The term trismus was originally only used for describing the
incapacity of patients with tetanus to open their mouths. Currently, it has been
widely used to describe any type of restriction in mouth opening after trauma,
muscle diseases, or neoplasms, triggered by a primary lesion resulting from
surgical procedures or radiotherapy1,2. The diagnosis
of trismus should be based on objective criteria. The measurement of the mouth
opening with a millimeter ruler between the upper and lower central incisors at
the maximum opening is the most frequently used measurement.
Adults with measurements of < 35 mm are considered as having trismus by most
authors1,3-8. The subjective diagnosis based on the clinical complaint of
patients, such as difficulty in mouth opening, mouth locking, and muscle
stiffness, should be considered but is less reliable from the scientific point
The impact of limited mouth opening on quality-of-life is considered relevant.
However, subjective information loses value when this symptom is analyzed in the
general context of treatment outcomes. According to Vartanian et al.11, the subjective concept of
quality-of-life should be transformed into a quantitative measure so that it can
be used both clinically and in research. To this end, questionnaires for
assessing quality-of-life are widely used, and the greater the dissemination and
administration of standardized questionnaires, the greater their validity in
terms of scientific evidence.
Vartanian et al.11 also observed that most
of the instruments developed were primarily in English, which may hinder their
international use. Simply translating the questionnaire to the language of
another country does not ensure that it can be used in that country. For this, a
more complex validation process is required. Only after validation can the
questionnaire be administered like the original. Several research groups in
Brazil have already validated the Portuguese versions of quality-of-life
questionnaires to apply them with scientific validation12,13.
Until recently, quality-of-life questionnaires generally only addressed
Johnson et al.14 proposed a
quality-of-life questionnaire specific for the assessment of trismus, called
Gothenburg Trismus Questionnaire (GTQ), that was developed by
the Department of Otorhinolaryngology and Head and Neck Surgery, Sahlgrenska
Academy, University of Gothenburg, Sweden, with only its English version
validated. Currently, the GTQ is the only questionnaire specific for trismus
(Figure 1). It is filled out by the
patient and composed of 21 questions divided into 7 domains:
Figure 1 - Letter of acceptance.
Figure 1 - Letter of acceptance.
I. Joint Problems
II. Food Problems
III. Muscular Tension
IV. Facial Pain
V. Impact of Pain
VI. Mandibular Limitation
VII. Impact of Mandibular Limitation
This study aimed to present and validate the Portuguese version of the GTQ to
allow its effective use in Brazilian-speaking populations.
The process of validation of the Portuguese version of the GTQ began in January
2014, with a request for authorization from the authors of the original
questionnaire, and was completed in July 2015, with its application beginning in
September 2014 until July 2015 as part of the validation process.
With the authorization to use and translate the instrument, the validation
process was initiated in accordance with the validation procedure proposed by
Guillemin et al.15-17.
The validation process was performed in four steps as follows: translation,
retranslation, cultural adaptation, and revalidation:
1. Translation: performed by two native Brazilian translators in Brazil,
where the instrument will be used, with the first version being
completed after consensus meetings between the translators and the
2. Back translation: translation of the preliminary Portuguese version into
the source language of the questionnaire. This step was performed by two
translators who had no prior knowledge of the original instrument. This
version in English was analyzed in consensus meetings and sent to the
original authors of the questionnaire for their analysis. To proceed
with the process, the authors of the original questionnaire needed to
formally agree with the back translation.
3. Cultural adaptation: administration of a preliminary version of the GTQ,
with analysis of semantic equivalence (meaning of words, correct use of
vocabulary, and grammar), idiomatic equivalence (use of colloquialism),
and conceptual equivalence (adequacy of questions to the environment or
the local situation).
4. Revalidation: evaluation of the psychometric characteristics of the
instrument regarding reliability (reproducibility and internal
consistency), validity (comparison of results with other studies), and
responsiveness of the questionnaire. Johnson et al. also considered cost
characteristics, minimum filling time (approximately 15 min),
comprehension (to be self-explanatory), and possibilities of
After completing the 4 steps, the translated and validated GTQ
into Portuguese (Figure 2) was administered
to a population sample of 30 individuals without oral disorders to assess its
In each domain, the participants answered the questions, marking the most
convenient answers qualitatively (e.g., answering the question on mandibular
fatigue with “not at all,” “mild,” “moderate,” “severe,” and “very severe”) and
assigning scores to the questions so that a higher score meant worse
quality-of-life regarding trismus.
For analysis of reproducibility, the internal consistency was assessed using
Cronbach’s alpha coefficient, and the reproducibility of the test-retest was
assessed using the intraclass correlation coefficient. For the assessment of
construct validity, the Pearson and Spearman correlation tests were used for
continuous and categorical variables, respectively18.
The GTQ was successfully translated and was validated and approved by the
original authors (Figure 1).
The administration of the GTQ questionnaire took an average of 15 minutes in the
selected sample of patients. As this is a sample of asymptomatic cases, the
scores showed no trismus.
Trismus causes damage to usual activities such as eating, swallowing, talking,
and performing oral hygiene, causing great discomfort to patients. It can be
measured both objectively and subjectively, and the subjective measurement of
quality-of-life is important to evaluate new treatment technologies.
The use of quality-of-life questionnaires enables the evaluation of the success
of a given treatment, especially in patients with chronic diseases. Its
translation plays an important role in promoting health knowledge to populations
in different countries.
The administration of an assessment instrument validated in another language
should allow comparison between different populations, countries, or cultures.
Simply translating them does not ensure reliable results because it does not
provide sufficient parameters to evaluate whether the results between two
samples actually differ or whether they are different owing to translation
Thus, all the steps proposed in the methodology here described, including back
translation, must be followed.
The Portuguese version of the GTQ is a valid and reliable instrument for the
evaluation of patients with limited mouth opening.
Conception and design study, final manuscript approval, project
administration, validation, writing - review & editing.
Final manuscript approval, writing - original draft preparation,
writing - review & editing.
Analysis and/or data interpretation, conception and design study,
data curation, investigation, realization of operations and/ or
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Original Gothenburg Trismus Questionnaire (GTQ).
Translated Gothenburg Trismus Questionnaire (GTQ).
1 . Hospital das Clínicas, Faculdade de Medicina da
USP, São Paulo, SP, Brazil.
2. AC Camargo Cancer Center, São Paulo, SP,
3. HOSPITAL MUNICIPAL INFANTIL MENINO JESUS, SÃO
PAULO, SP, BRAZIL.
Corresponding author: Dov Goldenberg, Rua Arminda
93 cj. 121, São Paulo, SP, Brazil, Zip Code 04545-100. E-mail:
Article received: May 13, 2019.
Article accepted: June 11, 2019.
Conflicts of interest: none.