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NCT Number: NCT07580170

Randomized Clinical Trial for Tonsil Surgery in Adults With Obstructive Sleep Apnea and Enlarged Tonsils

The aim is to investigate whether the tissue-preserving tonsil surgery technique is as effective as complete tonsil removal in the treatment of obstructive sleep apnea. The primary outcome measure is the change in the apnea-hypopnea index (AHI) before surgery and at 4-6, 24, and 60 months after surgery.

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Key information

Conditions

Sleep Apnea, Obstructives Apnea Dyssomnias Nervous System Diseases Respiration Disorders Respiratory Tract Diseases Sleep Apnea Syndromes Sleep Disorders, Intrinsic Sleep Wake Disorders Tonsil Hypertrophy

Age range

18 year–65 year

Sex eligibility

All sexes

Study type

Interventional

Phase

Not applicable

Primary location

Helsinki University Hospital, Helsinki, Finland

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About this study

Adult reviews suggest tonsillotomy (TT) reduces morbidity compared to tonsillectomy (TE). In pediatric populations, the effectiveness of partial tonsil surgery for sleep apnea (OSA) is well-documented. It remains unclear if TT is non-inferior to TE in adults in the treatment of OSA. This study compares TE with TT in adults using change in apnea-hypopnea index as the primary endpoint.

The hypothesis is that TT is non-inferior compared to TE in treating patients with moderate or severe OSA and grade 2 to 4 tonsil size.

Participants are blinded to the allocated intervention with an allocation ratio 1:1. Participants will be recruited from patients referred to an outpatient hospital clinic. The trial will be carried out in four tertiary hospitals in Finland.

Who can participate

Healthy volunteers accepted: No

Only the study team can determine whether someone qualifies for participation.

Inclusion criteria

  • BMI < 35
  • Tonsil size 2 - 4
  • Otherwise healthy patient fit for tonsil surgery
  • Apnea-hypopnea index > 15
  • Obstructive sleep apnea symptoms

Exclusion criteria

  • Pathological hemostasis or use of anticoagulation
  • Craniofacial deformities
  • Neurological condition with muscular hypotonia
  • Other surgical treatment for OSA

Treatment and study plan

Tonsillectomy

Procedure

TE will be performed by dissection in the peritonsillar plane. Parts of the upper and lateral palatal mucosal arches will be incised, and an extracapsular dissection for complete tonsil excision will be performed.

Tonsillotomy

Procedure

TT will be performed by removing approximately 60 - 90% of the tonsillar tissue, leaving a rim of tonsillar tissue on the tonsillar fossae. The tonsil capsule will not be breached.

Primary outcomes

  1. Changes in AHI at baseline and after surgery

    Time frame: baseline, 4-6, 24 and 60 months after surgery.

    The primary outcome is changes in AHI measured with home sleep study

Secondary outcomes

  1. Daytime sleepiness

    Time frame: Baseline and 6, 12, 24 and 60 months after surgery

    Measured with Epworth Sleepiness Scale (ESS) questionnaire (patient-reported). Points 0-18, higher is worse.

  2. Changes in insomnia symptoms

    Time frame: Baseline and 6, 12, 24 and 60 months after surgery

    Measured with Insomnia Severity Index (ISI) questionnaire, points range 0-28, higher is worse.

  3. Surgical success rate

    Time frame: Baseline and 6, 12, 24 and 60 months after surgery

    Defined according to Sher's criteria: a reduction in AHI of >50% and a total AHI of <20 after surgery

  4. Surgical cure rate

    Time frame: Baseline and 6, 12, 24 and 60 months after surgery

    Defined as a total AHI of <5 after surgery

  5. Changes in nocturnal desaturation

    Time frame: Before surgery and 4-6, 24 and 60 months after surgery

    Changes in nocturnal desaturation measured with oxygen saturation (SaO2) mean, min, and SpO2 <90% (T90) and ODI3, measured with home sleep study

Study contacts

Contact information is provided by the study sponsor or research team.

Henrik Sjöblom, MD

CONTACT

[email protected]

+35823130000

Jaakko M Piitulainen, MD, PhD

CONTACT

[email protected]

+35823130000

Sponsors and collaborators

Lead sponsor

Turku University Hospital

Other Gov

Collaborators

  • Helsinki University Central Hospital
  • Oulu University Hospital
  • Tampere University Hospital

Registry information

Official study title

Multicenter, National, Randomized, Patient-Blinded, Parallel Group, Non-Inferiority Trial To Compare Tonsillotomy Versus Extracapsular Tonsillectomy in Adults With Obstructive Sleep Apnea and Tonsil Hypertrophy: The TONOS Trial.

Acronym: TONOS

Important dates

Study start
2026
Primary completion
2031
Study completion
2036
First posted
May 12, 2026
Registry last updated
Jun 3, 2026

OpenTrials presents study information sourced from ClinicalTrials.gov. The official registry record should be consulted for the latest information.

View the official ClinicalTrials.gov record (opens in a new tab)

This listing is for discovery and informational purposes only. It is not medical advice, does not guarantee that a study is recruiting, and does not determine eligibility. Contact the study team and a qualified healthcare professional when considering participation.

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