Kearns-Sayre syndrome is a rare disorder caused by dysfunctional mitochondria, the powerhouse of the cell. This condition affects eyesight through chronic progressive external ophthalmoplegia (weakness of eye muscles) and pigmentary retinopathy (breakdown of light-sensing tissue at the back of the eye). Due to muscle weakness and reduced growth, people with Kearns-Sayre syndrome may also experience heart problems, a short stature, muscle weakness in the face and limbs, ataxia (lack of coordination due to poor muscle control), endocrine disorders (insufficient hormone production), and progressive deafness (loss of hearing) – all of which may impact quality of life. Although there is no current cure for Kearns-Sayre syndrome, early detection and supportive treatment can help reduce the impact of symptoms and improve quality of life.  

In this article, we will look at a brief overview of the causes and symptoms of Kearns-Sayre syndrome, followed by an examination of how occupational therapy can improve the quality of life for people with this condition.

Causes 

Kearns-Sayre syndrome is caused by dysfunctional mitochondria – but what are mitochondria? Mitochondria are a type of structure (known as organelles) within our cells. With the job of providing energy to facilitate cellular processes, they are often called ‘the powerhouse of the cell’. Unlike most organelles, mitochondria possess their own DNA, separate from the DNA of the cell. The mitochondrial DNA, or mtDNA for short, encodes genes which allow the mitochondria to function. 

Rarely, large deletions in mtDNA may occur, causing the genes essential for mitochondrial function to be lost. Mitochondria become less able to provide energy to the cell, leading to Kearns-Sayre syndrome. 

Symptoms

Symptoms of Kearns-Sayre syndrome usually appear before the age of 20, with the two main characteristic findings being chronic progressive external ophthalmoplegia and pigmentary retinopathy. This may eventually lead to reduced eyesight. Heart issues such as cardiomyopathy (stiff heart muscle) and arrhythmia (irregular heartbeat) are common. People with Kearns-Sayre syndrome may also experience short stature, muscle weakness in the face and limbs, lack of coordination due to poor muscle control, endocrine disorders, and progressive deafness.^1,2

Chronic progressive external ophthalmoplegia

Chronic progressive external ophthalmoplegia is a weakness or paralysis in the eye muscles, which may occur in one or both eyes. It results in impaired eye movement (known as ophthalmoplegia) and drooping eyelids (known as ptosis), potentially leading to reduced eyesight. As ophthalmoplegia worsens, patients may need to turn their heads to see in different directions. Similarly, ptosis may cause patients to use their forehead muscles to lift their eyelids or lift their heads in order to see clearly. 

Pigmentary retinopathy

Pigmentary retinopathy is a condition caused by the breakdown of tissue at the back of the eye, leading to the loss of peripheral and night vision. The back of the eye, known as the retina, is lined with light-sensing cells called photoreceptors. Humans possess two types of photoreceptors: rods, responsible for night and peripheral vision, and cones, responsible for colour vision. In pigmentary retinopathy, these photoreceptors degenerate. 

Rod cells are affected first, causing a loss of night and peripheral vision (tunnel vision). As cone cells begin to degenerate, colour vision may also be reduced. Tunnel vision may increase as the person becomes less able to see.

Cardiomyopathy and arrhythmia

Kearns-Sayre syndrome may lead to heart issues, including cardiomyopathy and/or an arrhythmia. In people with cardiomyopathy, the walls of the heart chamber grow thickened and become stiff, causing the heart to be less able to pump blood. People with arrhythmia have an unsteady heartbeat. This may lead to heart block – an irregular and/or slowed heartbeat due to the blockage of the electric signal governing the heartbeat. Symptoms of heart block include chest pain, fatigue, dizziness, shortness of breath and fainting. Heart issues are the symptom most likely to cause life-threatening complications in Kearns-Sayre syndrome, with up to 20% of patients experiencing sudden cardiac death.³

Other symptoms

Short stature and developmental delays are often the first noticeable symptoms of Kearns-Sayre syndrome. Diagnostic tests must be performed to confirm the cause of the symptoms, as they can also indicate the presence of other conditions affecting growth. 

