Sciatica

Sciatica or lumbar sciatic pain is the L5 or S1 nerve reaches the level of the spine (lumbar spine) or in its immediate vicinity.  It must be differentiated from the sciatic nerve, sometimes called “sciatica” and simply arises from a combination of several nerve roots (including L5 and S1).  A lesion of the latter causes sciatica.

Etiology

A herniated disc causes 90% of cases
The malignancy (Benin or malignant)
Infectious process (spondylodiscitis, epidural)
Fracture or fracture-vertebral
Spinal stenosis
Infectious meningo-radiculitis (Borreliosis, HSV)
Pelvic tumor or abscess.
Epidemiology

It is a common disease: it affects 5 to 10% of patients with back pain.  Age, stress, smoking and a job involving movement of the back increases the risk.
Symptoms

The pain is typically intermittent, one side (unilateral) radiating into the toes, sometimes increased during coughing or defecation and relieved by resting lying down or standing.
It can be triggered by sitting (particularly driving).  It is sometimes accompanied by a constellation of symptoms such as tingling (paresthesia) located in the leg or toes, a certain perception of painful stimuli (allodynia) or a loss of sensation of part of the leg. A loss (or substantial reduction) of the ankle jerk is another indicator of the sciatic (only in the case of sciatica).

Note that there may be a form with blockage of the lumbar spine called lumbago.  It is reproduced by the passive flexion of the hip (caused by the examiner). The “Lasegue crossover”, where the pain is reproduced by raising the other leg, is more specific but less sensible.  The topography may be indicative of nerves reached: lateral leg and dorsum of foot to big toe (hallux) for the root L5, posterior calf and sole of the foot to the S1 root.
Elements diagnoses

The description of pain is sufficient in 90% of cases.  Plain radiography of the lumbar spine is necessary if we suspect a cause other than a herniated disc, or in cases of sciatica recurrent and resistant to treatment.

It does not however show the hernia (the intervertebral disc is radio-transparent).  Only MRI and CT scans can visualize spinal hernias. The sensitivity and specificity of these tests are far from absolute: one fifth to one third of patients have a herniated disc and have never suffered from sciatica.  Sacco-radiculography by direct injection of contrast into the spinal canal, is a technique used since the 1990s.  Laboratory tests are useful in certain situations (sedimentation rate and blood cell count).  The Electromyogram is unnecessary in typical forms (aid in the differential diagnosis)
Differential Diagnosis
Pseudosciatique sportsman and piriformis syndrome

The piriformis muscle pain or pyramid, which originates on the sacrum within the pelvis and goes outside to his hip to fix the upper femur, is also called the greater trochanter and may be responsible for pain suggestive of sciatica but the cause and treatment are different.  Indeed, the piriformis muscle, contrary to what its name suggests, is not very wide.

The sciatic nerve also passes through this gap between the piriformis muscle and other muscles, or for a small percentage of the population (less than 15%) directly inside the pyramidal. This muscle, which is an external rotator of the thigh, is very busy during running and cycling, and prone to overwork.  Moreover, it can suffer from partial ischemia if one stays too long sitting on a seat that is compressed, which may be the case among cyclists.

More rarely, a pyramid of suffering can occur without exercise or sport among people who keep too long a position putting the muscle in a state of ischemia (head pressing hard in the wrong place) and keep their leg(s) in a stretch position or bending constant muscle.

The painful contraction that follows can compress or irritate the sciatic nerve. In principle, the maneuver does not show nerve compression in the spine.  Usually recommended is rest and stretching specific muscles, possibly as part of physiotherapy. Anti-inflammatory medication may be prescribed. In cases of failure of these treatments, infiltration of the muscle may be proposed, based on anti-inflammatory and/or corticosteroids and/or botulinum toxin, or a combination of the three.
Evolution

It can sometimes persist or recur.  In rare cases, it is complicated by a syndrome of the cauda equina with an onset of paralysis and sphincter disorders requiring urgent surgery.
Processing
Medical treatment
It was traditional to prescribe bed rest on a hard surface during sciatica. This has not proved effective. Similarly, administration of analgesics (pain killers) or anti-inflammatory steroids are not better than placebo.  The injection of corticosteroids into the spinal canal (epidural infiltration) seems to have a beneficial effect but is controversial.  Wearing a brace and physical therapy can be prescribed.  Massages and other practices (chiropractic, traction etc) are also effective.
Surgical treatment
It is to remove the herniated disc. It should be offered only in 3 cases: motor deficit or sphincter disorders, pain despite opioid therapy and corticosteroid or disease duration greater than 3 months despite treatment.