Fixed strabismus

Introduction to fixed strabismus Fixed strabismus (strabismusfixus) refers to a special strabismus in which one eye or both eyes are fixed at a certain position and cannot be rotated in other directions. It is of the same type as extensive fibrosis syndrome, but the lesion is limited to one group of antagonist muscles. Clinically, fixed strabismus is less common, and fixed exotropia is less common than fixed endotropia. The exact cause is unknown, which may be related to the change of extraocular muscle secondary to nerve palsy caused by congenital development or trauma. basic knowledge The proportion of illness: 0.02%-0.05% Susceptible people: no specific population Mode of infection: non-infectious Complications: paralytic strabismus common strabismus

Cause of fixed strabismus

(1) Causes of the disease

The exact cause is unknown, which may be related to the change of extraocular muscle secondary to nerve palsy caused by congenital development or trauma.

(two) pathogenesis

Congenital factor

Domestic literature (1985-2000) reports that 80% of congenital strabismus is fixed. Therefore, fixed strabismus is mostly an inherited hereditary disease, and some cases occur in the early postnatal period. After an extraocular muscle paralysis, the consequences of antagonistic muscle hypertrophy belong to secondary strabismus fixus. As the age increases, the antagonistic muscle contracture becomes more and more obvious, and the eyeball inclination will become more and more. The large, contractured muscle finally loses its elasticity and is fibrotic. Finally, all or most of the cornea is covered. Only the white sclera or a few corneas are exposed in front of it. Clinically, the most fixed strabismus is fixed, followed by fixed upper strabismus, fixation. Exotropia, at least the fixed lower strabismus, if the intraocular rectus muscles are replaced by strip-like fibrous tissue, causing fixed esotropia; if the external rectus muscles are replaced by strip-like fibrous tissue, causing fixed exotropia, Similarly, the superior rectus or inferior oblique muscle fibrosis causes fixed upper strabismus, and the inferior rectus muscle or superior oblique muscle fibrosis causes fixed lower strabismus. In China, 2 cases have congenital double straightness. In the absence of patients, the performance of the two eyes fixed upper strabismus, intraoperative high rectus muscle hypertrophy, part of the fibrotic cord, if multiple extraocular muscle fibrosis is called extraocular muscle extensive fibrosis syndrome (general Extraocular muscle fibrosis syndrome).

2. acquired factors

Common causes are cerebral palsy caused by head trauma. In the long-term, the rectus contracture causes the cord-like fibrous tissue to change, forming a fixed esotropia. In addition, there is a fixed esotropia that occurs in high myopia, mostly monocular. The eye can not be fixed. At the beginning, the internal oblique is lighter, and then gradually becomes heavier. Finally, the inner rectus muscle is highly contracted to form a fixed esotropia. The cause of high myopia combined with fixed esotropia is still uncertain, because the disease is late and non-congenital abnormality As a result, due to the normal rectus muscle EMG, it also ruled out the possibility of rectus recession caused by external rectus paralysis. A Japanese scholar believes that it may be related to the following factors:

1 adjust the imbalance of the convergence ratio;

2 internal rectus muscle and surrounding tissue lesions;

3 axial length may be related to internal rectus muscle lesions;

4 Muscle changes are part of the body muscles, abnormal nerves;

5 external rectus muscle abnormalities, Demer, Ruttun et al believe that the cause is due to high myopia, posterior scleral staphyloma and sacral wall contact, limiting eye movement caused by Bagolini that the cause and external rectus muscle compression, causing capillary endothelial changes, Muscle fibrosis, associated with increased connective tissue.

In the domestic literature (1985 ~ 2000) reported fixed strabismus, combined with high myopia in 53 cases, accounting for 44.17%, the old extraocular muscles can also cause fixed esotropia, exotropia, upper strabismus or lower strabismus, Villaseca It is thought that it is caused by secondary medial rectus contracture caused by bilateral numbness. Wilcox is considered to be a kind of abnormal systemic fascia. It is caused by extraocular muscle contraction caused by rectus muscle contracture. Adhesion around the muscles, caused by fibrosis, Mare's electrophysiological examination of the patient found that the external rectus muscle EMG is normal, and some cases have a certain external rotation function after surgery, it is concluded that the abnormality of the medial rectus muscle is the main cause Some people have reported this pathologically: striated muscle hyperfibrosis, degeneration and atrophy, no inflammatory cell infiltration showing musculitis and hypertrophy of blood vessel wall.

Fixed strabismus prevention

There is no effective preventive measure for this disease. Early detection and early diagnosis are the key to the prevention and treatment of this disease.

