Background

In periradicular therapy (PRT), painkilling and anti-inflammatory drugs (anesthetic/cortisone mixture) are administered to the painful nerve root with millimeter precision under computer tomographic (see CT) or radiological position control. A cortisone syringe is usually used for this purpose.

Orientation wire on the back surface
Infiltration planning: depth and lateral distance to the orientation wire
Basins
Nerve root exit 1st sacral root (S1) right
Vertebral body
Vertebral joint
Vertebral arch (Lamina)
Whirling spinous process
Spinal Canal

The figure shows a CT-guided periradicular therapy of the first sacral root (S1) on the right, which is particularly often irritated by a herniated disc of the last lumbar disc (L5/S1).

PRT leads to a containment of the inflammation around the nerve root and to a decongestant nerve root. In the case of a herniated disc, sometimes a shrinking of the displaced disc tissue can be observed. Often several such infiltrations are necessary to achieve the desired therapeutic effect.

The swelling of the nerve root means that there is relatively more space in the nerve exit area of the spine. And although constricting bone edges or a herniated disc in the lumbar or cervical spine remain, freedom from pain can be achieved. In addition, the anti-inflammatory effect of cortisone means that the nerve root no longer reacts so sensitively to mechanically or chemically irritating stimuli (e.g. disc tissue).

The procedure is not a substitute for surgical therapy, but can be used as an alternative to immediate surgery in the case of therapy-resistant pain in the absence of neurological deficits or only minor neurological deficits. The use of computed tomography is not absolutely necessary for injection treatment. Image converter (mobile X-ray unit) supported infiltration, open MRI and even infiltration without imaging are possible.

In the latter case, one orients oneself to certain points on the body (anatomical landmarks). If a sufficiently large infiltration volume is selected, an almost exact syringe placement is sufficient because the administered active substances are distributed in the environment and can still effectively flood the compressed nerve root. An exact procedure using CT (computed tomography) as the imaging method is nevertheless recommended, especially if the infiltrations are intended to confirm a diagnosis.

The pain therapeutic effect is very good. The infiltration can be repeated several times, has few complications and can be carried out on both an outpatient and inpatient basis. Anesthesia is not necessary.

The patient is placed on the computer tomography table on his stomach. The arms are placed forward under the forehead. Then a metal orientation wire is glued to the middle of the (mostly) lumbar spine on the naked back.

(Periradicular therapy is also suitable for nerve root irritation of the cervical and thoracic spine). Finally, CT (computed tomography) is used to obtain an overview image of the affected back region. The doctor can then use this image to determine the location of the pathological nerve root exit.This area is then displayed precisely with the CT (computed tomography).

Once the desired nerve root exit has been determined, the infiltration depth and lateral deviation from the center of the spine for infiltration are determined. The previously attached wire, which is visible as a point on the CT sectional image on the patient’s back, serves as orientation. A light strip projected onto the patient’s back now shows the physician the infiltration height.

The determined lateral deviation from the orientation wire is measured with the ruler and marked on the skin. After skin disinfection, the needle (cannula) is then placed in position. With a cannula that takes the infiltration depth into account, the predetermined path to the nerve root is now stung.

In order to confirm the correct placement, the position of the cannula tip in relation to the nerve root is again shown in the CT (computer tomography). If the cannula tip is correct, the mixture of a local anaesthetic and cortisone is injected as described above. If the doctor has deviated from the cannula placement, the position of the cannula must be corrected and checked again. After the infiltration the patient should lie down for 2 hours if possible. Leg weakness due to nerve blockage is possible.