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PubMed This is a summary of 19 peer-reviewed journal articles Updated
Neurology

Symptoms and the Path to Diagnosis

At a Glance

Kearns-Sayre Syndrome (KSS) is a progressive, multisystem disorder that usually begins before age 20 with drooping eyelids and limited eye movement. Because it can eventually cause dangerous heart block, obtaining an accurate diagnosis and regular cardiac monitoring is critical.

Kearns-Sayre Syndrome (KSS) is often called a “multisystem” disorder because it can affect many different parts of the body over time [1][2]. Because the symptoms develop gradually and often begin with the eyes, it is very common for the diagnosis to be missed or mistaken for other conditions in the early stages [3][4].

The First Signs: Ocular Symptoms

For most people, the journey with KSS begins before age 20 with changes in the eyes [5][6]. These early signs include:

  • Ptosis (Drooping Eyelids): This often starts in both eyes and slowly worsens over years [5][7].
  • Ophthalmoplegia: This is a limitation in eye movement. You might find you have to turn your whole head to look at something because your eye muscles are too weak to move the eyeball fully [8][9].

Why KSS is Often Misdiagnosed

The most common misdiagnosis for KSS is Myasthenia Gravis (MG), another condition that causes drooping eyelids and eye muscle weakness [3][7].

Feature Kearns-Sayre Syndrome (KSS) Myasthenia Gravis (MG)
Fluctuation Symptoms are constant and progress slowly [7]. Symptoms often “ebb and flow” or get worse when tired [3].
Fatigue Muscles are weak but do not necessarily “tire out” more with use [7]. Muscles get significantly weaker after repetitive use [3].
Other Signs Includes retina changes and heart issues [8]. Does not affect the retina or cause “heart block” [7].

Because KSS is so rare, doctors may first test for MG. If MG treatments (like steroids) don’t work, it often prompts doctors to look closer at mitochondrial causes [3][7].

Systemic Symptoms: Beyond the Eyes

As KSS progresses, it can involve other “high-energy” systems in the body. These symptoms do not all appear at once; they often emerge over years [1][2].

The Heart (Cardiac Conduction)

This is the most critical systemic feature. KSS can disrupt the heart’s internal electrical system, leading to heart block (where electrical signals move too slowly or not at all) [10][11]. This can cause dizziness, fainting, or even sudden heart failure, which is why regular heart monitoring is vital [11][12].

The Brain and Nervous System

  • Ataxia: A loss of coordination or balance, which may look like stumbling or clumsiness [8][13].
  • Hearing Loss: This usually affects both ears and is caused by damage to the nerves in the inner ear [14][15].

The Endocrine System

Mitochondrial dysfunction can affect hormone-producing glands, leading to:

  • Diabetes Mellitus: Problems regulating blood sugar [16][17].
  • Hypoparathyroidism: Low levels of parathyroid hormone, which can cause low calcium and muscle cramps [16][18].
  • Growth Issues: Short stature or delayed puberty [16][17].

A Note on Progression

It is important to remember that KSS is progressive, meaning symptoms change over time [2]. However, the pace of change is different for everyone. Some people may only ever have eye and heart issues, while others may develop more systemic symptoms [19][14]. Regular screening helps “catch” these symptoms early, often before they cause major problems [11].

Common questions in this guide

Why is Kearns-Sayre Syndrome often misdiagnosed as Myasthenia Gravis?
Both conditions cause drooping eyelids and eye muscle weakness. However, Myasthenia Gravis symptoms fluctuate and worsen with muscle use, whereas KSS symptoms are constant and progress slowly over time.
What are the first signs of Kearns-Sayre Syndrome?
The earliest signs usually appear before age 20 and affect the eyes. Patients typically experience ptosis, which is a drooping of the eyelids, and ophthalmoplegia, which makes it difficult to move the eyes fully.
How does Kearns-Sayre Syndrome affect the heart?
KSS can disrupt the heart's internal electrical system, leading to a condition called heart block. This slows or stops electrical signals, causing dizziness, fainting, or sudden heart failure, which is why regular EKGs are essential.
What endocrine problems are associated with KSS?
Mitochondrial dysfunction in KSS can affect hormone-producing glands. This may lead to problems like diabetes mellitus, low calcium from hypoparathyroidism, or delayed puberty and short stature.

Questions to Ask Your Doctor

Curated prompts to bring to your next appointment.

  1. 1.Why was Myasthenia Gravis ruled out in my case, and what specific tests confirmed KSS instead?
  2. 2.Given the risk of heart block, how often should I have an EKG or a Holter monitor test?
  3. 3.At what point should we consider a prophylactic pacemaker, even if I don't have heart symptoms yet?
  4. 4.What signs of endocrine issues (like diabetes or parathyroid problems) should I be watching for at home?
  5. 5.Is a hearing test necessary now, and how often should it be repeated?

Questions For You

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References

References (19)
  1. 1

    Recognizing the evolution of clinical syndrome spectrum progression in individuals with single large-scale mitochondrial DNA deletion syndromes (SLSMDS).

    Ganetzky R, Stanley KD, MacMullen LE, et al.

    Genetics in medicine : official journal of the American College of Medical Genetics 2025; (27(5)):101386 doi:10.1016/j.gim.2025.101386.

    PMID: 39985363
  2. 2

    Clinical and Brain Magnetic Resonance Imaging Features in a Cohort of Chinese Patients with Kearns-Sayre Syndrome.

    Yu M, Zhang Z, Wang QQ, et al.

