Sciatica: symptoms and causes

Sciatica is one of the names of the symptom complex that arises from the inflammation or compression of the sciatic nerve or its roots. This condition is most often secondary and has a vertebrogenic nature. But other causes of sciatica are possible, including primary damage to the nerve. This should be taken into account when selecting a treatment regimen. About what are the symptoms and causes of the disease, and talk in this article.

Anatomy of the sciatic nerve

The sciatic nerve (Nervus ischiadicus) is the paired largest nerve peripheral trunk. It originates from the sacral plexus and is formed from several nerve fibers, the roots of which depart from the LIV, LV, SI-SIII segments of the spinal cord. After the formation of a single trunk, the sciatic nerve descends along the wall of the small pelvis and exits through the sub-tubular orifice. Sometimes it is already divided into two pelvic cavities in the pelvic cavity, which can penetrate through the thickness of the pear-shaped muscle or through the tubercle-shaped orifice.

On the thigh, the sciatic nerve gives off small twigs to the muscles, skin and joints. And at the level of popliteal fossa it is divided into small and tibial nerves, which also divide. The terminal branches of the tibial nerve go to the skin and muscles of the foot.

In the sciatic nerve are sensitive and motor fibers that provide innervation of most of the lower limbs. Its branches extend to all the muscles of the leg, except for a group of flexors of the hip joint, knee extensors and some gluteal muscles. The sciatic nerve also innervates capsules of the hip and knee joints, the skin of the posterolateral surface of the thigh and lower leg. Such a vast innervation zone causes the diversity and prevalence of symptoms in sciatica.

Etiology of sciatica

Conditions that can lead to the appearance of symptoms of sciatica:

• degenerative-dystrophic diseases of the spine, leading to squeezing the roots of the sciatic nerve with vertebral osteophytes or a deformed intervertebral disc;
• congenital deformations of the spinal column: stenosis, curvature, pathological fusion of the arches and vertebral bodies;
• myositis of the lumbar muscle group;
• pronounced muscular-tonic syndrome vertebrogenic nature;
• cider pear-shaped muscle;
• trauma of the spine or pelvic bones with displacement, fracture, deformation of bone structures, pathological fractures of the lumbar vertebrae;
• compression of rootlets or nerve trunk with a tumor, abscess, tuberculosis, extensive hematoma, iliac artery aneurysm;
• infectious lesion of the nerve trunk;
• exotoxic damage to the sciatic nerve (arsenic and mercury compounds, quinine, alcohol, narcotic substances);
• endotoxic damage in case of gout, severe diabetes mellitus, and disproteinemia.

In women, sciatica may first appear in the second half of pregnancy. This is due to the compensatory change in the angle of the physiological lumbar lordosis, which can contribute to the infringement of the radicular part of the sciatic nerve.

Pathogenesis

The appearance of symptoms of sciatica is possible with irritation or damage to the sciatic nerve. Moreover, the level of damage can be radicular (before the formation of a single nerve trunk) or stem.

When exposed to neighboring anatomical formations, the nerve can be pushed aside from its physiological position or squeezed. Compression leads to irritation, and then to damage to nerve fibers. As a result, it is difficult to transfer impulses from the spinal cord to peripheral tissues, there are various neurological symptoms.

The compression of the nerve trunk or spine triggers a nonspecific inflammatory response.
The release of mediators of inflammation and prostaglandins begins, there is edema of the tissues, which further breaks the nerve conduction. A concomitant violation of microcirculation and lymph drain aggravates the situation. Neuropathy passes into neuritis.

With a long course of the disease, adhesions between individual fibers of the sciatic nerve, as well as between the nerve trunk and its membrane, are formed. Due to persistent infringements of innervation, symptoms of sciatica become relapsing, and motor impairment is accompanied by muscle atrophy.

Pain is the brightest symptom of sciatica

The main symptom of sciatica leading patients to see a doctor is pain - ischialgia. It is felt along the course of the affected sciatic nerve and most often has a one-sided character. The pain syndrome is so severe that it significantly limits the patient's ability to move independently. The pain extends from the buttock down the posterior-external surface of the thigh and lower leg, sometimes reaching the outer part of the rear of the foot and even the fingers. With a rootlet lesion, discomfort can also be felt in the lumbosacral region. In this case, they speak of lumboschialgia.

Pain in sciatica can be burning, aching, pulling, shooting. It increases in sitting position, when coughing, sneezing and laughing. Rising, twisting the trunk, jumping, riding in jolting transport often lead to painful lumbago - a fit of sharp intense pain that spreads along the sciatic nerve.

A sharp increase in pain is also noted when the bent leg is withdrawn (Bonnet's symptom) and the straight leg is raised in the supine position (Laceg's symptom). This is due to the tension of the affected sciatic nerve. The volume of active movements in the lower part of the body also changes, while the body deviates toward the affected nerve when walking. Often there is a smoothing of lumbar lordosis due to attempts by the patient to spare the affected area and the reflex tonic tension of the lumbosacral muscles. This can aggravate the compression of the spinal cord and lead to aching pain in other parts of the back.

Nebolae manifestations of sciatica

In addition to the pain syndrome, other signs are characteristic for sciatica:

• a violation of superficial sensation, accompanied by a feeling of numbness and crawling of the goose, can be seen on the posterolateral surface of the thigh and lower leg, certain areas of the foot;
• decrease in vibration sensitivity in the area of ​​the external ankle;
• violation of deep (muscular-articular) sensitivity in the area of ​​the toes and ankle;
• peripheral paresis of the posterior group of hip muscles, feet and fingers;
• vegetative disorders - a change in the color of the skin on the leg, swelling of the tissues, chilliness of the foot;
• trophic disorders (with a long course of the disease) - hyperkeratosis of the sole, hair loss on the posterior-lateral side of the tibia, change in sweating.

Peripheral paresis on the leg is characterized by a decrease in strength and tone in the involved muscles, prolapse of tendon reflexes (knee and Achilles). Perhaps the appearance of fasciculations (muscle twitching). And with a long-term disruption of innervation, the muscles atrophy. The paresis of the posterior group of hamstrings during sciatica leads to the appearance of a characteristic gait with a straightened leg, when a step forward is not accompanied by bending of the knee. This is due to the predominance of the function of the antagonist muscle (quadriceps femoris muscle), which leads to a persistent extension of the leg.

If the cause of compression of the sciatic nerve is preserved, the symptoms of sciatica acquire a prolonged and recurrent course. There are irreversible changes in muscles. A persistent and pronounced pain syndrome can cause psychoemotional disorders, sleep disorders and disability. Therefore, the treatment of sciatica should be in accordance with the prescription of the doctor, while it is necessary to influence not only the symptoms, but also the cause of the disease.

TVC, the program "Doctors", the issue on the topic "Sciatica":

Treatment of Sciatica and Sciatic Nerve Compression

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A cognitive video on "Sciatica and Ishialgia":

Sciatica (Ishialgia)

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