Septo-optic dysplasia

Septo-optic dysplasia is a disorder that affects early brain development. This condition is typically defined as a combination of at least two of the following three features: underdevelopment (hypoplasia) of the nerves that carry visual information from the eye to the brain (optic nerves); abnormal development of the structures that separate the right and left halves (the midline) of the brain; and hypoplasia of the hormone-producing gland (pituitary gland) at the base of the brain. The signs and symptoms of septo-optic dysplasia can vary widely among affected individuals. Less than half of people with septo-optic dysplasia have all three of the main features. 

In individuals with optic nerve hypoplasia, the optic nerves are often abnormally small and make fewer connections than usual between the eyes and the brain. As a result, affected individuals have impaired vision in one or both eyes. People with optic nerve hypoplasia can also have other eye abnormalities, including rapid, involuntary eye movements (nystagmus) and eyes that do not point in the same direction (strabismus).

Abnormal development of the structures along the midline of the brain occurs in many people with septo-optic dysplasia. These structures include the corpus callosum, which is a band of tissue that connects the two halves of the brain, and the septum pellucidum, which separates the fluid-filled spaces in the brain. In affected individuals, these structures may form abnormally or fail to develop at all. Additional brain abnormalities, such as slits or clefts in one or both halves of the brain (schizencephaly), may also be present in people with septo-optic dysplasia. Depending on which structures are affected, abnormal brain development can lead to intellectual disabilities and other behavioral and neurological problems, including recurrent seizures (epilepsy); developmental delays; and autism spectrum disorder, which is characterized by impaired social skills and communication problems.

Many people who have septo-optic dysplasia have an underdeveloped pituitary gland. Pituitary hypoplasia can lead to a shortage (deficiency) of essential hormones. These hormones help control growth, reproduction, and other critical body functions. In most cases, pituitary hypoplasia causes growth hormone (GH) deficiency, which results in slow growth and short stature. Less commonly, individuals who have septo-optic dysplasia have panhypopituitarism, a condition in which the production of multiple hormones is impaired. Panhypopituitarism can be associated with slow growth, low levels of glucose in the blood (hypoglycemia), genital abnormalities, and problems with sexual development.

Because the signs and symptoms of septo-optic dysplasia can vary significantly, researchers have suggested that this condition may actually represent a spectrum of related conditions rather than a single disorder. Researchers have suggested various names for this spectrum, including "septo-optic-pituitary dysplasia,"  "septo-optic pituitary dysplasia complex," and "hypothalamo-pituitary-optic dysplasia." Researchers are working to better understand this condition.