Undifferentiated Back Pain — Clinical Case

DCE Long Case

Patient brief (provided to trainee)

Patient: Mr David Tran, 34 years old, software engineer. [1]

Presenting complaint: A three-year history of progressive low back pain and morning stiffness, with a worsening over the last three months. The pain is in the lower back and the buttocks, it is worse in the morning, it improves with exercise, and it wakes him in the second half of the night — he gets up and walks around for relief. He has morning stiffness for over an hour. [1]

Past history: Psoriasis (on the scalp and the extensor surfaces, treated with a topical corticosteroid) and one episode of a painful red right eye six months ago, treated as iritis by his optometrist. No bladder or bowel symptoms, no weight loss, no fever. No other medical history. He takes ibuprofen as needed, which helps. He is a non-smoker, he drinks alcohol in moderation, and there is no family history of note. [1]

Examination findings (trainee elicits):

• Afebrile, alert and oriented.
• Reduced lumbar flexion (the modified Schober test increases by 3 cm).
• Reduced chest expansion (4 cm at the fourth intercostal space).
• Tenderness over both sacroiliac joints.
• The straight leg raise is full and painless bilaterally.
• The lower limb neurological examination is normal.
• The skin shows psoriatic plaques on the scalp and the extensor surfaces of the elbows and the knees.
• No active eye inflammation. The abdomen is soft and non-tender. The pulses are present. The per rectal examination is normal. [1]

Investigations (available results):

• FBC, renal and liver function: normal.
• CRP raised at 24 (normal less than 5).
• ESR 38 mm per hour.
• HLA-B27 positive.
• The pelvic X-ray: bilateral grade 2 sacroiliitis. [1]

Candidate's structured presentation (model)

Opening statement (SASPOP): [1]

"Mr David Tran is a 34-year-old software engineer presenting with a three-year history of progressive inflammatory low back pain — pain that is worse in the morning, that improves with exercise, that wakes him at night and improves on rising, with morning stiffness over an hour — on a background of psoriasis and a prior episode of anterior uveitis. His main problem is axial spondyloarthritis, most likely ankylosing spondylitis, supported by the inflammatory back pain criteria, the psoriasis, the uveitis, the raised inflammatory markers, the HLA-B27 positivity and the bilateral grade 2 sacroiliitis on the pelvic X-ray. My priorities are the confirmation of the diagnosis with an MRI of the sacroiliac joints to assess the active inflammation, the rheumatology referral for the treat-to-target management, the assessment of his cardiovascular and pulmonary risk, the screening of his eyes for the recurrent uveitis, and the discussion of the prognosis and the lifestyle — the smoking cessation, the exercise and the physiotherapy." [1]

Management plan: [1]

1. Confirm the diagnosis and assess the activity. An MRI of the sacroiliac joints for the active (oedematous) sacroiliitis, which guides the escalation to a biologic.
2. Rheumatology referral and the treat-to-target approach. A trial of a full-dose NSAID (naproxen 500 mg twice daily, with a proton pump inhibitor), with a regular reassessment of the disease activity (the BASDAI score); escalation to a tumour necrosis factor inhibitor (adalimumab, etanercept) or an interleukin-17 inhibitor (secukinumab) for the refractory or the high-activity disease, guided by the NICE NG65 [6].
3. Physiotherapy and exercise. A structured programme of the spinal mobility, the postural exercise and the core strengthening, the cornerstone of the long-term management.
4. The uveitis. The ophthalmology link for the early treatment of the recurrence.
5. The cardiovascular and the pulmonary surveillance. A baseline echocardiogram and a chest X-ray, and the vigilance for the chest pain and the breathlessness.
6. The lifestyle and the psychosocial. The smoking cessation, the ergonomic advice, the occupational therapy, and the discussion of the prognosis.

