Strabismus

Dear Lisa,

My 2 year old child recently had an MRI to make sure that the cause of his Strabismus was strictly the eyes and nothing more. His MRI results revealed white matter on the brain of an unknown cause that could be progressive. He was sent to the lab where blood & urine were taken to check his amino acids, organic acids, and for very long fatty chains. The amino & organic test results have all come back normal. We are just waiting for the other test. My question is, is it possible to have an abnormal MRI revealing this, but it not be anything to worry about? My son has no other medical problems besides the strabismus and has had breath holding spells when he was younger.

“Concerned Mom”

Dear “Concerned Mom”,

Strabismus is the misalignment of the eyes due to the lack of muscle coordination. (1) About 50% of all children with Strabismus have a family member with the condition. (2) Symptoms of Strabismus include difficulty seeing at close range, deviation of the eye, squinting, headache, lack of coordination, double vision, closing one eye, and head tilting. (2) The most common cause of strabismus is imbalance of the muscle alignment of the eyes. Other less common causes include retinoblastoma, loss of vision, myasthenia gravis, cataracts, infection and brain tumor.

In infancy, it is normal for infants to experience intermittent Strabismus due to the immaturity of their eye muscles. (1) This type of Strabismus is called Congenital Infantile Esotropia and is found in approximately 1 – 2% of infants. (1) These infants present with an intermittent inward deviation of one or both eyes. (1) By the age of three months normal ocular movement is usually established. (3) By six months old the infant’s symptoms should be totally resolved. An infant who displays symptoms beyond this point needs an evaluation by a Pediatric Ophthalmologist. Any child with a constant deviation, even if they are under 6 months old, also needs an evaluation by a Pediatric Ophthalmologist. (1)

Congenital Exotropia is a type of Strabismus that is less common. In this condition the eye turns away from the midline. It is usually noticed when a child is fixating on a distant object, daydreaming or fatigued. This condition tends to be associated with an underlying neurological problem such as Periventricular Leukomalacia or other neurological disorders. (1)

Early detection and treatment of Strabismus is essential to prevent Strabismus Amblyopia. (1, 2) Strabismus Amblyopia is the loss of vision in the deviating eye of a child with Strabismus. Visual loss occurs because of the body's attempt to suppress the double vision experienced by the child with Strabismus.

Some childhood disorders are associated with other conditions. When a child is diagnosed with one disorder, diagnostic testing is commonly performed in order to rule out potentially associated findings. Just because a particular condition may be associated with another disorder, does not necessarily mean that every child will develop that problem.

Without knowing your son’s diagnosis, complete history, physical findings or physically seeing your child I cannot offer you any specific information about his condition that may be helpful for you. I can only tell you that generally speaking white matter changes on an MRI of the brain can be associated with neurological conditions. In some conditions, white matter changes are associated with structural brain changes. Cognitive function can be impaired in patients with additional structural brain changes. (4) In general, cognitive function can be normal in children with isolated white matter changes. (4)

The significance of the white matter on your son’s Brain MRI can best be determined by his neurologist who reviewed the films and is familiar with his condition. It is important to remember that a child’s Neurological development with any type of neurologic anomaly can be quite variable and depends upon the extent of the malformation. (5)

Your doctors have performed a comprehensive work-up and in time will be able to give you the answers that you need. It is reassuring to know that the amino acid tests are normal so far. This type of testing typically ascertains the probability of an inborn error of metabolism or genetic syndrome. It is also good news that your son is not presently displaying any abnormal neurologic signs or developmental delays. Although waiting for test results and a diagnosis is extremely stressful, it may be helpful to concentrate on the positive findings that you know so far.

I wish you and your son well.

References:
(1)Wagner R. Understanding Strabismus in the Pediatric Patient. The Diagnosis and Treatment of Ophthalmic Abnormalities in Children: an update. Infectious Diseases In Children. 2002. May:S13-15.
(2)Betz C, Hunsberger M, Wright S. Family-Centered Nursing Care of Children. 2nd ed. Philadelphia, PA:W.B.Saunders Company. 1994:2048-2051.
(3)Graham M, Uphold C. Clinical Guidelines in Child Health. Gainsville, Florida: Barmarrae Books. 1994:338-339.
(4)Mercuri E. Longman C. Congenital Muscular Dystrophy. Pediatric Annals. 2005. 34(7):560-568.
(5) Behrman R, Kliegman R. Nelson Essentials of Pediatrics. Philadelphia ,PA: W.B.Saunders Company. 1990:652.

Lisa-ann Kelly R.N., P.N.P.,C.
Certified Pediatric Nurse Practitioner

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