How long does a cervical epidural last

Orthopedic pain therapy

Degenerative diseases of the supporting and locomotor organs are a widespread disease. The painful conditions that occur here affect 60 percent of all pain patients. The orthopedic surgeon treats this pain causally with his organ-specific means such as manual therapy, physiotherapy, orthopedic aids, bandages and local injections

The economic importance of spinal and joint diseases is evident from their relative frequency and constant increase in the statistics of health and pension insurance providers: The first serious illness in an adult's life and the most common cause of lost work and early retirement primarily affect the supporting and locomotor organs (7). Health insurance companies have registered an enormous increase in musculoskeletal diseases in the incapacity for work certificates in recent years, while respiratory, circulatory and digestive diseases are stagnating in comparison (7).

The focus is on pain
When patients with joint or spinal problems see the doctor, pain is the main focus. Stress-dependent, but also nocturnal complaints in the affected skeletal sections hinder the patient at work and do not allow him to rest even at night. In a comparative survey, two thirds of the patients in orthopedic practices stated that they had consulted the doctor primarily because of pain (7). Restriction of movement, muscle weakness, swellings and deformities were of secondary importance. Practices from other specialist disciplines had a significantly lower proportion of pain patients. The composition of the patients in the pain clinics is correspondingly (9, 3) (Figure 1).

Pain in the area of ​​the supporting and locomotor organs has its origin in mechanically irritated parts of the joint capsules, ligaments and muscle attachments, which are richly provided with neural sensors known as nociceptors. Nociceptors are particularly dense and diverse on the spine in the immediate vicinity of the vertebral joints and intervertebral discs, which are known to show early wear-related form and functional disorders in humans (5). Acute and chronic irritation of pressosensitive nociceptors in the movement segment lead via reflex muscle tension to poor posture, which in turn triggers pain. A vicious circle is set in motion. With the sensitization of the nociceptors, the pain threshold lowers. The intensity of the stimuli at which the painful sensory experience (8) sets in becomes less and less. The pain rocks, the nerves learn the pain. The pathological reflex activity is based on an impairment of the control function of the neuromuscular system (10). Every smallest nociceptive stimulus emanating from the disturbed movement segment or from the joint capsule causes relatively severe pain. Pain becomes the dominant symptom of the disease - a pain disorder of the supporting and locomotor organs. In this situation, it is not appropriate to flood the organism with analgesics. Increasing doses with secondary diseases and mental disorders are the result.
The therapeutic approach lies in the elimination or compensation of the mechanical or functional primary disturbance and in the elimination of the nociceptors at the starting point of the pain. However, the exact diagnosis must be made beforehand.

Pain diagnosis
The therapy of the pain disorder, which originates from the supporting and locomotor organs, requires an exact diagnosis of the primary disorder, which is only possible with the examination technique of manual medicine, probatory local injections and with the help of imaging procedures.
Shape and functional disorders in one section of the skeleton can cause functional disorders and pain in another region of the musculoskeletal system as a so-called secondary pain disease due to poor posture. Typical are, for example, pain in the sacrum or in certain lumbar vertebral joints with leg length differences and gait irregularities. General diagnoses such as lower back, shoulder and neck pain are not the basis for specific pain therapy. Before starting pain treatment in the supporting and locomotor organs, diagnoses are for example: segmental loosening C5 / 6 with radicular / pseudoradicular symptoms, supraspinatus tendon syndrome with incipient abduction, segmental loosening L5 / S1 with S1 ischialgia and irritation of the sacrum joint. The pain therapy is correspondingly specific.

Causal pain therapy
The principles of orthopedic pain therapy include eliminating the cause. The primary disorder identified during the examination, such as a leg length difference, muscular imbalance or segment loosening in the spine, must be treated with specific orthopedic measures (Figure 2). First of all, the patient must be thoroughly informed about the pain-inducing mechanism using blackboards and models to ensure that the prescriptions are applied consistently, such as:
1 gymnastic exercises,
1 leg length compensation,
1 relieving storage,
1 Use of orthopedic aids.
With these measures, the cause of the pain is often eliminated. However, this sometimes continues because pain has become the dominant symptom of the disease - the pain disorder. The sensitized nociceptors react when the pain threshold is lowered, even with apparently normal postures and movements. Therefore, a temporary elimination of sensitized nociceptors is necessary as part of symptomatic pain therapy.

