My Bladder, My Back

What is the most likely diagnosis?

Spondyolodiscitis. This heterogenous term spans vertebral osteomyelitis, spondylitis, and discitis [1]. See Image 2 for the annotated plain film. 

Image 2. Loss of T12-L1 disc space with destruction and collapse of adjacent vertebral bodies. Plain radiograph of the lumbar spine, lateral. Annotation by author. Image courtesy of Matt Skalski, Radiopaedia.org, rID: 25127

What is the pathophysiology of the diagnosis?

The patient likely has a concomitant urinary tract infection versus pyelonephritis. Therefore, he is at risk for hematogenous spread from the bladder - his reported fevers and chills may indicate transient bacteremia. There is also the possibility that there is contiguous spread from the kidney.

• Pearl: The Batson venous plexus is a series of valveless veins that anastomose with the pelvic venous plexus. There is a debated theory that disease including pathogens and even metastases can spread from the pelvis to the spine via this plexus [2]. 

What physical exam findings are expected?

Fever, tenderness to palpation of the spine, or neurologic symptoms. A high index of clinical suspicion is often needed to make this difficult diagnosis.

• Pearl: Focal back pain is the single most common physical exam finding. Fever is not sensitive for spondylodiscitis. Neurologic symptoms may raise concern for associated epidural abscess [3].

What imaging modality is useful?

Magnetic resonance imaging (MRI) is the gold standard. CT scan and bone scintigraphy are alternative modalities but not considered first line imaging. Plain radiograph is the initial study of choice for undifferentiated low back pain [4]. 

• Pearl: Contrast enhanced CT can be considered when attempting to diagnose paravertebral abscess [1].

What is the management in the ED?

Admission. Bloodwork such as leukocyte count, C-reactive protein, and blood cultures are important. Given this patient’s plain radiograph, MRI should be pursued. Empiric antibiotics are the cornerstone of therapy for spondylodiscitis. The Infectious Diseases Society of America recommends 6 weeks of antibiotic therapy [5].

• Pearl: If a concomitant abscess is found, percutaneous abscess drainage via ultrasound or CT guidance can be performed if the appropriate size [1]. 

When do you consult orthopedics?

Surgical indications include neurologic deficits, sepsis, presence of intraspinal empyema, large (>2.5 cm) abscess, failure of conservative therapy, or spinal instability [1].