A 28-year-old man comes to the office due to a 4-month history of pain and stiffness in the lower back and neck. Symptoms are worse with prolonged rest and in the early morning. The patient also has fatigue and poor sleep. He has no other medical conditions and takes no medications. Vital signs are normal. Examination shows limited forward bending of the trunk. Lower extremity muscle power and reflexes are normal. Which of the following is most likely to confirm the diagnosis?

Question

A 28-year-old man comes to the office due to a 4-month history of pain and stiffness in the lower back and neck.  Symptoms are worse with prolonged rest and in the early morning.  The patient also has fatigue and poor sleep.  He has no other medical conditions and takes no medications.  Vital signs are normal.  Examination shows limited forward bending of the trunk.  Lower extremity muscle power and reflexes are normal.  Which of the following is most likely to confirm the diagnosis?

Quizplus · Accepted Answer

11ec160b_3a54_a593_9249_8b1e8903cc33_MD0001_00 This patient with chronic pain and stiffness in the spine and reduced spinal mobility likely has ankylosing spondylitis (AS). The pain in AS is generally better with activity and worse at night and with rest, which can lead to disrupted sleep and daytime fatigue. AS is characterized by bony erosions and excessive formation of new bone in the axial skeleton, primarily around the vertebral margins. Patients with suspected AS should undergo x-ray of the spine and pelvis, which can assist in the diagnosis: X-ray of the pelvis shows inflammatory arthritis of the sacroiliac joints (ie, sacroiliitis), visible as joint erosions with subchondral sclerosis. These findings are relatively specific for spondylarthritis (including AS) and, in association with typical symptoms, are often adequate for diagnosis. As the disorder progresses, the joint space is obliterated, leading to bony fusion (ankylosis). Spinal x-ray may show heterotopic ossification affecting the margins of the vertebral bodies, which are visible as bridging syndesmophytes. Advanced and continuous syndesmophyte formation is termed bamboo spine. AS is a seronegative spondyloarthropathy, and there are no serologic tests to confirm the diagnosis. Although most cases are associated with human leukocyte antigen B27 (HLA-B27), most patients with HLA-B27 never develop AS, so this marker does not confirm the diagnosis. Patients often have elevated inflammatory markers (eg, erythrocyte sedimentation rate, C-reactive protein) and abnormal blood counts (eg, anemia, leukocytosis), but these findings are nonspecific (Choices A and B). (Choice C) Nerve conduction studies are typically used to identify peripherial nerve lesions in patients with deficits on neurologic examination. This patient has normal examination findings, so electrodiagnostics would have little utility. (Choice D) Rheumatoid factor is used in the diagnosis of rheumatoid arthritis (RA), which typically occurs in patients age >40 and is more common in women (AS is more common in men). RA usually causes a symmetric peripheral arthritis; cervical involvement can occur, but the lumbar spine is usually spared. Educational objective: Ankylosing spondylitis presents with chronic back pain with reduced spinal mobility. X-rays of the spine and pelvis can aid in diagnosis by identifying specific findings such as sacroiliitis (eg, joint erosions with subchondral sclerosis and eventual ankylosis) and bridging syndesmophytes (heterotopic ossification affecting vertebral body margins).

A 28-Year-Old Man Comes to the Office Due to a 4-Month