Symptomatic pain management
Basically, a therapy of pain emanating from the supporting and locomotor organs is also possible through the general use of analgesics and myotonolytics. In the case of acute and, above all, modified pain, however, large amounts of systemically administered medication are required in order to reach the nociceptors of the joint capsules, muscles and ligaments in the necessary concentration. Eliminating the nociceptors by local treatment appears to be more sensible. As far as this can be achieved through external agents, use is made of them in orthopedic pain therapy: heat or cold packs, ointments, plaster bandages and others. Local injection treatment is particularly effective. By injecting analgesic, anti-inflammatory and anti-swelling agents at the point of origin of the pain, one can have a direct influence on painful primary disorders of the supporting and locomotor organs without burdening the entire organism with drugs more than necessary (7). A few milliliters of a low concentration (one to one and a half percent) local anesthetic solution are sufficient to switch off sensitized nociceptors. Repeated local injections as so-called therapeutic local anesthesia desensitize the nociceptors and raise the pain threshold. Patients with pain syndromes in the joint or in a certain movement segment of the spine already have an improvement in mobility and pain relief immediately after the local injection, which is sustained after repeated injections if the mechanical primary disorder is eliminated at the same time. In the event of accompanying inflammatory reactions in the surrounding tissue, additional steroids - also in low doses - can be infiltrated at the beginning.

Proven and new injection techniques
Injections are given in joints, in the joint capsules and bursa, on painful muscle and ligament attachments as well as in various places in the movement segment of the spine, the main starting point for neck, sacrum and sciatica complaints.
Finding the starting point for pain in the movement segment, especially in the case of degenerative diseases with changes in the shape of the intervertebral discs and vertebral joints, requires some experience. There are numerous possible complications due to the proximity of the spinal cord and its exiting nerves. Special care and precautionary measures are required. Injections near the spine in degenerative spinal diseases are therefore among the exceptionally difficult medical services (7).
The starting points of pain in the movement segment of the spine are located on the irritated spinal nerve itself with its branches to the muscles and vertebral joint capsule (ramus dorsalis), connection to the border cord (ramus communicans) and to the posterior longitudinal ligament, which is richly provided with nociceptors, and the dorsal portion of the annulus fibrosus via the ramus recurrens, which pulls from the exiting spinal nerve through the intervertebral foramen back into the spinal canal.
In addition to injections into the vertebral joint capsules (so-called facet infiltration), the injection forms that cause analgesia and desensitization of one or more spinal nerves in the main irritation area, i.e. in the spinal canal as local or epidural analgesia or as spinal nerve analgesia on the intervertebral foramina, have proven particularly successful in recent years, in which the ramus dorsalis, ramus meningicus and ramus communicans are infiltrated at the same time.
The special features of local injections near the spine in the context of orthopedic pain therapy are that
1 the application site on the affected spinal nerve is determined using a precise manual examination technique,
1 analgesia and anti-inflammatory treatment of a spinal nerve requires only small amounts of low-dose local anesthetics and steroids,
1 the accompanying causal therapy is an essential part of the therapy concept.

Facet infiltration
The principle consists in switching off sensitive fibers in the vertebral joint capsule by temporarily blocking them with a local anesthetic, possibly with the addition of steroids. The indication includes complaints that originate from the vertebral joints, i.e. facet syndromes, hyperlordosis, lower back pain and pseudoradicular syndromes of the cervical and lumbar spine. The accompanying physical therapy consists primarily of delordosing the affected spinal column sections with careful exercises in the relief posture.

Spinal Nerve Analgesia
The cervical and lumbar spinal nerve analgesia as so-called paravertebral root infiltration (Figure 3) has been a proven treatment method in orthopedics for decades. Paravertebral spinal nerve analgesia is achieved by the posterolateral injection of a local anesthetic into the foramino-articular region of the movement segment (4). This technique is used to reach the spinal nerve root, the spinal ganglion and parts of the sympathetic nerve in the affected segment.
After paravertebral spinal nerve analgesia in the technique described, the patient feels a reduction in pain in his back and leg pain, which lasts for an average of three and a half hours when using a one percent local anesthetic solution. In addition, there is a feeling of relaxation with subjective warming in the back and the affected leg. Temporary symptoms of paralysis or a feeling of lameness in the leg can be expected in 8 percent of cases. One must make the patient aware of this. The effectiveness of paravertebral spinal nerve analgesia has been proven in open and placebo-controlled studies (4).
Spinal nerve analgesia is performed in the same way on the cervical spine (Figure 1). Here, too, the goals are to desensitize the irritated spinal nerve root and to temporarily eliminate parts of the cervical sympathetic nerve with its various interlacing in the area surrounding the vertebral artery. One indication is primarily cervicobrachial syndromes, but also local and cervicocephalic syndromes. The dorsal access (Figure 1) allows access to the cervical spinal nerves without the risk of dural puncture or damage to the large cervical vessels (4).

