Lumbar disc signs

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  1. Moderate compression of a nerve root in the absence of inflammation will produce paresthesias, not pain; when inflammation is present, a sharp pain is elicited starting in the low back and proximal portion of the leg and progressing distally in a typical dermatomal pattern. Compression by a lumbar disc is generally directed onto the nerve root itself or shoulder of the nerve root. The crossed Lassegue sign suggests localization of the disc compression to the axilla of the nerve root: the affeted root cannot move when the unaffected leg is lifted. Pain radiates down the affected leg when lifting the unaffected leg.
  2. L5-S1; S1 radiculopathy
    1. pain is on the posterior or lateral aspect of the leg and may go into the lateral aspect of the heel and smaller toes; patient may tilt away from the affected side; any maneuver that increases intraspinal pressure such as coughing or sneezing will exacerbate the radiculopathy
    2. in sciatic pain syndromes the presence of an ipsilateral straight leg raising sign is very common (sensitive) and pain on contralateral straight leg raising is more highly predictive (specific) of lumbar disc herniation
    3. the ankle jerk reflex may be diminished or absent
    4. may have weakness of the gastrocnemius muscle
  3. L4-5; L5 radiculopathy
    1. pain radiating down the posterolateral aspect of the thigh and leg with numbness on the outside of the shin and dorsum of the foot, that may extend to the great toe
    2. weakness of extensor hallicus longus and dorseflexion can also be demonstrated
    3. straight let raise is often present and contralateral straight leg raise is very specific test
    4. there is no reflex to test that is specific to this level
  4. L3-4; L4 radiculopathy
    1. associated with pain radiating down the anterior aspect of the thigh and occasionally down to the lower leg
    2. knee jerk reflex may be depressed
    3. quadriceps muscle is often weak
    4. straight leg raise is most commonly normal but signs may be reproduced by hyperextending the affected leg with the patient in the prone position
  5. L2-3; L3 radiculopathy
    1. may cause pain to radiate into the groin or upper thigh
    2. psoas muscle weakness is occasionally seen

Note: Levels of radiculapathy above are for typical paracentral disk herniations. Paracentral disc herniations affect the traversing nerve root (eg. a L5-S1 disc affects the passing S1 nerve root). Foraminal or far lateral disk herniations will affect the exiting, rather than the traversing, nerve root (example: L5-S1; L5 radiculopathy).

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