Piriformis Syndrome

　　How is the piriformis syndrome caused? The following is a brief description:

　　1. Etiology

　　Similar to the sciatic nerve pelvic outlet stenosis, in fact, it can also be considered as one of the causes of sciatic nerve pelvic outlet stenosis. The pathological changes in the early stage of the disease are mostly traumatic reactions after local injury (extremely abducted and externally rotated acute sprains are more common, followed by sudden standing up from a squatting position), with mild cases showing edema, exudation, and dilatation of capillaries in the piriformis muscle fibers, and severe cases may present with spasm, hemorrhage, and swelling of the piriformis muscle. If the injury is minor or effective treatment is provided in a timely manner, it is generally possible to recover to a normal state. However, if the injury is severe or repeated multiple times, and combined with other pathogenic factors such as cold and dampness, this pathological process may continue to develop, forming a chronic process with a series of secondary changes.

　　2. Pathogenesis

　　It is rare for the symptoms to be caused by the itself thickening of the piriformis muscle or scar tissue compressing the sciatic nerve trunk. More often, the condition is due to the contraction of the piriformis muscle causing a narrowing of the sciatic nerve pelvic outlet, leading to the sciatic nerve and others being trapped in this narrow outlet, resulting in symptoms. The pathogenesis is essentially consistent with the sciatic nerve pelvic outlet stenosis, and therefore, similar secondary changes occur, including local varicose veins, thickening of arterial walls, and other findings.

　　In cases with a longer course of the disease, foot drop may occur. This is one of the signs of foot drop in orthopedics. When the patient is sitting, the two lower limbs are naturally suspended. If the foot is in a plantar flexed position and cannot be actively dorsiflexed and inverted, it is considered foot drop. This sign can be seen in sciatic nerve palsy and peroneal nerve palsy. The former causes the sign where the toes cannot be dorsiflexed or plantarflexed; while the latter causes the sign where the toes can be plantarflexed. Based on this, the two can be distinguished. In addition, this sign can also be seen in poliomyelitis, progressive muscular dystrophy, hypokalemic periodic paralysis, and lower limb paralysis, etc.

　　What are the symptoms of piriformis syndrome? Briefly described as follows:

　　1. Symptoms of sciatic nerve injury

　　It is mainly manifested as the characteristics of dry involvement, that is, the radiation pain along the sciatic nerve and the movement (posterior thigh, anterior and posterior lower leg, and various muscle groups of the foot), sensation (lateral lower leg, sole, and anterior part of the foot), and reflex (Achilles reflex and plantar reflex) disorders in the area it支配, in the longer course of the disease, there may be symptoms such as muscle atrophy of the lower leg and even foot drop.

　　2. Tenderness points

　　The most severe tenderness is at the surface projection of the pelvic outlet of the sciatic nerve (Shangjiao point), and it radiates downward along the nerve trunk. In addition, about half of the cases have a tenderness phenomenon at the tibial or fibular point. The tenderness point of piriformis syndrome is slightly higher than the former by 1 to 2 cm.

　　3. Lower limb rotation test

　　The limb is internally rotated to make the piriformis and upper adductor, obturator internus, and lower adductor muscles in a tense state, thereby aggravating the stenosis at the outlet, which can induce symptoms of sciatic nerve. In addition to the radiation pain along the path of the sciatic nerve, there is also numbness in the lateral part of the lower leg down to the sole of the foot. However, for those with simple piriformis syndrome, symptoms are induced by external rotation. This is mainly due to the narrowing at the outlet being promoted when the contracted and scarred piriformis contracts, the lower limb is externally rotated.

　　4. Straight leg raise test

　　Generally, it is positive, and the pain degree is between radicular pain and plexopathy pain. This test is not specific.

　　5. Tissue hydrostatic pressure measurement

　　It is more than 1 times the normal value (1.33 kPa, 10 mmHg), more than 50% higher than the normal value is considered abnormal. This measurement is mainly used for some difficult-to-diagnose cases.

　　How to prevent piriformis syndrome? Briefly described as follows:

　　1. Maintain an optimistic and cheerful mood. Strong and long-term or repeated emotional changes such as stress, anxiety, irritability, and pessimism can disrupt the balance of excitation and inhibition processes in the cerebral cortex.

　　2. Need high-protein, high-energy diet supplements, providing the necessary substances for the reconstruction of nerve cells and skeletal muscle cells to enhance muscle strength, increase muscle mass. Early adoption of high-protein, vitamin-rich, phospholipid and trace element foods, and actively cooperate with medicinal diet, such as yam, Job's tears, lotus seed core, tangerine peel,太子参, lily, etc., avoid spicy food, quit smoking and drinking.

　　3. Combine work and rest, avoid forced functional exercise, because forced functional exercise will cause skeletal muscle fatigue, which is not conducive to the recovery of skeletal muscle function, muscle cell regeneration and repair.

　　What examinations should be done for piriformis syndrome? Briefly described as follows:

　　1. Electromyography

　　As a means of determining the function of the motor system, it is now widely used to distinguish between muscle weakness and muscle atrophy, whether it is caused by myopathy, neuropathy, or other causes. Through needle electromyography, the muscles of different parts of the body are measured.

　　2. Nerve Conduction Velocity

　　It is a diagnostic technique for evaluating the conduction function of peripheral motor and sensory nerves. It is mainly used for the diagnosis of peripheral neuropathy, such as polyneuropathy, hereditary peripheral neuropathy, Guillain-Barré syndrome, carpal tunnel syndrome, peripheral nerve trauma, etc., and can differentiate anterior horn cells, nerve roots, peripheral nerves, and myopathic diseases, etc. in combination with electromyography.

　　The diet of patients with piriformis syndrome generally has no special requirements, but the recommended dietary principles are:

　　1. Pay attention to a light diet, eat more vegetables and fruits, and rationally match the diet.

　　2. Avoid spicy foods, smoking and alcohol.

　　The following is a brief description of the treatment methods for piriformis syndrome:

　　I. Treatment

　　Non-surgical treatment should be chosen, and surgical treatment should be performed only when non-surgical treatment is ineffective.

　　1. Non-surgical Therapy

　　(1) Eliminating pathogenic factors: such as long-term sitting, cold and dampness in the lumbar sacral region, heavy manual massage and buttock trauma, etc., should be avoided.

　　(2) Preventing and treating tissue adhesion: 2ml of placental tissue fluid is injected, once a day, 30 times as a course of treatment, with good effects and no side effects; α-chymotrypsin has a strong effect, but has a tendency to cause hemorrhage, attention should be paid when using it, generally 5mg each time, added with 5ml of isotonic sodium chloride injection, intramuscular injection, once every 4-5 days.

　　(3) Supplementing nerve trophic agents: mainly vitamin B1, B6, B12, etc.

　　(4) Others: such as physical therapy, external application of traditional Chinese medicine, compound salvia miltiorrhiza injection, etc. For acute onset, in addition to absolute bed rest, oral hydrochlorothiazide (25mg of dihydrochlorothiazide, 3 times a day, 3-5 days) and other diuretics can be taken to eliminate local edema. More than half of the cases can be effective.

　　2. Surgical Therapy

　　For those who are ineffective to the above therapies or have severe symptoms and need early surgery, piriformis section (excision) surgery can be performed.

　　II. Prognosis

　　The prognosis is good after treatment.