Sciatica

Procedure

Patient sits upright at the edge of the plinth with knees bent, hands behind the back. In sequence: slump the thoracic and lumbar spine, flex the neck (chin to chest), extend the knee on the tested side, then dorsiflex the ankle. Stop at the first symptoms. Then ask the patient to lift the head and note any change.

Positive Finding

The patient's familiar leg symptoms reproduced in the slumped position and eased when the neck is released.

Sensitivity / Specificity

Reference: Majlesi J, Togay H, Unalan H, Toprak S. The sensitivity and specificity of the Slump and the Straight Leg Raising tests in patients with lumbar disc herniation. J Clin Rheumatol. 2008;14(2):87-91.

Interpretation

A positive slump with relief on neck release suggests the leg pain comes from irritable neural tissue. Many people feel a normal stretch behind the knee in this position, so compare sides and look for the patient's own symptoms. From one case-control study (Majlesi 2008) of 75 outpatients with back and/or leg pain: 38 had a disc herniation on MRI and 37 did not. The comparison patients had symptoms too, which is the fair comparison. But a herniation on MRI is not always the cause of the pain. In the same patients the straight leg raise scored 52% / 89%.

Procedure

Patient supine, legs straight, no pillow under the head. Lift the symptomatic leg slowly with the knee held straight until the patient reports symptoms. Note the angle and where the symptoms are felt, then add ankle dorsiflexion.

Positive Finding

The patient's familiar leg pain, usually below the knee, reproduced as the leg is raised and increased by ankle dorsiflexion. A posterior thigh stretch alone does not count.

Sensitivity / Specificity

Reference: van der Windt DA, Simons E, Riphagen II, Ammendolia C, Verhagen AP, Laslett M, et al. Physical examination for lumbar radiculopathy due to disc herniation in patients with low-back pain. Cochrane Database Syst Rev. 2010.

Interpretation

A negative SLR makes a disc herniation causing the sciatica less likely. A positive SLR supports nerve-root irritation, but on its own proves little. Combine it with the crossed SLR, the neurological examination and the history. Pooled in a 2010 Cochrane review (van der Windt) from studies where surgery confirmed the diagnosis. Those patients were already selected for surgery (58–98% had a herniation), so specificity is poorly estimated, and sensitivity was lower in studies that used imaging or were done in primary care. A negative SLR makes a disc herniation causing leg pain less likely; a positive SLR on its own proves little.

Procedure

Patient supine. Lift the unaffected leg with the knee straight while the patient reports any symptoms in the painful leg.

Positive Finding

Reproduction of the familiar sciatic pain in the symptomatic leg when the opposite leg is raised.

Sensitivity / Specificity

Reference: van der Windt DA, Simons E, Riphagen II, Ammendolia C, Verhagen AP, Laslett M, et al. Physical examination for lumbar radiculopathy due to disc herniation in patients with low-back pain. Cochrane Database Syst Rev. 2010.

Interpretation

Usually negative, so a negative result does not rule out a herniation. When positive, a disc herniation compressing the nerve root is much more likely. Check the neurological examination and red flags carefully. Pooled in a 2010 Cochrane review (van der Windt), mostly from surgical populations. A positive crossed SLR makes a disc herniation more likely; because it is usually negative, a negative result does not rule one out.

Procedure

Perform the straight leg raise to the point where leg symptoms appear, lower the leg a few degrees until they ease, then dorsiflex the ankle.

Positive Finding

The familiar leg pain returns or increases when the ankle is dorsiflexed.

Sensitivity / Specificity

Reference: Homayouni K, Jafari SH, Yari H. Sensitivity and Specificity of Modified Bragard Test in Patients With Lumbosacral Radiculopathy Using Electrodiagnosis as a Reference Standard. J Chiropr Med. 2018;17(1):36-43.

Interpretation

Dorsiflexion tensions the sciatic and tibial nerves without changing hamstring length, so a return of pain supports a neural source. This entry previously said dorsiflexion relieves the pain, which is the reverse of the finding. Figures are for the "modified" version: raise the straight leg to 70°; if that causes no leg pain, firmly dorsiflex the foot. A study of 506 people referred for nerve testing with one-sided leg pain (Homayouni 2018) used it in the 203 whose straight leg raise was negative, with nerve conduction and EMG as the reference. It was positive in 69% of those with L5/S1 radiculopathy and negative in 67% of those without. The figures apply only to people whose straight leg raise is negative.

Procedure

Patient prone. Bend the knee towards the buttock; if no symptoms appear, gently extend the hip while stabilising the pelvis. Compare with the other side.

Positive Finding

Reproduction of familiar pain in the front of the thigh or groin. A quadriceps stretch alone does not count.

Interpretation

Tests the upper lumbar roots (L2–L4), which do not form the sciatic nerve. In a patient with sciatica it is usually negative; a positive result points to an upper lumbar root and a different pain pattern (front of thigh) than classic sciatica. In a study of 54 people with a compressed nerve root on MRI (Suri 2011), this test was positive in none of the 29 with an L5 or S1 root compressed (the roots behind typical sciatica) and in half of those with an L2–L4 root compressed. A positive test therefore points away from typical sciatica, towards a higher lumbar root. No figure is shown because this is not a test for sciatica itself.

Procedure

Test strength by myotome (knee extension L3–4, dorsiflexion L4, big-toe extension L5, plantarflexion S1), light-touch and pin-prick sensation by dermatome, and the patellar (L4) and Achilles (S1) reflexes, comparing both sides.

Positive Finding

Weakness, altered sensation or a reduced reflex that fits one nerve root and matches the leg pain, for example a reduced Achilles reflex and weak plantarflexion with S1.

Interpretation

A matching deficit supports nerve-root compression and suggests the level. A normal examination does not exclude it. Progressive weakness, saddle numbness, or bladder or bowel change needs same-day medical assessment.