Communication and shared decision-making: Explain to Mr Tran that he has an inflammatory condition of the spine (axial spondyloarthritis), that it is treatable and manageable in the modern era, and that the combination of the medication, the physiotherapy and the lifestyle will preserve his function and his quality of life. Surface the prognosis honestly — the condition is chronic but the modern treatment has transformed the outlook — and set the expectation that the management is a partnership between him, the rheumatologist, the physiotherapist and the general practitioner. [1]

Examiner discussion questions

Q1: "How do you distinguish his inflammatory back pain from mechanical back pain?" [1]

"The ASAS inflammatory back pain criteria are my framework. Mr Tran meets at least four of the five: the age of onset under 40, the insidious onset, the improvement with exercise, the lack of improvement with rest, and the night pain improving on rising. He also has the morning stiffness over an hour. The discriminating features from the mechanical pain are the opposite response to activity (the inflammatory improves, the mechanical worsens), the night pain that improves on rising (the mechanical is typically relieved by lying down), and the morning stiffness over 30 minutes. The extra-articular features — the psoriasis and the uveitis — are the clinching evidence that this is a spondyloarthritis [6]. The registrar who attributes this presentation to a lumbar strain has missed the diagnosis by years."

Q2: "His pelvic X-ray shows bilateral grade 2 sacroiliitis. Does he need an MRI?" [1]

"The X-ray confirms the structural sacroiliitis, which is sufficient for the modified New York criteria for ankylosing spondylitis, so the MRI is not needed to make the diagnosis. But I would arrange the MRI of the sacroiliac joints to assess the active inflammation (the bone marrow oedema), because the presence and the degree of the active inflammation guide the escalation to a biologic. The MRI is also the investigation that detects the early sacroiliitis before the radiographic change, which is the value of the ASAS imaging arm in the patient with the clinical picture but the normal X-ray [6]."

Q3: "He is HLA-B27 positive. Does that confirm the diagnosis?" [1]

"No. The HLA-B27 is neither necessary nor sufficient for the diagnosis. It is a supporting feature in the ASAS clinical arm, but Mr Tran already meets the imaging arm, so the HLA-B27 is confirmatory rather than diagnostic. The HLA-B27 is present in about 90 per cent of the patients with ankylosing spondylitis but also in about 8 per cent of the general population, most of whom never develop the disease — so a positive test in isolation does not diagnose the axial SpA, and a negative test does not exclude it. The test is most useful in the patient with the clinical picture and the normal imaging, where it raises the pre-test probability enough to justify the MRI [6]."

Q4: "What is your approach to his pharmacological management?" [1]

"The first-line is a full-dose NSAID at the maximum tolerated dose for at least two to four weeks — naproxen 500 mg twice daily, or celecoxib 200 mg twice daily, with a proton pump inhibitor. The response to NSAIDs is itself a SpA feature, and about half to two-thirds of the patients respond adequately [6]. If the NSAID is insufficient, or if there are contraindications, or if the disease is high-activity, I escalate to a biologic under the rheumatology guidance — a tumour necrosis factor inhibitor (adalimumab 40 mg subcutaneously every two weeks) or an interleukin-17 inhibitor (secukinumab), guided by the NICE NG65 [6]. I avoid the systemic corticosteroid for the axial disease and I reserve the intra-articular corticosteroid for the peripheral joint. The non-pharmacological management — the structured physiotherapy, the daily spinal mobility and the smoking cessation — is the other cornerstone."

Q5: "What are the extra-articular complications you would screen for?" [1]

"The anterior uveitis (the commonest, in about a third of the patients — I link him to ophthalmology), the cardiovascular associations (the aortic regurgitation and the conduction disease — a baseline echocardiogram and an ECG), the pulmonary associations (the apical pulmonary fibrosis and the restrictive chest wall disease — I monitor the chest expansion and the spirometry), the osteoporosis (the inflammation and the immobility increase the fracture risk — a DEXA scan), and the inflammatory bowel disease (I ask about the chronic diarrhoea and the rectal bleeding). The teaching point is that the axial SpA is a systemic disease, and the surveillance spans the eyes, the heart, the lungs, the bones and the gut [6]."

Q6: "What is the single most important lesson from this case for a registrar managing undifferentiated back pain?" [1]

"The single most important lesson is to ask the inflammatory back pain questions in every patient under 40 with back pain. Mr Tran's diagnosis was delayed for three years because the registrar who saw him first attributed the pain to a lumbar strain and did not ask about the morning stiffness, the night pain improving on rising, the improvement with exercise, or the psoriasis and the uveitis. The registrar who asks the inflammatory back pain criteria, examines for the extra-articular features, and measures the modified Schober and the chest expansion has made the diagnosis that day, and the patient is spared the years of the untreated inflammation and the progressive structural damage [1][2][3]. The corollary is the triage: most back pain is mechanical and needs no imaging, but the minority with the inflammatory, the infective, the malignant and the cauda equina features must not be missed — and the red flag and the inflammatory screen on every patient is the safeguard."

