What is Septo-optic Dysplasia: Causes, Symptoms, Treatment, Prognosis, Risk Factors

Septo-optic Dysplasia was discovered for the first time by Dr. Reeves in 1941. Septo-optic Dysplasia was previously called as de Morsier’s syndrome. Since it consists of three major symptoms, it is currently called as Septo-optic Dysplasia (SOD) complex.

Septo-optic dysplasia is a rare congenital disorder, wherein there is an early developmental abnormality of the forebrain. Septo-optic dysplasia is characterized by a triad of symptoms, which includes underdevelopment of optic nerve, absence of septum pellucidum and underdeveloped pituitary gland (pituitary hypoplasia).

The optic nerve underdevelopment or hypoplasia leads to optic nerves which are small and make fewer contacts than normal between the eyes and the brain. It leads to impaired or poor vision in either one or both the eyes and in some cases it leads to blindness. It is also associated with unusual side to side movements and other eye problems.

Further symptom of Septo-optic dysplasia indicates that during early developmental phase, there is an abnormal development of structures, especially of the septum pellucidum, which separates the right and left halves of the brain. There is either an abnormality or the septum pellucidum fails to develop which in turn leads to neurological problems.

The third symptom is of pituitary hypoplasia. The pituitary gland present at the base of the brain produces important hormones that control main functions of our body. Due to which it is called as the master control gland. When there is underdevelopment of this gland, it leads to either no or less production of hormones. This in turn affects the entire development of an individual.

The signs and symptoms of Septo-optic Dysplasia can vary in individuals. Some people suffering from Septo-optic dysplasia may present with all the three characteristics, while some may present with any two symptoms. Only in 30% cases all the symptoms of Septo-optic dysplasia are observed, while in 62% cases any two symptoms of Septo-optic dysplasia are seen. When any one of the symptom is found in isolation, it is not considered as a case of Septo-optic Dysplasia.

The following symptoms of Septo-optic dysplasia are observed:

• Optic nerve abnormality leads to visual impairment. There are unusual eye movements, since the eyes are not able to focus well.
• Absence of septum pellucidum leads to abnormal brain development. This in addition is associated with epileptic seizures, developmental delay, intellectual problems, cerebral palsy and abnormal movements.
• Pituitary hypoplasia or hypopituitarism has very less production of the essential hormones, which results in slow growth and in short stature. In case of pan hypopituitarism, there is no production of any hormones and is associated with very slow growth, hypoglycaemia and problems in sexual development.
• Septo-optic Dysplasia is a highly variable abnormality. Many patients show additional symptoms (which are not always described) such as the digital defects.

Septo-optic dysplasia is uncommon and occurs in 1 in 10,000 live births. Septo-optic dysplasia can be seen in both male and female babies. Although most cases are sporadic, there are some patients which show familial inheritance pattern.

The earlier the diagnosis of Septo-optic dysplasia is done, the better is the outcome. When child is untreated for abnormalities, the patient with Septo-optic dysplasia is at increased risk of hypoglycaemia, adrenal crises and ultimately death.

The exact cause for Septo-optic dysplasia is not known. It is observed that Septo-optic dysplasia takes place in the infants born to very young aged mothers. It is sporadic and does not show recurrence with subsequent pregnancies.

Genetic and molecular studies revealed genes HESX1, OTX2 and SOX2 play an important role in embryonic development and are necessary for the formation of eyes, pituitary gland and forebrain structures. Any mutations in these genes lead to abnormalities during development of these structures. The ongoing researches aim to find more such genetic mutations which might be leading to the condition of Septo-optic dysplasia.

Most of the Septo-optic Dysplasia cases are sporadic; while few show familial inheritance as either autosomal recessive condition or autosomal dominant pattern of inheritance.

Both genetic and environmental factors are predicted to play a role in causing septo-optic dysplasia. Environmental risk factors of Septo-optic dysplasia include viral infection, some medicines, alcohol and obstruction to the flow of blood to specific areas of the brain during important developmental phases of the foetus.

Diagnosis of Septo-optic dysplasia involves multidisciplinary diagnosis with clinicians from different fields.

• The eye doctor or ophthalmologist diagnoses the eyes with help of an ophthalmoscope and checks for the optic nerve and the eye movements.
• The brain specialist observes the brain structure by suing Computed tomography (CT) scan or Magnetic Resonance Imaging (MRI) scan. By performing these tests, the doctor should be able to detect if there is any abnormality with the brain or if there will be any problems with the brain in future.
• The endocrinologist will check if there are any abnormalities in the hormonal levels by performing blood tests of the patient especially to check for pituitary functions. Even if the child does not have problems in initial stages of development, they will develop them later in life. Hence, one needs to check for hormonal abnormalities very often as the child is growing.

There is no single medical treatment available to treat Septo-optic dysplasia completely. Generally, surgery can be performed to correct the optic nerve abnormalities. Hormonal therapy or hormonal replacement therapy for Septo-optic dysplasia is given to correct the less amount of hormones produced by the pituitary gland.

Patients with Septo-optic Dysplasia are required to go for regular follow-ups with multi-disciplinary team. The patient needs to check with the functioning of the eye, hormonal levels and brain development. Genetic counselling is done in cases where there is associated familial risk.

Septo-optic dysplasia is a very rare, heterogenous disorder. Due to its variable symptoms, there is significant delay in its exact diagnosis. Overall, more research studies are required to get better understanding of Septo-optic dysplasia which will enable appropriate diagnosis and treatment strategies to help the patient lead a better life in future.