NP, MIB), Carthage Area
Hospital, Carthage; the Department of Orthopaedic Surgery (PC), Fort Drum; and the Department
of Orthopaedic Surgery (DJF), New York Presbyterian Lower Manhattan Hospital, New York, New
York.
The authors have no relevant financial relationships to disclose.
Correspondence should be addressed to:
Darren J. Friedman, MD, Department of Orthopaedic Surgery, New York Presbyterian Lower
Manhattan Hospital, 170 William St, New York,
NY 10038 ([email protected]).
Received: July 9, 2015; Accepted: August 7,
2015.
doi: 10.3928/01477447-20160526-09
Copyright © SLACK Incorporated
n Case Report
(5=normal). Active range of motion of
the right shoulder was full and symmetric
with the contralateral extremity. All of the
other muscles of the right shoulder girdle
and right upper extremity were found to
be of normal strength (5 out of 5) without
any visualized atrophy.
Sensory and vascular examination of
the right upper extremity were normal.
Magnetic resonance imaging (MRI) of
the cervical spine, brachial plexus, shoulder, and chest was performed 3 months
after the onset of symptoms. Magnetic
resonance imaging of the chest revealed
intramuscular edema and muscular atrophy of the pectoralis major without fatty
infiltration (Figure 2). Electromyography
(EMG) of the right upper extremity performed 3 months after the onset of symptoms revealed fibrillations and positive
sharp waves with reduced recruitment
of the upper two-thirds of the pectoralis
major consistent with mononeuropathy of
the lateral pectoral nerve likely secondary
to Parsonage Turner syndrome. No other
neurologic abnormalities were identified.
Nerve conduction study of the right upper
extremity performed at the same time was
normal.
Based on the history, examination, and
diagnostic studies, the diagnosis of likely
Parsonage Turner syndrome was made.
Treatment included reassurance, physical
therapy including active and passive range
of motion exercises, eventual strengthening exercises of the pectoralis major muscle, and analgesics as necessary.
Nine months after the onset of symptoms, the patient reported significant subjective improvement. Physical examination revealed decreased muscle atrophy
with improved pectoralis muscle strength
(4 out of 5). Follow-up EMG of the right
upper extremity 6 months after the initial
EMG demonstrated interval improvement. Eighteen months after the onset
of symptoms, the patient reported full
recovery with no residual pain or weakness. He had returned to his baseline activity with full function, including bench
JULY/AUGUST 2016 | Volume 39 • Number 4
Figure 1: Photograph showing wasting of the pectoralis major muscle at presentation.
press and weight lifting. Visual analog
pain scale was 0 out of 10, and his right
subjective shoulder value was 100% of
normal. Physical examination revealed
normal muscle bulk of the pectoralis major muscle that was symmetric with the
contralateral side (Figure 3). Pectoralis
major muscle strength was symmetric and
5 out of 5 bilaterally.
Discussion
The pectoralis major muscle is a large
fan-shaped muscle composed of 3 heads:
clavicular, sternal, and sternoabdominal.
It is innervated by both the lateral pectoral
nerve, which branches off the lateral cord
of the brachial plexus and receives innervation from the C5-C6 nerve roots, and
the medial pectoral nerve, which branches
off the medial cord of the brachial plexus
and receives innervation from the C7-C8
and T1 nerve roots.2 The lateral pectoral
nerve runs along the medial aspect of the
pectoralis minor muscle and then along the
A
Figure 2: T2-weighted axial magnetic resonance
image showing intramuscular edema and muscular atrophy without fatty infiltration of the pectoralis major muscle.
undersurface of the pectoralis major muscle along with the pectoral branch of the
thoracoacromial artery, supplying roughly
the upper two-thirds of the pectoralis major
muscle. The medial pectoral nerve pierces
the pectoralis minor muscle and then runs
along its lower border to supply the lower
one-third of the pectoralis major muscle.
The lateral pectoral nerve is larger in size
compared to the medial pectoral nerve, innervating a greater percentage of the pectoralis major muscle.3
The pectoralis major is an important
contributor to the shoulder’s internal rotation, adduction, and forward flexion. The
most commonly reported pectoralis major
injury in weight lifters is tendon rupture
from the humeral insertion, which usually
is an acute well-defined injury characterized by immediate pain, diminished ante-
B
Figure 3: Coronal (A) and sagittal (B) photographs 18 months after presentation showing no residual
wasting of the pectoralis major muscle.
