Download Isolated Atraumatic Injury of the Supraspinous and

SPINE
ABBREVIATION KEY:
Isolated Atraumatic Injury of the
Supraspinous and Interspinous
Ligaments
V. Joshi, A. Casden, B. Skovrlj, and A. Doshi
ABSTRACT
We reported a rare case of atraumatic injury to the supraspinous and interspinous ligaments
in a 33-year-old woman. Without the typical history or imaging findings of trauma to the
vertebral bodies, imaging findings associated with injury to the posterior ligament complex
may be difficult to distinguish between posterior ligament complex rupture, lumbar strain,
or fluid collection. This case highlighted the radiologic modalities and imaging findings that
may aid in the diagnosis and treatment of equivocal cases.
CASE REPORT
A 33-year-old woman with a medical history of pneumonia diagnosed 1 month earlier presented to an outpatient clinic with
severe back pain. The patient had mild low
back pain for roughly 1 month, which began at the same time that she was diagnosed with pneumonia. On the day of her
presentation, her pain suddenly became severe and was 9 of 10 on a pain scale. The
patient did not report any trauma, participation in any sports, overstretching, or
heavy lifting. The pain was worse on both
flexion and extension. The patient did not
have any muscle weakness, bladder or
bowel incontinence, or loss of sensation.
Results of a review of symptoms was only
positive for occasional severe cough during
and after her episode of pneumonia, which
was gradually improving. The patient had
no other significant medical history. Her
only medications included oral contraceptives and Tylenol (McNeil Consumer
Healthcare, Fort Washington, PA) and
Advil (Pfizer Consumer Healthcare, New
York, NY) for pain.
The patient’s vital signs were stable, including a normal oral temperature. Physical examination revealed severe tenderness
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to palpation of the upper lumbar region.
She was neurologically intact. The patient had limited range of motion of the
lumbar spine secondary to pain, in particular, her severe pain limited flexion.
The skin tissue over the lumbar spine did
not demonstrate bruising or discoloration on visual inspection.
Frontal and lateral radiographs of the
lumbar spine were obtained, with a marker
placed over the area of focal tenderness
(Fig 1) approximately centered from L1 to
L3. The lumbar radiographs were unremarkable. Lumbar spine MR imaging
without contrast was obtained (Fig 2),
which demonstrated increased subcutaneous signal intensity that extended within
the deep soft tissues and musculature adjacent to the spinous process from the L1 to
L4 levels. This was thought to represent
either edema or a fluid collection. A small
amount of fluid was also noted to extend
between the L1 and L2 supraspinous and
interspinous ligaments. There was no evidence of other thoracolumbar pathology.
The differential diagnosis at this point included lumbar strain or supraspinous and
interspinous ligament tear. However, given
the patient’s unusual history for posterior
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CT ⫽ computed tomography images
ISL ⫽ interspinous ligament
MR ⫽ magnetic resonance
PLC ⫽ posterior ligament complex
SSL ⫽ supraspinous ligament
STIR ⫽ short T1/tau inversion
recovery sequence.
Received April 22, 2014; accepted
June 27, 2014.
From the Department of Radiology
(V.J., A.D.), Orthopedic Surgery
(A.C.), Mount Sinai School of
Medicine, New York, New York, and
Department of Neurosurgery (B.S.),
Radiology (A.D.), Mount Sinai
Medical Center, New York, New
York.
Please address correspondence to
Vivek Joshi, MD, Department of
Radiology, Mount Sinai School of
Medicine, One Gustave L. Levy Pl.,
Box 1234, New York, NY 10029;
e-mail: [email protected].
http://dx.doi.org/10.3174/ng.6150132
DISCUSSION
Fig 1. (A) Frontal and (B) lateral lumbar radiographs are unremarkable,
with no evidence of bony or soft-tissue abnormality. A paper clip was
used as a marker to demonstrate the area of focal tenderness, which
ranges from L1 to L3.
Fig 2. (A) Sagittal STIR image of the lumbar spine. (B) Axial T2-weighted
MR image centered at the L1–L2 interspinous process. Images demonstrate increased signal intensity along the subcutaneous tissues posterior to the spinous process, which extends from L1 to L4 (asterisk). In
addition, increased signal intensity extends into and disrupts the supraspinous ligament and partially between the interspinous ligament
(arrows).
ligamentous tear as indicated by MR imaging and the
recent history of pneumonia, an infected fluid collection
was considered. Given the ability for good soft-tissue contrast,
lack of radiation, and ability to perform aspiration for this
relatively superficial abnormality, sonography was performed.