    Chinese medical journal 2016; (129(12)):1419-24 doi:10.4103/0366-6999.183417.

    PMID: 27270536
  3. 3

    KEARNS-SAYRE SYNDROME MASQUERADING AS MYASTHENIA GRAVIS.

    Sokol JT, Hoyek S, Fulton AB, Patel NA

    Retinal cases & brief reports 2024; (18(3)):396-399 doi:10.1097/ICB.0000000000001397.

    PMID: 36729003
  4. 4

    Kearns-Sayre syndrome presenting with progressive external ophthalmoplegia and third-degree atrioventricular block diagnostic challenge in resource-limited settings: a case report.

    Azibte GT, Ayalew ZS, Molla BA, et al.

    Journal of medical case reports 2025; (19(1)):127 doi:10.1186/s13256-025-05086-5.

    PMID: 40114248
  5. 5

    Expanding the Genetic and Phenotypic Spectrum of Kearns-Sayre Syndrome: A Case Report.

    Messina C

    Cureus 2025; (17(5)):e84293 doi:10.7759/cureus.84293.

    PMID: 40524992
  6. 6

    Ophthalmologic school-based screening revealing Kearns-Sayre syndrome: a case report.

    Ennejjar A, Moutamani S, Boutaj T, et al.

    The Pan African medical journal 2022; (41()):226 doi:10.11604/pamj.2022.41.226.33085.

    PMID: 35721635
  7. 7

    Teaching NeuroImages: Kearns-Sayre syndrome.

    Nguyen MTB, Micieli J, Margolin E

    Neurology 2019; (92(5)):e519-e520 doi:10.1212/WNL.0000000000006861.

    PMID: 30635486
  8. 8

    A rare case of Kearns-Sayre syndrome in a 17-year-old Venezuelan male with bilateral ptosis as the initial presentation.

    Leal M, Dhoble C, Lee J, et al.

    Oxford medical case reports 2016; (2016(3)):34-6 doi:10.1093/omcr/omw007.

    PMID: 26949540
  9. 9

    Diagnose Kearns-Sayre syndrome genetically and investigate the phenotype comprehensively.

    Finsterer J, Zarrouk-Mahjoub S

    Oxford medical case reports 2016; (2016(8)):omw059 doi:10.1093/omcr/omw059.

    PMID: 29497555
  10. 10

    Progressive Conduction Disease in a Mitochondrial Disorder.

    Amaro T, Bueno S, Guirão C, et al.

    JACC. Case reports 2026; 107749 doi:10.1016/j.jaccas.2026.107749.

    PMID: 42171571
  11. 11

    Prophylactic pacemaker placement at first signs of conduction disease in Kearns-Sayre syndrome.

    Trivedi M, Goldstein A, Arora G

    Cardiology in the young 2018; (28(12)):1487-1488 doi:10.1017/S1047951118001609.

    PMID: 30326976
  12. 12

    The necessity of implantable cardioverter defibrillators in patients with Kearns-Sayre syndrome - systematic review of the articles.

    Imamura T, Sumitomo N, Muraji S, et al.

    International journal of cardiology 2019; (279()):105-111 doi:10.1016/j.ijcard.2018.12.064.

    PMID: 30642644
  13. 13

    Kearns-Sayre syndrome with rare imaging finding of SLC25A4 Mutation.

    Zhao H, Shi M, Yang F, Yang X

    Neurosciences (Riyadh, Saudi Arabia) 2022; (27(2)):111-115 doi:10.17712/nsj.2022.2.20210123.

    PMID: 35477912
  14. 14

    Should Patients with Kearns-Sayre Syndrome and Corneal Endothelial Failure Be Genotyped for a TCF4 Trinucleotide Repeat, Commonly Associated with Fuchs Endothelial Corneal Dystrophy?

    Dudakova L, Skalicka P, Davidson AE, et al.

    Genes 2021; (12(12)) doi:10.3390/genes12121918.

    PMID: 34946867
  15. 15

    Kearns-Sayre syndrome: Two case reports and a review for the primary care physician.

    Richmond C, Powell L, Brittingham ZD, Mancuso A

    Journal of family medicine and primary care 2023; (12(4)):792-795 doi:10.4103/jfmpc.jfmpc_1790_22.

    PMID: 37312792
  16. 16

    Fatal pneumonia in a patient with Kearns-Sayre syndrome case report and literature review.

    Zhang J, Song Z, Zhou H, et al.

    Frontiers in medicine 2025; (12()):1575384 doi:10.3389/fmed.2025.1575384.

    PMID: 40823579
  17. 17

    A case of hypopituitarism accompanying Kearns-Sayre syndrome treated with human chorionic gonadotropin: A case report and literature review.

    Kang YX, Wang YJ, Zhang Q, et al.

    Andrologia 2017; (49(8)) doi:10.1111/and.12711.

    PMID: 27709644
  18. 18

    Nutritional issues in a diabetic patient with Kearns-Sayre syndrome.

    Szwilling A, Dzygalo K, Nowaczyk J

    Endocrinology, diabetes & metabolism case reports 2020; (2020()).

    PMID: 33434157
  19. 19

    Ophthalmoplegia in Mitochondrial Disease.

    Lee SJ, Na JH, Han J, Lee YM

    Yonsei medical journal 2018; (59(10)):1190-1196 doi:10.3349/ymj.2018.59.10.1190.

    PMID: 30450853

This page explains Kearns-Sayre Syndrome symptoms and diagnostic pathways for informational purposes only. Always consult your neurologist or healthcare provider about your specific symptoms and required testing.

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