Lumbar peridural analgesia
With the application of local anesthetics and (or) anti-inflammatory agents to the lumbar epidural space, even small doses can influence the starting point of pain in lumbar root syndrome (Figure 4). The nerve root is washed around with anesthetic and (or) anti-inflammatory agent at the point where it is mechanically irritated, edematous and pinched by disc tissue, bones or postoperative scarring. Substances applied epidurally reach the spinal nerve roots via microvascular transport mechanisms (6). The lumbar epidural injections are therefore one of the most effective methods in orthopedic pain therapy and have been there for years (2, 4, 9). In addition to the previously common approaches via the sacral hiatus and straight interlaminar dorsal path, there is a new epidural-perineural technique using an inclined interlaminar approach with a double needle, with which the irritated nerve root in the ventral epidural space can be reached selectively. With a little practice, this injection will succeed without the aid of imaging techniques. In the initial phase and with particularly difficult interlaminar access, CT-guided epidural-perineural injection is recommended. This injection is performed while the patient is seated. An introducer cannula is advanced 1 centimeter below and 1 centimeter contralaterally at an angle of 20 to 30 degrees up to the ligamentum flavum or just before it. A 29G spinal needle is pushed through the introducer cannula until bone contact is felt with the needle tip. 1 milliliter of local anesthetic (lidocaine) and 10 milligrams of steroids (triamcinolone) are injected. Controlled studies have proven the effectiveness of lumbar epidural injections in lumbar root syndrome. The newly developed epidural-perineural injection with the double needle technique showed particularly good results (5).

How dangerous are the injections?
When injecting a local anesthetic into the spinal nerves or into the lumbar epidural space, one must always reckon with temporary symptoms of motor failure up to partial spinal anesthesia in the event of (unintentional) intrathecal application. As with most medical interventions, material and personnel requirements in the practice or outpatient clinic with appropriate precautionary measures must be prepared for an emergency.
On the other hand, in the case of local injection treatment with low-dose local anesthetics, as listed in the EBM, it is not necessary to create an intravenous access and an ECG before each injection. Effort and patient annoyance are disproportionate to the actual risk. In over 100,000 spinal nerve and epidural analgesia in the context of orthopedic pain therapy in the past ten years (5), we have not experienced any situations that would justify this effort as a routine precautionary measure. Special precautionary measures such as intravenous access and ECG monitoring are only to be taken if there are special risk factors, such as conduction disorders after a heart attack, circulatory insufficiency or if 25 percent of the maximum dose of the local anesthetic is exceeded (1), which is usually not the case with orthopedic pain therapy Case is.

Contraindications and Complications
When using local anesthetics and steroids, the known contraindications to these agents, such as severe conduction disorders, allergies and heart failure, apply. Injections into the spinal canal are prohibited in the case of neurological seizure disorders, blood clotting disorders and infections at the injection site.
Post-injection headaches occur after accidental dura puncture. Since using the 29G cannulas, however, we have seen this complication much less often and if so, then in a milder form. Nerve lesions and bleeding complications in the epidural space have not yet been observed.
The incidence of epidural abscesses after epidural injection is very low. With a single epidural injection, the risk of infection is 1 in 30,000 (9).

quality assurance
The injection technique itself, especially for injections close to the spine, requires special training, which the orthopedic surgeon is taught during his further training as a doctor for orthopedics and in special injection courses. Standardization and quality assurance of orthopedic pain therapy with local injection treatment are carried out in a special working group that is also involved in the project of the Federal Ministry of Health for the standardization of quality assurance and pain therapy in medicine. In cooperation with orthopedic surgeons, anesthetists and psychologists, standards for orthopedic pain therapy are set up, which lead to adequate pain treatment across Germany.Similar to the special surgical procedures, an update of the injection technique and injection media as well as the emergency preparedness is necessary through participation in seminars, such as those of the Professional Association of Doctors for Orthopedics, the German Society for Orthopedics and Traumatology and the International Society for Orthopedic Pain Therapy (IGOST ) Tobe offered.

How this article is cited:
Dt Ärztebl 1996; 93: A-1961-1965
[Issue 30]

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Author's address:
Prof. Dr. med. Jürgen Krämer
Director of the Orthopedic University Clinic St. Josef Hospital
Gudrunstrasse 56
44791 Bochum, Germany