This examination demonstrated disruption of the supraspinous ligament and a heterogeneous and/or hypoechoic area
between the L1 and L2 spinous processes (Fig 3). A needle for
aspiration was advanced into this heterogeneously echogenic
area (Fig 4). Several attempts to draw fluid from this area
were unsuccessful. This area may have represented a hematoma and/or disrupted elements of the posterior ligament
complex (PLC). Given the lack of discrete fluid, the findings
were more suggestive of a ruptured PLC. Bupivacaine was
injected into the site under sonography guidance. The patient’s pain had almost completed subsided a few minutes
after injection. On follow-up examination 1 week later, the
patient reported resolution of her pain and complete return
of mobility.
The PLC is composed of the facet joint capsules, ligamentum flavum, interspinous ligament, and supraspinous ligament.1,2 Functionally, the PLC is thought to act as both a
stabilizer and protector of the thoracolumbar spine.2,3 Anatomically, the supraspinous ligament connects the apices
of the spinous processes from the seventh cervical vertebrae
to the sacrum (Fig 5). The interspinous ligament is a thin
membranous ligament that extends from the inferior aspect
of the spinous processes to the superior aspect of the next
spinous process. Anterior to the interspinous ligament is the
ligamentum flavum and, posteriorly, is the supraspinous
ligament. We reported a very rare case of isolated injury
to the supraspinous and interspinous ligaments without
trauma in a 33-year-old woman. Damage to the PLC has
nearly always been described in the setting of spinal trauma,
which includes vertebral body fractures and subluxation.
To our knowledge, there have been no cases described in the
literature of isolated atraumatic injury to the PLC complex
without any evidence of trauma to the vertebral thoracolumbar spine.
In our case, the patient was young, with no medical
history other than a recent episode of pneumonia a month
earlier, and no history of trauma. Both plain radiographs
and MR imaging of the lumbar spine demonstrated no evidence of trauma to the thoracolumbar spine, including vertebral body fracture or subluxation, or abnormal signal
intensity within any of the thoracolumbar spinal bony
structures. The differential diagnosis for the T2 signal intensity abnormality within subcutaneous tissues posterior
to the lumbar spinous processes included subcutaneous
fluid collection and/or abscess, lumbar strain and/or posterior ligament damage without rupture, or posterior ligament complex rupture. Even though, to our knowledge,
there has been no documented study that indicates an association of community-acquired pneumonia with subcutaneous abscess, an infected collection remained part of the
differential diagnosis, given the patient’s atraumatic history. Ultrasonographic images demonstrated a heterogeneous soft-tissue collection, which did not return any fluid
on aspiration, which indicated a diagnosis other than abscess. In addition, the patient’s history consisted of an acute
episode of severe back pain, which resolved on sonographyguided bupivacaine injection, which is consistent with a
musculoskeletal injury.
The distinction between lumbar strain and PLC injury
without rupture and frank PLC disruption can be difficult.
MR imaging demonstrated increased linear T2 signal intensity within the supraspinous ligament that extends horizontally into the obliquely oriented interspinous ligament. On
ultrasonographic images, there was disruption of the vertically oriented bands of the supraspinous ligament by a heterogeneous collection. Based solely on imaging features,
damage to the PLC with rupture of the supraspinous ligament was considered. However, patients with disruption of
the PLC would not be expected to have such a favorable
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Fig 3. (A) Sagittal color-Doppler sonography image at the normal T12–L1 level, demonstrating an intact supraspinous ligament (arrowheads) and
spinous processes (arrows). (B) Sagittal sonography images centered between the spinous processes of L1 and L2, demonstrating disruption of the
vertically oriented bands of the supraspinous ligament by a heterogenous soft-tissue collection (calipers). Superficial to this lesion, the subcutaneous
tissue appears hypoechoic, which indicates some degree of edema.
Fig 4. Transverse sonography image centered at the L1–L2 level demonstrates attempted needle aspiration of heterogeneously echogenic lesion (asterisk) in the expected location of the supraspinous ligament just
superficial to the spinous process (arrow).
outcome or recover full mobility so quickly with conservative measures.4 As such, the imaging and clinical findings
may represent injury and strain to an intact PLC, with surrounding inflammatory changes and hematoma formation.
The mechanism for isolated supraspinous and interspinous ligament injury is unclear. A possible mechanism for
injury in this case may have been related to the chronic
coughing associated with the patient’s recent episode of
pneumonia. The chronic cough may have predisposed the
supraspinous ligament to repetitive flexional forces, which
may have caused inflammation and weakness of the ligament. Also, a forceful cough may have resulted in excessive
sudden flexional force on a weakened supraspinous ligament and caused a tear. An infectious process of the subcutaneous tissue and ligaments or an underlying connective
tissue disorder could also possibly predispose a patient to
more fragile ligaments; however, our patient had no history
to indicate these etiologies.
