Kearns-Sayre Syndrome - Cause, Symptoms, Diagnosis, and Management

What Is Kearns-Sayre Syndrome?

Kearns-Sayre syndrome is a rare neuromuscular disorder that affects the multiple systems in the body, especially the eyes. An estimated one to two children in 100,000 is found with this syndrome. Children with this disorder are often seen with impaired eye movements with the drooping appearance of eyelids.

Moreover, the affected people are also found with conditions related to the eyes, such as pigmentary retinopathy caused by degeneration of light-sensing tissues located at the back of the eyes. The disorder in newborns is often seen as associated with imbalanced walking and abnormalities related to heartbeat. There are children with compromised cognitive functions seen with this syndrome. This condition is caused by an abnormal ragged microscopic structure called mitochondria that acts as a powerhouse for a cell’s biochemical reactions.

Kearns-Sayre syndrome is a part of mitochondrial encephalomyopathies, where the abnormality of the genes arises from the part of the cell called mitochondria.

What Are the Causes of Kearns-Sayre Syndrome?

• Mainly the mitochondria is affected, which causes the disorder. Mitochondria is a membrane-bounded round to oval structure that converts oxygen into energy. Mitochondria acts as a storage for cells to store calcium, which is used to send signals and promote cell growth and death. Many structures of the body do not contain mitochondria into their structure such as red blood cells. However, structures such as the liver and other muscles contain mitochondria in the cell structure. The spongy structure of the mitochondrial membrane is absorptive to small molecules, but the large ones have to transport through special channels. The chemiosmotic process converts the by-products of the citric acid cycle into energy, where the protein component of the cells goes through oxidation-reduction reactions to separate electrons to move forward towards the next protein component. This chemiosmotic process aids the brain and muscle activities in the body.

• On the other hand, most of the DNA is packed with protein to contain chromosomes in the center. Likewise, the mitochondria contain a small portion of their DNA, called mtDNA, that are essential for normal mitochondrial function. The people with Kearns-Sayre syndrome have almost 1,000 to 10,000 mtDNA omitted due to some unknown reasons. This loss of mtDNA or genes obstructs normal mitochondrial protein formation and other functions. Moreover, the cellular energy production procedure is also disturbed by this loss of genes. The eyes of the infant are affected by this because it is dependent on mitochondrial energy production.

• It is rarely an inherited condition, but in some cases, the inheritance of the genes during embryonic development is from the egg cells of a mother, making this disorder maternally inherited.

What Are the Signs and Symptoms of Kearns-Sayre Syndrome?

There is multisystem involvement seen with this syndrome that shows different signs and symptoms, such as:

• Ptosis: It is one of the classic signs of the Kearns-Sayre syndrome, where the upper eyelid has a droopy appearance.

• Pigmentary Retinopathy: It is a condition caused by the underlying retinal epithelial cell damage resulting in atrophy or cell death of photoreceptors of the adjacent layer of the retina. Children with this condition are unable to see during the nighttime with weak peripheral vision (trouble seeing things in the corner of the eyes).

• Chronic Progressive External Ophthalmoplegia: Kearns-Sayre syndrome causes the condition in children where they slowly lose the ability to move their eyes and eyebrows. This is another classic sign of Kearns-Sayre syndrome.

• Cognitive Impairment: Children with Kearns-Sayre syndrome often face difficulties in concentrating and learning new things. The syndrome affects the daily lifestyle of the children.

• Deafness: Children with this disorder might face hearing loss or defect.

• Cardiac Conditions: Muscular atrophy or weakness can cause heart problems in many children putting them at risk of having cardiac arrest or heart attack.

• Endocrine Abnormalities: Children with this disorder can face hormonal imbalances causing thyroid disease, diabetes, gonadal failure, and hyperaldosteronism.

• Short Stature: Usually, children with this syndrome are seen with short height.

• Seizures: Due to impairment of brain activity, children with this disorder might face this sudden uncontrolled electrical disturbance in the brain called seizures.

• Weakness: Due to low energy levels, children might feel lazy or weak during day-to-day functions.

How to Diagnose Kearns-Sayre Syndrome?

There are many diagnostic and investigation methods used for this disorder, such as:

• Medical and Family History: Although the inheritance of the syndrome is very rare, the case history can reveal many hidden aspects and help in the proper diagnosis.

• Physical Exam: Different diagnostic methods, such as slit-lamp examination, evaluation of extraocular movements, and dilated fundus examination, are used to see signs and symptoms of this disorder. For instance, the slit-lamp examination is for anterior segment evaluation, dilated fundus examination is for pigmentary retinopathy, and the evaluation of extraocular movements is for the extent of ophthalmoplegia.

• Blood Test: This diagnostic method is used for nutrition imbalance and hormonal imbalance in the body.

• Spinal Tap: It is also known as a lumbar puncture. The test is performed to collect cerebrospinal fluid for inflammation, infections, or any other complications.

• Genetic Counseling and Testing: This diagnostic method is used along with laboratory tests to check for the disorder and other disorders associated with it.

• Biopsy: The mitochondria is a microscopic structure, and with this diagnostic method, the doctor can check for tissue samples for abnormalities, and also it can be used for genetic testing.

• Electrocardiogram (ECG): This diagnostic method is used for checking any heart block or abnormality related to the heart.

• Magnetic Resonance Imaging (MRI): This diagnostic method can help to check for any progressive lesions involving the brain or other organs.

How to Manage Kearns-Sayre Syndrome?

• Due to its prevalence and progress in children, there are many treatment options recommended according to the system's involvement. Additionally, there is no cure for the syndrome, but an early diagnosis and supportive treatment plan can help to solve the complications associated with health.

• According to the system involved, a child might have to visit different specialists such as eye care specialists, hearing specialists, heart specialists, genetic specialists, nervous system experts, psychologists, and hormone-related disease experts.

• Myriad supportive tools and surgeries are recommended for children, such as an eyelid sling for keeping eyes open, a hearing aid, eyelid surgery, a pacemaker for arrhythmias in the heart, hormone replacement therapy, and insulin treatment for diabetes.

• Lastly, post-surgical care and regular follow-up visits to the doctor can prove very helpful in managing the symptoms.

Conclusion

As the Kearns-Sayre syndrome is a rare genetic disorder, the early and timely detection of the disease is crucial to reducing the risk factors associated with it. The parents or caregivers should maintain regular and early visits to the newborns for checkups and immunizations. Even though the recovery rate is very low due to the rareness of the disorder and no treatment plan availability, there are chances to maintain good health with medical support and surgeries.