People with Kearns-Sayre syndrome may also experience muscle weakness in the face and limbs, as well as ataxia (lack of coordination due to poor muscle control). Poor coordination is caused by degeneration of the cerebellum, the part of the brain which controls movement and balance. They may have endocrine disorders caused by insufficient production of hormones – such as type 1 diabetes (high blood sugar caused by insufficient insulin production), growth hormone deficiency, hypogonadotropic hypogonadism (insufficient sex hormone production), adrenal insufficiency (insufficient adrenaline production), and primary hypoparathyroidism (insufficient parathyroid hormone production which leads to low calcium levels and high phosphorus content in blood).¹ Deafness may also occur due to dysfunction of the cochlea, a snail-shaped organ in the inner ear which converts sounds into electrical signals the brain can understand.⁴ 

Treatments

Although a cure has yet to be developed for Kearns-Sayre syndrome, the condition can be managed through treatments directly targeting symptoms. As each individual with Kearns-Sayre syndrome experiences a different combination of symptoms with varying severity, treatment plans are personalised to better benefit the patient. A team of specialists may collaborate to provide an optimised treatment plan.⁵ Regular checkups are also necessary to track the progression of the disease. The following are some common treatments for people with Kearns-Sayre syndrome:

Chronic progressive external ophthalmoplegia

Patients with chronic progressive external ophthalmoplegia often experience ptosis (drooping eyelids), which may limit their eyesight. Surgery may be recommended to lift the eyelids, improving their field of vision. Glasses with a lid and crutches to help the patient lift the upper eyelid may also be prescribed.

Cardiomyopathy and arrhythmia

As cardiac complications are the most life-threatening of all complications from Kearns-Sayre syndrome, it is especially important that heart issues are properly evaluated and treated. To treat cardiomyopathy (thickened heart muscles), septal ablation may be recommended. Alcohol is injected into a blood vessel which supplies the thickened heart muscles. This causes the thickened muscles to shrink, improving blood flow. People with arrhythmia (irregular heartbeat) may also be advised to have a pacemaker implanted. Pacemakers are small devices implanted next to the heart to help regulate the heartbeat. They release small electrical impulses at a regular rhythm to stimulate the heart to contract, ensuring the heart beats are at a regular rate and rhythm. 

Other symptoms

To treat endocrine disorders, hormone replacement therapy may be recommended. Hormones are injected into the bloodstream to alleviate the patient’s naturally low hormone levels. The injection of growth hormone has also been suggested to help children with Kearns-Sayre syndrome grow taller. However, this is a controversial treatment as growth hormone also increases the body’s demand for energy. At the same time, Kearns-Sayre syndrome decreases the amount of energy available to the body. While young patients provided with growth hormone show an increase in height, some also experience side effects such as muscle weakness, ataxia (poor balance), and even organ failure.⁵ To improve muscle strength and reduce the impact of ataxia, occupational therapy can be recommended.

Use of occupational therapy

Occupational therapy aims to help patients improve their daily functioning so that they can complete their daily routines more easily. People with Kearns-Sayre syndrome can undergo occupational therapy to improve their muscle strength, balance and coordination. This can be done through various exercises taught to patients during occupational therapy sessions. For example, patients may be given therapy balls or putty for squeezing, which helps build up hand strength and fine motor coordination. Activities such as shifting body weight from one leg to another, standing on one leg, and heel-to-toe walking can similarly help improve balance. 

To improve daily functioning, occupational therapy does not focus only on improving body functions. Therapists may suggest tailoring the patient’s living space to better accommodate their condition. For example, patients with mobility aids may widen their doorways and living spaces to make it easier to get around with mobility aids. Handrails can be installed on walls and in the shower to reduce the risk of falling, which is useful for Kearns-Sayre syndrome patients experiencing ataxia.^5,6 

Summary

Kearns-Sayre syndrome is a systemic condition caused by dysfunctional mitochondria, leading to a large variety of symptoms which affect many parts of the body. Treatments to improve quality of life include surgical intervention, assistive devices such as lid crutches and pacemakers, hormone injections, and occupational therapy. Occupational therapy provides a holistic, non-invasive approach to improve the daily functioning of people with Kearns-Sayre syndrome. Therapists may recommend exercises to improve a patient's strength and balance. They may also suggest tailoring the patient’s living environment to better accommodate their condition, in order to achieve a better overall quality of life.