[The diagnostic value of selective lumbar nerve root block].

In patients with a neurogenic claudication syndrome root tension signs and neurological deficits are usually not observed. Lumbar myelography and CT scanning show also in a number of asymptomatic elderly people signs of nerve-root involvement. When stenosis of the vertebral canal is excluded the correlation in patients between symptoms and radiological signs is not clear. To improve the diagnostic ability selective lumbar root sheath infiltration was introduced by MacNab. The diagnostic value of this test was assessed prospectively. In 24 patients with a classic disk protrusion syndrome the sensitivity was 100%. The predictive value in patients with nerve-root-entrapment due to degenerative narrowing of the nerve-root was 70-80%.