Strabismus due to paralysis of the nuclei and nerves that govern eye movements and the extraocular muscles themselves is called paralytic strabismus. It is classified as congenital or acquired.
In children, paralytic strabismus is most often caused by congenital developmental abnormalities, birth injuries and diseases within the first few months of life. The cause should be sought first, and consultation should be requested from otorhinolaryngology, neurology, cerebral surgery, pediatrics and other departments to exclude diseases such as periocular sinus, cerebral nerve and intracranial tumor, to accurately diagnose the primary cause and prevent delay in treatment. Clinical manifestations of congenital paralytic strabismus:
1. Eye position deviation eye movement disorder
When an extraocular muscle is paralyzed, the relative strength of its antagonist muscle is too strong, and the eye deviates in the direction opposite to the action of the paralyzed muscle. The direction of rotation to the paralyzed muscle is limited. If the external rectus muscle is paralyzed, the eye is restricted to turn outward and is oblique internally; if the internal rectus muscle is paralyzed, the eye is restricted to turn inward and is oblique externally.
2. Diplopia
Diplopia due to disruption of fusion function, seeing one object as two objects, orientation and localization disorders, dizziness and nausea, unstable gait, symptoms are obviously reduced or disappear when one eye is masked.
3.Replacement head position
In order to overcome the interference of diplopia, the patient automatically tilts the head to the side where the paralyzed muscle acts, and at the same time can also turn the face to overcome diplopia caused by internal and external rectus muscle paralysis; or lift the chin up or inward, plus lightly turn the face to overcome diplopia caused by upper and lower rectus muscle paralysis; or tilt the head to the shoulder and turn the chin and face to overcome diplopia caused by upper and lower oblique muscle paralysis. The purpose is to obtain binocular monocularity and avoid diplopia and the series of characteristics of performance.
4.The second oblique angle is larger than the first oblique angle
When gazing with the affected eye, the cerebral cortex needs to enhance the nerve impulse to the paralyzed muscle, which is also transmitted to the mate muscle of the paralyzed muscle at the same time, causing the healthy eye to deviate significantly.
Diagnosis
1.Ocular movement examination
If one eye is restricted to nasal, temporal, superior temporal, inferior temporal, superior nasal and inferior nasal rotation, it means that the internal rectus, external rectus, superior rectus, inferior rectus, inferior oblique and superior oblique muscles are paralyzed respectively. If the eye is fixed, the whole extraocular muscle is paralyzed.
2.Retrophotometry
First, determine whether the compound image is ipsilateral or crossed; then determine whether the horizontal or vertical separation is dominant, whether the compound image is tilted, and find out the maximum separation orientation and the peripheral object image belonging to the eye according to the six diagnostic eye positions.
3.Surrogate cephalometric analysis
(1) The right eye is restricted to turn to the left side, showing ipsilateral complex image, horizontal separation is dominant, the maximum separation orientation is on the right side, the peripheral object image belongs to the right eye, the patient’s face is turned to the right, that is, the right external rectus muscle paralysis.
(2) The right eye is restricted to turn to the upper right, crossed complex image, vertical separation is dominant, the maximum separation orientation is the upper right, the peripheral object image belongs to the right eye, the patient’s chin is raised, the face is turned to the left, the head is slightly tilted to the left shoulder, that is, the right superior rectus muscle palsy.
(3) The right eye is restricted to turn above the nose, with the same side of the complex image, vertical separation is dominant, the image is skewed toward the temporal side, the maximum separation is above the temporal side of the left eye, that is, above the nose of the right eye, the peripheral object image belongs to the right eye, the patient’s head is skewed to the right shoulder, the chin is raised, the face is slightly turned to the right, that is, the right inferior oblique muscle paralysis.
(4) The head tilt test can identify children with superior oblique muscle palsy and superior rectus muscle palsy.
(5) The masking test can determine the correction effect after surgery.
Parents of babies with congenital paralytic strabismus will find that their children look askew when they are very young. Parents of children with large strabismus are easy to find and bring their children to the ophthalmology department, so it is not easy to delay the condition of such children. Some children are even misdiagnosed and undergo surgery on the sternomastoid muscle, and after surgery the child still has a tilted head. At this point, the ophthalmology department will have missed the best opportunity to operate on the child.
One of the easiest ways to identify whether a child’s head is tilted due to ophthalmic strabismus is to cover one of the eyes with gauze, and if the child’s tilted head decreases or disappears after covering, the child should be highly alert to compensatory head position caused by congenital strabismus.
Treatment of fresh paralytic strabismus can be treated with oral and intramuscular injections of vitamin B1, vitamin B12, inosine, coenzyme A, ATP, etc., in addition to treatment for the cause. Acupuncture and physiotherapy can also be used to promote the recovery of paralyzed muscles. If the patient cannot recover after six months of treatment, surgery can be considered.
For patients with a small degree of upward strabismus, we can consider using trigeminal correction to compensate for the head position.
Children with larger strabismus should be considered for early surgical treatment. For this kind of congenital paralytic strabismus, foreign ophthalmologists advocate staged surgery, while we adopt more staged surgery for children who live closer to home and have better financial situation. For children who live in remote areas. For children who live in remote areas and those who are in poor financial situation, we try to solve the problem in one surgery. However, this makes the surgery more difficult. The design of the surgery must be carefully communicated and discussed with the parents before the surgery, in order to obtain their understanding and cooperation.
For congenital paralytic strabismus in children, surgery is still the main treatment, because there is not much chance of forming amblyopia in congenital paralytic strabismus, and the monocular function of both eyes is often maintained because of compensatory head position; even if the monocular function of both eyes is incompetent or lost, as long as the surgery is early and the eye position is corrected after the surgery, the compensatory head position will disappear soon, and the monocular function of both eyes will be restored soon to achieve the purpose of functional cure. In older children with paralytic strabismus, surgery can correct the strabismus, but leaves permanent abnormalities in the cheeks, spine, and teeth, so children with compensatory head position should Therefore, children with compensatory head position should be corrected surgically as soon as possible.