Lumbar radiographs are often the first imaging study
ordered in patients with lower back pain. It should be
noted, however, that, as per the American College of Radiology appropriateness criteria, in patients with an uncom256
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Fig 5. Two-dimensional illustration of the midline lumbar spine in sagittal
projection. The supraspinous ligament (SSL), colored in blue, traverses
across the apices of the spinous processes (SP). The ligamentum flavum,
colored in green, is the anterior border of the interspinous ligament
(ISL). The SSL is the posterior border of the ISL. The ISL consists of
obliquely oriented fibers, colored in red, that travel from the inferior
aspect of 1 spinous process to the superior aspect of another spinous
process.
plicated acute lower back pain presentation, all imaging
studies, including plain films, are usually considered inappropriate.5 Conservative management is indicated in these
cases. Factors that may indicate a more-complex acute back
pain picture include recent significant trauma or milder
trauma at age ⬎50 years, unexplained weight loss, unexplained fever, immunosuppression, history of cancer, intravenous drug use, prolonged steroid use or osteoporosis, age
⬎70 years, or focal neurologic deficit with progressive or
disabling symptoms.5 As per American College of Radiology guidelines, in patients with suspected infection or immunosuppression, radiographs “may be appropriate” and
MR examination is “usually appropriate.”5
Indirect evidence on a lumbar radiograph to indicate the
possibly of damage to the PLC complex includes focal kyphosis without vertebral body injury, interspinous spacing
greater than that of the level above or below on anteroposterior radiograph, ⬎50% compression of the anterior vertebral body on lateral radiograph without fracture of the
posterior wall, vertebral body translation, diastasis of the
facet joints, or avulsion off the superior or inferior aspect of
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a spinous process.6 The radiograph in our patient did not
demonstrate these signs.
Although plain radiographs and CTs have the capability
to indicate indirect evidence of damage to the PLC, MR
imaging has the ability to more directly evaluate the PLC.7
A previous study by Rhin et al,8 indicated that MR imaging
may have a sensitivity between 78% and 100%, and a specificity of 51%– 81% to detect damage to the various components of the PLC. To best evaluate injury to the PLC on
MR imaging, fluid-sensitive sequences, such as a fat suppressed T2-weighted or STIR sequences, should be included
as part of the study.4 In the setting of normal plain film
radiographs, signs to indicate PLC damage on MR imaging
include hyperintense signal intensity changes, which indicate edema in the region of the posterior ligaments on fluidsensitive sequences, diastasis of facet joints on T2 axial
sequence, and disruption of PLC on T1 sagittal sequence.3
Due to this patient’s atypical history and imaging findings for PLC injury, the patient underwent a spinal sonography to further evaluate the region of high signal intensity
seen on MR imaging. Sonography is a relatively inexpensive
imaging technique that is easily available, results in no ionizing radiation, and can be used in patients with contraindications to MR imaging and as an adjunct to MR imaging,
as in this case.9-11 A recent study by Vordemvenne et al10 of
13 patients with acute burst fractures demonstrated sonography to have a 91% sensitivity and 75% specificity to
detect PLC damage. Sonography imaging findings of PLC
damage may include a subcutaneous hypoechoic and/or
heterogeneous lesion, disruption of the normal hypoechoic
and echogenic lines of the supraspinous ligament and interspinous ligament, avulsed bony spinous processes, or inhomogenous arrangement of paravertebral muscles.10,11 In
our case, sonography demonstrated disruption of the supraspinous and interspinous ligaments as well as a heterogeneously echogenic area that may have represented a hematoma and/or disrupted PLC components. Sonography
not only allowed us to evaluate the PLC, but it also allowed
us to administer pain medication to the area of abnormality,
which was of great benefit to the patient in our case. In
addition, it also allowed us to determine if any fluid collection for aspiration was available.
In conclusion, we a reported a very rare case of isolated
nontraumatic posterior ligament complex injury in a 33year-old woman. To our knowledge, all reports in the literature of posterior ligament complex injury have been associated with significant trauma and imaging findings, which
demonstrated injury to the thoracolumbar vertebrae. Although MR imaging has good sensitivity and specificity to
detect injury to the PLC, sonography may be a complemen-
tary and cost-effective tool in the diagnosis of equivocal
cases. Moreover, sonography-guided needle biopsy or aspiration of the site in question can help with the diagnosis and
management. Further research is necessary to evaluate the
role of sonography in PLC injury.
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