Case Presentation: 69 y/o female presents to the emergency department with acute on subacute low back pain in the setting of fall 12 weeks prior. Treated outpatient with conservative therapy including topicals, NSAIDs, tramadol, Flexeril and physical therapy. PMH of asthma, migraines, breast cancer in remission (s/p lumpectomy, chemotherapy and radiation in 2015, last annual mammogram negative), previous colonic polyps and osteopenia. Severe pain awakened her at night with new urinary incontinence. Denies fevers, saddle anesthesia or change in lower extremity strength. Reports fatigue, loss of appetite, and 10 lb weight loss in one month. Labs show normocytic anemia Hgb 8.2, leukocytosis WBC 15.3, AKI creatinine 1.35 (baseline 1.04), calcium 9.6, ferritin 1542. Spine surgery consulted, MRI showed advanced spinal canal stenosis with cord compression at T11 and T12, several enhancing lesions in the cervical, thoracic and lumbar spine and multiple pathologic compression fractures. No acute surgical intervention recommended. SPEP, UPEP and polyclonal gammopathy testing returned negative. CT chest/abdomen/pelvis showed right hilar and retroperitoneal lymphadenopathy, with mixed lytic and sclerotic lesions seen throughout axial and appendicular skeleton. Retroperitoneal lymph node biopsy returned positive for metastatic breast adenocarcinoma. Acute pain inadequately controlled with opioids, antispasmodics, and steroids, Radiation Oncology then involved for radiation therapy to the spine.
Discussion: Low back pain is typically classified into nonspecific, associated with radiculopathy/ spinal stenosis or with another specific cause. Majority of patients with acute back pain do not require imaging and improve over time with conservative management. Emphasis should be on history of constitutional symptoms, triggering trauma, malignancy, recent infections, procedures, IV drug use, immunosuppression, unimproved back pain with conservative therapy, or progressive neurologic deficits including urinary retention, overflow urinary or fecal incontinence, saddle anesthesia or progressive lower extremity weakness. Patients with the above red flag symptoms require urgent imaging, as these symptoms could be suspicious for spinal cord or cauda equina compression, spinal infection including spinal epidural abscess or osteomyelitis, malignancy or vertebral compression fracture. MRI is the imaging modality of choice, particularly without and with intravenous contrast to evaluate for underlying infection or mass, osseous involvement and potential epidural disease. Presence of skeletal lesions on imaging should prompt classification into characteristic of the lesion, including purely osteolytic (seen in multiple myeloma) vs osteoblastic (seen in prostate cancer) vs mixed lesions (seen in breast cancer). If suspicion for metastatic cancer is highest, biopsy is typically indicated for diagnostic confirmation for those with cancer in remission. Those confirmed malignancy positive should have involvement with radiation oncology.
Conclusions: Acute back pain is frequently encountered in the hospital. While most cases do not require advanced imaging, it is important for the hospitalist to recognize red flag symptoms concerning for malignancy, cauda equina syndrome, spinal epidural abscess, osteomyelitis or compression fracture. These red flags require expedited workup, since any delay in the diagnosis may lead to significant morbidity and mortality.
