Sciatica may begin either suddenly with physical activity or slowly. Sciatic pain has
aching and sharp components and radiates along a broad line from the middle or
lower buttock, proceeding dorsolaterally in the thigh in cases of compression of
the L5 nerve root and posteriorly in cases of compression of S1. With L4 compression,
the pain is anterolateral in the thigh and may be misattributed to hip disease.
If nerve-root pain extends below the knee, its location conforms to the superficial
sensory distribution of the affected spinal root.
Sciatica is usually unilateral, in
keeping with the common dorsolateral configuration of disk rupture and with
foraminal stenosis from osteoarthritic disease of the spine. There may be bilateral
pain in central disk herniation, lumbar stenosis, and spondylolisthesis.
Low back pain of variable severity accompanies sciatica but is not a consistent
feature. Aching in the L5–S1 area or in the upper sacroiliac joint is common with
disk rupture. Increased back and sciatic pain with coughing, sneezing, straining, or
other forms of the Valsalva maneuver suggests disk rupture. Depending on the site and size of the rupture, the patient may adopt a
posture of ventroflexion and either reduced or exaggerated
lumbar lordosis, minimizing pressure
on the root. Bilateral sciatica that is brought on
by walking and simulates vascular claudication
is the result of compression of the cauda equina
roots. Such compression is known as neurogenic
claudication (the Verbiest syndrome).