Fixed strabismus complications Complications paralytic strabismus common strabismus

Fibrosis and degeneration of the extraocular muscles are the main complications in the later stage.

Fixed strabismus symptoms Common symptoms Internal oblique A sign Internal oblique V sign Eye fund abnormal eye muscle paralysis Eye tremor Eye infection

Fixed strabismus can be divided into congenital strabismus fixus and acquired strabismus fixus according to its pathogenesis. It is divided into fixed esotropia and fixed exotropia according to the direction of eye position deviation. , fixed upper strabismus and fixed lower strabismus.

1. The clinical manifestations of congenital fixed strabismus have the following 7 points:

(1) Mostly internal oblique, external oblique is rare.

(2) The age of onset is small, mostly for both eyes.

(3) The eye position is obviously oblique in all directions, and both eyes are always in the inner rotation position.

(4) The eyeball can't be turned outwards, forcibly pulled outward, and the eyeball can't reach the midline. Generally, there is no vertical movement limitation.

(5) The tensile test is strongly positive.

(6) In the operation, the affected extraocular muscle contracture can be seen and it is fibrous.

(7) EMG examination showed no discharge of the rectus muscle or only weak discharge during the intraocular rotation.

2. The clinical manifestations of acquired fixed strabismus have the following 7 points:

(1) It is more common in progressive strabismus in adults after age 40.

(2) Esotropia is more common, exotropia, upper strabismus and lower strabismus are rare.

(3) more common in monocular or binocular vision, and close to high myopia, individual cases have a history of trauma.

(4) The eye position is obviously oblique in all directions, and the external rotation can be forced to reach the middle line or slightly over the center line.

(5) The pull test is positive.

(6) The intraocular rectus abnormal contracture can be seen during surgery.

(7) The EMG examination showed that the rectus muscles had different degrees of discharge when the eyeball was rotated.

Fixed strabismus examination

Extraocular muscle electromyography (EMG) examination revealed different degrees of discharge in the rectus muscle during intraocular rotation.

Fixed strabismus diagnosis

Diagnostic criteria

1. Suffering from strabismus, the fixation cannot be rotated.

2. When the forced rotation test is performed, the eyeball cannot be pulled in the opposite direction of the strabismus or the eyeball cannot be pulled at all.

3. The antagonistic muscle and its surrounding tissue contracture, and the paralyzed muscle is thin and tension-free.

4. Pathological examination showed antagonism of muscle fibrosis.

5. The horizontal oblique viewing angle is more than 45°, and the vertical oblique viewing angle is more than 25°. Therefore, clinical diagnosis can be made based on clinical features such as medical history, large strabismus and positive traction test.

Differential diagnosis

1. Duane syndrome is limited in external rotation, and the retraction of the eyeball and the reduction of the cleft palate are the three characteristics of the syndrome. EMG examination can have a discharge phenomenon when the eyeball is turned inside and outside, while the fixed strabismus has no cleft palate and the eyeball retreats. EMG has no discharge or only weak discharge in the eyeball. The degree of internal oblique deviation of fixed strabismus is large and the tensile test is strongly positive, while the degree of internal inclination of Duane syndrome is less than or equal to fixed esotropia and mild passive movement. limit.

2. Extraocular muscle extensive fibrosis syndrome Fixed strabismus is extraocular muscle fibrosis, but the degree of development and the number of muscles involved are different. Fixed horizontal strabismus generally has no vertical movement limitation, and fixed vertical strabismus generally has no horizontal movement. Restricted, but if other muscle fibrosis is not easy to identify at the same time, the extraocular muscles are extensively fibrotic into multiple extraocular muscles, accompanied by ptosis, the eyeball is fixed in the lower position, and both eyes cannot rotate, which may be obvious. In the head position of compensation, multiple extraocular muscle fibrosis can be seen during surgery.

3. Squint caused by primary neuromuscular spasm in strabismic strabismus is rare, only occasionally seen in cases of tetanus, neurosis, etc. The majority of extraocular muscles encountered in clinical practice are secondary to Some of the extraocular muscles have insufficient function. The point of identification with fixed strabismus is whether the muscle is paralyzed and relaxed after intramuscular injection of lidocaine. If it is a sputum, the eyeball is pulled to the opposite side after injection. No obvious resistance, while fixed strabismus does not reduce the resistance.

4. Möebius syndrome This syndrome is bilateral congenital VI and VII cranial nerve palsy, horizontal movement of the eye is restricted and vertical movement is good, no muscle contracture, the cause may be brain stem nucleus hypoplasia, sometimes involving the first III brain nerve.

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