Differentials
Spinal tumour
SIGNS / SYMPTOMS
A benign or a malignant spinal tumour can present with back pain with radicular symptoms. The pain from a spinal tumour is a constant, dull ache, associated with loss of appetite and weight loss, and is not necessarily related to activities but is present at rest as well. The presence of nocturnal pain is a red flag.
INVESTIGATIONS
MRI scans are the definitive test for assessing spinal tumours. The disc space is usually preserved and the bone may be destroyed with associated compression on the neural structures.
Spinal infection
SIGNS / SYMPTOMS
Spinal infection can present with a gradual onset of back pain that is associated with bending and twisting activities. It may be associated with systemic signs and symptoms and progress at a pace that is much more rapid than that seen with a degenerative pathology.
INVESTIGATIONS
Blood inflammatory markers are usually elevated. The MRI findings are diagnostic with a destruction of adjacent vertebrae and loss of the disc space.
Postural back pain
SIGNS / SYMPTOMS
A poor sitting posture, a desk job with inappropriate working conditions, and the lack of suitable muscle tone and core stability can lead to back pain. This is amenable to treatment by physiotherapeutic modalities and weight reduction.
INVESTIGATIONS
Workplace assessment may detect poor posture during work-based activities.
If pain persists, further imaging is warranted.
Muscular pain secondary to lower extremity malalignment
SIGNS / SYMPTOMS
Limb length discrepancy (malaligned hip, knee arthroplasty, malunited fracture) may lead to secondary asymmetrical stresses on the lumbar spine. This may lead to accelerated asymmetrical wear and symptoms akin to primary disc degeneration.
INVESTIGATIONS
Full limb radiographs, scannograms, MRI scans: confirm limb-length discrepancy noted on clinical examination.
Sacroiliac joint pathology
SIGNS / SYMPTOMS
Pain referred from a painful sacroiliac joint may be to the low back, buttocks, groin, or the thighs. This pattern may mislead the clinician to believe the cause to be a degenerate disc.
Inflammatory conditions such as ankylosing spondylitis have characteristic inflammatory back pain. This is defined as back pain that is of insidious onset, is worse in the morning, and improves with exercise.
INVESTIGATIONS
Inflammatory markers (erythrocyte sedimentation rate, CRP) may be elevated and specific markers (HLA-B27) may be positive.
Pelvic radiograph, bone scan, single photon emission CT, MRI: inflammation.
Intra-abdominal pathology
SIGNS / SYMPTOMS
Lesions in the kidneys, pancreas, and the intraperitoneal viscera can lead to referred back pain. The location and type of pain and associated features guide diagnostic evaluation.
INVESTIGATIONS
Investigations should be tailored to history and examination findings and be made on a case-by-case basis.
Ultrasound abdomen, CT abdomen, or contrast imaging for the kidneys and the pelvicalyceal system may be differentiating tests used depending on the clinical features present.
Pelvic pathology
SIGNS / SYMPTOMS
Intrapelvic space-occupying lesions such as tumours, abscesses, pelvic inflammatory disease can lead to back and gluteal pain. The location and type of pain and associated features guide diagnostic evaluation. May be associated gastrointestinal, gynaecologic, or urinary symptoms, and abnormalities on abdominal and pelvic examination.
INVESTIGATIONS
Ultrasound/CT pelvis: may show structural abnormality.
Myopathy
SIGNS / SYMPTOMS
Primary pathology (congenital or acquired) of the trunk muscles in the form of a myopathy can lead to axial back pain.
INVESTIGATIONS
Serum CK: elevated.
Muscle biopsy: histological findings specific to type of myopathy.
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