Sciatica is a syndrome in which the pain is mainly in the sciatic nerve pathway and distribution area. The majority of cases of sciatica are secondary to the stimulation and compression of the sciatic nerve by lesions of the local sciatic nerve and surrounding structures, called secondary sciatica.
Clinical manifestations
1. General symptoms
(1) Pain is mainly limited to the sciatic nerve distribution area, posterior thigh, posterior lateral calf and foot, and patients with severe pain may be in a characteristic posture; lumbar flexion, knee flexion and toe landing. If the lesion is located in the nerve root, the pain is aggravated by increased pressure in the spinal canal (coughing, exertion).
(2) The degree of muscle weakness may vary greatly depending on the cause, location of the lesion, and the degree of damage, and may include total or partial weakness or paralysis of the muscles innervated by the sciatic nerve.
(3) There may or may not be pressure pain of the sciatic nerve trunk at the sciatic notch.
(4) There is a positive sciatic nerve pulling sign, Lasegue’s sign and its equivalence sign, the presence of which often parallels the severity of the pain. The sign may disappear with local anesthesia of the sciatic nerve root or nerve trunk.
(5) The Achilles tendon reflex is diminished or absent, and the knee reflex may be increased by stimulation.
(6) There may be hypoesthesia or loss of various sensations in the area of sciatic nerve innervation, including hypoesthesia of vibration in the outer ankle, and there may be very mild sensory disturbance.
2. Sciatic neuritis
Sciatic neuritis is often accompanied by various types of infections and systemic diseases, such as upper respiratory tract infections. Because the sciatic nerve is superficial, it is prone to sciatica when exposed to moisture and cold. When sciatica occurs in systemic diseases, attention should be paid to the presence of collagen disease and diabetes.
Sciatica is mostly unilateral and is not accompanied by lumbar or back pain; the pain is usually persistent or episodic, and the symptoms are aggravated by increased pressure in the spinal canal and can radiate along the sciatic nerve pathway. Pain and muscle weakness are not parallel, generally pain is heavy, but muscle weakness is not obvious. In the acute stage, it is more difficult to judge motor function because of pain, foot drop, gastrocnemius and tibialis anterior muscle atrophy can be detected; Achilles reflex is reduced or disappeared, but Achilles reflex can be normal, knee reflex is normal, and superficial sensory impairment is obvious.
3. Secondary sciatica
(1) Lumbar disc herniation is the most common cause of sciatica, mostly occurs in lumbar 4-5 and lumbar 5-sacral 1, about 1/3 cases have a history of acute lumbar trauma, most patients occur between 20 and 40 years old, clinical characteristics are weeks or months of low back pain, and then sciatica in one lower limb. In addition to the general symptoms of sciatica, physical examination also shows tension in the low back muscles, limitation of lumbar movement, scoliosis, and pressure pain in the spinous process of the lesion.
(2) Lumbar spine osteoarthropathy is mostly seen in people over 40 years old, with subacute chronic onset, mostly with a history of long-term lumbar pain, difficulty in standing up after sitting for a long time and difficulty in sitting down after standing for a long time, which may clinically manifest as sciatica and symptoms of the lumbar region on one or both sides.
(3) congenital malformation of lumbosacral spine lumbosacralization, sacral lumbarization, occult spina bifida, the latter may manifest with sciatica, often with a history of enuresis, physical examination often with foot deformity, lumbosacral skin abnormalities, such as a small concavity behind the anus, a small angioma on the midline of the sacrum, this often objectively and accurately indicates the unhealed part of the vertebral plate.
(4) Sacroiliac arthritis is commonly rheumatoid and tuberculous lesions, which stimulate the lumbar 4 to 5 nerve trunk when there is exudative destruction of the joint capsule, and some patients may have sciatica symptoms.
Examination
1. Imaging examination
It has an important status, including lumbosacral spine and sacroiliac joint X-ray, spinal MRI, myelography plus CT, and CT or MRI of the pelvis can be done in addition to clinical physical diagnosis of the pelvis.
2. Electrophysiological examination
①EMG of the paravertebral muscles can assist in identifying radicular sciatica and distal lesions. ②EMG of the short head of the biceps femoris can help to identify the lateral sciatic nerve from the common peroneal neuropathy. ③Patients with pelvic or femoral fractures are difficult to perform routine physical examinations, and EMG can assist in evaluating nerve function. ④The femoral and common peroneal nerve motor nerve conduction velocity and F wave may be abnormal, and sciatic nerve conduction velocity is difficult to stimulate the proximal end of the lesion.
3. Other
The application of corticosteroid or local anesthetic drugs injected into the pear muscle can help the diagnosis of pear muscle syndrome if the pain is relieved.
Differential diagnosis
Attention should be paid to differentiate it from lumbar muscle strain, gluteal fibrous histitis and other painful diseases of the buttocks and posterior thighs, which are localized pain without neurological signs such as sensory impairment, muscle weakness, and decreased heel reflex.
Treatment
First of all, the cause should be treated, and attention should be paid to symptomatic treatment. All sciatica should be treated with bed rest and a hard bed. Apply vitamin B drugs, analgesic treatment, and withhold physical therapy until the cause is known.