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n Case Report
rior axillary fold, weak horizontal adduction, and cosmetic deformity that includes
bulging at the origin of the muscle on the
medial aspect of the chest accompanied
by typical defect at the lateral aspect of
the anterior chest wall. In cases of complete or high-grade partial tears, surgical
anatomic repair generally is advised to
restore function, improve cosmesis, and
increase overall patient satisfaction compared to nonsurgical treatment.1
The current case lacked the history
and characteristic findings of acute tendon
tear, leading the authors to investigate less
common etiologies for pectoralis major
wasting such as cervical radiculopathy,4
tumor of the spinal cord or brachial plexus,5 peripheral nerve injury,4,6 or amyotrophic lateral sclerosis. The history of
sudden onset of intense pain with no inciting trauma that improved spontaneously
and was followed by weakness and muscle atrophy suggested Parsonage Turner
syndrome. In addition, MRI studies of
the C-spine, brachial plexus, shoulder,
and chest ruled out structural abnormality.
Diagnosis was confirmed on EMG, which
established isolated mononeuropathy of
the lateral pectoral nerve likely due to
Parsonage Turner syndrome.
Parsonage Turner syndrome is a rare
syndrome of unknown etiology with an
incidence of less than 2 in 100,000.7 It
affects men more than women, with occurrence reports ranging from 2:1 to 12:1.
In one-third of cases, it occurs bilaterally. The etiology of Parsonage Turner
syndrome is still unclear7 with factors
proposed to be: recent immunization,8 recent surgery in remote area of the body,9
trauma,10 infection,11 and autoimmune
disease.12
The typical presentation of Parsonage
Turner syndrome is acute severe pain in
the neck, shoulder, and arm that resolves
spontaneously in a few weeks, followed
by weakness and atrophy affecting muscles around the shoulder region. Parsonage Turner syndrome most commonly
presents as a global plexopathy, with iso-
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lated involvement of a nerve branch being
less common.7 However, several cases of
single phrenic nerve involvement,13 anterior interosseous nerve involvement,12 and
involvement of the anterior branch of the
axillary nerve14 have been described. To
the best of the authors’ knowledge, this
is the first published report of isolated involvement of the lateral pectoral nerve.
The results of basic laboratory investigations (complete blood test, erythrocyte
sedimentation rate, and antiviral antibodies), as in this case, typically are normal
in Parsonage Turner syndrome. MRI findings of an affected muscle or muscles in
Parsonage Turner syndrome is nonspecific
and defined as features of denervation involving muscles of the shoulder girdle and
upper extremity, including intramuscular
edema, muscular atrophy with or without
fatty infiltration, or a combination of these
findings.5 In the current case, there was
evidence on the MRI of pectoralis major
intramuscular edema and muscular atrophy without fatty infiltration.
Electrodiagnostic studies can aid in
confirming the diagnosis of Parsonage
Turner syndrome, with changes often
found 3 weeks or more after the onset of
symptoms.7 In this case, EMG of the pectoralis major muscle demonstrated fibrillations and positive sharp waves with reduced recruitment of the upper two-thirds
consistent with lateral pectoral nerve involvement. Normal motor unit potentials
were recorded at all other muscles of the
right upper extremity. Most Parsonage
Turner syndrome patients have normal
nerve conduction studies.15
Overall, Parsonage Turner syndrome is
a self-limiting condition, with the mainstay of treatment being supportive. In
their review of 99 patients, Tsairis et al16
found no significant benefit for patients
who had a course of corticosteroids. They
also found that physical therapy did not
appear to improve time to functional recovery. Provision of adequate analgesia
during the initial phase of this condition
is recommended with no substantial sup-
portive evidence for the use of other modalities such as massage, ultrasound, or
electrical stimulation therapy. Prognosis
is favorable with an estimated 75% of
all patients making a complete recovery
within 2 years and approximately 90%
demonstrating complete recovery in 3
years.16
Conclusion
Mononeuropathy and Parsonage Turner
syndrome must be included in the differential diagnosis of patients with weakness,
wasting of the pectoralis major muscle, and
shoulder girdle pain, along with neuropathic muscular changes on MRI. Atraumatic
history must raise suspicion, with EMG
of the affected extremity confirming diagnosis. Conservative treatment of pectoral
nerve palsy secondary to Parsonage Turner
syndrome has a favorable outcome but can
take 2 to 3 years for full recovery.
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