Differential Diagnosis
- Single most likely diagnosis
- Epidural abscess: This diagnosis is the most likely due to the patient's recent history of epidural injection, which is a known risk factor for epidural abscess. The patient's symptoms, including acute low back pain radiating to the foot, fever, and elevated leukocyte count, are also consistent with this diagnosis. The positive straight-leg raising test and muscle weakness (3/5 on dorsiflexion of the right ankle and great toe) further support this diagnosis.
- Other Likely diagnoses
- Spinal osteomyelitis: This diagnosis is also likely, given the patient's history of recent epidural injection and the presence of fever, elevated leukocyte count, and elevated erythrocyate sedimentation rate (ESR). Spinal osteomyelitis can present with similar symptoms to epidural abscess, including back pain and neurological deficits.
- Further herniation of the disc at L4 to L5: Although the patient had a recent diagnosis of disc herniation at L4 to L5, it is possible that further herniation has occurred, especially given the patient's history of recent relief with ibuprofen followed by recurrence of pain.
- Do Not Miss (ddxs that may not be likely, but would be deadly if missed.)
- Meningitis: Although meningitis is less likely given the patient's lack of mental status abnormalities, it is a potentially life-threatening condition that must be considered, especially in the context of recent epidural injection and the presence of fever and elevated leukocyte count.
- Rare diagnoses
- Compression fracture of the spine: This diagnosis is less likely, given the patient's history and symptoms, but could be considered in the context of osteoporosis or trauma, which are not mentioned in the case.
- Other infectious or inflammatory conditions, such as spinal epidural hematoma or cauda equina syndrome, could also be considered, but are less likely given the patient's history and symptoms.