The aim of this methodological study is to translate the Impact of Brachial Plexus Injury Questionnaire (IMBPIQ) into Turkish, culturally adapt it, and evaluate its validity and reliability for use in adults with brachial plexus birth palsy. The study will include 50 adult participants aged 18 years and older with a diagnosis of brachial plexus birth palsy. Participants will complete the Turkish version of the IMBPIQ, as well as the Disabilities of the Arm, Shoulder and Hand questionnaire and the Short Form-36. The psychometric properties of the Turkish IMBPIQ will be examined using reliability and validity analyses, including internal consistency, test-retest reliability, and construct validity.

The Impact of Brachial Plexus Injury Questionnaire (IMBPIQ) is a disease-specific patient-reported outcome measure developed to evaluate the impact of brachial plexus injury on daily life, functional status, and psychosocial well-being. There is currently no Turkish version of the IMBPIQ with established validity and reliability. Considering the increasing importance of culturally adapted patient-reported outcome measures, this study aims to translate the IMBPIQ into Turkish, perform its cultural adaptation, and evaluate the validity and reliability of the Turkish version for use in adults with brachial plexus birth palsy.

This study is designed as a methodological validity and reliability study. Written permission has been obtained from the original developers of the IMBPIQ for translation, cultural adaptation, and psychometric testing. The English version of the questionnaire will be translated into Turkish by independent translators. The translated versions will be reviewed by a committee, and a single Turkish version will be created based on consensus. This Turkish version will then be back-translated into English by a translator whose native language is English and who is proficient in both languages. The original version and the back-translated version will be compared in terms of semantic equivalence, linguistic appropriateness, and cultural adaptation, and the final Turkish version of the questionnaire will be established.

A pilot test will be conducted with 10 participants to evaluate the comprehensibility and applicability of the Turkish version of the questionnaire. Based on the feedback obtained from the pilot test, final revisions will be made before the main study. The main study will include 50 adult participants aged 18 years and older with a diagnosis of brachial plexus birth palsy. Participants will complete a sociodemographic and clinical information form, the Turkish version of the IMBPIQ, the Disabilities of the Arm, Shoulder and Hand questionnaire, and the Short Form-36.

The IMBPIQ consists of 43 items and includes four main subdomains: symptoms, limitations, emotional status, and expected or achieved improvement after surgery or treatment. Raw scores obtained from the responses are converted into normalized standard scores ranging from 0 to 100. The disability domain score is calculated using the symptoms, limitations, and emotional status subdomains, with higher scores indicating greater disability and psychosocial impact. The improvement domain score reflects the expected or achieved improvement related to surgery or treatment, with higher scores indicating greater expected or perceived improvement.

The Disabilities of the Arm, Shoulder and Hand questionnaire will be used to evaluate upper extremity symptoms and functional disability. The Short Form-36 will be used to assess health-related quality of life. These measures will be used to examine the construct validity of the Turkish IMBPIQ through correlations with related patient-reported outcome measures.

Statistical analyses will be performed using IBM SPSS Statistics software. Descriptive statistics will be calculated to summarize participants' sociodemographic and clinical characteristics. Internal consistency reliability will be evaluated using Cronbach's alpha coefficient. Test-retest reliability will be examined by re-administering the Turkish IMBPIQ to 30 participants after a two-week interval, and agreement between the two assessments will be analyzed using the intraclass correlation coefficient. Construct validity will be assessed using Pearson or Spearman correlation analyses between the IMBPIQ scores and the scores obtained from the Disabilities of the Arm, Shoulder and Hand questionnaire and the Short Form-36. The statistical significance level will be accepted as p < 0.05.

Inclusion Criteria:

• Being 18 years of age or older.
• Having a diagnosis of brachial plexus birth palsy.
• Having the ability to read, write, speak, and understand Turkish.
• Agreeing to participate voluntarily in the study and signing the informed consent form.

Exclusion Criteria:

• Having a neurological disease.
• Having another orthopedic problem or a history of trauma in the affected upper extremity.
• Having a severe cognitive or communication impairment that may prevent completion of the questionnaires or understanding of the study instructions.
• Having a history of systemic disease requiring an acute attack or hospitalization within the last three months.
• Being pregnant or being in the postpartum period of less than 6 months.

The study population will consist of adults aged 18 years and older with a diagnosis of brachial plexus birth palsy who are able to read, write, speak, and understand Turkish. Participants will be recruited on a voluntary basis from individuals with brachial plexus birth palsy who meet the eligibility criteria. Both female and male participants will be included.

Individual participant data will not be shared in order to protect participant privacy, confidentiality, and ethical data protection principles.