An unusual cause of back pain: Vertebral fracture with bilateral psoas muscle hematomas

A 62-year-old male presented to A&E with a two-week history of undulating lower back pain. Whilst fixing his spring-loaded bed, a metal part detached and hit the patient’s chest, which caused him to lose balance and fall on to his back. He reported immediate lumbar back pain but was able to mobilize after the injury.

In the lateral lumbar radiograph (Figure 1), there are fractures of the superior and inferior endplates of the L4 vertebral body with loss of height of the anterior vertebral body of approximately 40%. Part of the anterior vertebra is displaced and angled anteriorly.

In the post-contrast CT coronal images (Figure 2), there are bilateral well-defined low-density lesions within the anterior aspect of both psoas muscles at the L4/L5 level. Both contain high densities in the superior aspects compatible with acute blood. The bleeding seems to be from the segmental arteries arising from the aorta. The left measured 1.5 cm (AP) x 2 cm (W) x 6 cm (CC) and on the right 2.3 cm (AP) x 2.3 cm (W) x 4 cm (CC).

In the T2 weighted MRI lumbar spine axial images (figure 3), bilateral high signal well-defined lesions corresponding with haematomas and the low-density lesions seen on the CT.

Spinal fractures are important trauma-related pathologies that should not be missed in A&E due to the significant impact on daily living activity, leading to significant primary and secondary socioeconomic cost burden [1]. At the initial injury, he did not report any leg weakness, paresthesia or incontinence and, hence, was treated conservatively without imaging. However, days later, he reported worsening focalized pain, mainly in the lumbar area, and right anterior thigh pain, despite taking regular analgesia with associated paresthesia on the posterior aspect of both thighs, knees and lower legs. He had no past medical history and was not on any medication. He attended his local A&E and was discharged with general back pain advice and physiotherapy referral. Due to ongoing pain, he went to see his GP, who, on examination, demonstrated only L4 region tenderness on palpation with normal power, reflex, sensation in both lower limbs with down going plantars and normal anal tone. He was then re-referred to A&E for imaging.

An initial lumbar radiograph demonstrated an acute displaced fracture of the L4 vertebral body (Figure 1). Considering this, a trauma CT was obtained and demonstrated indeterminate bilateral psoas hypodensities adjacent to the burst fracture (Figure 2). His blood tests were unremarkable. He was then placed in a lumbar brace and transferred to the trauma centre for further management. Following this, an MRI was performed for further characterization, which demonstrated focal high T2 signal in both psoas muscles in keeping with hematomas and confirmed a burst L4 fracture with retropulsion of bony fragments into the central canal but no spinal cord injury (Figure 3). Given he had no acute neurology and after neurosurgical discussion, he was given the option of conservative or operative (spinal fixation) treatment.

Psoas hematomas are rare occurrences occurring up to 0.1-0.6% with risk factors including being on anticoagulants, old age and undergoing hemodialysis [2] and can pose a mortality rate of up to 30 % [3]. The psoas muscle is covered by multiple layers of fascia reinforcing its strength, thus with any insult causing intramuscular bleeding will lead to the expansion of the psoas muscle, increase in intra-compartmental pressure and nearby nerve effacement, which may cause pain [4].

In the literature, exclusively unilateral psoas haematomas are reported. For example, patients on anticoagulants or with a history of liver cirrhosis developing a unilateral psoas haematoma due to vertebral compression fracture [5,6]. Consequently, cross-sectional imaging is essential in diagnosing psoas haematoma early on in trauma. Treatment of traumatic psoas haematomas, depending on severity, include conservative management, surgical intervention or percutaneous intervention, specifically transcatheter arterial embolization.

Written informed patient consent for publication has been obtained.