DCE Short Case — The Systematic Spine Examination

Instruction

"You are the medical registrar assessing a 34-year-old man in the outpatient clinic with a three-year history of progressive low back pain and morning stiffness. Examine his spine, present your findings, and offer a differential diagnosis. You have 5 minutes to outline your examination approach and 5 minutes for discussion." [1]

Provided data: The patient is a 34-year-old man with the history above. On examination: a mildly stooped posture with a reduced lumbar lordosis; a reduced lumbar flexion (the modified Schober increase of 3 cm); a reduced chest expansion of 4 cm; tenderness over both sacroiliac joints; the straight leg raise full and painless; the lower limb neurological examination normal; psoriatic plaques on the scalp and the extensor surfaces. [1]

Presentation template

"I have examined this man's spine. At the end of the bed he is a young man with a mildly stooped posture and a reduced lumbar lordosis. His gait is normal. His hands show psoriatic plaques on the extensor surfaces. The abdomen is soft with no pulsatile mass. The spine shows a reduced lumbar flexion — the modified Schober test increases by only 3 cm — and a reduced chest expansion of 4 cm. There is tenderness over both sacroiliac joints. The extension and the lateral flexion are reduced. The straight leg raise is full and painless bilaterally. The lower limb neurological examination is normal. My findings are most consistent with an axial spondyloarthritis — the reduced lumbar flexion, the reduced chest expansion, the sacroiliac tenderness and the psoriasis — and I would confirm with an MRI of the sacroiliac joints, the HLA-B27 and the inflammatory markers, and a rheumatology referral [6]."

Discussion

Examiner: "Why is the chest expansion reduced in ankylosing spondylitis?" [1]

"The inflammation and the syndesmophyte formation at the costovertebral and the costotransverse joints stiffen the rib cage, so the patient cannot expand the ribs on inspiration and becomes dependent on the diaphragm. A chest expansion of less than 2.5 cm at the fourth intercostal space is one of the modified New York criteria for ankylosing spondylitis. The reduction is a marker of the spinal rigidity, and it predicts the restrictive lung disease that complicates the advanced condition [6]."

Examiner: "How would you investigate this patient?" [1]

"My framework is the triage. Mr Tran has the inflammatory back pain criteria and the extra-articular features, so he is in the suspected axial SpA bin. My investigations are: the inflammatory markers (the CRP and the ESR, raised), the HLA-B27 (positive, supportive), the pelvic X-ray for the sacroiliitis (the structural change), and the MRI of the sacroiliac joints for the active inflammation. I would also screen for the extra-articular associations — the echocardiogram for the aortic regurgitation, the chest X-ray for the apical pulmonary fibrosis, the ophthalmology review for the uveitis, and the questions for the inflammatory bowel disease. The registrar who investigates the back pain with a lumbar spine MRI has missed the diagnosis, because the pathology is at the sacroiliac joints, not the lumbar spine [1][6]."

Examiner: "What is the lesson about the missed diagnoses in back pain?" [1]

"The lesson is that the missed diagnoses in back pain are the inflammatory causes (the axial spondyloarthritis, missed because the registrar does not ask the inflammatory back pain criteria), the infective causes (the vertebral osteomyelitis and the epidural abscess, missed because the X-ray is normal in the early stage and the registrar does not check the CRP and the ESR or image with the MRI), the malignant causes (the bony metastases and the myeloma, missed because the registrar does not take the history of the cancer and the weight loss or check the age-appropriate bloods), and the cauda equina syndrome (missed because the registrar does not ask about the bladder and the bowel and does not perform the per rectal examination) [1][4][5]. The corollary is that the red flag and the inflammatory screen on every back pain patient is the safeguard that sorts the patient into the right bin and prevents the diagnostic delay and the missed emergency."